Hypogenic Paroxysmal Dystonia Or Epilepsy

Lugaresi and Cirignotta (1981) described five patients with recurrent nocturnal episodes of agitation during nonrapid eye movement (NREM) sleep, consisting of violent limb movements and tonic spasms of 15-45-s duration with preserved consciousness, responsive to carbamazepine. Impressed by the resemblance of these clinical manifestations to the attacks of paroxysmal kine-sigenic choreoathetosis and the absence of epileptiform EEG changes, they coined the term "hypnogenic paroxysmal dystonia." Further, they proposed the existence of a distinct nosological entity akin to the former disorder, suggesting that the paroxysmal motor events, although a possible epileptic origin was discussed, might represent dystonic episodes triggered by arousals. Later Lugaresi et al. (1986) presented a larger group of patients with similar symptoms, in addition to two patients with longer lasting attacks unresponsive to medication (one of which was diagnosed with Huntington's disease at a later date), and again raised the question of a possible new syndrome of sleep-related motor attacks of uncertain nosologic classification, comprising two variants with short-and long-lasting attacks. A subsequent publication by the same group of researchers (Tinuper et al., 1990) seemingly resolved the controversy by demonstrating that the nocturnal episodes of three of their patients had an epileptiform EEG correlate, thus concluding that nocturnal paroxysmal dystonia was indeed a form of frontal lobe epilepsy. They also noticed episodes of different duration in the same patients and suggested that these represented fragments of different intensity of the same type of seizure. Meierkord et al. (1992), using a more systematic approach, compared the semiology of motor attacks among groups of patients with nocturnal paroxysmal dystonia, daytime frontal lobe seizures, and proven epileptic nocturnal motor seizures, concluding there were no clinical features that would allow a distinction between these groups. Similar observations had been made by Fusco and colleagues (1990), who described the clinical and EEG characteristics of a group of patients with nocturnal seizures of mesial frontal lobe origin consisting of repetitive rhythmic movements and dystonic postures with preserved consciousness, accompanied by bizarre vocalization, and suggested that this type of epilepsy was probably underdiagnosed.

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