Airway Management in Adults after Cervical Spine Trauma · facilitate airway management, although there is considerable, favorable experience with the direct laryngoscope in cervical

� REVIEW ARTICLE

David C. Warltier, M.D., Ph.D., Editor

Anesthesiology 2006; 104:1293–318 © 2006 American Society of Anesthesiologists, Inc. Lippincott Williams & Wilkins, Inc.

Airway Management in Adults after Cervical Spine TraumaEdward T. Crosby, M.D., F.R.C.P.C.*

This article has been selected for the AnesthesiologyCME Program. After reading the article, go to http://www.asahq.org/journal-cme to take the test and apply forCategory 1 credit. Complete instructions may be found inthe CME section at the back of this issue.

Cervical spinal injury occurs in 2% of victims of blunt trau-ma; the incidence is increased if the Glasgow Coma Scale scoreis less than 8 or if there is a focal neurologic deficit. Immobili-zation of the spine after trauma is advocated as a standard ofcare. A three-view x-ray series supplemented with computedtomography imaging is an effective imaging strategy to rule outcervical spinal injury. Secondary neurologic injury occurs in2–10% of patients after cervical spinal injury; it seems to be aninevitable consequence of the primary injury in a subpopula-tion of patients. All airway interventions cause spinal move-ment; immobilization may have a modest effect in limitingspinal movement during airway maneuvers. Many anesthesiol-ogists state a preference for the fiberoptic bronchoscope tofacilitate airway management, although there is considerable,favorable experience with the direct laryngoscope in cervicalspinal injury patients. There are no outcome data that wouldsupport a recommendation for a particular practice option forairway management; a number of options seem appropriateand acceptable.

THE provision of acute medical care to patients withcervical spinal injuries (CSIs) is a complex, challenging,and rewarding task. It is also an anxiety-provoking en-deavor because care is provided in a milieu where thereis constant concern about medical interventions result-ing in the conversion of a spinal injury without neuro-logic sequelae to one in which the two are now concur-rent. It is also a topic of continuous debate because careproviders struggle in an environment of limited data andincomplete answers to try to craft clinical care para-digms designed to optimize preservation and return ofneurologic function, while minimizing the risk of creat-ing additional injury and neurologic compromise. Manyquestions regarding the initial care of these patients,particularly as they relate to airway management, remain

unresolved, but there has been great effort, energy, andenthusiasm expended during the past two decadessearching for these answers. This article reviews theliterature that has been generated on the topic of airwaymanagement after CSI, particularly that published in thepast 10 yr, identifying new areas of knowledge andevolving practice patterns. It also attempts to addressand resolve controversy surrounding areas of care thathave proven more contentious, most particularly the useof the direct laryngoscope to facilitate direct trachealintubation in these patients.

The Adult Cervical Spine: Stability, Injury,and Instability

Movement and Stability of the Upper Cervical SpineFlexion–extension occurs in the upper cervical spine

at both the atlanto-occipital and atlantoaxial articula-tions, and a combined 24° of motion may be achieved.1

Flexion is limited by contact between the odontoid pro-cess and the anterior border of the foramen magnum atthe atlanto-occipital articulation and by the tectorialmembrane and posterior elements at the Cl–C2 level.Extension is limited by the contact of the posterior archof the atlas with the occiput superiorly and with the archof the axis inferiorly. The distance from the posteriorarch of the atlas to the occiput is termed the atlanto-occipital gap, and a narrow atlanto-occipital gap hasbeen cited as being a cause of difficult intubation.2 Ni-chol and Zuck2 suggested that attempts to extend thehead in patients with a narrow atlanto-occipital gapresults in anterior bowing of the cervical spine, forwarddisplacement of the larynx, and a poor view duringlaryngoscopy. This concept, although offering an elegantanatomical explanation for the clinical experience ofdifficult laryngoscopy, has yet to be validated, and thetruth may be simpler. Calder et al.3 have reported thatlimited separation of the occiput from the atlas and theatlas from the axis yields an immobile upper spine andreduces both cervical spine extension and mouth open-ing, resulting in difficult direct laryngoscopy.

The ligaments contributing to the stability of the uppercomplex are the transverse, apical, and alar ligamentsas well as the superior terminations of the anterior andposterior longitudinal ligaments (fig. 1). In adults, thetransverse ligament normally allows no more than 3mm of anteroposterior translation between the dens and

* Professor.

Received from the Department of Anesthesiology, University of Ottawa, Ot-tawa, Ontario, Canada. Submitted for publication March 10, 2005. Accepted forpublication October 24, 2005. Support was provided solely from institutionaland/or departmental sources.

Address correspondence to Dr. Crosby: Department of Anesthesiology, TheOttawa Hospital–General Campus, Room 2600, 501 Smyth Road, Ottawa, On-tario, Canada, K1H 8L6. [email protected]. Individual article reprints may bepurchased through the Journal Web site, www.anesthesiology.org.

Anesthesiology, V 104, No 6, Jun 2006 1293

the anterior arch of the atlas. This may be measured onlateral radiographs of the neck and is termed the atlas–dens interval. If the transverse ligament alone is dis-rupted and the alar and apical ligaments remain intact,up to 5 mm of movement may be seen. If all the liga-ments have been disrupted, 10 mm or more of displace-ment may be seen. Destruction of these ligaments is acommon consequence of severe and long-standing rheu-matoid arthritis.4

Significant posterior displacement of the dens reducesthe space available for the spinal cord (SAC) in thevertebral column. The SAC is defined as the diameter ofthe spinal canal measured in the anteroposterior plane,at the Cl level, that is not occupied by the odontoidprocess. The SAC represents the area composed of bothcord and space. The area of the spinal canal at Cl may bedivided into one third odontoid, one third cord, and onethird “space.” The one third space allows for some en-croachment of the spinal lumen without cord compro-mise. However, when this margin of safety has beenexhausted, compression of neural elements will occur;persistent compression will eventually lead to myelopa-thy and neurologic deficit. The cord occupies a greaterproportion of the available SAC in the subaxial spine; atthe C6 level, approximately 75% of the SAC is occupiedby the cord.5

Movement and Stability of the Lower CervicalSpineA further 66° of flexion–extension may be achieved in

the lower cervical spine, with the C5–C7 segments con-tributing the largest component. There is an inverserelation between age and range of motion, i.e., as ageincreases, mobility decreases. However, most of the de-crease occurs at the C5–C7 motion segments, and thisusually does not have a significant impact on the ease ofdirect laryngoscopy. With the head in the standard sniff-ing position, the cervical spine below C5 is relativelystraight; there is increasing flexion from C4 to C2, andthe occipitoatlantoaxial complex is at or near full exten-sion.

In the lower cervical spine, the structures contributing

to stability include, from anterior to posterior, the ante-rior longitudinal ligament, the intervertebral discs, theposterior longitudinal ligament, the facet joints withtheir capsular ligaments and the intertransverse liga-ments, the interspinous ligament, and the supraspi-nous ligaments (fig. 2). The posterior longitudinal lig-ament and the structures anterior to it are grouped asthe anterior elements or anterior column (fig. 3). Theposterior elements or posterior column are thosegrouped behind the posterior ligament. Motion seg-ments are defined as two adjacent vertebrae and theintervening soft tissue elements.

Fig. 1. Ligaments of the atlantoaxial joint. View is from above,with the skull removed.

Fig. 2. The ligaments of the lower cervical spine, sagittal section.

Fig. 3. Schematic representation of the two column concept ofthe spine. From White AA III, Panjabi MM: Clinical biomechan-ics of the spine. Philadelphia, JB Lippincott, 1978; used withpermission.

1294 EDWARD T. CROSBY

Anesthesiology, V 104, No 6, Jun 2006

Cervical Spinal Instability after Injury: Mechanismsand ConsequencesWhite et al.6 have defined stability as “the ability of the

spine to limit its pattern of displacement under physio-logic loads so as not to allow damage or irritation of thespinal cord or nerve roots.” Instability occurs whenphysiologic loading causes patterns of vertebral displace-ment that jeopardize the spinal cord or nerve roots.7

Instability may result from congenital anomalies, ac-quired conditions related to chronic disease, and acutelyafter trauma. The following discussion will primarilyrelate to traumatic instability.

One element in the injured column must be preservedto achieve spinal stability. Clinically, to ensure a marginof safety, preservation of elements in the injured columncannot be assumed, and the spine must be considered tobe potentially unstable until proven otherwise. The an-terior column contributes more to the stability of thespine in extension, and the posterior column exerts itsmajor forces in flexion. Therefore, the anterior elementstend to be disrupted in hyperextension injuries, and theposterior elements tend to be disrupted in hyperflexioninjuries. With extreme flexion or extension or if either acompressive or rotational force is added, both columnsmay be disrupted.

Flexion injuries usually cause compression of the an-terior column and distraction of the posterior column(fig. 4).5 Pure flexion trauma may result in wedge frac-ture of the vertebral body without ligamentous injuries.These injuries are stable and are rarely associated withneurologic injuries. With more extreme trauma, ele-ments of the posterior column are disrupted as well, andfacet joint dislocation may result. These injuries are un-stable and are associated with a high incidence of corddamage. Flexion–rotation injuries also commonly dis-rupt the posterior ligamentous complex and may alsoproduce facet joint dislocation. They tend to be stableand are not usually associated with spinal cord injury,although cervical root injury is common. Hyperexten-sion injuries cause compression of the posterior column

and distraction of the anterior column (fig. 4). Hyperex-tension combined with compressive forces (e.g., divinginjury) may result in injury to the lateral vertebralmasses, pedicles, and laminae. Because both anterior andposterior columns are disrupted, this injury is unstableand is associated with a high incidence of cord injury.Violent hyperextension, with fracture of the pedicles ofC2 and forward movement of C2 on C3, produces atraumatic spondylolisthesis of the axis, or hangman’sfracture. The fracture is unstable, but the degree ofneurologic compromise is highly variable, because thebilateral pedicular fractures serve to decompress thespinal cord at the site of injury.

Burst fractures are caused by compressive loading ofthe vertex of the skull in the neutral position and are notas common as flexion–extension injuries. Compressionforces in the lower cervical spine result in the explosionof intervertebral disc material into the vertebral body.Depending on the magnitude of the compression load-ing and associated angulating forces, the resulting injuryranges from loss of vertebral body height with relativelyintact margins, to complete disruption of the vertebralbody. Posterior displacement (retropulsion) of commi-nuted fragments may result, producing cord injury; thespine is usually stable. Pure distraction injuries areuncommon but, if severe, may result in ligamentousdisruption causing both cord trauma and an unstablespine.

Determining Stability of the Cervical Spine afterInjuryBecause spinal instability usually results in vertebral

displacement, it may be detected in many instances byradiography. White and Panjabi8 identified the upperlimit of vertebral displacement and that which is beyondthe physiologic range. They concluded that a normaladult spine would not permit horizontal motion greaterthan 2.7 mm between vertebrae. Therefore, if horizontaldisplacement exceeding 3.5 mm (corrected for x-raymagnification) or 20% of the vertebral body width was

Fig. 4. Injuring force mechanisms and re-sulting lesions. In A, a compression hy-perextension force has resulted in dis-traction of the elements of the anteriorcolumn and compression of posteriorcolumn elements; an avulsion fracturefrom the anterior-inferior margin of thevertebral body (small arrow 2) and afracture of the articular process (smallarrow 1) have resulted. In B, a flexion(large arrow 2), compression (large ar-row 1) force has produced a wedge frac-ture of the vertebral body (small arrow2) and an incomplete disruption of theinterspinous and supraspinous liga-ments (small arrow 1).

1295AIRWAY MANAGEMENT AFTER CERVICAL SPINE INJURY


found on lateral radiographs of the neck (or with flex-ion–extension views or dynamic fluoroscopy), this mo-tion was deemed abnormal and the spine was consid-ered unstable. With respect to angular displacement, theupper limit of physiologic angular displacement of avertebral body compared with adjacent vertebrae was11°. If there is greater angulation of the vertebra inquestion demonstrated on imaging studies, the spine isdeemed unstable at the site of the excessively rotatedvertebra.

The ligamentous structures, intervertebral discs, andosseous articulations have been extensively studied, andtheir major role in determining clinical stability has beendemonstrated.7 Although the muscles in the neck exertsome stabilizing forces, the contribution that they maketoward clinical stability has not been studied. The re-peated observation that secondary neurologic injuriesoccur frequently in spine-injured patients who are notimmobilized suggests that muscle splinting is not highlyprotective after injury.9,10

Not all cervical spine injuries result in clinical instabil-ity. Generally, fractures are considered to be clinicallyinsignificant if failing to identify them would be unlikelyto result in harm to the patient or, alternatively, recog-nizing the injury would prompt no specific treatment.Two groups have categorized, by expert consensus, anumber of injuries as not clinically important.11,12 TheNational Emergency X-Radiography Utilization Study(NEXUS) group identified the following injuries as notclinically significant: spinous process fractures, wedgecompression fractures with loss of 25% or less of bodyheight, isolated avulsion fractures without ligament in-jury, type 1 odontoid fractures, end-plate fractures, iso-lated osteophyte fractures, trabecular fractures, and iso-lated transverse process fractures.11 Similarly, theCanadian CT Head and Cervical Spine Study group iden-tified the following injuries as not significant: simpleosteophyte fractures, transverse process fractures, spi-nous process fractures, and compression fractures withloss of less than 25% of body height.12

Mechanisms of Spinal Cord InjuryThere are a number of mechanisms implicated in pri-

mary spinal cord injuries. Immediate neural damage mayresult from shear, compressive, ballistic, or distractingforces, which primarily avulse and devitalize tissues.Persistent cord compression from fracture–dislocationmay lead to ischemia. The cord may be injured by bonefragment or missile injury with resultant laceration, con-tusion or concussion.13 Secondary and progressive in-jury may also result from local perfusion deficits due tovascular compression by deranged anatomy (e.g., tissuedamage or edema) or from global perfusion compromisecaused by systemic hypotension. In addition, tissue hy-poxemia leading to secondary injury may also occur as aresult of hypoventilation caused by head or cord injury

or by primary lung trauma. Finally, there are multiplemechanisms at the cellular and subcellular level that mayresult in exacerbation of the injury resulting in an exten-sion of the clinical deficit.14

The impact of persistent cord compression and thebenefits of urgent decompression of injured cord havebeen assessed by a number of authors. Carlson et al.15

determined the relation between the duration of sus-tained spinal cord compression and the extent of spinalcord injury and the capacity for functional recovery afterimmediate decompression. Sixteen dogs underwent spi-nal cord compression for 30 or 180 min. Sustained cordcompression was associated with a gradual decline inthe amplitude of evoked potentials. Within 1 h of de-compression, dogs that had experienced 30 min of com-pression had recovery of the evoked potentials, but noanimal that had been subjected to 180 min of compres-sion had similar recovery. Motor tests demonstratedrapid recovery of hind-limb function in the 30-mingroup, but there was considerable impairment in the180-min group, and this impairment was persistent. In asimilar model, Delamarter et al.16 demonstrated thatneurologic recovery after 1 h of cord compression oc-curred after immediate decompression but not whencord compression persisted for 6 h or more.

