Paroxysmal dystonia with thalamic lesion in multiple sclerosis.

Paroxysmal dystonia (PD) is a usually painful, unilateral dystonic posture, precipitated by voluntary movement, tactile stimulation, startling noise or hyperventilation. We describe two cases of paroxysmal dystonia in multiple sclerosis, both with a critically localized lesion in the thalamus, contralateral to the paroxysmal symptoms. Only one other case of paroxysmal dystonia with a demyelinated lesion of the thalamus has been reported previously.