Monday, November 3, 2008 - 7:54 AM

Mercedes Benz Pattern Complex Craniosynostosis

Jennifer L. Rhodes, MD and Jeffrey A. Fearon, MD, FACS, FAAP.

PURPOSE:  The “complex craniosynostoses,” which include all non-syndromic multiple sutural fusions, represent a small fraction of patients presenting with craniosynostosis. Among the complex synostoses is the Mercedes Benz pattern, identified in a focused report of 3 children with sagittal and bilateral lambdoid synostosis.  The purpose of this report was to retrospectively review our series of the Mercedes Benz pattern craniosynostosis in order to identify associated anomalies and to assess outcomes, in hopes of improving treatment strategies.

METHODS:  A retrospective clinical review was performed of all patients with craniosynostosis presenting to our craniofacial center using a prospectively maintained computer database. Records of all patients presenting with the Mercedes Benz pattern were reviewed.  Growth was assessed by direct anthropologic measurements that were converted to standard Z-scores for comparative purposes and significance was assessed by the Student's test.

RESULTS:  Over a 17-year period, of 802 patients presenting with craniosynostosis, 11 patients with the Mercedes Benz pattern synostosis were identified (1.4%). 3/11 patients had additional sutural involvement (2 unicoronal, 1 metopic), and 2/11 had identifiable genetic syndromes. Those patients with an isolated Mercedes Benz pattern of craniosynostosis underwent a single posterior cranial vault remodeling procedure, at an average age of 7-months.   Patients with additional sutural involvement (n=3) required subsequent remodeling procedures.  Almost two thirds of all patients (7/11) had cerebellar tonsillar herniation on initial pre-operative imaging, and 4 symptomatic patients (36%) have required surgical intervention.  Symptomatic Chiari malformations did not present until after two years of age.  Serial pre- and postoperative anthropologic measurements show that with growth the skull shape becomes slightly more brachycephalic, with overall growth in head circumference and skull length less than predicted.  At a mean follow up of over 4 years, (range: 8 months – 6.5 years), overall cognitive function appears grossly normal in all but one patient (diagnosed concurrently with Opitz BBB).

CONCLUSION:  Children affected with the Mercedes Benz pattern of craniosynostosis do not have normal growth postoperatively.  Diminished growth is seen in overall head circumference and skull length (resulting in progressive brachycephaly).  Based on these findings, in spite of the involvement of the sagittal suture, the goals for surgical correction should include posterior lengthening.  We also identified a significant association with progressive symptomatic cerebellar tonsillar herniation and, therefore, recommend routine screening postoperatively with magnetic resonance imaging.