Despite the basic science support for early decompres-sion after spinal cord injury, two recent reviews haveconcluded that the evidence supports decompression asa practice option only.17,18 The authors of these reviewsconcluded that the data assessing the impact of earlydecompression on neurologic outcomes was limited,consisted of primarily class III (case series, retrospectivereviews, and opinion) and limited class II (prospectivecohort studies or controlled studies with comparisoncohorts) evidence, and demonstrated a possible benefitto patients with incomplete injury only. Both early de-compression and conservative management were asso-ciated with neurologic improvement in some patientsand deterioration in others. Both groups of authors ac-knowledged the need for randomized, controlled trialsto better delineate the role of surgery in the managementof acute spinal cord injury.17,18

Biomechanics of the Spinal Cord and CanalFor proper functioning of the spinal cord, a minimum

canal lumen is required, both at rest and during move-ment. Cord compromise will result if the canal space isless than that required for cord function; neurologicinjury will occur if this reduction in canal space is per-sistent. The neurologic injury results from sustained me-chanical pressure on the cord leading to both anatomicaldeformation and ischemia. A reduction in canal size isoften seen with age-related changes in spinal anatomysuch as disc degeneration, osteophyte formation, hyper-trophy of the ligaments of the spinal column, and thevertebral subluxations common in the chronic arthriti-



des. Canal size may also be reduced acutely with trau-matic injury to the spinal column. Although neurologicdeficits do not directly correlate with the degree ofposttraumatic reduction of the spinal canal, canal im-pingement is more commonly observed in patients withboth spinal injury and neurologic deficit than in patientswho do not have a deficit after spinal injury.19

The functional size of the spinal canal may be furtherreduced with movement. The spinal canal is a column ofrelatively fixed volume.20 As it lengthens, its cross-sec-tional area will be reduced, and as it is shortened, its areawill be increased; this behavior is termed the Poissoneffect. With flexion, the canal length is increased and itsarea is reduced; the cord is stretched. This occurs be-cause the axis of rotation of the spine is centered in thevertebral body.21 As the spine flexes, the rotation pointswill transcribe an arc; posterior spinal elements, includ-ing the canal, will also transcribe an arc, but that of alarger circle and will axially lengthen (fig. 5).22 ThePoisson effect dictates that both the lumen of the canaland the spinal cord will narrow as they lengthen. Thecord will tolerate a degree of elastic deformation whilemaintaining normal neurologic function.20 It may befurther stretched and deformed if there is a local anom-aly such as an osteophyte, prolapsed disc, or subluxedvertebral body projecting into the canal. These deforma-tions may, over time, result in the application of strainand shear forces to the cord and ultimately result inaxonal injury and myelopathy.23

With extension, the canal length is decreased and itsarea is increased; the cord is shortened. Again, this is aneffect of the axis of rotation being centered in the ver-tebral bodies and the posterior spinal elements includingthe canal now transcribing the arc of a smaller circle; thePoisson effect will dictate canal widening. However, theshortening and folding of the cord when the spine is inextension may result in a relative increase in the ratio ofcord size to canal lumen, despite the potential increasein the lumen. As well, there is posterior protrusion of thedisc annulus and buckling of the ligamentum flavum inextension, which may further reduce canal dimensionsand the space available for the cord at any given verte-

bral level. A number of age-related pathologic processes,including osteophyte formation and ossification of theposterior longitudinal ligament, may lead to further im-pingement on the canal lumen; these typically manifesta greater impact during spinal extension.

Ching et al.24 measured the impact of different posi-tioning on canal occlusion in a cervical spine burstfracture model. Extension increased the canal occlusionto levels normally associated with the onset of neuro-logic injury. Flexion did not result in a significant in-crease in canal occlusion. These observations run coun-terintuitive to what might be expected on the basis ofthe Poisson effect and are likely manifestations of boththe soft tissue buckling and bone fragment retropulsionwhich occur during extension. Prone positioning is alsooften associated with modest degrees of extension, andthere is evidence that canal stenosis is increased withpatients with cervical myelopathy who are positionedprone compared with supine positioning.25 Again, this islikely a manifestation of the soft tissue encroachment onthe spinal canal with extension and aggravated by thepreexistent canal compromise. The clinical relevance ofthese findings is that a persistent malposition of an ab-normal neck may result in a degree of cord compression.If the abnormality is modest, it is likely that the malpo-sition will need to be of greater magnitude and moreprolonged to cause harm; as the anatomical derange-ment is increased, the duration of positional stress re-quired to cause harm is shortened.15,26 Prone position-ing is also associated with increases in vena cavalpressures that may further reduce cord blood flow al-ready compromised by cord compression.27

Dominguez et al.28 reported the occurrence of irre-versible tetraplegia in a 21-yr-old woman without cervi-cal pathology whose neck was maintained in extremeflexion after tracheal reconstruction; a magnetic reso-nance imaging (MRI) study was consistent with cordinfarction. Deem et al.29 reported the occurrence ofquadriparesis in a 60-yr-old man with severe cervicalstenosis after thoracolumbar surgery in the prone posi-tion. The patient’s trachea was intubated, and he waspositioned prone while still awake; anesthesia was in-

Fig. 5. The Poisson effect: schematic rep-resentation. The axis of rotation is indi-cated by the small squares superimposedon the vertebral bodies. In the neutralposition (A), the gentle arc of the normallordotic curve is transcribed. In exten-sion (B), the elements posterior to thebodies, including the canal, transcribethe arc of a smaller circle than that of thevertebral bodies, indicated by the smallcircles. In flexion (C), the opposite effectis seen, and the arc of a larger circle istranscribed by the posterior elements.The Poisson effect dictates that as thelength increases (the arc is of a largercircle), the cross-sectional area (lumen)of the column will decrease.



duced after his cervical spinal positioning was ascer-tained to be near neutral, and neurologic examinationresults were deemed normal. When he awoke from an-esthesia after 6 h of surgery, there was evidence of acentral cord syndrome. The authors acknowledge thepossibility that, even though extreme degrees of flexionand extension were avoided, more subtle degrees ofmalpositioning may have been present. Unfortunately,cord injury may occur when positions detrimental tocanal architecture are persistent; the greater the degreeof underlying spinal pathology is, the lesser the magni-tude of malpositioning required to cause harm is. Theprone position may be especially threatening in theseinstances for the reasons already outlined.

Patients with severe cervical spondylosis may manifestsuch severe positional intolerance that they developsymptoms of cord compromise with degrees of malpo-sition that may be imperceptible to the caregivers. Milleret al.30 described exacerbation of neurologic symptomsin a 74-yr-old women with an osseous bar at C3–C4 whopresented with signs of cord compression and wasbooked for cervical laminectomy. On the first surgicaloccasion, after awake tracheal intubation accomplishedwith sedation, she was considerably weaker than beforeintubation. Surgery was cancelled, and her trachea wasextubated; her neurologic condition returned to baselinewithin 2 h. Four days later, she presented for surgery inhalo traction, and after sedation with intravenous diaze-pam, her neurologic condition deteriorated. A joint de-cision was made to induce anesthesia and proceed withtracheal intubation and surgical laminectomy at theC3–C5 spinal levels. Although she awoke with signs ofneurologic deterioration, she recovered to her baselinecondition by the fourth hour. The authors of this reportpostulated that the increased neurologic symptoms werean effect of the medications administered to facilitateawake intubation. Whether the drugs actually causeddeterioration in the patient’s neurologic status or madethe neurologic assessment less reliable is not certain.Equally unknown is whether, in general, patients mightbe more likely to overlook or underreport neurologicchanges that occur if they were sedated during awakeintubation. The reliability of a neurologic assessment ina sedated patient might be questioned, especially if oneis seeking evidence of subtle changes.

Bejjani et al.31 reported the case of a 54-yr-old womanwith cervical spondylosis and canal stenosis from C4 toC7 who developed signs of cord compression while herhead was restrained in a plastic head-holder for thepurpose of cerebral angiography. Approximately 45 minafter the procedure had begun, she reported neck painand upper extremity weakness; her symptoms were at-tributed to anxiety, and she was sedated. At the termi-nation of the procedure, she was hemiparetic on the leftside; an MRI study revealed a high-signal lesion consis-tent with edema. She recovered completely over the

next 6 weeks. The potential for general anesthesia topermit positioning for MRI in postures not tolerated byawake patients with resultant neurologic injury has alsobeen reported.32

Magnaes33 measured cerebral spinal fluid pressurewith the neck in the extended position for trachealintubation, in eight patients with a compromised spinalcanal due to cervical spondylosis. Pressures up to ap-proximately 140 cm H2O were recorded. Longitudinalskeletal traction with the tong placed frontally signifi-cantly reduced the pressure on the spinal cord in allpatients. This finding would suggest that there is likely abenefit, in terms of decreased intracanal pressures, inmaintaining the compromised cervical spine in as closeto the neutral position as possible at all times after injury.As has already been noted, it may be very difficult todetermine neutral position in some patients.

Persistent severe malpositioning at the extremes of thespinal range of motion has the potential to cause harmeven in the normal spine–cord complex. In patientswith disease processes that result in spinal canal com-promise, minor degrees of malpositioning may also re-sult in severe stress to the cord. If these positions areenforced, especially for prolonged periods, neurologicinjury may result. As well, the use of sedation or anes-thesia to allow patients to be maintained in positions thatare neurologically intolerable to them while awake mayalso result in neurologic injury.

Cervical Spine Trauma: Epidemiology andClinical Characteristics

The Incidence of Cervical Spinal Injury after BluntTraumaThe incidence of CSI in victims of blunt trauma is

estimated to be 0.9–3%, with a weighted average of1.8%.34 Many of these previously published studies eval-uating CSI after blunt trauma involved data from individ-ual institutions or limited populations of trauma victims;there have been few data available regarding injury pat-terns at a national level. A substudy of NEXUS wasdesigned to provide such data regarding the prevalence,spectrum, and distribution of CSI after blunt trauma.35 Atotal of 34,069 patients with blunt trauma undergoingcervical spine radiography at 21 US institutions wereenrolled. Consistent with past reports, 818 (2.4%) oftrauma victims had a total of 1,496 distinct CSIs. Thesecond cervical vertebra (C2) was the most commonlevel of injury (24.0% of all fractures), and 39.3% offractures occurred in the two lowest cervical vertebrae(C6, C7). The vertebral body was the most frequentanatomical site of fracture; nearly one third of all injuries(29.3%) were considered clinically insignificant.



Cervical Spine Injury and AssociatedCraniocerebral TraumaAlthough it has been reported that patients with

craniocerebral trauma had an incidence of CSI similar tothat of the general trauma population, review of thelarge databases evolving at major trauma centers nowdispute this finding. Holly et al. 36 reviewed 447 consec-utive, moderately to severely head-injured patients pre-senting to two level l trauma centers. Twenty-four pa-tients (5.4%) had a CSI; patients with an initial GlasgowComa Scale (GCS) score less than 8 were more likely tosustain both a CSI and a cord injury than those withhigher scores. Demetriades et al.37 conducted a similarreview of all CSI patients admitted over a 5-yr period ata major trauma center. During the study period, therewere 14,755 admissions and 292 patients with CSI, foran overall incidence of 2.0%. Again, the incidence of CSIvaried with the GCS score, being 1.4% if the GCS scorewas 13–15, 6.8% when it was 9–12, and 10.2% when itwas less than 8. Hackl et al.38 used a large computerizeddatabase to assess the association between CSI and facialinjuries in 3,083 patients with facial injuries. Two hun-dred six (6.7%) of these patients had experienced aconcomitant CSI, an incidence substantially higher thanwould be expected after blunt trauma. Blackmore etal.39 reviewed their institutional experience with 472patients with trauma (168 with cervical fractures, 302without fractures) to delineate the clinical characteris-tics of trauma patients with cervical fracture. The clinicalpredictors of cervical spine injury included severe headinjury (odds ratio, 8.5; 95% confidence interval [CI],4–17) and focal neurologic deficit (odds ratio, 58; 95%CI, 12–283). In patients with head injury, those whowere persistently unconscious had an even higher like-lihood of spinal injury (odds ratio, 14; 95% CI, 6–35)than those with head injury who were not unconscious.Therefore, new evidence has emerged that consistentlysuggests a higher incidence of cervical injury in patientswho have experienced craniocerebral trauma, especiallyamong those with increasing severity of craniocerebralinjury as determined by low GCS score and unconscious-ness. The finding of a focal neurologic deficit has beenidentified as a highly important clinical finding predict-ing spinal injury.39

Systemic Injuries Associated with Cervical SpineInjuryThe majority of patients with CSI also have other

injuries; in only 20% of instances are traumatic injuriesrestricted to the cervical spine.40 Although 2–10% ofpatients with craniocerebral trauma have CSI, 25–50% ofpatients with CSI have an associated head injury. Patientswith additional injuries are more likely to experiencehypoxia and hypotension, both of which may not onlyprompt urgent airway intervention, but may also predis-pose to secondary neurologic injury. There is data to

suggest reduced neurologic recovery and increased mor-tality in cord-injured patients who have concurrent in-jury. It is not clear whether these patients experiencedmore severe primary injury or whether they are morelikely to experience secondary injury leading to thepoorer outcome.

