CHIARI MALFORMATION IN CROUZON SYNDROME

Background.- Use of MRI makes the association Chiari malformation-cran io-facial synostosis more frequent than expected. The aim of this work was to ascertain the true incidence of Chiari malformation and to und erstand the reasons of the association between a bone pathology and a CNS malformation. Patients and methods.- The anatomy of the posterior cranial fossa in Crouzon syndrome was retrospectively studied on MRI s can in 49 patients. Results.- A chronic tonsillar hemiation, similar t o a Chiari malformation was observed in 71.4% of the cases. All the pa tients with Crouzon syndrome and progressive hydrocephalus had a Chiar i malformation, but only 19 out of the 33 patients without associated hydrocephalus had a Chiari malformation (57.6%). Significant differenc es between the pattern of lambdoid suture closure were founded between both groups, with and without Chiari malformation, the lambdoid closu re appearing earlier in patients with Chiari malformation. Conclusion. - The high incidence of chronic tonsillar herniation in Crouzon syndro me seems related to the premature synostosis of the lambdoid suture.