Epilepsy in type 1 Chiari malformation.

In patients with Chiari malformation type 1 (CMI), epileptic seizures are occasionally reported both in symptomatic patients candidate to surgery and in patients without symptoms of tonsillar displacement in whom CM1 is often an incidental finding in the diagnostic work up for idiopathic epilepsies. In both groups of patients, the course of epilepsy is almost invariably favorable, with a few seizures easily controlled by treatment. In a subset of CM1 patients, epilepsy occurs in the context of neurodevelopmental disorders that also include mental retardation, autism and somatic dysmorphisms. Epileptic seizures must be accurately differentiated by potentially harmful paroxysmal events due to compression of the medulla, particularly by the cerebellar fits characterized by drop attacks, abnormal extensor posturing and apnea.