Defining the Low-risk Trauma PatientThe National Emergency X-Radiography Utiliza-

tion Study. The majority of patients who have experi-enced a blunt traumatic injury do not have a CSI. Enor-mous resources are currently expended to clear thespine (determine the absence of injury when injury doesnot exist) in these patients. The NEXUS project at-tempted to derive a set of clinical criteria to identifyblunt trauma victims at low risk for CSI.41 The decisioninstrument required patients to meet five criteria to beclassified as having a low probability of injury: (1) nomidline cervical tenderness; (2) no focal neurologic def-icit; (3) normal alertness; (4) no intoxication; and (5) nopainful, distracting injury. Distracting injuries were de-fined as including long bone fractures; visceral injuriesrequiring surgical consultation; large lacerations; burns;degloving or crush injuries; or any injury that mightimpair the patient’s ability to participate in a generalphysical, mental, or neurologic examination. The deci-sion instrument was applied to 34,069 patients and iden-tified as high risk all but 8 of the 818 patients who hada CSI (sensitivity, 99%; 95% CI, 98–99.6%). The negativepredictive value was 99.8% (95% CI, 99.6 –100%),the specificity was 12.9%, and the positive predictivevalue was 2.7%. Only two of the eight patients missedby the screening protocol had a clinically significantinjury. In the NEXUS study, plain radiographs alonerevealed 932 injuries in 498 patients but missed 564injuries in 320 patients.42 The majority of missed in-juries (436 injuries in 237 patients) occurred in casesin which plain radiographs were interpreted as abnor-mal (but not diagnostic of injury) or inadequate. How-ever, 23 patients had 35 injuries (including three po-tentially unstable injuries) that were not visualized onadequate plain film imaging. In the absence of all fiveclinical risk factors identified by the NEXUS study aspredicting an increased risk of CSI, the likelihood of asignificant injury is low. The practice of withholdingimaging for patients who meet these exclusionarycriteria has been endorsed by recent neurosurgicalguidelines.43

The Canadian C-Spine Rule for Radiography afterTrauma. The Canadian CT Head and Cervical SpineStudy Group attempted to derive an optimally sensitiveclinical decision rule to allow for selectivity in the use ofradiography in alert and stable trauma patients.12 A pro-spective cohort study was conducted in 10 large Cana-dian hospitals and included 8,924 consecutive adult pa-tients presenting to emergency departments after



sustaining acute blunt trauma to the head or neck. Pa-tients were eligible for enrollment if they were alert(GCS of 15), if they had stable vitals signs, and if they hadeither neck pain after injury or had no neck pain butvisible injury above the clavicles after a dangerous mech-anism of injury. The patients were assessed using 20standardized clinical findings from the history, generalphysical examination, and an assessment of neurologicstatus. Patients then underwent diagnostic imaging atthe discretion of the treating physician; this imagingconsisted of a minimum of three views of the cervicalspine.

Among the study sample, 151 patients (1.7%) had animportant cervical injury. The resultant rule that wasderived comprises three questions: (1) Is there any high-risk factor present that mandates radiography? (2) Arethere low-risk factors that would allow a safe assessmentof a range of motion? and (3) Is the patient able toactively rotate the neck 45° to the left and to the right?When applied to the study population, the derived rulehad 100% sensitivity and 42.5% specificity for identifyingpatients with clinically important injuries. The rule alsoidentified 27 of 28 patients with clinically unimportantcervical injuries (primarily avulsion fractures), defined asthose not requiring stabilization or follow-up.

The NEXUS Low-Risk Criteria were compared prospec-tively with the Canadian C-Spine Rule in 8,283 patientspresenting to Canadian hospital emergency departmentsafter trauma.44 Two percent of patients had clinicallyimportant cervical injuries, and the C-Spine Rule wasboth more sensitive than the NEXUS criteria (99.4% vs.90.7%) and more specific (45.1% vs. 36.8%) for injury.The C-Spine Rule would have missed one patient, andthe NEXUS criteria would have missed 16 patients withimportant injuries.

Strategies to define a low-risk clinical population con-tinue to evolve. It must be emphasized that the primaryfocus and utility of these strategies is to allow for selec-tive use of diagnostic imaging in patients who have alow-risk of injury, thus reducing imaging use and patientexposure, conserving resources, and allowing for expe-dited and simplified care for this patient group. A criti-cism leveled at the NEXUS protocol is that applicationwould have a limited impact in reducing imaging be-cause only 12.9% of patients presenting after traumawould be deferred; most would not meet at least onedeferral criteria.45 Application of the C-Spine Rule wouldallow for the exclusion of 42.5% of trauma patients fromradiographic imaging. The original rationale for the der-ivation of the protocols, to provide more efficient careand conserve imaging resources, is satisfied to a verylimited degree by the NEXUS protocol but to a greaterdegree by the C-Spine Rule. Application of either proto-col will still demand imaging in a large portion of thetrauma patient population at low risk for CSI.

There will be a small population of patients presenting

for urgent surgical intervention after minor injury whoare fully evaluable using either the NEXUS criteria(12.9%) or the C-Spine Rule (42.5%); it is likely notnecessary to delay surgery to clear the cervical spine ofthese patients with detailed imaging. Unfortunately,many patients presenting for urgent operative interven-tions after trauma will manifest more severe injuries; itwill not be possible to clinically rule out injury in thispatient cohort, and they will still require diagnostic im-aging. As well, application of these protocols is compli-cated by the fact that there is a lack of agreement on thedefinitions of both distracting injury and intoxication.Failure to appreciate the degree of both distraction andintoxication may reduce the clinical index of suspicionfor injury, resulting in missed diagnosis.

Patterns of Practice in Evaluating and Clearing theCervical Spine after TraumaTwo authors have recently reported descriptions of

patterns of practice in the United States and the UnitedKingdom obtained through postal surveys regardingevaluation and clearance of the cervical spine after trau-ma.46,47 Grossmann et al.46 surveyed 165 US traumacenters and reported that between 26 and 73% hadwritten protocols for cervical spine clearance aftertrauma. It was more common for level I and academiccenters to have protocols. In most instances where aprotocol existed, it also described the radiographic ap-proach to clearance; most centers did not consider thateither computerized tomography (CT) or MRI was thestandard of care in this setting. The use of a five-viewseries was moderately prevalent in response to specificscenarios, and the problem of visualizing the cervicotho-racic junction was dealt with in most centers (68%) usingan axillary/swimmer’s radiographic view. For patientswith a head injury who are comatose or who havealtered mental status and who have normal plain films,21% of level II and 10% of level I centers advocatedremoval of the cervical collar without further testingbeyond a five-view series.

Jones et al.47 surveyed 27 United Kingdom neurosur-gical and spine injury units to determine the methods ofcervical spine clearance used in unconscious, adulttrauma patients and the point at which immobilizationwas discontinued. Most centers did not have either awritten protocol to perform clearance or one regardingdiscontinuing cervical immobilization (78%). All unitsrelied to some degree on plain radiography for clear-ance; 10 units (37%) performed only a single lateral viewas the initial evaluation, and the remainder performedtwo more views. Five units routinely used CT imaging,and 17 units (63%) made no use of CT to screen forcervical injury. If the initial investigations were normal,12 units (44%) would discontinue immobilization, and10 units continued it until the patient could be evaluated



clinically irregardless as to the results of the screeningimaging.

The Eastern Association for the Surgery of Traumarecently reported the results of a survey of 31 largeAmerican and Canadian trauma centers.† Centers wereasked to identify their routine practice for determiningcervical spinal stability in obtunded or comatose patients.Twenty-four centers (77%) reported using three views ofthe cervical spine (lateral, odontoid, and antero-posteriorviews) supplemented by CT through suspicious or poorlyvisualized areas. Three centers (9.7%) relied on three viewsonly, and three centers (9.7%) added a swimmer’s view tovisualize the lower cervical spine and the cervicothoracicjunction.

There is considerable variation in the approach thatdifferent centers take in the performance of radiographicevaluation of at-risk patients, making the determinationthat the spine has been cleared, and reaching the deci-sion that immobilizing devices can be safely removed.The most common pattern of practice in North Ameri-can centers is to rely on multiple (at least three views)plain radiographs; the use of supplementary CT is alsocommon.

Radiographic Assessment after Blunt Trauma:Evolving a Best PracticeAn evaluative approach that would provide timely and

accurate assessment of cervical stability in patients whomay not be reliably examined clinically so that immobi-lizing devices can be safely removed is desirable. Thiswould minimize the potential for sequelae related toprolonged immobilization. The reader is referred tothree excellent reviews on the topic of evaluating andclearing the cervical spine in high-risk patients; thesereviews form the basis of the subsequent discus-sion.45,48,49

The cross-table lateral radiograph, of acceptable qual-ity and interpreted by an expert, will disclose the major-ity of injuries. However, the sensitivity of the cross-tableview is such that up to 20% of patients with cervicalinjury will have a normal study. Half of cross-table viewsare deemed inadequate to properly assess the entirecervical anatomy; injuries at both the craniocervical andthe cervicothoracic junctions are often not well visual-ized in the cross-table view. Too many injuries aremissed when only a cross-table view is used for it to beconsidered an acceptable study to rule out injury in ahigh-risk patient. The sensitivity of three views (cervicalseries) approximates 90%; the cervical series was longregarded as an acceptable radiologic evaluation in pa-tients deemed at risk for CSI. Similar technical concerns

apply to the cervical series as to the cross-table lateralview with respect to both anatomical limitations at thecervical junctions and inadequate studies being issues. Itis estimated that 1% of clinically important injuries willbe missed even with a technically adequate cervicalseries.

A three-view cervical series supplemented by CTthrough areas that are either difficult to visualize orsuspicious on plain radiography will detect most spinalinjuries. The negative predictive value of this combina-tion of studies is reported to be 99–100% in several classII and III evidence studies.45,48,49 In the obtunded pa-tient with a normal cervical series and appropriate sup-plemental CT of the cervical spine, the incidence ofsignificant spine injury is less than 1%. High-resolutionCT scanning with sagittal reconstruction of the entirecervical spine rather than directed scanning of only at-risk areas may be even more effective in capturing vir-tually all injuries.

The use of MRI in addition to plain radiography andsupplemental CT has been advocated to perform spinalclearance; the significance of a positive MRI study in thesetting of negative CT imaging is currently unclear be-cause many false-positive findings are reported withMRI. As well, MRI is less sensitive than CT for injuries inthe upper and posterior cervical spine. Shuster et al.50

studied the role of MRI in assessing the spines of patientswith persistent cervical pain and no motor deficits aftertrauma when the CT imaging was negative for injury.Ninety-three patients (3.4%) had a normal admissionmotor examination, a CT result negative for trauma, andpersistent cervical spine pain; they underwent MRI ex-amination. All MRI examinations were negative for clin-ically significant injury, and no patient subsequently ex-perienced a neurologic deterioration. Hogan51 assessedthe role of magnetic resonance imaging in 366 obtundedor unreliable patients who had normal CT imaging aftertrauma. Magnetic resonance images were negative foracute injury in 354 of 366 patients; the most commoninjury seen was a cervical cord contusion, identified in 7patients. Magnetic resonance images were also negativefor spinal ligament injuries in 362 of 366 patients; 4patients had ligament injuries, but in all cases, the injurywas limited to the ligaments of a single column. CT hadnegative predictive values of 98.9% for ligament injuryand 100% predictive value for unstable cervical injury;MRI identified a small number of patients with ligamentinjuries not diagnosed with CT, but none of these weredeemed to be unstable injuries.

In summary, in a patient at high risk for cervical injury,who cannot be evaluated clinically, a three-view cervicalseries supplemented by high-resolution CT scanningwith sagittal reconstruction will reduce the likelihood ofan occult fracture to less than 1%. After a technicallyadequate imaging series has been reviewed and clearedby a radiologist, it is prudent to remove cervical immo-

† Eastern Association for the Surgery of Trauma: Determination of cervicalspine stability in trauma patients. Winston-Salem, North Carolina, EAST, 2000.Available at: www.east.org/tpg/chap3u.pdf. Accessed October 27, 2005.



bilization. If there is evidence of a neurologic deficitreferable to the cervical spine despite the finding ofnormal cervical radiography and CT imaging, MRI shouldbe considered.

Spinal Ligament Injuries and Spinal Cord Injurywithout Radiographic AbnormalitySpinal ligament injuries are of particular concern be-

cause of the high incidence of resultant spinal instability,the potential for cord injury, and the hemodynamicinstability common at presentation in this subpopula-tion. In Demetriades’37 review of CSI patients admittedduring 5 yr to a major trauma center, 31 patients (10.6%)had a ligament injury (subluxation without fracture), and11 patients (3.8%) had an isolated spinal cord injurywithout fracture or subluxation (spinal cord injury with-out radiographic abnormality [SCIWORA]). Of the 31patients with ligament injury, one third required trachealintubation before clinical evaluation of the spine wascompleted. Of the 11 patients with spinal cord injurywithout radiographic abnormality, 27.3% required intu-bation before spinal evaluation occurred. The diagnosisof cord injury was made on admission in only 5 patients(45.5%) with spinal cord injury without radiographicabnormality. In 3 patients, the neurologic examinationon admission was normal, and neurologic deficits ap-peared a few hours later. In the remaining 3 patients (2intubated, 1 intoxicated), the diagnosis was missed ini-tially. Patients who required urgent airway interventionwere less likely to have had a complete neurologic eval-uation and were more likely to have neurologic injurythan those who did not require urgent interventions.Chiu et al.52 also investigated the incidence of cervicalspinal ligament injury in 14,577 blunt trauma victims. Sixhundred fourteen patients (4.2%) had CSI, and 87 (14%of CSI) had dislocation without evidence of fracture.There were 2,605 (18%) patients who could not beassessed for symptoms, and 143 (5.5%) of these unreli-able patients had a CSI; 129 (90%) had a fracture, and 14had no fracture.

