Nonsyndromic craniosynostosis

Abstract

Nonsyndromic craniosynostosis is more commonly encountered than syndromic cases in pediatric craniofacial surgery. Affected children display characteristic phenotypes according to the suture or sutures involved. Restricted normal growth of the skull can lead to increased intracranial pressure and changes in brain morphology, which in turn may contribute to neurocognitive deficiency. Management has primarily focused on surgical correction of fused sutures prior to 12 months of age to optimize correction of the deformity and to ameliorate the effects of increased intracranial pressure. However, emphasis has recently shifted to better understanding the pathogenesis of neurocognitive impairment observed in these children, along with genetic mutations that contribute to premature suture fusion. Such understanding will provide opportunities for earlier and more specific neurocognitive interventions and for the development of targeted genetic therapy to prevent pathologic suture fusion. The authors review the common types of nonsyndromic craniosynostosis and the epidemiological, genetic, and neurodevelopmental details that are currently known from the literature. In addition, they present the rationale for surgical correction, offer suggestions for timing of intervention, and present some nuances of techniques that they find important in producing consistent results.

Keywords: cranial suture; craniosynostosis; neurocognitive development; nonsyndromic craniosynostosis.

Figure 1

Three-dimensional computed tomography reconstructions of sagittal synostosis. (A) Lateral view demonstrating scaphocephaly and saddle deformity of the skull. (B) Vertex view (forehead is oriented downward) demonstrating a partially fused sagittal suture. Classic parietal and occipital narrowing is apparent.

Figure 2

Three-dimensional computed tomography reconstructions of unicoronal synostosis (A) Top-down view demonstrating the unilateral forehead retrusion and anterior displacement of the zygoma on the affected side. (B) Anterior view demonstrating the periorbital deformities and maxillary rotation “facial twist,” with nasal tip deviation to the contralateral side.

Figure 3

Three-dimensional computed tomography reconstructions of bicoronal synostosis. (A) Oblique top-down view to include the face. This demonstrates the bilateral forehead retrusion. (B) Lateral view demonstrating the typical appearance of the turribrachycephaly phenotype.

Figure 4

Three-dimensional computed tomography reconstructions of metopic synostosis. (A) Top-down view demonstrating trigonocephaly of the forehead. (B) Anterior view demonstrating the bitemporal narrowing and medialization of the superior medial orbits.

Figure 5

Unilateral lambdoid synostosis. (A) Clinical photograph of the posterior view. This shows the inferior displacement of the ear on the affected side as well as the oblique towering appearance of the skull on posterior view. (B) Three-dimensional computed tomography reconstruction (posterior view) demonstrating a partially fused left lambdoid suture. The classic mastoid bulge and tilt of the skull base is apparent.

Figure 6

Intraoperative photographs of the described modified Pi procedure. (A) Posterior and vertex view with the patient in prone position. The occiput is flattened with bilateral medially based occipital wedge osteotomies. The occipital contour can be held into place with resorbable plates and screws as shown or allowed to float without fixation. (B) Lateral view with the patient in prone position. This shows the lateral barrel stave osteotomies down to the level of the squamosal sutures. The coronal suture is centered on the anteriormost barrel stave. The lambdoid suture is centered on the posteriormost barrel stave.

Figure 7

Reshapened frontal bandeau (ex situ) in reconstruction of unicoronal synostosis. (A) Top-down view. This shows the asymmetric design of the orbital bandeau to include a longer temporal segment on the affected side. The bandeau is bent to the desired overcorrection. Resorbable plates and screws are placed on the intracranial side at the glabella and the temporal wing on the affected side to hold the shape of the advancement and twist. (B) Anterior view. This shows the asymmetric design of the lateral orbital cuts. The osteotomy on the affected side is performed to include the entire lateral orbital rim down to the body of the zygoma, similar to a C-shaped osteotomy of the zygoma. Onlay bone grafts can be considered for additional brow projection on the affected side. However, the long-term viability and resorption of these grafts are unknown.

Figure 8

Lateral view of the frontal bandeau and frontal bone placed back in situ. The frontal bandeau is advanced and twisted, which rotates the temporal wing of the bandeaus superiorly. This maneuver produces enhanced brow prominence. The bifrontal bone is contoured to the reconstructed bandeau configuration and replaced as a single unit.

Figure 9

Reconstructed in situ appearance of the frontal bandeau. (A) Top-down view demonstrating the significant improvement in intracranial volume after appropriate advancement and twist of the frontal bandeau with fixation to the nasofrontal region and zygoma bilaterally. (B) Lateral view of the frontal bandeau showing the desired position of the temporal wings of the bandeau after the advancement and twist maneuver.

Figure 10

Forehead contour of metopic synostosis versus benign metopic ridge. (A) Typical view of forehead contour in a patient with metopic synostosis. The classic features of trigonocephaly are apparent. (B) Typical view of the forehead contour in a patient with benign metopic ridge. The forehead is normally round without trigonocephaly and normal bitemporal width. (C) Three-dimensional computed tomography reconstruction of the forehead contour in metopic synostosis. (D) Three-dimensional computed tomography reconstruction of the forehead contour in benign metopic ridge.

Figure 11

Frontal bandeau in metopic craniosynostosis. (A) Top-down view of the frontal bandeau ex situ prior to reshaping. (B) Top-down view of the frontal bandeau back in situ after reshaping. A central bone graft is placed in the glabellar region of the bandeau to flatten and widen the forehead contour for a more normal anatomic configuration of the forehead region. Bilateral posteriorly based barrel stave osteotomies are seen in the parietal regions, which are out-fractured to correct the narrowing of the skull in parietal regions.