[Chiari "malformation" in Crouzon syndrome].

BACKGROUND

Use of MRI makes the association Chiari malformation-cranio-facial synostosis more frequent than expected. The aim of this work was to ascertain the true incidence of Chiari malformation and to understand 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 scan in 49 patients.

RESULTS

A chronic tonsillar herniation, similar to a Chiari malformation, was observed in 71.4% of the cases. All the patients with Crouzon syndrome and progressive hydrocephalus had a Chiari malformation, but only 19 out of the 33 patients without associated hydrocephalus had a Chiari malformation (57.6%). Significant differences between the pattern of lambdoid suture closure were founded between both groups, with and without Chiari malformation, the lambdoid closure appearing earlier in patients with Chiari malformation.

CONCLUSION

The high incidence of chronic tonsillar herniation in Crouzon syndrome seems related to the premature synostosis of the lambdoid suture.