Trauma patients with greater severity of injury aremore likely to have had a CSI; clinical evaluation is moredifficult in these patients, typically because of depressedconsciousness. Patients with ligament injury of the cer-vical spine without fractures frequently require urgentintubation, and not uncommonly, clinical evaluation iseither not possible or not complete at the time thatintervention is required; delay in the diagnosis of injuryis common in these patients.

Failure to Diagnose Cervical Spine Injury at InitialAssessment: Factors and ConsequencesPatients with decreased mental status from trauma,

alcohol, or drugs and patients with other painful ordistracting injuries have an unreliable history andphysical examination for CSI; patients with these char-

acteristics have spinal injuries that are also more likelyto be missed on initial presentation. The commonestreasons for missed diagnosis are failure to obtainradiographs, poor quality of the imaging study, ormisinterpretation of the radiographs.9,10 Inadequateradiographic studies are more likely in patients withhemodynamic compromise on admission or in thosepatients urgently requiring intervention for operativetreatment of associated injuries. Unfortunately, missedinjuries are often unstable, and secondary neurologiclesions occur in 10 –29% of patients whose injuries arenot diagnosed at initial evaluation.9,10 Failure to im-mobilize the spine in patients whose injuries aremissed at the initial assessment is considered to be aleading cause of secondary injury.

Poonnoose et al.53 conducted a detailed review of theexperience of a specialty spinal cord injury unit to de-termine both the incidence of missed injury and theclinical mismanagement that occurred in the setting ofmissed injury. The medical records of 569 patients withneurologic deficits secondary to traumatic spinal cordinjury were reviewed. In 52 instances (9.1%), the diag-nosis was initially missed, and 26 of these patients (50%)had evidence of neurologic deterioration after admissionto care. The median time to recognition of the injury was4 days. Therapeutic interventions were performed in 34patients that were deemed inappropriate to their condi-tion before the diagnosis was made. In 19 patients, therewere significant neurologic findings present on initialassessment, and in 7, the initial neurologic deficit wasminimal. Nine patients eventually developed paralysis,and 6 died with the deaths attributed to the delay indiagnosis. Again, the major cause for delayed diagnosiswas related to radiographic assessments: In 18 cases, theinitial images were of poor quality; in 11 patients, thearea of concern was not adequately visualized; in 10cases, an obvious fracture was missed; in 11 cases, facetjoint malalignment was not recognized; and in 10 cases,prevertebral hematoma went undetected. It was com-mon for the clinicians to consider the spine clearedwhen the radiographs “failed” to reveal injury and toattribute neurologic findings to either preexistent con-ditions (e.g., ankylosing spondylitis) or peripheral trau-matic injuries. As well, 7 patients with evidence of neu-rologic deficits were initially labeled as “hysterical” andnot managed as at-risk.

It is unfortunately the case that patients with CSI arefrequently not correctly diagnosed at the time of initialpresentation.9,10,53,54 This may occur in a small percent-age of CSI patients because the injury is a ligamentousone and the screening imaging seems on initial review tobe negative.37,54 However, it more commonly occursbecause there is a low index of suspicion for injurydespite high-risk mechanisms, inadequate radiographicstudies are deemed acceptable, and neurologic signs orsymptoms are either attributed to other causes or ig-



nored entirely. Delayed diagnosis is associated with avery high incidence of secondary injury, and the magni-tude of that injury is often considerable.9,10,53,54

Secondary Neurologic Injury after Cervical SpineInjurySecondary injury may be precipitated in CSI victims

when management is suboptimal, and in particular whenthe injured spine is not immobilized. However, there isalso evidence that neurologic deterioration occurs afteracute injury despite appropriate management para-digms; the reported incidence of neurologic deteriora-tion in this setting ranges from 2 to 10%.55 Frankel56

reported the occurrence of an ascending myelopathy2–18 days after spinal cord injury despite appropriateclinical management. Only patients with ascension ofinjury level of at least four levels were included in thisanalysis; despite the high threshold for inclusion, thismagnitude of secondary injury occurred in 1% of 808patients admitted to the center. Frankel attributed thedeterioration to either vascular catastrophes (arterial in-sufficiency or venous thrombosis) or inflammation; thisreport predated MRI, so no imaging is available in thesepatients to support the clinical conjecture. Marshall etal.55 reported a prospective study assessing neurologicdeterioration in cord-injured patients conducted in fiveUS trauma centers. Deterioration occurred in 4.9% ofpatients and was consistent across the five centers. Al-though the deterioration was often associated with aspecific intervention (surgery in 4 patients, traction ap-plication in 3, halo vest application in 2, Stryker framerotation in 2, and rotobed rotation in 1), there was noevidence that these procedures were performed poorlyor that they could have been performed in an alteredfashion to prevent the deterioration. There were 375such interventions recorded among the 283 patients.The authors concluded that deterioration is an inevitableconsequence of providing care to cord-injured patientsand will occur in some patients despite acceptable carepractices.

Farmer et al.57 reported the experience of a US re-gional spinal cord center regarding neurologic deterio-ration after cervical cord injury. Deterioration was evi-dent in 1.84% of 1,031 patients assessed. The averagetime from injury to deterioration was 3.95 days, anddeteriorations were associated with early surgery (� 5days after injury), sepsis, ankylosing spondylitis, andtracheal intubation. Tracheal intubation was associatedwith two minor and two major deteriorations, but nofurther details were offered regarding this cohort; it ispossible that the intubation was necessitated by theneurologic deterioration and not the cause of it. In thepatients who experienced deterioration and survived,92% of patients eventually had improvement in theirneurologic status. Harrop et al.58 analyzed the cases of

12 of 186 patients (6%) with acute traumatic cord inju-ries who demonstrated neurologic ascension within 30days after injury. Three subgroups were defined: an earlydeterioration group who worsened within 24 h, a de-layed deterioration group (1–7 days), and a late (beyond7 days) deterioration group. Two patients in the lategroup had vertebral artery injury; vertebral artery injuryis common after midcervical injury, and its clinical sig-nificance is uncertain.59,60

Yablon et al.61 described 14 cases of ascending my-elopathy (involving 1–4 levels) that occurred in the first4 weeks after injury. These cases were attributed tospinal cord edema; MRI studies demonstrated evidenceof this as well as diffuse intrathecal hemorrhage. Be-langer et al.62 identified a similar occurrence of ascend-ing myelopathy, which they labeled as subacute post-traumatic ascending myelopathy, occurring within thefirst 2 weeks after injury. This syndrome occurred inthree patients who experienced neurologic deteriora-tion with a secondary injury ascending six or more levels(6, 9, and 17 levels) from the initial level after an un-eventful early course. No etiologic factors could be iden-tified. In all three patients, T2 weighted MRI studiesrevealed a high signal intensity located centrally withinthe cord and extending rostrally from the site of injury.T2-weighted images are sensitive to the presence ofedema and effectively distinguish pathologic from nor-mal tissue; the high signal intensity identified indicatesinjury and edema.

The above reports suggest that there is a progressivepostinjury course in some patients leading to a second-ary neurologic injury and ascension of injury level, some-times to a striking degree. In some instances, this dete-rioration has been associated with clinical interventions,including immobilization, traction, surgery, intubation,and sepsis. In other instances, no clear factors are asso-ciated, and in particular, both extrinsic cord compres-sion and vascular interruptions have been excluded. Thissyndrome, when witnessed early in the course afterinjury, has usually been attributed to vascular perturba-tions or cord edema and inflammation; MRI studies havebeen consistent with this attribution. More recent workhas also suggested a role for apoptosis in the causationand progression of ascending myelopathy.63 A diagnosisof ascending myelopathy must be considered when asecondary injury has occurred; there is natural tempta-tion to attribute the deterioration to temporally relatedclinical interventions but, in fact, these interventions arerarely associated with neurologic sequelae. Progressiveneurologic injury after CSI may be inevitable in somepatients because of pathophysiologic processes initiatedat the time of the application of the injuring forces andmay occur despite the provision of appropriate manage-ment paradigms and interventions.



Clinical Care of the Spine-injured Patient

Spinal Immobilization in Trauma Patients: TheOverviewDuring the past 30 yr, the neurologic status of spinal

cord–injured patients arriving in emergency depart-ments has dramatically improved, and the odds of dyingduring the first year after injury have been significantlyreduced.64,65 The improvement in the neurologic statusof patients has been attributed to improved initial careand retrieval systems, recognition of the importance ofinstituting prehospital spinal immobilization, maintain-ing immobilization until clearance is obtained or defini-tive therapy is applied, and hospital practices designedto prevent secondary injury. The routine use of spineimmobilization for all trauma patients, particularly thosewith a low likelihood of spinal injury, has been chal-lenged on the basis that it is unlikely that all patientsrescued from the scene of an accident or site of trau-matic injury require spine immobilization.66 A Cochranesystematic review also concluded that the impact ofimmobilization on mortality, neurologic injury, and spi-nal stability was uncertain and that direct evidence link-ing immobilization to improved outcomes was lacking.67

The Cochrane review further concluded that the poten-tial for immobilization to actually increase morbidity ormortality could not be excluded based on a review of theliterature. However, the current consensus among ex-perts remains that all patients with the potential for a CSIafter trauma should be treated with spinal column im-mobilization until injury has been excluded or definitivemanagement for CSI has been initiated.64

The benefits, consequences, and sequelae of spinalimmobilization in at-risk patients have been recentlyanalyzed, and the reader is referred to these reviews formore detailed discussions.64,68,69 The chief concern dur-ing the initial management of patients with potential CSIis that neurologic function may be further compromisedby pathologic motion of the injured vertebrae. Manage-ment of the potentially traumatized spine emphasizesthree principles: (1) restoration and maintenance of spi-nal alignment, (2) protection of the cord with preserva-tion of intact pathways, and (3) establishment of spinalstability. To achieve these principles, immobilization ofthe cervical spine before radiographic assessment andclearance is the accepted standard of care. The rationalebehind early immobilization is the prevention of neuro-logic injury in the patient with an unstable spine. Insti-tution of a clinical care paradigm that features immobi-lization as a core element has resulted in improvedneurologic outcomes in spine-injured patients during thepast three decades.64,65 Failure to immobilize in thecontext of missed or delayed diagnosis is also associatedwith an increased incidence of neurologic injury.9,10,53

Lack of immobilization has been cited as a cause ofneurologic deterioration among acutely injured trauma

patients being transported to medical facilities for defin-itive care.70

A number of complications to prolonged immobiliza-tion have been identified.64,68,69 Cutaneous ulcerations(pressure sores) are common, and the incidence in-creases when immobilization is prolonged beyond48–72 h. Airway management, central venous accessand line care, provision of oral care, enteral nutrition,and physiotherapy regimes are all made more difficultwhen immobilization must be maintained. The need formultiple staff to allow for safe positioning and transfer ofimmobilized patients makes barrier nursing more diffi-cult and may result in higher rates of cross-contamina-tion and infection in high-dependency units.

The application of cervical collars has also been asso-ciated with increased intracranial pressure (ICP) in bothinjured patients and healthy volunteers. Davies71 pro-spectively analyzed ICP in a series of injured patientstreated with a rigid collar. The ICP increased a mean of4.5 mmHg when the collar was firmly in place. Kolb72

also examined changes in ICP after the application of arigid Philadelphia collar in 20 adult patients. ICP aver-aged 17.68 cm H2O initially and increased to an averageof 20.15 cm H2O after collar placement. Although thedifference in ICP of 2.47 mm H2O was statistically sig-nificant, it remains uncertain that it has clinical rele-vance. Nonetheless, this modest increase in pressuremay be magnified in patients who already have increasedICP and poor intracranial compliance. The potential forcomplications should not discourage the use of immobi-lization where indicated. Rather, because many of thecomplications are time dependent, they should encour-age attempts to promptly assess the patient for cervicalinjury to expedite the discontinuance of immobilizationin those patients whose spines can be cleared.

Techniques and Devices for Preadmission SpinalImmobilizationThe position in which the injured spine should be

placed and held immobile, the “neutral position,” ispoorly defined. De Lorenzo et al.,73 in an MRI study of 19adults, found that 2 cm of occiput elevation produced afavorable increase in spinal canal/spinal cord ratio at theC5 and C6 levels, a region of frequent unstable cervicalspine injuries. Podolsky et al.74 evaluated the efficacy ofcervical spine immobilization techniques. Hard foam andhard plastic collars were better at limiting cervical spinemotion than soft foam collars, although the use of collarsalone did not effectively restrict spinal motion. The useof sandbag-tape immobilization was more effective atreducing spinal movement than any of the other individ-ual methods tested. Adding a Philadelphia collar to thesandbag–tape construct reduced neck extension but hadno effect on any other motion of the cervical spine.These authors found that sandbags and tape combinedwith a rigid cervical collar was the most effective con-



struct of those evaluated to limit cervical spine motion,restricting movement to approximately 5% of the normalrange. The sandbag–tape–backboard–collar and varia-tions thereof have become the most commonly usedextrication and transport assembly in prehospital traumacare to provide spinal immobilization.

