Squamosal suture synostosis: a cause of atypical skull asymmetry

The squamosal suture is markedly different from the major calvarial sutures of the human skull. The unique properties of the suture are a result of the complex developmental biology of the temporal bone and biomechanical force exerted by surrounding structures. The dysmorphic effects of premature fusion of the suture, and possible treatment strategies in cases of synostosis, have received only brief description in the literature.

A retrospective case series was performed. The study included patients evaluated by one of the senior authors (S.P.B., R.R.R., and D.J.S.) between 1993 and 2009. All pertinent patient data including inpatient and outpatient charts, photographic records, and radiographic scans were reviewed. Any management performed under the direction of a craniofacial surgeon was documented--including orthotic helmet therapy and operative management.

The study included 14 patients. Synostosis of the squamosal suture was noted to occur either in an isolated fashion or in the setting of other craniofacial malformations. Patients with isolated squamosal synostosis often suffered from a deformity that was mild in severity and tended to improve with time. However, when occurring in the setting of other forms of craniosynostosis, the deformity was often progressive, and transcranial surgery was frequently required.

Synostosis of the squamosal suture can result in, or contribute to, significant craniofacial dysmorphism. The optimal form of therapy for this disorder is evolving.