Progressive myoclonus epilepsies: clinical and neurophysiological diagnosis.

Diagnosis and management of the progressive myoclonus epilepsies (PMEs) provides a challenge to the clinician and neurophysiologist. Over 15 specific disorders can cause the PME syndrome; all are rare, and individual physicians are unlikely to have experience in all of them. Accurate diagnosis is essential to provide a prognosis, optimal therapy, and genetic counseling. The major causes are PME of the Unverricht-Lundborg type, Lafora disease, neuronal ceroid lipofuscinoses (three forms), MERRF (myoclonus epilepsy and ragged red fibers), and sialidoses (two forms), in addition to a number of even rarer disorders. Here we review the clinical aspects and neurophysiology of these disorders, which can now be diagnosed in life by relatively simple methods in the vast majority of cases.