Bednar75 assessed the efficacy of soft, semirigid, andhard collars to immobilize the neck in a destabilizedelderly cadaver model. Bednar’s experiment involvedcreation of unstable motion segments at the C3–C4,C4–C5, or C5–C6 levels; isolated posterior column, com-bined column, and then anterior column injuries weresequentially assessed. Soft, semirigid, and rigid collarswere used in an attempt to restrict neck movements, andthen the spines were subjected to unrestrained gravita-tional forces with flexion, lateral side-bending, and ex-tension. The collars were not effective in reducing spinalmovement; in fact, there was evidence for increasedspinal movement. Bednar hypothesized that the in-creased movement resulted from the levering of themobile head and proximal cadaver neck over the collaredge. The model described allowed for the applicationof forces that would rarely be applied or permitted inclinical settings but did emphasize the very limited rolethat collars would play in limiting spinal movement if thespine were subjected to very hostile forces.

Goutcher and Lochhead76 measured maximal mouthopening (interincisor distance) in 52 volunteers, beforeand after the application of a semirigid cervical collar.Three collars were assessed: the Stifneck (Laerdal Medi-cal Corp., Wappinger’s Falls, NY), the Miami J (JeromeMedical, Moorestown, NJ) and the Philadelphia (Phila-delphia Cervical Collar Co., Thorofare, NJ). Applicationof a collar significantly reduced interincisor distancefrom a mean of 41 � 7 mm in the control state to 26 �8 mm with the Stifneck, 29 � 9 mm with the Miami J,and 29 � 9 mm with the Philadelphia. There was a widevariation between subjects, and a significant proportionhad an interincisor distance reduced to less than 20 mmafter application of the collar (Stifneck, 25%; Miami J,21%; Philadelphia, 21%). Goutcher and Lochhead con-cluded that the presence of a semirigid collar signifi-cantly reduced mouth opening and would likely ofteninterfere with airway management; removal of the ante-rior portion of the collar before attempts at trachealintubation was encouraged by these authors.

Manual In-line ImmobilizationThe goal of manual in-line immobilization (MILI) is to

apply sufficient forces to the head and neck to limit themovement which might result during medical interven-tions, most notably, airway management. MILI is typi-cally provided by an assistant positioned either at thehead of the bed or, alternatively, at the side of thestretcher facing the head of the bed. The patient ispositioned supine with the head and the neck in neutral

position. Assistants either grasp the mastoid processedwith their fingertips and cradle the occiput in the palmsof their hands (head-of-bed assistant) or cradle the mas-toids and grasp the occiput (side-of-bed assistant). WhenMILI is in place, the anterior portion of the cervical collarcan be removed to allow for greater mouth opening,facilitating airway interventions. During laryngoscopy,the assistant ideally applies forces that are equal in forceand opposite in direction to those being generated bythe laryngoscopist to keep the head and neck in theneutral position.

Avoiding traction forces during the application of MILImay be particularly important when there is a seriousligamentous injury resulting in gross spinal instability.Lennarson et al.77 noted excess distraction at the site ofa complete ligamentous injury when traction forceswere applied for the purposes of spinal stabilizationduring direct laryngoscopy. Similarly, Kaufmann et al.78

demonstrated that in-line traction applied for the pur-poses of radiographic evaluation resulted in spinal col-umn lengthening and distraction at the site of injury infour patients with ligamentous disruptions. Bivins etal.79 reported that traction applied during orotrachealintubation in four victims of blunt traumatic arrest withunstable spinal injuries resulted in both distraction andposterior subluxation at the fracture site. It is possiblethat the fracture site distraction that was observed re-sulted from application of traction forces not appropri-ately axially aligned.

Majernick et al.80 demonstrated that MILI reduced totalspinal movement during the process of laryngoscopyand tracheal intubation; movement was not reduced to asimilar degree by collars. Similarly, Watts et al.81 mea-sured a reduction of spinal movement with the applica-tion of MILI during tracheal intubation in patients withnormal spines during general anesthesia. However, Len-narson et al.82 were unable to demonstrate that applica-tion of MILI resulted in any significant reduction inmovement during intubation in a cadaver model with aposterior column injury. In a cadaver model with com-plete ligamentous instability, Lennarson et al.77 reportedthat application of MILI minimized distraction and angu-lation at the injured level but had no effect on subluxa-tion at the site of injury.

Manual in-line immobilization may be effective in re-ducing overall spinal movements recorded during airwaymaneuvers but may have lesser restraining effects at theactual point of injury. This may be because spinal move-ment is restricted by the weight of the torso at the caudalend and the MILI forces at the cephalad end but isunrestricted by any force at its cervical midpoint. It ispossible that application of traction forces during MILIwould also reduce midcervical movement in some pa-tients, but traction forces may also result in distraction atthe site of injury; the use of such forces during applica-



tion of in-line immobilization continues to be discour-aged.

Impact of MILI on the View Obtained atLaryngoscopyThe application of MILI during airway maneuvers may

result in decreases in overall spinal movement, but theevidence also suggests modest, if any, effect at individualmotion segments.77,82 However, the use of MILI mayhave lesser impact on the view obtained during directlaryngoscopy than relying on other immobilization tech-niques, such as axial traction or a cervical collar, tape,and sandbags. Heath83 examined the effect on laryngos-copy of two different immobilization techniques in 50patients. A grade 3 or 4 laryngoscopic view (partial or noview of the glottic structures) was obtained in 64% ofpatients immobilized with a collar, tape, and sandbagscompared with 22% of patients stabilized with MILI. Thelaryngeal view improved by one grade in 56% of patientsand by two grades in 10% when MILI was substituted forthe collar, tape, and sandbags. The main factor contrib-uting to the increased difficulty of laryngoscopy whenpatients were wearing cervical collars was reducedmouth opening. Gerling et al.84 reported the findings ofan analogous study using a cadaver model with a C5–C6destabilization and arrived at similar findings. MILI al-lowed less spinal movement than did cervical collarimmobilization during laryngoscopy and intubation andwas associated with improved laryngeal visualization.

Hastings and Wood85 measured the degree of headextension required to expose the arytenoid cartilagesand glottis and determined the impact of applied MILI.The subjects were 31 anesthetized patients (24 study, 7control) with normal cervical spines and Mallampati 1views on preoperative airway assessment. Two methodsof immobilization were assessed. Either axial tractionwas applied, wherein the assistant pulled the head in acaudal to cephalad direction as strongly as he or shethought was necessary to immobilize the neck, or forcewas applied to the head in a downward direction to holdthe head onto the table. Without stabilization, the bestview of the glottis was achieved with 10°–15° of headextension. Head immobilization reduced extension an-gles of 4°–5° compared with no stabilization, and it wasmore effective than axial traction immobilization in lim-iting extension. In 4 of the 24 study patients (17%), 2 ineach immobilization group, the laryngoscopic view de-teriorated from grade I or II to grade III with the appli-cation of immobilizing forces. Therefore, the use of MILIreduced the amount of head extension that was neces-sary for laryngoscopy but resulted in a poorer view in aportion of the patients studied.

Although MILI seems to have the least impact of allimmobilization techniques on airway management, itmay make direct laryngoscopy more difficult in somepatients than if no immobilizing forces are being applied.

Nolan and Wilson86 assessed the impact of MILI withcricoid pressure on the view obtained at laryngoscopy in157 normal patients and compared it with the viewobtained in the same patients while in the sniffing posi-tion. With application of MILI and cricoid pressure, theview remained the same in 86 patients (54.8%), wasworse by one grade in 56 (35.6%), and was worse by twogrades in 15 (9.5%). A grade 3 view (partial glottic view)was obtained in 34 restrained patients (21.6%) comparedwith 2 (1.3%) in the sniffing position. Wood et al.87 alsostudied the effect of cervical stabilization maneuvers onthe view obtained at laryngoscopy in 78 uninjured, elec-tive surgical patients and concluded that cervical immo-bilization commonly worsened laryngoscopic view. Theeffects of MILI on laryngeal view were in a similar direc-tion to those reported by Hastings but occurred morecommonly in Wood’s study. Anterior laryngeal or cricoidpressure often improved the view of the larynx whenthe neck was immobilized. Concern has been expressedin the past regarding the use of anterior cervical pressurein patients at risk for CSI, but Donaldson et al.88 reportedthat application of cricoid pressure did not result inmovement in an injured upper cervical spine in a ca-daver model.

Manual in-line immobilization may have lesser impacton airway interventions than do other forms of immobi-lization. The experience supports routinely removing atleast the anterior portion of collars to facilitate airwayinterventions provided that cervical spinal immobiliza-tion is maintained by MILI. Removal of the anteriorportion of the collar improves mouth opening and facil-itates airway management; reapplication of the mechan-ical immobilization should occur promptly when airwayinterventions are complete. MILI may increase laryngo-scopic grade in some patients; this may be counteredwith anterior laryngeal or cricoid pressure.

Spinal Movement during Airway InterventionsThe early biomechanical analyses of spinal motion typ-

ically used static radiography to determine the relationsbetween the vertebral elements of the cervical spine andto quantify spinal movements. Unfortunately, no stan-dardized technique of measurement has been used in theworks since published, which have evaluated spinalmovement during airway interventions. Both static radi-ography and dynamic fluoroscopy have been used; studyfindings have been reported movement as absolute dis-tances, relative distances (typically a percentage of ver-tebral body width), and degrees of motion and havefurther been categorized relative to individual motionsegments or upper and lower cervical spinal divisions orsummated across the entire cervical spine. There is alsolittle guidance available as to the clinical importance ofthe movements recorded, especially as they relate to theinjured spine. Those spinal movements that fall withinphysiologic ranges have usually been considered to be



nonthreatening to the cord; whether they are in fact andremain so in a spine with a canal lumen already compro-mised by an acute, a chronic, or an acute superimposedon chronic anatomical derangement is by no meanscertain. Unfortunately, as we analyze the publishedworks, we typically find ourselves in the position ofcomparing the recorded results with physiologic normsand then drawing an empiric conclusion as to the po-tential risk of such movements.

The Effects of Basic Airway Maneuvers on theInjured Neck. Aprahamian89 studied the effect of bothairway maneuvers on a human cadaver, unstable spinemodel. The anterior and most of the posterior columnwere surgically disrupted; the interspinous and supraspi-nous ligaments were spared. Lateral cervical spine radio-graphs were taken during both basic and advanced air-way maneuvers. Basic maneuvers included chin lift, jawthrust, head tilt, and placement of both oral and esoph-ageal airways. Advanced maneuvers included placementof the following: an esophageal obturator airway; anorotracheal tube placed with both a straight and acurved laryngoscopic blade; and a nasotracheal tube,blindly placed. Chin lift and jaw thrust resulted in ex-pansion of the disc space more than 5 mm at the site ofinjury. When blind nasotracheal intubation was facili-tated by anterior pressure to stabilize the airway, 5 mmof posterior subluxation occurred at the site of injury.The other advanced airway maneuvers produced 3–4mm of disc space enlargement. The study was repeatedafter the application of both soft and semirigid cervicalcollars; collars did not effectively immobilize the neckfor either basic or advanced airway maneuvers.

Hauswald90 also determined the impact of basic airwaymaneuvers on cervical spine movement. Eight humantraumatic arrest victims were studied within 40 min ofdeath. All subjects were ventilated by mask, and theirtracheas were intubated orally with a direct laryngo-scope, over a lighted oral stylet and using a flexiblelaryngoscope, and nasally. Cinefluoroscopic measure-ment of maximum cervical displacement during eachprocedure was made with the subjects supine and im-mobilized by a hard collar, backboard, and tape. Themean maximum cervical spine displacement was foundto be 2.93 mm for mask ventilation, 1.51 mm for oralintubation, 1.85 mm for guided oral intubation, and 1.20mm for nasal intubation. Ventilation by mask causedmore cervical spine displacement than the other proce-dures studied. It was concluded that mask ventilationmoves the cervical spine more than any of the com-monly used methods of tracheal intubation.

Airway maneuvers will result in some degree of neckmovement, both in general and specifically at the sites ofinjury. The amounts of movement are small, typicallywell within physiologic ranges, and their impact onsecondary neurologic injury has not been defined. How-ever, as will be subsequently discussed, airway interven-

tions are frequently performed on at-risk trauma pa-tients, and there seems to be a very low incidence ofsecondary injury in these patients associated with airwayclinical interventions.

Cervical Spinal Movement during Direct Laryn-goscopy in Normal Patients. Sawin et al.91 deter-mined the nature, extent, and distribution of segmentalcervical motion produced by direct laryngoscopy andorotracheal intubation in normal human subjects. Tenpatients underwent laryngoscopy while paralyzed andduring general anesthesia. Minimal displacement of theskull base and cervical vertebral bodies was observedduring laryngoscope blade insertion; elevation of thelaryngoscope blade to achieve laryngeal visualizationcaused superior rotation of the occiput and Cl and mildinferior rotation of C3–C5. The largest magnitude mo-tions were at the atlanto-occipital and atlantoaxial joints,but there was extension at each motion segment as-sessed. Tracheal intubation created slight additional su-perior rotation at the craniocervical junction but causedlittle alteration in the postures of C3–C5. Horton et al.92

conducted a similar experiment in volunteers duringtopical anesthesia only. Subjects in a supine, sniffingposition underwent direct laryngoscopy, and at full glot-tic exposure, a lateral radiograph of the head and neckwas performed. The radiographs indicated that exten-sion at the craniocervical junction was near maximal andthat there was progressively increasing extension fromC4 to the base of the skull, but that the position of thelower cervical spine remained static during laryngos-copy. Both Sawin et al. and Horton et al. agreed that,during laryngoscopy, in both awake and unconscioussubjects, most cervical motion occurs at the craniocer-vical junction; the subaxial cervical segments subjacentto and including C4 are minimally displaced (fig. 6).91,92

Spinal Movement during Laryngoscopy in In-jured Spine Models. Donaldson et al.88 studied themotion that occurred during intubation in a cadavermodel with an unstable C1–C2 segment. The followingwere measured in the intact specimen and then againafter creation of the unstable segment: angulation, dis-traction, and the space available for the cord (SAC). Withmaximum flexion and extension, the SAC was narrowed

Fig. 6. Impact of direct laryngoscopy and tracheal intubation oncervical spine movement.91,92



1.49 mm in the intact cervical spine but 6.06 mm in theunstable spine. Chin lift and jaw thrust reduced the SACby 1 mm and 2.5 mm, respectively; oral intubation andnasal intubation created a similar (1.6 mm) reduction ofSAC. Distraction at the unstable injured level was similarfor chin lift, jaw thrust, and crash intubation (1–2 mm);distraction during gentle oral intubation and nasal intu-bation was less than 1 mm. Chin lift and jaw thrustcreated similar angulations (4°–5°) to those of the oralintubation techniques, but nasal intubation caused less(2.5°). Cricoid pressure resulted in no significant move-ments when it was applied in either the stable or unsta-ble model. Donaldson et al. concluded that (1) the SACwas narrowed to a greater degree by preintubation ma-neuvers than it was by intubation techniques, (2) nasaland oral intubation techniques resulted in similaramounts of SAC narrowing, and (3) application of cri-coid pressure produced no significant movement at thecraniocervical junction.

