Background
Craniosynostosis occurs in approximately 1 in 2000 live births. The term craniosynostosis refers to premature closure of one or more of the cranial vault sutures—namely, the metopic, sagittal, coronal, 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).
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. 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:
-
According to the clinical deformity itself (eg, trigonocephaly)
-
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. [2] 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:
-
Trigonocephaly corresponds to metopic synostosis (see the first image below) and is derived from the Greek words trigonos ("triangular") and kephale ("head")
-
Scaphocephaly corresponds to sagittal synostosis (see the second image below) and is derived from the Greek words scaphos ("boat") and kephale
-
Plagiocephaly corresponds to unilateral coronal synostosis (see the third image below) and is derived from the Greek words plagios ("oblique or sloping") and kephale
-
Posterior plagiocephaly corresponds to lambdoid synostosis (see the fourth image below)
Etiology
The etiology of craniosynostosis is not clear at present, 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 fewer than 10% of the patients. First-degree relatives are affected most commonly in cases of metopic craniosynostosis, followed by sagittal, lambdoid, and, rarely, coronal craniosynostosis. [3] 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. [4]
Epidemiology
The overall prevalence of craniosynostosis is estimated as 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. SSC has classically been regarded as a benign entity in terms of neurologic function. The decision to perform surgery was made purely for the purpose of correcting a physical deformity.
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. [5, 6] As many as half of all SSC patients may be found to have neurodevelopmental issues. [4, 7] Nevertheless, the cause of these subtle learning disabilities has not been elucidated.
Although it has sometimes been assumed that increased intracranial pressure (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. [8] Advanced imaging (diffusion tensor imaging [DTI]) has also suggested persistent altered brain connectivity in children with treated sagittal craniosynostosis. [9]
Regardless of the timing or type of surgery performed, there is an increased incidence of mild neuropsychological deficits.
-
Normal anatomic suture configuration.
-
Metopic craniosynostosis (trigonocephaly).
-
Sagittal craniosynostosis (scaphocephaly).
-
Unilateral coronal craniosynostosis (anterior plagiocephaly).
-
Lambdoid craniosynostosis (posterior plagiocephaly).
-
Sagittal craniosynostosis (scaphocephaly) repair. Delineation of planned incision.
-
Sagittal craniosynostosis repair. Bicoronal incision with placement of Raney clips.
-
Sagittal craniosynostosis repair. Full view of skull from patient's right.
-
Sagittal craniosynostosis repair. Intraoperative planning.
-
Sagittal craniosynostosis repair. Separation of anterior fontanelle from surrounding skull.
-
Sagittal craniosynostosis repair. Removal of sutures with craniotome.
-
Sagittal craniosynostosis repair. After suture removal.
-
Sagittal craniosynostosis repair. Reshaping bossed frontal bone.
-
Sagittal craniosynostosis repair. Evaluating placement of reshaped frontal bones.
-
Sagittal craniosynostosis repair. Final configuration secured in place.
-
Sagittal craniosynostosis repair. Final result after closure.
-
Unilateral coronal craniosynostosis repair. Left unilateral craniosynostosis.
-
Unilateral coronal craniosynostosis repair. Reflection of scalp.
-
Unilateral coronal craniosynostosis repair. Removal of frontal bones.
-
Unilateral coronal craniosynostosis repair. Removal of superior orbital rim.
-
Unilateral coronal craniosynostosis repair. Excised superior orbital rim.
-
Unilateral coronal craniosynostosis repair. Remodeling of superior orbital rim.
-
Unilateral coronal craniosynostosis repair. Superior orbital rim remodeled.
-
Unilateral coronal craniosynostosis repair. Completed correction of left unilateral coronal craniosynostosis.
-
Unilateral coronal craniosynostosis repair. Closure is complete.
-
3D reconstruction of child with sagittal craniosynostosis.
-
3D reconstruction of child with right unilateral coronal craniosynostosis.
-
3D reconstruction of child with bilateral coronal (bicoronal) craniosynostosis.
-
3D reconstruction of child with metopic craniosynostosis.
-
3D reconstruction of child with left lambdoid craniosynostosis. 3D-reconstructed CT venography of same child with left lambdoid craniosynostosis demonstrating dominant right transverse sinus.
-
Sagittal craniosynostosis repair. 3D rendering of thick-slice CT scan performed on postoperative day 1 following a bifrontal craniotomy, bioccipital craniotomy, and and H-type sagittal suturectomy with postcoronal and prelambdoid strip craniectomies.
-
Unilateral coronal craniosynostosis repair. 3D-rendered standard CT performed on postoperative day 1 in child with right unilateral craniosynostosis. Note “overcorrected” right previously recessed right forehead.
-
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.
-
Bilateral coronal craniosynostosis repair. 3D rendering of standard CT performed on postoperative day 1 after subsequent fronto-orbital advancement.
-
Metopic craniosynostosis repair. 3D rendering of standard CT performed on postoperative day 1 following fronto-orbital advancement procedure.
-
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.
Tables
What would you like to print?
- Overview
- Presentation
- 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
- Show All
- Media Gallery
- References
