Correction of sagittal synostosis using a modified Π method

Clin Plastic Surg 31 (2004) 489–498

Correction of sagittal synostosis using a modified P method

Paul T. Boulos, MDa, Kant Y.K. Lin, MDb, John A. Jane, Jr, MDa,John A. Jane, Sr, MD, PhDa,*

aDepartment of Neurological Surgery, Box 212, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USAbDepartment of Plastic Surgery, University of Virginia Health Sciences Center, Charlottesville, VA 22908, USA

Craniosynostosis occurs at a rate of 1 in 2500 live early attempts were criticized owing to high opera-

births. The premature fusion of one or more of the

cranial sutures may occur sporadically or syndromi-

cally. Some of the first observations regarding abnor-

mal skull growth secondary to premature suture fusion

were made by Sommering [1] in 1791. Rudolph

Virchow [2] observed in 1851 that premature fusion

of a suture inhibits skull growth perpendicular to the

fused suture. In 1989, Jane [3] observed that the

deformity in craniosynostosis was not only secondary

to the inhibition of growth perpendicular to the fused

suture but also related to the compensatory growth

that occurs at adjacent sutures. The rules for compen-

satory growth at adjacent sutures helped to emphasize

that premature fusion of a suture affects the entire

skull; therefore, procedures to correct craniosynosto-

sis must address the entire skull, not just the fused

suture. Moss proposed in 1959 that the primary

pathophysiologic event was abnormal growth at the

skull base in craniosynostosis, not the premature

fusion of the cranial vault suture. Since this proposal,

several animal models developed by Persing [4,5]

have refuted Moss’s hypothesis in favor of the belief

that the premature fusion of the cranial vault suture is

the initial event.

Isolated sagittal synostosis is the most common

form of craniosynostosis, accounting for approxi-

mately 60% of cases [6,7]. There is a male to female

ratio of approximately 4:1. Six to ten percent of ca-

ses are familial [7–9]. Odilon Lannelongue in 1890

[10] and Lane in 1892 [11] were the first to describe

an operative treatment for sagittal synostosis. These

0094-1298/04/$ – see front matter D 2004 Elsevier Inc. All right

doi:10.1016/j.cps.2004.03.011

* Corresponding author.

E-mail address: [email protected] (J.A. Jane, Sr).

tive morbidity.

Shillito et al in 1968 [6] and Hunter et al in 1976

[7] revisited the idea of operative correction of the

deformity using a strip craniectomy. Although this

technique is safe and well-tolerated and can provide

adequate cosmetic results in selected patients with

mild deformity, the strip craniectomy has several dis-

advantages. It does not provide an immediate cos-

metic improvement, and most patients continue to

require prolonged helmeting. The procedure does not

sufficiently shorten the antero-posterior dimension

of the skull or address frontal bossing. It also leaves

a large unprotected area over the vertex of the skull,

and restenosis can occur with time. The fundamen-

tal problem with suturectomy is that single suture

fusion causes abnormalities in the shape of the entire

cranial vault. A procedure that addresses only the

fused suture is less likely to provide a satisfactory

cosmetic outcome.

This problem inspired Jane et al [12] in 1978

to propose total cranial vault reconstruction for the

treatment of sagittal synostosis. The technique, termed

the P procedure because of the shape of the bone

removal, was the first to address not only the primary

stenosis but also the resultant deformity of the entire

cranial vault. The P procedure widened the narrow

skull, shortened the antero-posterior dimension, and

addressed the frontal bossing. It provided an imme-

diate correction of the abnormality, without any large

defects in the calvarium. Since 1978, Boop et al [9],

Albright et al [13], Epstein et al [14], Fata et al [15],

Greene et al [16], Persing, Renier, and Pensler et al

[17], among others, have described variations of the

total calvarial reconstruction, and these techniques

have gained wide acceptance.

s reserved.

P.T. Boulos et al / Clin Plastic Surg 31 (2004) 489–498490

Nevertheless, strip craniectomy continues to be

performed, and the more recent introduction of neuro-

endoscopic strip craniectomy has renewed interest in

the procedure. Jimenez and others [18–20] have

described extensively their experience with the endo-

scopic strip craniectomy, using a molding helmet.

Kaiser, Marsh, Maugans and Panchal have all

reported on direct comparisons of strip craniectomy

with more extensive calvarial remodeling. Kaiser

[21] found that with vertex calveriotomies 83% of

cases had correction of the calvarial indices, as op-

posed to strip craniectomy which only had a 43%

correction rate. Marsh et al [22] found that, statisti-

cally, the total calvarial remodeling procedure im-

proved the calvarial indices more than the strip

craniectomy. Maugans et al [23] found the cosmetic

outcomes of total calvarial reconstruction to be

superior to strip craniectomy, with 79% in the calvar-

ial remodeling group rated as excellent as opposed

to 41% in the strip craniectomy group. They also

commented that two patients required a second

operation for poor cosmetic results with the strip

craniectomy. Panchal et al [24] found that the per-

centage improvement in the cranial index 1 year

postoperatively was greater in the subtotal calvarec-

tomy group than in the extended strip craniectomy

group. They were able to achieve a normal width to

length proportion with the subtotal calvarectomy and

were not able to do so with the extended strip

craniectomy. Although mathematical indices of cos-

Fig. 1. Schematic drawing of sagittal synostosis. (A) Frontal vie

decreased height. (B) Lateral view illustrating the increased anterior

the central portion of the skull.

metic results are imperfect, the literature that directly

compares results from strip craniectomy with those

from more extensive calvarial reconstructions indi-

cates that the more extensive procedure produces a

better cosmetic result.