Stabilization during Airway Interventions in Ca-daver Models of an Injured Spine. Lennarson et al.82

evaluated the impact of commonly used immobilizationtechniques in limiting spinal motion in an injured-spinemodel; the model involved the creation of a posteriorligamentous injury at the C5 level and compared theeffects of MILI and Gardner-Wells traction. The predom-inant motion measured at all spinal levels during laryn-goscopy and intubation in the intact spine was exten-sion; this was consistent with the findings of Donaldsonet al.,88 Sawin et al.,91 and Horton et al.92 Subluxation inthe anterior–posterior dimension remained less than 1mm in both the intact and the partially destabilizedspine; rotatory or angular movements were the onlysignificant movement recorded. Application of Gardner-Wells traction limited rotatory motion at the craniocer-vical junction after destabilization; MILI did not have asimilar effect.

Lennarson et al.77 conducted a similar experimentassessing the efficacy of immobilization maneuvers in amodel of complete C4–C5 segmental instability. Move-ment was measured at the injured level during the ap-plication of traction, during MILI, and without stabiliza-tion. Traction resulted in distraction at the site of injurywhen instability was complete; the magnitude of thesemovements was not reduced by MILI, although theyremained within physiologic limits. Gerling et al.84 alsoevaluated the effect of both MILI and cervical collarimmobilization on spinal movement during direct laryn-goscopy in an unstable C5–C6 cadaver model. Althoughthere was less displacement (2 mm) measured withapplication of MILI compared with collars, the magni-tude of movement was small overall and within physio-logic ranges.

Brimacombe et al.93 assessed spinal movement in acadaver model with a posterior injury at C3, with MILIapplied as various airway interventions (facemask venti-

lation, direct laryngoscopy and tracheal intubation, fiber-optic nasal intubation, laryngeal mask insertion, intubat-ing laryngeal mask airway insertion followed byfiberoptic intubation, and insertion of a Combitube)were performed. Posterior displacement was less whenintubation was performed nasally with a flexible scope(0.1 � 0.7 mm) than for any other maneuver; mostmaneuvers caused 2–3 mm of displacement.

Influence of Laryngoscope Blade Type on SpinalMovement during Direct Laryngoscopy. Three au-thors have assessed the influence of the type of laryngo-scope blade on the spinal movements generated duringdirect laryngoscopy. MacIntyre et al.94 compared theMacintosh and McCoy blades in patients with normalspines during general anesthesia with cervical collarsapplied. There were no significant differences betweenthe two blades with respect to the amount of spinalmovement generated during intubation. Hastings et al.95

compared head movement occurring during laryngos-copy in patients with normal spines using Macintosh andMiller laryngoscopes, and again, there were no differ-ences in the amount of movement measured. Finally,Gerling et al.84 compared spine movement in a cadavermodel with a C5–C6 transection injury while performinglaryngoscopy with Miller, Macintosh, and McCoy-typeblades. There was no difference in the movements re-corded with the different blades with regard to eitheranteroposterior displacement or angular rotation. Lessaxial distraction was measured with the Miller bladecompared with the other two blade types; in absoluteterms, the differences was 1.7 mm. Overall, there seemsto be little difference in the spinal movement resultingfrom direct laryngoscopy relative to the type of bladeused during laryngoscopy.

Cervical Spinal Movement with Indirect Rigid Fi-beroptic Laryngoscopes. Watts et al.81 compared cer-vical spine extension and time to intubation with theBullard (ACMI Corp., Southborough, MA) and Macintoshlaryngoscopes during a simulated emergency with cervi-cal spine precautions taken. Twenty-nine patients wereplaced on a rigid board, and anesthesia was induced.Laryngoscopy was performed on four occasions, twiceeach with the Bullard and Macintosh laryngoscopes,both with and without MILI applied (MILI was appliedwith cricoid pressure). Cervical spine extension (fromthe occiput to C5) was greatest with the Macintosh andwas reduced both when the Macintosh was used withMILI and when the Bullard was used with or withoutstabilization. Times to intubation were similar for theMacintosh with MILI and for the Bullard without MILI.MILI applied during laryngoscopy with the Bullard re-sulted in further reduction in cervical spine extensionbut a prolonged the time to intubation, although it stillwas achieved in less than a minute. In a study designsimilar to that of Watts et al., Hastings et al.95 found thatcervical spine extension from the occiput to C4 was



decreased when comparing the Bullard with both theMacintosh and the Miller laryngoscope blades.

The times to achieve intubation using the Bullard la-ryngoscope, in the study of Watts et al.,81 are similar toothers reported in the literature. Twenty-two of 29 pa-tients (76%) were intubated in less than 30s when usingthe Bullard under standard conditions.81 In a study usingthe dedicated intubating stylet, Cooper et al.96 found70% of patients were intubated in less than 30 s. Therewas also better exposure of the larynx during laryngos-copy with the Bullard than with the direct laryngoscope.Application of MILI resulted in deterioration in the gradeview of the larynx when using the Macintosh in 19 of 29patients (65%). In contrast, only 2 patients (7%) pre-sented an inferior view of the larynx after application ofMILI and cricoid pressure when using the Bullard laryn-goscope.

Rudolph et al.97 compared movement in the uppercervical spine in 20 patients scheduled to undergo elec-tive surgery, when laryngoscopy was performed withthe Bonfils intubation fiberscope (Karl Storz EndoscopyLtd., Tuttlingen, Germany) and the Macintosh laryngo-scope. With the patient’s head in neutral position on thetable and no pillow used, a baseline lateral radiographwas taken. The head was extended, laryngoscopy wasperformed using the Macintosh, a second radiographwas taken, and the head was returned to the neutralposition. Laryngoscopy was then performed with theBonfils fiberscope, and the trachea was intubated. Withthe Macintosh, views at laryngoscopy were class I in 8patients, II in 5, and III in 7; all views obtained with theBonfils fiberscope were class I. The time between inser-tion of the instrument and achievement of optimumview was similar for both instruments. Laryngoscopywith the Macintosh resulted in spinal movement thatwas greater in magnitude than that measured duringBonfils fiberscopy.

The Glidescope (Saturn Biomedical Systems, Burnaby,British Columbia, Canada) is a new video laryngoscopethat incorporates a high resolution digital camera in theblade tip; the image is transmitted to a liquid crystaldisplay monitor via a dedicated video cable. Agro et al.98

compared the laryngeal view obtained initially with aMacintosh and then with the Glidescope in 15 normalpatients presenting for general anesthesia who werewearing cervical collars. The laryngeal view was reducedby one Cormack grade in 14 of the 15 patients (93%)studied when the Glidescope was used compared withthe Macintosh; the average time to intubation with theGlidescope was 38 s. Turkstra et al.99 compared cervicalspine movement, measured fluoroscopically, during in-tubation with a Macintosh, a light wand, and the Glide-scope. In-line immobilization was achieved by taping thepatients’ heads into a Mayfield-type headrest; movementwas measured at the Oc–C1, C1–C2, C2–C5, and C5–Thlevels. The largest amount of motion measured was at

the Oc–C1 complex with all devices. Cervical spinalmovement was reduced 57% overall (all segments com-bined) comparing the light wand with the Macintosh;reduced movement was apparent at each level. Spinalmovement was reduced only at the C2–C5 segmentwhen the Glidescope was compared with the Macin-tosh; 6.9° � 5.2° of flexion was measured during Macin-tosh laryngoscopy, and this was reduced by 50% usingthe Glidescope. Motion was not significantly altered atthe three other segments studied. The time to intubationwas longest with the Glidescope (27 � 12 s) but similarwith the light wand (14 � 9 s) and the Macintosh (16 �7 s).

Cervical spine movements are generally less whenrigid indirect laryngoscopes are used compared with theML direct laryngoscope. Visualization of the glottis is alsoimproved with the use of the rigid laryngoscopes, butthe time to achieve the best view is somewhat longer;these times tend to be short, and the difference com-pared with the direct laryngoscope is likely to be of littleclinical relevance.

Cervical Spinal Movement and Laryngeal MaskAirways. Kihara et al.100 measured cervical movementproduced by the intubating laryngeal mask airway dur-ing MILI in 20 anesthetized patients with cervical pathol-ogy undergoing cervical spine surgery. During the inser-tion of the intubating laryngeal mask airway, C5 andsuperior segmental levels were flexed by less than 2°.During intubation, C4 and superior segmental levelswere flexed by 3° or less, and C3 and levels above wereflexed by an average of 1° during removal. There wassome posterior displacement at the C2–C5 levels duringinsertion and intubation but not during removal.

Keller et al.101 implanted microchip sensors into thepharyngeal surfaces of C2 and C3 in 20 cadavers todetermine the pressures exerted against the cervicalvertebrae by both the standard laryngeal mask airwayand the intubating laryngeal mask airway during inser-tion and manipulation. The impact of these pressures oncervical spine movement was also determined. Keller etal. concluded that laryngeal mask devices exert highpressures against the upper cervical vertebrae duringinsertion, during inflation, and while in situ; these pres-sures could produce posterior displacement of the up-per cervical C-spine. The clinical relevance of thesefindings as they relate to CSI has yet to be clarified.

Cervical Spinal Movement during Surgical Crico-thyrotomy. Surgical cricothyrotomy was initially advo-cated as a preferred airway intervention in patients atrisk for CSI compared with orotracheal intubation andnow is deemed to be an appropriate alternative if oral ornasal routes cannot be used or are unsuccessful. Al-though long considered safe in the presence of a CSI, itsapplication in this scenario has not been well studiedwith respect to either spinal movements or neurologicoutcomes. Gerling et al.102 used a cadaver model to



quantify movement during cricothyrotomy. Standardopen cricothyrotomy was performed in 13 cadavers withcomplete C5–C6 transection injuries, and cervical spineimages were recorded fluoroscopically during the pro-cedure. Peak axial distraction was measured at 4.5% ofthe C5 width, amounting to 1–2 mm of axial compres-sion; peak antero-posterior displacement was measuredat 6.3% of the C5 width, equivalent to 1–2 mm of dis-placement. Although these values were statistically sig-nificant, there clinical relevance has yet to be deter-mined.

The Clinical Practice of Airway Management inPatients with Cervical Spine InjurySurveys of Patterns of Clinical Practice Regarding

Airway Management after Cervical Spine Injury.Four authors have surveyed North American anesthesi-ologists as to their preferred methods of airway manage-ment in patients with cervical spine trauma or disease.Lord et al.103 compared practice preferences amongsurgical members of the Eastern Association for the Sur-gery of Trauma with anesthesiologists in US anesthesiol-ogy training programs. In the elective situation (CSI butbreathing spontaneously with stable vital signs), anesthe-siologists stated that they were less likely to use nasotra-cheal intubation (53% vs. 69%), equally likely to useorotracheal intubation, and more likely to use the fiber-optic bronchoscope than were trauma surgeons. In theurgent scenario (patient with unstable vital signs), anes-thesiologists tended to use both nasotracheal and orotra-cheal intubation in a manner similar to that of the sur-geons but more frequently (16%) preferred thebronchoscope. In an emergency situation (apneic pa-tient with unstable vital signs), both anesthesiologistsand surgeons relied extensively on the direct laryngo-scope (78% and 81%); anesthesiologists were more likelyto use the bronchoscope (15%) than were surgeons butused a surgical airway less frequently than did the sur-geons (7% vs. 19%).

Rosenblatt et al.104 received 472 responses from 1,000active members of the American Society of Anesthesiol-ogists who were surveyed as to their preferences formanagement methods for the difficult airway in cooper-ative adult patients. With respect to patients with CSI,78% of respondents expressed a preference for an awakeintubation and the use of bronchoscope; the bulk of theremainder induced general anesthesia and used a directlaryngoscope. Rosenblatt et al. did not request informa-tion regarding the levels of experience attained with thedevices preferred but did ascertain that they were avail-able to the practitioners who stated that they would usethem. Jenkins et al.105 collected 833 responses from1,702 members of the Canadian Anesthesiologists’ Soci-ety surveyed regarding their management choices forthe difficult airway in Canada. When faced with a patientwith a cervical cord compression and neurologic deficit

presenting for discectomy, 67% expressed a preferencefor awake intubation, and most (63%) stated that theywould use a bronchoscope. Thirty-one percent wouldinduce general anesthesia before airway intervention,and slightly more would use a direct laryngoscope thanpreferred a lighted stylet in this setting. Jenkins et al. didnot solicit information regarding the level of experiencewith the methods identified as being preferred by thesurvey respondents.

Ezri et al.106 surveyed 452 American-trained AmericanSociety of Anesthesiologists members attending the 1999Annual Meeting. When faced with a cooperative adultpatient with cervical spine disease (rheumatoid arthritisor ankylosing spondylitis) presenting for elective sur-gery, awake fiberoptic intubation was preferred by most.Although 75% stated that they would use it in some ofthe scenarios outlined, only 59% or respondents re-ported skill in the use of the bronchoscope.

