Practice Essentials
Craniosynostosis occurs in approximately 1 in 2000 live births. The term craniosynostosis refers to premature closure of one or more of the major cranial vault sutures— the sagittal, coronal, metopic, and lambdoid sutures. [1] (See the image below.)
Premature closure of a suture leads to characteristic changes in the shape of the skull, which relate not only to the reduced growth at the fused suture but also to the compensatory growth at adjacent open sutures. The resultant deformity is often observable in the neonatal period, but milder forms may not be immediately apparent. Most cases of craniosynostosis involve a single suture, occur sporadically without a prior family history of craniosynostosis, and are not associated with other physical abnormalities (ie, are nonsyndromic). [2]
No medical treatment exists for craniosynostosis and helmet therapy alone does not correct the head shape. Most children with craniosynostosis are recommended for surgery; however, children with mild deformities or those who present late without signs of increased intracranial pressure (ICP) are occasionally treated without surgery.
There are several options for treatment, ranging from removal of the closed suture (suturectomy) to reconstruction of the cranial vault. Each of these options has inherent advantages and disadvantages. (See Treatment.) The focus of this article is on options for cranial vault reconstruction of the more common nonsyndromic single-suture craniosynostoses (SSCs).
Anatomy
The types of craniosynostosis may be described in either of the following ways:
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According to the clinical deformity itself often described by its shape (eg, trigonocephaly)
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According to the sutures affected (eg, metopic synostosis)
The former descriptive approach was developed by Virchow, who was influenced by then-prevailing anthropologic concepts; the latter was developed by Ingraham and Matson and was based mainly on radiologic evidence of fused sutures. There is considerable correspondence between the two nomenclatures, which is better appreciated in single-suture forms of craniosynostosis.
The rules for growth with regard to the fused sutures are indicated by the arrows in the illustrations below. Closure of a single suture not only causes restriction of growth perpendicular to the fused suture but also causes compensatory growth at adjacent sutures. [3] If the adjacent suture is parallel to the fused suture, the compensatory growth occurs equally in both directions. If the suture is perpendicular to the fused suture, the compensatory growth occurs away from the fused suture.
The following are four common types of craniosynostosis (in order of frequency):
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Scaphocephaly corresponds to sagittal synostosis (see the first image below) and is derived from the Greek words skaphos ("boat") and kephale ("head")
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Plagiocephaly corresponds to unilateral coronal synostosis (see the second image below) and is derived from the Greek words plagios ("oblique or sloping") and kephale
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Trigonocephaly corresponds to metopic synostosis (see the third image below) and is derived from the Greek words trigonos ("triangular") and kephale
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Posterior plagiocephaly corresponds to lambdoid synostosis (see the fourth image below)
Etiology
The etiology of craniosynostosis has not been fully elucidated, but genetic defects are increasingly being recognized. No inheritance pattern has been identified for nonsyndromic forms of craniosynostosis, though a familial occurrence has been observed in the vast minority of patients. First-degree relatives are affected most commonly in cases of metopic craniosynostosis, followed by sagittal, lambdoid, and, rarely, coronal craniosynostosis. [4] In familial cases, variable vertical and horizontal penetrance has been observed.
In 2010, a retrospective genetic study of craniosynostosis showed mutations as the cause in 37.5% of bilateral coronal, 17.5% of unilateral coronal, and 11% of multiple-suture craniosynostosis. The mutations were absent in all patients with nonsyndromic metopic, sagittal, and lambdoid craniosynostosis. [5]
Epidemiology
The overall prevalence of craniosynostosis has been estimated to be 1 case in 2000 live births. Of the SSCs, the most common, in order of decreasing incidence, are sagittal, unilateral coronal, metopic, and lambdoid synostosis.
Prognosis
Surgery improves the cranial deformity in most patients with SSC. However, it is not uncommon to perceive some residual skull-shape abnormality. In a minority of patients, the deformity recurs after a few years and necessitates reoperation. The majority of patients with SSC are treated primarily from a progressive deformity standpoint and do not develop elevated ICP or other neurological sequelae.
Some studies of children who have SSC have suggested that although there does not appear to be an increased incidence of intellectual disability, craniosynostosis may be associated with an increased incidence of subtle learning disabilities. [6, 7] As many as half of all SSC patients may be found to have neurodevelopmental issues. [5, 8] Nevertheless, the cause of these subtle learning disabilities has not been fully elucidated.
Although it has sometimes been assumed that increased ICP plays a role, only a minority of infants with SSC are found to have increased ICP; yet a higher percentage have learning disabilities. Altered brain morphology has also been proposed as an explanation, but studies have not shown worsened cognitive outcomes in children with more severe deformities. [9] Advanced imaging (diffusion tensor imaging [DTI]) has also suggested persistent altered brain connectivity in children with treated sagittal craniosynostosis. [10]
Junn et al retrospectively reviewed long-term neurocognitive outcomes in 204 pediatric patients (mean age at surgery, 9.0 ± 12.2 mo; mean age at testing,10.9 ± 4.0 y) who underwent surgical correction of nonsyndromic SSC (139 sagittal, 39 metopic, 22 unicoronal, 4 lambdoid). [11] Patients with metopic synostosis had lower scores in verbal IQ, full-scale IQ, visuomotor integration, visual perception, and motor control after surgical correction than patients with sagittal synostosis did. Patients with unicoronal had lower visuomotor integration and visual perception scores.