Neurosurgeons who advocate the strip craniec-

tomy maintain that the more extensive procedures

carry a higher operative morbidity and mortality, have

a greater need for blood transfusion, and are associ-

ated with a longer hospital stay. Several large series

have been published indicating that the morbidity and

mortality are quite low for total calvarial reconstruc-

tions. Boop et al [9] described 85 cases with only

three simple dural lacerations. Kanev et al [25]

reported 65 cases without incident. McComb [26]

reported 24 infants without incident. Nevertheless,

the more extensive procedures do require more blood

transfusions. In the authors’ practice, they routinely

arrange living related donor blood preoperatively and

transfuse at the outset of the operation. The more

extensive procedures also require a longer hospital

stay. The authors’ patients typically stay up to 5 days.

In this article, they discuss their current surgical

technique for correction of this deformity.

Terminology

The compensations that result from sagittal synos-

tosis cause various degrees of scaphocephaly, frontal

w illustrating the decreased biparietal diameter as well as

-posterior dimension and the decreased height, particularly in

Fig. 2. Sagittal synostosis repair. The first step in the cor-

rection is removal of the sagittal, bilateral coronal, and bi-

lateral lambdoid sutures.

P.T. Boulos et al / Clin Plastic Surg 31 (2004) 489–498 491

bossing, occipital knob, the golf tee deformity, or

bathrocephaly. The authors have categorized sagittal

synostosis into three basic varieties: anterior, poste-

rior, and complete sagittal synostosis. Anterior sagit-

tal synostosis is associated with frontal bossing,

posterior closure causes occipital bossing, and com-

plete closure causes a combination of anterior and

Fig. 3. Sagittal synostosis repair. (A) The parietal bones are outfr

remodeling. The sagittal suture is used as a strut to increase the bipa

in place.

posterior compensations. The authors believe the dis-

tinction is important because each variety requires a

different surgical approach: individual varieties re-

quire individual operations.

Diagnosis

The initial diagnosis of sagittal synostosis is typi-

cally made by the primary care physician who ob-

serves the keel-like shape of the skull, as seen in

Fig. 1. Once the patient has been referred for neuro-

surgical consultation, the diagnosis is typically con-

firmed with plain radiographs and CT examinations

of the skull with three-dimensional reformatting.

Both modalities reveal suture fusion, as well as scle-

rosis around the suture. Although the distinction may

be apparent on physical examination, these studies

can also help define whether the abnormalities are

more frontal or occipital. A CT venogram is helpful

to define the dural venous sinus anatomy, particu-

larly the superior sagittal sinus and the torqula.

Preoperative evaluation in a multidisciplinary team

setting should be made with both plastic surgery

and neurosurgery.

Natural history

Patients with sagittal synostosis present with ex-

aggerated length to width ratios; their skulls are

actured. Vertical barrel staves may be used to facilitate the

rietal diameter. (B) Absorbable plates are used to fix the strut

Fig. 4. Sagittal synostosis repair. The anterior-posterior

dimension is corrected by fixing the frontal and occipital

bones to the parietal bones. In this process the frontal and

occipital bones can be adjusted by bringing them closer to

the center. The skull is returned to the normal shape by

manipulation of its length, width, and height.

Fig. 5. Schematic drawing of frontal bossing.


abnormally long and narrow (see Fig. 1). Although

one might assume that this abnormal length to

width ratio would continue to increase over time, the

authors’ data indicate that the ratio actually does not

change [27]. The cranial vault does not progressively

become longer and narrower; the abnormally in-

creased length to width ratio is relatively fixed. How-

ever, this does not necessarily mean that the cranial

shape and cosmetic appearance are not deteriorating.

If the length to width ratio is followed in children

with normal cranial vaults, the ratio decreases over

time. That is to say, the normal cranial vault becomes

more round as it develops. Therefore, despite the

ratio’s not deteriorating in the individual patient with

sagittal synostosis, the shape does worsen compared

with normal age-matched controls. Moreover, the

absolute length of the skull is much longer than

normal controls, adding to the perceived deformity.

Increased intracranial pressure may be an issue in

a number of patients with sagittal synostosis. Thomp-

son et al [28] reported on 74 children with single

suture premature fusion and found that 17% had

elevated intracranial pressure (ICP), defined as a

mean ICP above 15 mm Hg, and 38% had borderline

intracranial pressure, defined as 10–15 mm Hg. They

found elevated intracranial pressure more common in

the midline suture abnormalities. Patients who pres-

ent with sagittal synostosis later than 1 year more

often display signs of delayed mental development

[29]. Furthermore, patients who are operated on be-

fore 1 year of age seem to have a better functional

cognitive outcome [29]. Studies also indicate that, left

untreated, these patients may develop psychological

problems with self perception [30]. In light of these

findings we recommend early operative correction.

