Craniofacial Clefting and Syndromic Congenital Craniofacial Anomalies
Craniofacial clefts occur as a result of a developmental arrest or mechanical disruption of development. Etiologic theories include a failure of neural crest cell migration and a failure of fusion or movement of facial processes. Facial clefts in the skeletal structures are distributed around the orbit and maxilla; clefts in the soft tissues are most apparent around the eyelids and lips. Examples of clefting syndromes affecting the orbit and eyelids include some forms of midline clefts with hypertelorism as well as the oculoauriculovertebral spectrum, which includes hemifacial microsomia, oculoauriculovertebral dysplasia (Goldenhar syndrome), and mandibulofacial dysostosis (Treacher Collins syndrome, Fig 3-4A).
The bones of the skull or orbit may also have congenital clefts through which the intracranial contents can herniate. These protruding contents can be the meninges (meningocele), brain tissue (encephalocele), or both meninges and brain tissue (meningoencephalocele). When these herniations involve the orbit, they most commonly present anteriorly with a protrusion subcutaneously near the medial canthus or over the bridge of the nose. Straining or crying may increase the size of the mass, and the globe may be displaced temporally and downward (inferolaterally). Such herniations less commonly move into the posterior orbit; these lesions may cause anterior displacement and pulsation of the globe. Intranasal extension may occur, causing life-threatening airway obstruction. Treatment is surgical and should be carried out in collaboration with a neurosurgeon. Meningoceles and encephaloceles adjacent to the orbit are frequently associated with anomalies of the optic nerve head, such as morning glory disc anomaly.
Figure 3-4 Craniofacial deformities. A, Mandibulofacial dysostosis (Treacher Collins syndrome). B, Craniofacial dysostosis (Crouzon syndrome).
(Courtesy of Jill Foster, MD.)
Craniosynostosis can occur as an isolated abnormality or in conjunction with other anomalies as part of a genetic syndrome. Syndromic craniosynostosis is the premature closure of 1 or more sutures in the bones of the skull and results in various skeletal deformities, including orbital defects. Associated ophthalmic problems include strabismus, astigmatism, ptosis, proptosis, nasolacrimal duct obstruction, and amblyopia. Secondary intracranial hypertension can be a complication. Hypertelorism and proptosis are frequently observed in craniosynostosis syndromes such as Crouzon syndrome (craniofacial dysostosis; Fig 3-4B) and Apert syndrome (acrocephalosyndactyly; Fig 3-5). Syndromic craniosynostosis is a genetically heterogeneous disorder, with mutations identified in several genes, predominantly the fibroblast growth factor receptor genes.
The severe orbital and facial defects associated with craniofacial disorders can sometimes be improved with surgery. Bony and soft tissue reconstruction is generally necessary. Such operations are often staged and usually require a team approach with multiple subspecialists.
Jadico SK, Huebner A, McDonald-McGinn DM, Zackai EH, Young TL. Ocular phenotype correlations in patients with TWIST versus FGFR3 genetic mutations. J AAPOS. 2006; 10(5):435–444.
Figure 3-5 Apert syndrome (acrocephalosyndactyly). A, Hypertelorism and proptosis. B, Syndactyly.
(Courtesy of Jill Foster, MD.)
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.