Hydromyelia and Chiari malformation in children and adolescents

Abstract

A series of 24 patients with Chiari malformation and hydromyelia, treated at the Prince of Wales Children's Hospital between 1975 and 1991, is reviewed. The age range of these patients was 3 to 19 years. Eleven had a Chiari 1 malformation and 13 had a Chiari 2 malformation. The follow-up period ranged from 6 months to 16 years with a mean of 5 years. Twenty-one patients had posterior fossa decompression procedures as the primary treatment, with or without plugging of the central canal at the obex. Forty-five per cent of the Chiari 1 patients and 62% of the Chiari 2 patients showed sustained neurological improvement. A further 36% of the Chiari 1 patients and 15% of the Chiari 2 patients had their neurological deficits stabilised. Following operation, sustained radiological collapse of the cavity occurred in 9 out of the 11 cases of Chiari 1 malformation. The follow-up radiology in the Chiari 2 patients has been incomplete. Complications following posterior fossa procedures with plugging of the central canal were transient and there has not been long-term morbidity. Posterior fossa decompression, fourth ventriculostomy, obex plugging and dural grafting is recommended in those cases where the surgical anatomy allows dissection of the tonsils from the brainstem. Plugging of the central canal at the obex is of value if the muscle plug is firmly secured.