The surveys are consistent in revealing that manyNorth American anesthesiologists express a preferencefor the use of a fiberoptic bronchoscope during airwaymanagement in patients with cervical spine disease orinjury including in apneic trauma scenarios. This prefer-ence persists despite the fact that some who state thispreference also acknowledge that they are not confidentregarding their skill levels with the bronchoscope. De-pending on the setting and the perceived urgency of thesituation, direct laryngoscopy is still commonly used,and use of the lightwand is preferred by a significantminority of anesthesiologists, at least in Canada.

Airway Management of Cervical Spine–injuredPatients: The Experience and Outcomes Reported.Meschino et al.107 reviewed their experience with 454patients with critical cervical cord or spine injuries orboth. One hundred sixty-five patients underwent awaketracheal intubation within 2 months of injury; 289 didnot require intubation during the same period. The di-rect laryngoscope was used in 36 patients (22%), thefiberoptic bronchoscope was used in 76 (46%), and 51patients (32%) underwent blind nasal intubation. Pa-tients undergoing intubation were more severely im-paired than those who did not require intubation. De-spite this, there was no difference in the incidence ofneurologic deterioration over time between the twogroups, and tracheal intubation was not associated withneurologic deterioration in any patient. Holley and Jor-dan108 conducted a retrospective analysis of traumatic,unstable cervical spine fractures requiring operativemanagement to determine both the airway managementtechniques used and the incidence of neurologic com-plications. One hundred thirty-three patients with 140fractures were reviewed. Ninety-four patients under-went nasal intubation in the operating room, and 29were intubated with direct laryngoscopy and in-line sta-bilization. No neurologic complications were recognizedin any patient.



Rhee et al.109 analyzed their experience with 21 pa-tients with cervical cord or spine injury who underwenttracheal intubation in the emergency room. Orotrachealintubation was used in 81% of CSI patients; neuromus-cular blockers were used in 82% of these intubations.The authors concluded that no injury was recognized tobe caused or exacerbated by airway maneuvers. How-ever, one patient with a C7–T1 dislocation and a C7 cordtransection was noted to have absent sensation belowthe nipples before intubation (T4 level) and motor andsensory examination results consistent with a C7 cordtransection after intubation. Whether this disparity re-flect an ascension in the level of injury from T4 to C7 orthe difference in findings between an emergency roomscreening neurologic exam and a more precise examina-tion performed later is not certain; the authors’ conclu-sions seem to prefer the latter explanation. Scanell etal.110 reviewed their experience with 81 patients withCSI, including 58 with unstable fractures, who receivedemergency orotracheal intubations performed by expe-rienced anesthesiologists. Neurologic assessment wasdocumented before and after intubation, and in no in-stance was there a recognized deterioration of neuro-logic functions after tracheal intubation. Shatney et al.111

reviewed their experience with 81 patients with 98fractures who were neurologically intact on initial pre-sentations. Orotracheal intubation was performed in 48patients, and no neurologic deteriorations were recog-nized. In-line immobilization was used during the airwaymaneuvers, and agitated or combative patients weresedated, paralyzed, or both. Talucci et al.112 reviewedtheir experience with 335 patients requiring urgent in-tubations. Seven patients with unstable CSI underwentorotracheal intubation after induction of anesthesia andparalysis; none experienced neurologic compromise as aresult of airway management.

Suderman et al.113 reviewed the experience of 150patients with traumatic CSI and well-preserved neuro-logic function presenting for operative stabilization.General anesthesia before intubation was induced in 83patients, of whom 65 had their tracheas intubated withthe direct laryngoscope; 22 patients were intubatedwhile awake using the direct laryngoscope. The remain-der had tracheal intubation performed with a variety ofalternatives to the direct laryngoscope, most commonlythe bronchoscope; the majority of those latter intuba-tions were performed with the patient awake. Two pa-tients experienced new neurologic deficits; one had awire passed through the cervical cord accidentally dur-ing operative stabilization and was rendered quadriple-gic, the second recovered from a new single level radic-ulopathy attributed to the operative decompression.Both of these patients had their tracheas intubated witha direct laryngoscope while anesthetized. McCrory114

performed a similar retrospective analysis of the recordsof 45 patients who presented for operative stabilization

of cervical injuries resulting from trauma. Tracheal intu-bation was performed after induction of general anesthe-sia with neuromuscular block in 40% of cases; in theremainder, intubation was performed with a broncho-scope while the patient was awake. One awake trachealintubation was abandoned as a result of patient noncom-pliance; this patient’s trachea was intubated after induc-tion of general anesthesia. Weighted traction was used inall cases to immobilize the spine. No patient developedeither a new neurologic finding or worsening of a pre-existent deficit.

Wright et al.115 reviewed the records of 987 blunttrauma patients; 60 of the patients had a cervical frac-ture, and 53 of these were deemed to be unstable.Twenty-six patients’ tracheas were intubated orally, 25were intubated nasally, and two were intubated by cri-cothyrotomy. One patient who underwent nasotrachealintubation experienced a neurologic deterioration. Lordet al.103 reviewed the case records of 102 patients whohad a CSI and were admitted to their center after trauma.Sixty-two patients required airway management. Themost common method used was orotracheal intubationfacilitated by direct laryngoscopy (43%), followed bybronchoscope-assisted intubation (27%), nasotracheal in-tubation (22%), and tracheostomy (2%); in 4%, themethod could not be determined. No patient was recog-nized to have experienced a neurologic deteriorationassociated with airway management. Other authors havereported similar findings in smaller series of trauma pa-tients with CSI.112,116

These studies are limited by both their small samplesize and their retrospective nature. However, they doreveal that neurologic deterioration in CSI patients isuncommon after airway management, even in high-riskpatients undergoing urgent tracheal intubation. They arenot sufficient to rule out the potential that airway man-agement provided in isolation or as part of a more com-plex clinical intervention, even provided with the ut-most care, may rarely result in neurologic injury. To doso would require a study of enormous proportions. Asnoted previously, progressive neurologic deteriorationoccurs in a minority of CSI patients. If this incidence wasset at 2% and a study was designed to prove that anairway intervention did not double this baseline inci-dence, approximately 1,800 patients would need to bestudied. No method of airway intervention has beenevaluated with such a study, or anything close to it, andtherefore, statements comparing the relative safety ofdifferent methods have tenuous evidentiary support.

The Use of the Direct Laryngoscope after CervicalSpine Injury: The Debate. As part of the early effortsaimed at reducing secondary injuries in spine-injuredpatients, a hypothesis was generated that the tracheas ofpatients with unstable cervical spines could not be safelymanaged by direct laryngoscopy and oral intubation.117

Oral intubation was deemed dangerous because it alleg-



edly caused excessive spinal movement, and this move-ment could lead to secondary injury. Such secondaryinjury could theoretically be avoided by the careful per-formance of nasotracheal intubation or cricothyrotomy.These techniques were advocated as the emergencyairway maneuvers of choice in patients at risk for spinalinjury. There were no data at that time to support thisthesis, and the data collected since seem to suggest thatsecondary neurologic injury associated with any form ofairway management is exceedingly rare. The early Ad-vanced Trauma Life Support protocols for airway man-agement were consistent in their support for the nasalintubation/cricothyrotomy strategy, implying a lack ofsupport for the use of direct laryngoscopy in this clinicalsetting. Not all practitioners agreed that the use of directlaryngoscopy was contraindicated in patients at risk forcervical injury. There was evidence made available soonafter publication of these protocols that some experi-enced trauma centers (including our own) were ignoringthe Advanced Trauma Life Support recommendationsand performing direct laryngoscopy in at-risk popula-tions.107,113,118

McLeod and Calder119 examined the association be-tween the use of the direct laryngoscope in patients andsubsequent spinal injury or pathology. They suggestedthat the following five case features would add credenceto the diagnosis of a laryngoscopy-induced cord injury:(1) a short period of unconsciousness, (2) myelopathypresent on recovery, (3) autonomic disturbances afterlaryngoscopy, (4) difficult laryngoscopy, and (5) cranio-cervical disease or gross instability below C3. Thesecriteria were then used to evaluate the likelihood thatlaryngoscopy was the causative factor for neurologicdeterioration in the reports. Although they do makeintuitive sense, whether these criteria discriminate wellin assigning cause to injury recognized after intubation isnot established. Six reports dealing with 10 patients inwhich it was alleged that direct laryngoscopy contrib-uted to a neurologic injury were reviewed.57,120–124

With the possible exception of one case, they concludedafter review and analysis of the case reports, that thereports did not provide sufficient data to allow them tomake the determination that the use of the direct laryn-goscope was the cause of the neurologic injuries re-ported.

The first report analyzed was that of Farmer et al.,57

who reviewed their institutional experience with cord-injured patients. They reported that four patients hadneurologic deteriorations associated with tracheal intu-bation. Two deteriorations were classified as minor andtwo were classified as major, but no further details wereprovided regarding the cases or the intubations. Thesecond report was that of Muckart et al.,120 who re-ported two cases of neurologic deterioration after clini-cal interventions. The first patient was a 45-yr-old maninvolved in a motor vehicle accident who sustained

bilateral femoral fractures and a closed head injury. De-spite the mechanism of injury, a period of unconscious-ness, and the presence of neck pain, no imaging wasperformed, and his spine was not immobilized. He un-derwent anesthesia for operative repair of the femoralfractures and was quadriplegic on awakening; a C2 frac-ture–dislocation was subsequently diagnosed, and herecovered completely. The second patient was a 22-yr-old man with multiple gunshot wounds to the neck; hearrived in the hospital neurologically intact. Imaging ofthe neck revealed no apparent injury to the cervicalspine to a level of C5; the radiograph showed only theupper five vertebrae. He underwent emergency surgeryduring general anesthesia without neck immobilizationand was quadriplegic after. A CT scan demonstrated aburst fracture of C6 with a retropulsed fragment imping-ing on the canal. He was placed in traction, had opera-tive fixation, and recovered completely. Although directlaryngoscopy and tracheal intubation were componentparts of the care of both patients, they were not the soleinterventions; the lack of immobilization and the poten-tial for malpositioning cannot be excluded as significantrisk factors in both cases. The complete recovery in bothpatients suggests that malpositioning may have been anetiologic factor inducing a transient, compressive neura-praxia-like injury.

The third report analyzed was that of Redl,121 whodescribed the case of an 18-yr-old man with undiagnosedspondyloepiphyseal dysplasia congenita resulting in un-recognized craniocervical instability. He underwent gen-eral anesthesia and direct laryngoscopy with trachealintubation for removal of retained knee hardware. Theintraoperative and early postoperative course was un-eventful, but he developed a spastic quadriparesis theday after surgery. A CT scan demonstrated a congenitallyabnormal craniocervical junction with an os odontoi-deum (congenitally nonfused odontoid process) in theforamen magnum compressing the spinal cord. Al-though he made a full recovery, he awoke quadriplegicafter a subsequent craniocervical stabilization procedurefor which his trachea was intubated using a fiberopticbronchoscope. The precise role of the laryngoscopy inthe development of transient neurologic symptoms in apatient with a congenitally abnormal and unstable spineis uncertain; the development of symptoms on the dayafter laryngoscopy reduces the strength of a causativeassociation. The fourth report reviewed is that of Yanand Diggan,122 who described the occurrence of a cen-tral cord syndrome in a 42-yr-old woman with acquiredimmune deficiency syndrome who underwent urgentlaryngoscopy and intubation for respiratory failure. Be-fore her admission, she was using a walker and wheel-chair to ambulate. Following the recognition of upperextremity weakness after intubation and resuscitation,she underwent imaging and evaluation of her central andperipheral nervous system. There was no evidence of



spinal anomaly or instability; there was imaging evidenceof marked and generalized cerebral atrophy and a spinalcord contusion and electrodiagnostic evidence of bothcentral and peripheral neuropathy. The etiology of injurywas attributed to hyperextension, but there was alsoevidence of advanced neurologic disease likely related toinfection with human immunodeficiency virus. The fifthreport was that by Yaszemski et al.,123 who reported thecase of a 59-yr-old woman with advanced rheumatoidarthritis. She underwent a right wrist fusion during gen-eral anesthesia, and her trachea was intubated with abronchoscope while she was awake. Her trachea wasextubated at the end of the procedure, and the earlypostoperative course was uneventful. She had a cardiacarrest 10 h postoperatively and was intubated with di-rect laryngoscopy, but could not be resuscitated. Atautopsy, she was confirmed to have atlantoaxial instabil-ity (recognized preoperatively), and there was micro-scopic evidence of focal areas of ischemia and infarctionin the upper cord and lower medulla oblongata. Theauthors attributed the damage and the cause of death tothe resuscitation intubation, although she was alreadydead at the time of that intubation. Further, the patho-logic finding of infarction suggests that the injury likelytook place remotely from the time of death, perhapsduring the surgery, and may well have been a position-ing injury that was progressive.

The case that MacLeod and Calder cited as being mostlikely (four of five features present) a laryngoscopy-in-duced cord injury was that reported by Hastings andKelley.124 They reported of the case of a 65-yr-old manadmitted to hospital after a motor vehicle accident. De-spite reporting neck pain and exhibiting left arm weak-ness, CSI was not ruled out, nor was spinal immobiliza-tion enforced. His condition deteriorated some hourssubsequently, and after repeated, failed attempts at di-rect laryngoscopy without spinal immobilization, he un-derwent cricothyrotomy; 3 h later, he was found to beparaplegic. A review of the original cervical spine radio-graph demonstrated a widened disc space at C6–C7suggesting disruption of the anterior longitudinal liga-ment. CT scans confirmed that finding as well as notingcongenital spinal stenosis from C3 to C7, osteophytefragments in the spinal canal at C6, a fracture of theC6–C7 facet joint, a C7 laminar fracture, and a C6 spi-nous fracture. The constellation of symptoms could notbe attributed to a single cord lesion, and he was diag-nosed as having both an anterior cord syndrome affect-ing the T11 and subjacent levels and a central cordsyndrome at the cervical level. No MRI study was per-formed to detail the nature of the cord injuries, and it ispossible that his neurologic deterioration was inevitableand perhaps the cause of his respiratory insufficiency.However, at no time from admission until the occur-rence of his neurologic deterioration was his spine im-mobilized.