Operative technique

The authors will describe the operative tech-

nique for correction of sagittal synostosis in its com-

plete (equal anterior and posterior compensations),

anterior (frontal bossing), and posterior (occipital boss-

ing) forms.

Complete sagittal synostosis

The child is placed in the supine position. A

bicoronal incision is made with a lazy sigmoid curve.

The incision extends posterior to the ears bilaterally.

The curve in the incision allows the hair to cover the

incision once the patient has grown and resists

undesirable parting of the hair along the incision.

The scalp is reflected to expose the entire calvarium,

including the frontal, biparietal, and occipital bones.

The authors have found that blood loss can be

minimized if the pericranium is left on the skull dur-

ing scalp reflection.

If the anterior and posterior fontanelles are open,

they are often used for stripping the dura away from

Fig. 6. Frontal bossing. (A) A bifrontal craniotomy is performed. (B) The frontal bones are contoured using radial barrel staves

and the Tessier bender.


the calvarial bone. If they have closed, burr holes are

made on either side of the sagittal suture anteriorly as

well as posteriorly. As shown in Fig. 2, the sagittal as

well as bilateral coronal and lambdoid sutures are

removed. The extent to which the cranial vault can be

shortened is defined by the amount of bone that is

removed on either side of the coronal and lambdoid

sutures. By removing the sutures one frees the primary

points of fixation of the dura and calvarium, allowing

Fig. 7. Schematic drawing of occipital bossing.

the skull to be reshaped. As shown in Fig. 3A, the

parietal bones are then outfractured to increase the

width of the skull. In older children whose calvarial

bones have thickened and become overly stiff, barrel

stave osteotomies may be used. The removed sagittal

suture is typically cut in half, or fashioned to the

appropriate length, and rotated 90� so it may be used

as a strut to hold the biparietal bones outward. This

strut is held in place with absorbable plates (Fig. 3B).

Fig. 8. Schematic drawing of occipital bossing with the dural

venous sinuses overlaid.

Fig. 9. Occipital bossing repair. (A) An occipital craniotomy is performed. (B) The occipital bone is contoured using barrel stave

osteotomies and the Tessier bender.


Having addressed the width, the surgeons then direct

their attention to the length. As shown in Fig. 4, the

frontal and occipital bones are fixed to the parietal

bones using absorbable plates. At this time the ante-

rior-posterior dimension can be corrected to the extent

to which both the frontal and occipital bones are

brought toward the center axis. This is a judicious,

strategically oriented squeeze. By increasing the width

of the skull first, then shortening the length, the

surgeons can maintain the total intracranial volume.

Frontal bossing

The child is placed in the supine position. The

bicoronal incision is made and the scalp is reflected.

The sagittal coronal and lambdoid sutures are again

removed. The parietal and occipital remodeling is

performed as previously described. With frontal boss-

ing (Fig. 5), the frontal bones are also removed. The

frontal cut is taken just superior to the orbital rim, as

the frontal bossing typically extends to the orbital rim

(Fig. 6A). With use of the Tessier bender and rotation

of the frontal bones individually, a contour to the

frontal region can often be achieved (Fig. 6B).

Occipital bossing

In this case the child is placed in a modified prone

or sphinx position. This position allows easier access

to the dominant abnormality, yet still permits some

access to the anterior structures. The bicoronal scalp

incision generally may be made more posteriorly than

in the other procedures. Again the scalp is reflected

and the sutures are removed. The parietal bones are

widened and the frontal bones are brought in toward

the center axis as previously described. With occipital

bossing (Figs. 7,8), an occipital craniotomy is per-

formed (Fig. 9A). Often the craniotomy is brought

inferiorly to include the calvarium covering the tor-

qula. It is important to recognize this and pay special

attention to this region. We have found the CT

venogram to be helpful in defining the venous anat-

omy in this region. The occipital bone is then

remodeled and flattened, using radial osteotomies

and the Tessier bender to restore a normal contour

to the occipital region of the skull (Fig. 9B).

Results

The procedures described above have produced

a consistent correction for total sagittal synostosis,

frontal bossing, and occipital bossing. The authors are

able to do this with minimal operative morbidity. The

procedure does routinely require the use of blood

transfusion, which the authors typically obtain from a

living related donor. The hospital stay is typically up

to 5 days, with 1 day in the pediatric intensive care

unit. Three representative cases from the authors’

series of patients are illustrated in Figs. 10–12.

Fig. 10. Follow-up (A, B), postoperative (C, D), and preoperative (E, F) frontal and lateral pictures of a representative patient.







Summary

The authors’ current technique is a safe, effective

method for correcting the deformities associated with

sagittal synostosis. It provides an immediate correc-

tion that does not require any further manipulations to

the skull, such as a molding helmet. The technique

addresses all the aspects of the deformity. It increases

the width as well as the central height of the skull and

decreases the length of the skull to produce a rounder

cranial vault.

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Correction of sagittal synostosis using a modified Π method