The incidence of Chiari malformation in nonsyndromic, single suture craniosynostosis

This study was designed to determine the incidence of Chiari malformation (CM) in nonsyndromic single suture craniosynostosis (N-SSSC).

A retrospective analysis of brain magnetic resonance imaging (MRI) studies of children undergoing craniofacial surgery during 1 January, 2004-31 March, 2009 in Cleft Palate and Craniofacial Centre, Department of Plastic Surgery, Helsinki University Hospital, Helsinki, Finland, was conducted.

One hundred twenty-four N-SSSC patients were imaged using brain MRI. Of these 124 patients, seven patients were diagnosed with N-SSSC with an associated CM; the incidence CM in association with N-SSSC was thus 5.6%. The average age at the time of MRI was 37.7 months. All were males, except one. Only two types of synostosis were identified in this patient cohort: synostosis involving the sagittal suture in five cases and right coronal synostosis in two cases. The CM malformations were relatively large. The tonsillar herniation varied from 6 to 12 mm (median 9 mm). All these patients were asymptomatic of their CMs. None had operation designed directly to correct the CM.

As a conclusion, we state that the association of CM and N-SSSC is a relatively common finding, with an incidence of 5.6% in preoperative brain MRI. The significance of finding CM in preoperative brain MRI should be assessed individually in asymptomatic patients.