Progressive myoclonus epilepsy (PME) is different from myoclonic epilepsy. In myoclonic epilepsy, the myoclonic jerking motions occur as part of the seizure. In PME, myoclonus occurs separately from seizures, the two respond differently to the same drugs, they evolve differently during the natural history of the disease, and they cause different problems for the patient. Some drugs that are good for seizures, e.g. phenytoin and carbamazepine, may tend to make the myoclonus worse.