Electrophysiological Studies in Two Patients with Cherry Red Spot‐Myoclonus Syndrome

Abstract

Two unrelated patients with the cherry red spot-myoclonus syndrome, a rare chronic neuronal storage disorder that begins in childhood with progressive myoclonus, cherry red spots at the macula, and easily controlled seizures, but no dementia, were investigated electrophysiologically to characterize the myoclonic and EEG features of this syndrome. Phenomenologically, the disease most closely resembled the Ramsay Hunt syndrome, although certain unique features were noted and the patients were not photo-sensitive. Pathologically and clinically, the disease was related to mucolipidosis type I and atypical cases of GM1 gangliosidosis, and the EEG obtained were identical to those seen in mucolipidosis type I. Because of the unusual clinical picture presented in this disease, there should be no difficulty in differentiating it from other more malignant storage disorders and progressive myoclonus epilepsies of childhood. Electrophysiological findings suggested that the myoclonic jerks do not originate cortically, but the specific subcortical generators were not identified.