Decompressive craniectomy

Decompressive craniectomy for TBIDr. Joe M DasSenior ResidentDept. of Neurosurgery

HistoryICP and methods to reduce itDefinitionCraniectomy vs craniotomyCurrent evidenceIndicationsTypesProcedureComplications & their managementCranioplasty

HistoryAncient Egypt and Greece TBI, epilepsy, headache, mental illnessFirst described by Annandale (1894)Surgical decompression to treat elevated ICP Kocher (1901) and Cushing (1905) subtemporal and suboccipitalCushing H. The establishment of cerebral hernia as a decompressive measure for inaccessible brain tumors; with the description of intermuscular methods of making the bone defect in temporal and occipital regions. Surg Gynecol Obstet.1905;1:297314

Harvey Cushing spent several months in the lab of Kocher in 1900, performing cerebral surgery and first encountering the Cushing reflex .

Erlich (1940) For all head injuries with persistent coma for more than 24-48 hrsRowbotham (1942) All traumatic comas which improved at first and when medical treatment was ineffective for 12 hrsMunro (1952) If intra-op, the brain was contused and swollenGuerra (1999) personal results of 20 years 2nd tier therapy in refractory ICPGuerra WK, Gaab MR, Dietz H. et al: Surgical decompression for traumatic brain swelling: indications and results. J Neurosurg 90:187-196, 1999

ICPIn a normal adult, the cranial vault can accommodate an average volume of approximately 1500 mL.V Intracranial space = V Brain + V Blood + V CSFThe normal ICP ranges between 10 and 15 mm Hg in an adult.CPP = MAP ICPSystemic hypertension is required to maintain cerebral perfusionMonro A (1783). Observations on the structure and function of the nervous system. Edinburgh: Creech & Johnson.Kelly G (1824). "Appearances observed in the dissection of two individuals; death from cold and congestion of the brain". Trans Med Chir Sci Edinb 1: 84169.

Methods to reduce ICP

ACSSurgery Principles & Practice - Section 7 / Chapter 2 Injuries to the Central Nervous System

The limits of well-tolerated ICP together with lowering of CPP:SAH 18-20 mm HgMalignant Sylvian stroke 20-22 mm HgTrauma 25 mm HgSlow growing tumors and HCP 30-40 mm HgAschoff A., Schwab S., Spranger M, et al - The value of intracranial pressure monitoring in acute hemispheric stroke, Neurology 47 (1996): 393-398

A craniectomy of 8 cm 23 ml additional volume (1.5% of total cerebral volume).For real decompression, 12 cm or more (86 ml additional volume)Superior to the one realised by hyperventilation (2 mm Hg lowering of pCO2), ventricular tap of 20-30 ml and without the risk of loop diuretics.

Brain facts

Definition

Decompressive hemicraniectomy and durotomy is a surgical technique used to relieve the increased intracranial pressure and brain tissue shifts that occur in the setting of large cerebral hemisphere mass, or space-occupying lesions. In general, the technique involves removal of bone tissue (skull) and incision of the restrictive dura mater covering the brain, allowing swollen brain tissue to herniate upwards through the surgical defect rather than downwards to compress the brainstem.

Craniotomy vs craniectomy

Craniotomy the bone flap is returned to its previous location

Craniectomy the bone flap is not returned

Current evidenceEvidence supporting emergent DecompressiveCraniectomy in Trauma remains controversialIn animal studies, craniectomy has been a/w increased cerebral edema,hemorrhagic infarcts and cortical necrosis 1Decreased ICP2Improved Oxygen tension2Improved cerebral perfusion2

1.Forsting M, Reith W(1995) ; Wagener S et al(J Neurosurg 94:693-696, 2001)2. Burket W. Zentralbl Neurochir 50:318-323, 1988; Gaab M et al Childs brain 5:484-498, 1979Hatashita S, J Neurosurg 67:573-578, 1987

The role of decompressive craniectomy in TBI and in the control of intracranial hypertension remains a matter of debate.Youmans Neurological Surgery - Volume 4, Section XI, page 3442

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IndicationsSevere TBIHeterogeneous lesions in cerebral parenchymaFocal (contusions/hematoma) and diffuseMalignant MCA infarctionAneurysmal SAHOthersCentral venous thrombosisEncephalitisMetabolic encephalopathiesIntracerebral hematomaNeurosurg Clin N Am 24 (2013) 375391; Tarek Y. El Ahmadieh et al

Indications & Contraindications in TBIIndications: Coma or semicoma (GCS < 9)Pupillary abnormalities, but respond to mannitolSupratentorial lesion with midline shift on CTRefractory ICP despite best conventional therapyAge: initially < 80 years , now 70 years (Of patients who were > 70 years, 75% were dead)Contraindications:Fatal brain stem damageGCS < 4 or fixed and dilated bilateral pupils