Two additional cases of intubation-associated neuro-logic injury not reviewed by MacLeod and Calder havebeen reported.125,126 Liang et al.125 reported a case sim-ilar to that of Hastings and Kelley of a man involved in amotor vehicle accident with a suspected CSI who wasleft quadriplegic after airway management. Despite theevidence of a CSI (nature of injury not reported) and aneurologic deficit (limited movement in both upper ex-tremities), repeated and failed attempts were made atboth nasal (five attempts) and then oral intubation witha direct laryngoscopy (five attempts). The last threeattempts at oral intubation were made after removal ofthe cervical collar, but MILI was not used. The tracheawas eventually intubated via a surgical airway. There isno discussion of the care afforded after intubation withrespect to the spine injury or any description of subse-quent imaging studies performed. The next day, it wasrecognized that he was quadriplegic. Powell andHeath126 reported the case of 59-yr-old man found col-lapsed and unconscious. Paramedics found him to beapneic, cyanosed, and unresponsive and attempted butfailed to intubate his trachea. Tracheal intubation wasperformed in the emergency room, and then the spinewas immobilized. A lateral cervical radiograph revealedan odontoid peg fracture, and the patient’s conditionwas consistent with a complete cord injury at the C2level. Although it was inferred that the cord injury mayhave been caused or aggravated by the airway manage-ment, it was acknowledged by the authors that the injurywas probably sustained at the time of the accident.

A number of reports detailing a relation between air-way management and the occurrence of secondary neu-rologic injury in CSI patients have been reviewed. Thesereports consist typically of observations made in a singlepatient or in a small series of patients admitted to a singleinstitution. Although the deterioration has often beenassociated temporally with airway management, in mostcases, it is impossible to determine with certainty thecause of the deterioration because confounding factorsare typically present and acknowledged by the reportingauthors. As well, it is possible in some instances that theassociation between airway management and a worsen-ing neurologic state arises not because of cause andeffect but because the airway intervention was madenecessary by a progressively deteriorating clinical condi-tion such as an ascending myelopathy. It may well bethat the magnitude of the deterioration does not be-comes apparent until after clinical interventions, atwhich time they, themselves, become suspect culprits.As unsatisfactory as it might be, determining the truenature of the association (causal or otherwise) betweenairway management and adverse neurologic outcomes inCSI patients is not possible at this time, given the currentstate of our knowledge.



The Use of the Flexible Fiberoptic Bronchoscopein Cervical Spine Injury. There is considerable enthu-siasm, particularly among anesthesiologists, for the useof the fiberoptic bronchoscope in patients at risk forcervical spine disease. The advantages are its potentialfor use in awake patients, the minimal cervical move-ment required to achieve tracheal intubation, and theability to perform postintubation neurologic assessmentsin cooperative and cognitively intact patients. However,there have been have been relatively few reports recog-nized in the literature regarding the use of the broncho-scope in the emergency management of the airway aftertrauma.127 The overall success rate for intubation usingthe bronchoscope in the trauma setting has been cited at83.3% (95% CI, 72–94.6%).127 There is a report detailingthe successful use of the bronchoscope to facilitateawake intubation in 327 consecutive patients presentingfor elective cervical spine surgery; the bulk of the pro-cedures were surgeries for cervical disc prolapse, andthere were no patients with traumatic injuries includedin the review.128 Although the procedure was well tol-erated by the majority of the patients, 38 (12%) devel-oped low oxygen saturations; in this group, the meanoxygen saturation measured by pulse oximetry was 84 �4% (range, 72–89%). The potential for desaturation dur-ing bronchoscope-facilitated intubation seems to be asgreat or greater in CSI patients compromised by trau-matic injury as in these elective surgical patients; theincidence and magnitude of hypoxemia in a series ofCSI-trauma patients undergoing such management hasnot been reported.

There are no published data in the English literaturethat would indicate that the cited advantages of thefiberoptic bronchoscope translate into improved out-comes among CSI patients compared with other intuba-tion techniques. As well, Ezri et al.106 reported, after asurvey of American anesthesiologists, that more than40% of respondents acknowledged that they were notcomfortable using a bronchoscope for airway manage-ment. McGuire and El-Beheiry129 reported two cases ofcomplete airway obstruction during elective awakebronchoscope-assisted intubation in patients with unsta-ble cervical spine fractures; both patients were salvagedwith emergency surgical airways. In patients with braininjury, a common concurrent injury to CSI, the use of thebronchoscope is associated with significant increases inICP that are not prevented by the administration ofmorphine, midazolam, and nebulized lidocaine.130

Comparing Rigid and Flexible Fiberoptic Endo-scopes in At-risk Populations. Cohn and Zornow131

compared the fiberoptic bronchoscope and the Bullardlaryngoscope with respect to rapidity of glottic visualiza-tion and intubation in patients requiring cervical immo-bility during tracheal intubation. Seventeen adult pa-tients scheduled to undergo neurosurgical correction ofa cervical spine problem were studied. Each patient was

considered at risk for neurologic injury during trachealintubation based on a request for awake fiberoptic tra-cheal intubation by the neurosurgical team, or radicularsymptoms initiated or exacerbated by neck extension.Most showed evidence of spinal canal impingement on apreoperative MRI. Patients were allocated randomly toone of two study groups for tracheal intubation with theBullard (n � 8) or the fiberoptic bronchoscope (n � 9);before intubation, glottic visualization was performedusing the alternative technique. All intubations wereperformed with the neck in a comfortable position forthe patient and with any preexisting immobilization de-vice (e.g., collar, traction) in place. Glottic visualizationwas uniformly successful on the first attempt in bothgroups. Tracheal intubation was also uniformly success-ful, although one intubation in the bronchoscope grouptook 183 s because of difficulty passing the endotrachealtube through the glottis after an easy laryngoscopy. Nonew neurologic deficits were observed after trachealintubation in either group.

Practice Options for Airway Management afterCervical Spine Injury. There is discordant opinionexpressed in the literature regarding the optimal meansof securing the airway in patients with CSI. Enthusiasmis expressed by some neuroanesthesia experts for theexclusive use of the fiberoptic bronchoscope to facilitatetracheal intubation in spine-injured patients.132 Thereare a number of theoretical factors that would supportsuch a choice. The head and neck may be left in a neutralposition, and little spinal movement is required toachieve laryngeal visualization and tracheal intubation.The patient’s protective reflexes are largely left intact,and the potential for deleterious movements and posi-tioning is perhaps reduced. A neurologic assessment canbe made after intubation to ensure that there has beenno change in the patient’s status, although the accuracyof this evaluation may be diminished by sedation. Finally,the patient could be positioned awake to increase thelikelihood that potentially injurious position could beavoided. These considerations support the use of thetracheal intubation facilitated by a fiberoptic broncho-scope and performed by an experienced care provider asa practice option in the management of the airway inspine-injured patients. Survey evidence also supports theconclusion that many anesthesiologists are of the opin-ion that it is the preferred option, especially in electivescenarios. This preference persists even among physi-cians who acknowledge limited skills with the device.However, there are no data to suggest that better neu-rologic outcomes are achieved with its use. In fact, theapplication of a technique by practitioners not expert inits use may carry risk. Failed awake intubation has beenidentified as a cause of morbidity and mortality in thelatest analysis of difficult airway claims by the AmericanSociety of Anesthesiologists’ Closed Claims Project.133

The use of a direct laryngoscope after induction of



anesthesia is also deemed an acceptable practice optionby the American College of Surgeons as outlined in thestudent manual of the Advanced Trauma Life SupportProgram for Doctors; by experts in trauma, anesthesiol-ogy, and neurosurgery; and by the Eastern Associationfor the Surgery of Trauma.3,107,109,119,127,134–143 Theprinciple advantages of the direct laryngoscope are thatanesthesiologists are very experienced in its use and thatit is a highly effective tool; many anesthesiologists do notconsider themselves similarly skilled with other practiceoptions.106 Direct laryngoscopy can also be performedmore quickly than some, but not all, alternative tech-niques, and it does not require time to obtain and set upspecialized equipment. However, it has the potential tocause greater spinal movement than indirect techniques.In addition, if laryngoscopy is performed after the induc-tion of general anesthesia, the potential for difficult ven-tilation, a failed intubation, and a cannot-intubate, can-not-ventilate scenario cannot be excluded. Finally, ifthere is underlying severe, chronic cervical spinal pa-thology, difficult laryngoscopy should be anticipated be-cause it is more likely to occur.3 This is particularly trueif the upper cervical spine is severely impacted by thedisease process.

The use of the direct laryngoscope is a practice optionaccepted by expert practitioners; its use is commonlyencouraged in urgent or emergent situations. Otherpractice options, such as light wands, rigid fiberopticlaryngoscopes, and laryngeal mask airways, are alsodeemed appropriate. There is no published evidencethat would indicate that one intubation option is supe-rior to others with respect to outcomes in general and, inparticular, with respect to neurologic outcomes. Anycomparative study that could or would support a singlepractice option would have to be very large to be per-suasive.

Summary of the Literature

There is an incidence of CSI approximating 2% amongvictims of blunt trauma, and this incidence is trebled ifthe patient presents unconscious or with a GCS scorereduced to 8 or below. A finding of a focal neurologicdeficit also significantly increases the likelihood of acervical injury. The need to evaluate all at-risk patientswith a complete and technically adequate imaging seriesseems to be accepted as the standard of care, althoughthere is debate as to what constitutes the at-risk popula-tion and an acceptable imaging series. A three-viewspine series (lateral, antero-posterior, and odontoidviews) supplemented by computerized tomographic im-aging through areas that are difficult to visualize or sus-picious is effective in ruling out injury in both coopera-tive and noncooperative patients. MRI studies may beuseful in patients with neurologic symptoms but nega-

tive radiography and CT imaging; they seem to add littleto the evaluation of patients with persistent pain but anormal neurologic examination and negative imaging. Aswell, although MRI may identify CSI not captured by CT,these injuries are not usually unstable. Failure to diag-nose the injury at time of presentation is associated witha worse neurologic outcome; it occurs most commonlyas a result of either failure to appropriately image thespine or misinterpretation of appropriate imaging.

Immobilization of the spine in at-risk patients at thetime of first system contact and maintenance of theimmobilization until the spine is cleared is accepted byexpert consensus as the standard of care. However,there is some debate about the need for immobilizationin patients at low risk. Prolonged spinal immobilizationis costly in terms of system resources and not withoutrisk to the patient. Strategies that permit efficient andprudent spine clearance are available and their use isencouraged so as to reduce costs, conserve resources,and, most importantly, to prevent harm.

Secondary neurologic injury occurs after CSI and maybe associated with clinical care interventions. There isnow recognized a syndrome of progressive, ascendingmyelopathy that occurs in some patients and that ischaracterized by a widely distributed cord injury. It mayoccur after a period of relative clinical stability and in theabsence of both mechanical instability and canal com-promise at the spinal levels to which the injury hasascended. The use of MRI (especially T2-weighted stud-ies) has been instrumental in documenting both theoccurrence and the nature of this injury. It may alsopresent at a time when clinical interventions are ongoingto treat the original traumatic injuries. Although therehas been a past tendency to attribute many secondaryinjuries to clinical interventions, especially in a medical–legal context, critical examination of these cases, sup-plemented with MRI evaluations, may reveal that some,and perhaps most, are an inevitable consequence of theprimary injury.

The routine use of some form of immobilization duringairway maneuvers in at-risk patients is accepted as thestandard of care. All airway maneuvers will result insome degree of neck movement, both in general andspecifically at the sites of injury. The amounts of move-ment are small and may be restrained by in-line immo-bilization, but they are not eliminated. The available dataand the accumulated clinical experience support a con-clusion at the current time that these movements areunlikely to result in neurologic injury provided that rea-sonable care is taken during airway interventions. How-ever, a study of sufficient size to validate this statementhas not been performed.

The most appropriate technique for performing tra-cheal intubation in patients with cervical spine injurycontinues to be debated. There are no clinical outcomedata that suggest better neurologic outcomes with any



particular technique, and it is acknowledged that a verylarge study would be required to furnish such data.Surveys indicate that the majority of American anesthe-siologists would prefer to use a fiberoptic bronchoscopeto intubate the trachea of at-risk patients and to do sowith the patient awake. A significant proportion of thosesharing this preference acknowledge limited skills withthe bronchoscope. As well, failed awake intubation hasbeen associated with morbidity and mortality in recentanalyses of closed claims. Surprisingly, there are no re-ports of series of CSI patients treated in this fashion, andso it is not possible to comment on the outcomes of thisstrategy.

There are a large number of reports that confirm thatrapid sequence induction of general anesthesia followedby direct laryngoscopy and tracheal intubation is widelyperformed in patients at risk for and with confirmed CSI;the resulting neurologic outcomes compare favorably tosimilar patient populations undergoing awake trachealintubation and to patients who do not require airwayintervention after traumatic injury. This technique doesnot seem to be associated with a higher incidence ofsecondary injury when compared with any other tech-nique of intubation. Unfortunately, these reports arelimited by small sample size and their retrospective na-ture. The current evidence and opinion expressed in theliterature support the use of a range of practice optionsin the management of the airway in CSI patients.

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Airway Management in Adults after Cervical Spine Trauma · facilitate airway management, although there is considerable, favorable experience with the direct laryngoscope in cervical