Chiari Malformation Associated With Craniosynostosis

Jennifer Strahle, M.D.; Karin M. Muraszko, M.D.; Steven R. Buchman, M.D.; Joseph Kapurch, B.S.; Hugh J. L. Garton, M.D., M.H.Sc.; Cormac O. Maher, M.D.


Neurosurg Focus. 2011;31(3):e2 

In This Article

Abstract and Introduction


Object Chiari malformation (CM) Type I is frequently associated with craniosynostosis. Optimal management of CM in patients with craniosynostosis is not well-established. The goal of this study was to report on a series of pediatric patients with both craniosynostosis and CM and discuss their management.
Methods The authors searched the medical records of 383 consecutive patients treated for craniosynostosis at a single institution over a 15-year period to identify those with CM. They recorded demographic data as well as surgical treatment and outcomes for these patients. When MR imaging was performed, cerebellar tonsillar descent was recorded and any other associated findings, such as hydrocephalus or spinal syringes, were noted.
Results A total of 29 patients with both CM and craniosynostosis were identified. Of these cases, 28% had associated occipital venous abnormalities, 45% were syndromic, and 52% also had hydrocephalus. Chiari malformation was more likely to be present in those patients with isolated lambdoid synostosis (55%), multisuture synostosis (35%), and pansynostosis (80%), compared with patients with coronal synostosis (6%) or sagittal synostosis (3%). All patients underwent surgical repair of craniosynostosis: 16 had craniosynostosis repair as well as CM decompression, and 13 patients did not undergo CM decompression. Of the 7 patients in whom craniosynostosis repair alone was performed, 5 had decreased tonsillar ectopia postoperatively and 5 had improved CSF flow studies postoperatively. Both patients with a spinal syrinx had imaging-documented syrinx regression after craniosynostosis repair. In 12 patients in whom CM was diagnosed after primary craniosynostosis repair, 5 had multiple cranial vault expansions and evidence of elevated intracranial pressure. In 5 cases, de novo CM development was documented following craniosynostosis repair at a mean of 3.5 years after surgery.
Conclusions Chiari malformation is frequently seen in patients with both multi- and single-suture lambdoid craniosynostosis. Chiari malformation, and even a spinal cord syrinx, will occasionally resolve following craniofacial repair. De novo development of CM after craniosynostosis repair is not unusual.


The association between CM and craniosynostosis has been recognized for several decades.[36] Chiari malformation occurs in patients with both syndromic and nonsyndromic forms of craniosynostosis.[5,7,9,17,18,41,42] Up to 70% of individuals with Crouzon syndrome and 50%–82% of those with Pfeiffer syndrome have associated CM.[4,5,7] There are also several reports of CM with nonsyndromic synostosis involving the sagittal, coronal, and even the metopic sutures.[17,25,41] Cerebellar tonsillar ectopia in patients with craniosynostosis is thought to arise from disproportionately slow growth or the small size of the posterior fossa in many cases.[5] Hydrocephalus, venous hypertension, and associated congenital brain anomalies have also been proposed as possibly important factors leading to CM development in these patients.[5,34,39,40] The optimal management of CM in the setting of craniosynostosis is not well established. Some surgeons advocate simultaneous surgical correction of craniosynostosis and CM, and others suggest that CM should only be treated if it is symptomatic or associated with a syrinx.[5,7] We describe our experience with a group of children with synostoses of one or more cranial sutures and CM, and we propose a management strategy for these complex cases.


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