Lynn et al assessed neurodevelopmental outcomes in 66 patients with nonsyndromic SSC who were treated by means of cranial vault remodeling and were tested pre- and postoperatively with the Bayley Scales of Infant and Toddler Development (Third Edition) (BSID-III). [12] There were no significant changes between preoperative and postoperative neurodevelopmental functioning. The authors suggested that language and motor development are modestly delayed in such patients and that these delays are present before and after cranial vault remodeling. They did not find cranial vault remodeling to have a significant impact on the neurodevelopmental trajectory.
Regardless of the timing or type of surgery performed, there is an increased incidence of mild neuropsychological deficits.
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Normal anatomic suture configuration.
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Metopic craniosynostosis (trigonocephaly).
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Sagittal craniosynostosis (scaphocephaly).
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Unilateral coronal craniosynostosis (anterior plagiocephaly).
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Lambdoid craniosynostosis (posterior plagiocephaly).
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3D reconstruction of child with sagittal craniosynostosis.
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3D reconstruction of child with right unilateral coronal craniosynostosis.
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3D reconstruction of child with bilateral coronal (bicoronal) craniosynostosis.
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3D reconstruction of child with metopic craniosynostosis.
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3D reconstruction of child with left lambdoid craniosynostosis. 3D-reconstructed CT venography of same child with left lambdoid craniosynostosis demonstrating dominant right transverse sinus.
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Bilateral coronal craniosynostosis repair. 3D rendering of standard CT performed on postoperative day 1 after consolidation and then months later. Note lengthening of skull, as well as decrease in vertical height.
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Bilateral coronal craniosynostosis repair. 3D rendering of standard CT performed on postoperative day 1 after subsequent fronto-orbital advancement.
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Lambdoid craniosynostosis repair. 3D rendering of standard CT performed on postoperative day 1 following reconstruction. Bilateral parietal craniotomies were performed, leaving sagittal suture in place. Bioccipital craniotomy was accomplished, and overgrown mastoid bone was removed and then elevated with bone grafts from craniotomies. Bone from contraleral parietal bone was used for occipital reconstruction. Ipsilateral partietal bone was placed contralaterally, and bone from bioccipital craniotomy was used to reconstruct ipsilateral parietal bone.
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Preoperative view of patient with metopic craniosynostosis (supine position). Note bifrontal narrowing and posterior parietal widening giving triangular shape (trigonocephaly) to skull on top-down view.
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Preoperative CT of patient with metopic craniosynostosis. Note bifrontal narrowing and posterior parietal widening giving triangular shape (trigonocephaly) to skull on top-down view. Note fused (absent) metopic suture anteriorly at midline with other sutures patent (visible).
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Intraoperative view of released fronto-orbital bandeau (top-down) prior to remodeling. Note triangular shape with flattening laterally.
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Intraoperative view of metopic craniosynostosis skeletal deformity after scalp flap reflection.
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Completion of repair for metopic craniosynostosis with scalp closed.
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Preoperative view of sagittal craniosynostosis with bicoronal incision marked. Prone position. Note biparietal narrowing and occipital narrowing.
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Intraoperative view of sagittal craniosynostosis after scalp flap reflection. Note Raney clips on skin edges. Markings designate sites of craniotomy with exception of central marking, which identifies fused sagittal suture at midline. Central segment of bone including suture will be removed. Prone position.
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Intraoperative view of sagittal craniosynostosis after removal of bone. Parietal bones on each side have been divided into segments and widened. Occiput has been flattened, as demonstrated by surgeon's finger. Prone position.
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Sagittal craniosynostosis after repair with scalp closed. Prone position.
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Preoperative top-down view of patient with unilateral (right) coronal craniosynostosis. Note flattened right forehead with elevated orbit and contralateral left side prominence (bossing) of forehead.
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Preoperative top-down CT view of same patient with unilateral (right) coronal craniosynostosis. Note flattened right forehead with elevated orbit and contralateral left side prominence (bossing) of forehead.
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Intraoperative view of same patient with unilateral (right) coronal craniosynostosis, looking directly down onto forehead. Top of head is at bottom of picture. Two sides of forehead were exchanged, placing prominent left side on right and flattened right side on left after contouring. Right side is overcorrected in position as compared with left.
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Intraoperative top-down view of same patient with unilateral (right) coronal craniosynostosis at completion of repair. Right side is overcorrected in position as compared with left at orbital rim (upper right portion of image).
Tables
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- Overview
- Presentation
- DDx
- Workup
- Treatment
- Approach Considerations
- General Principles of Surgical Therapy
- Sagittal Craniosynostosis Repair
- Unilateral Coronal Craniosynostosis Repair
- Bilateral Coronal Craniosynostosis Repair
- Metopic Craniosynostosis Repair
- Lambdoid Craniosynostosis Repair
- Postoperative Care
- Complications
- Long-Term Monitoring
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- Media Gallery
- References
