A case with nocturnal paroxysmal unilateral dystonia and interictal right frontal epileptic EEG focus: a lateralized variant of nocturnal paroxysmal dystonia?

We report here a patient with frequent nocturnal attacks, characterized by paroxysmal dystonic posturing of the left arm and contraction of the lower face, lasting 20-30 seconds. The attacks occurred in clusters of up to 20 spasms during the NREM stage of sleep. Interictal EEG showed clear-cut epileptic discharges in the right frontal region. Repeated ictal video-EEG recordings revealed only arousal pattern immediately before and during seizures except in those which evolved to left sided clonic hemiconvulsions. The dystonic attacks here described share many features of nocturnal paroxysmal dystonia (NPD) of Lugaresi and Cirignotta in common, including nocturnal periodic occurrence, absence of ictal EEG changes during attacks, and favorable response to CBZ, except for their unilateral nature. It was assumed that our case may be a lateralized variant of NPD and would further support the hypothesis that NPD is one particular form of frontal lobe epilepsy.