When to perform?Bifrontal decompressive craniectomy is indicated within 48 hours of injury for patients with diffuse, post-traumatic cerebral edema and medically refractory elevated ICP.Subtemporal decompression, temporal lobectomy, and hemispheric decompressive craniectomy can be considered as treatment options for patients who present with diffuse parenchymal injury and refractory elevated ICP who also have clinical and radiographic evidence for impending transtentorial brain herniation.Bullock MR, Chesnut R, Ghajar J, et al. Neurosurgery 2006;58(Suppl 3) Surgical management of traumatic parenchymal lesions. :S2546 [discus-sion: Si-iv]. - BTF Guidelines

GuidelinesUp to date there are no specific guidelines or protocols stating exactly when or in what circumstances DC is appropriate, but there are some recommendations: The North American Brain Trauma Foundation suggests DC may be the procedure of choice in the appropriate clinical context and also considering the use of DC in the first tier of TBI management. (Bullock et al, 2006)European Brain Injury Consortium recommend DC as an option for refractory intracranial hypertension in all ages. (Maas et al,1997) A Cochrane review (2006) recommended DC may be justified in some children with medically intractable ICP after head injury but concluded there was no evidence to support its routine use in adults. (Sahuquillo & Arikan, 2006)

Types

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Decompressive hemicraniectomyFoam / rubber donutNo pinsCervical spine precautionsDont compress the jugulars

DHCSupineRolled towel beneath ipsilateral shoulderHead towards contralateral sideMark midlineIncision Reverse question markPosterior extent 15 cm behind key holeDeepened down to craniumMyocutaneous flap reflectedFive burr holes are made in the following locations: (1) temporal squamous bone superior to the zygomatic process inferiorly, (2) keyhole area behind the zygomatic arch anteriorly, (3) along the superior temporal line posteroinferiorly, and in the (4) parietal and (5) frontal parasagittal areas

Smaller craniectomy Damage to cortical veins and parenchymaDura dissected off from beneath the boneBur-holes connectedBone flap removedTemporal decompressionWax bone edgesDural tack-up stitchesDural opening (controlled manner) with radial incisions in stellate fashionClosure with dural substitute and after keeping suction drain

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Bifrontal craniectomyBifrontal contusions / diffuse cerebral edemaMark midline and coronal sutureBicoronal incision (2-3 cm behind coronal)Myocutaneous flap brought over the orbital rim (Preserve supra-orbital nerves)Bur-holes b/l keys, b/l squamous temporal, straddling the SSS just posterior to coronal sutureBone flapTemporal decompressionBone wax, dural tack-up stitchesDivide the anterior portion of SSS and falxDural opening wide

Kjellberg RN, Prieto A Jr: Bifrontal decompressive craniotomy for massive cerebral edema. J Neurosurg 34:488-493, 1971

What is the percentage reduction in ICP attained by DC?

Opening the dura has been shown to improve the reduction in ICP from 30% (dura left intact) to 85% (dura opened)

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Complications50-55 %Abnormalities in CSF absorptionExpansion of hematomas after decompressionSyndrome of the trephinedInfection

CSF absorption disordersSubdural hygromas & hydrocephalusCauses:Ruptured arachnoid One-way valve Pressure gradients between hemispheresAlteration in brains shapeTreatmentVentriculostomy & oversewing if CSF leakVP shunt (programmable)Cranioplasty

Expanding hematomasNew or existing mass lesions can develop postoperatively, especially given the high incidence of coagulopathy and platelet dysfunctionEvolution of both contusions and extra-axial hematomas can occur after the tamponading effects of cerebral edema, and elevated ICP has been relieved by decompressive craniectomy.Postoperative imaging is recommended especially in the setting of no ICP monitoring

SYNDROME OF THE TREPHINEDVariety of symptoms that can develop following craniectomy, including fatigue, headache, mood disturbances, and even motor weakness.Mechanisms:CSF flow abnormalitiesDirect atmospheric pressure on the brain Disturbances in cerebral blood flow.Often resolves with replacement of the bone flapThere is no evidence that it is harmful or that delay of cranioplasty can result in long-term consequences

CranioplastyUsually carried out 6 to 8 weeks after the DC, assuming that the patient has recovered from the initial injury and hydrocephalus or brain swelling is not present. In the interim - hockey helmet Autologous bone flap, (frozen after the initial surgery / kept in abdominal subcutaneous tissue) is used and provides good cosmetic results. The bone flap remains sterile in a 70C freezer for many months. Autoclaving of the bone (e.g., if contaminated by a compound scalp wound before cranioplasty) reduce the viability of the graft.

CranioplastyComplication associated with abdominal preservation of bone flap - bone resorption (5-10%) due to hypovascular bone necrosis and sepsis of the flap. Other materials - methyl methacrylate and titanium mesh when the bone is heavily comminuted or contaminated.For large, cosmetically important defects, the use of casts, stereolithographic models, and CT-based computer-assisted design reconstruction technology

ConclusionIC-HTN results from many disease processes.Decompressive craniectomy can be life preserving procedure.Selection criteria remains in involution.Best outcomes are achieved in young patients treated early in course of disease.

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