Nocturnal paroxysmal dystonia

Abstract

Nocturnal paroxysmal dystonia (NPD) along with paroxysmal arousals (PAs) and episodic nocturnal wanderings (ENW) are considered the three characteristic manifestations of nocturnal frontal lobe epilepsy (NFLE). Episodes of NPD begin as paroxysmal arousals, but are subsequently associated with more complex movements including bipedal automatisms, rhythmic twisting movements of the trunk and pelvis, vocalization, and tonic or dystonic posturing lasting less than a few minutes. The epileptic versus nonepileptic origin of NPD has been extensively debated. A network including frontal and possible extrafrontal limbic structures is involved in the genesis of the complex epileptic manifestations of NFLE. Recently, we have started recognizing the co-occurrence of NFLE with parasomnias. The observation that similar motor features can accompany both arousal disorder parasomnias and seizures, including those of NFLE has led to the hypothesis that both phenomena may indicate a release of normal neocortical inhibition of central pattern generators in mesencephalon, pons, and/or spinal cord. The predominant source of confusion is episodes characterized by sudden arousal from sleep with motor activity and often dramatic or bizarre behaviors. As such, the disorders to be considered are the NREM arousal parasomnias, rapid eye movement (REM) sleep behavior disorder, and nocturnal panic attacks as they may present in the similar fashion. A small dose of carbamazepine treatment is effective in 70 % of the patients, whereas a third of the patients, commonly with a high seizure frequency, are drug resistant. In patients with NFLE, use of individually tailored antiepileptic drug (AED) dosing, that is, higher doses of AEDs in the evening, may be helpful.