Hypnogenic paroxysmal dystonia: epileptic seizure or a new syndrome?

Five patients between the ages of 7 and 74 years presented with nocturnal episodes characterized by coarse, often violent movements of the limbs and by a tonic phase of variable duration. Seizures recurred every night or almost every night during slow wave (NREM) sleep and were not associated with electroencephalographic (EEG) abnormalities. Interictal EEGs were normal during both sleep and wakefulness. Carbamazepine treatment was effective in all patients. Uniform clinical behavior and EEG patterns indicate a distinct nosological entity whose pathophysiology is not yet understood.