HYDROMYELIA AND CHIARI MALFORMATION IN CHILDREN AND ADOLESCENTS

A series of 24 patients with Chiari malformation and hydromyelia, trea ted 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 f ollow-up period ranged from 6 months to 16 years,vith a mean of 5 year s. 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 t he Chiari 2 patients showed sustained neurological improvement. A furt her 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 pat ients has been incomplete. Complications following posterior fossa pro cedures with plugging of the central canal were transient and there ha s not been long-term morbidity. Posterior fossa decompression, fourth ventriculostomy, obex plugging and dural grafting is recommended in th ose cases where the surgical anatomy allows dissection of the tonsils from the brainstem. Plugging of the central canal at the obex is of va lue if the muscle plug is firmly secured. (C) Pearson Professional 199 6