Spastic Paraplegia With Myoclonic Epilepsy

Sommerfelt et al. (1991) described a seemingly new disorder in 4 sibs, the offspring of first-cousin parents: hereditary spastic paraplegia with epileptic myoclonus. The age of onset varied from the prenatal period to 10 years of age. The main finding when the sibs were examined between 26 and 42 years of age were spastic paraplegia, epileptic myoclonus, distal muscle atrophy, mental retardation or dullness, ataxia, hearing loss, and a progressive course. Differences in phenotypic expression were striking. One sister had progressive epileptic myoclonus, ataxia, and only slight distal wasting; if seen alone, the diagnosis of Unverricht-Lundborg disease (progressive myoclonic epilepsy; 254800) might be entertained. The patients were described as having massive, build-up myoclonic 'cascade' seizures.