Clinical neurophysiologic studies in stiff-man syndrome: use of simultaneous video-electroencephalographic-surface electromyographic recording.

Three patients with a clinical diagnosis of stiff-man syndrome were studied with simultaneous video-electroencephalographic-surface electromyographic recordings in addition to routine electromyography in order to obtain objective data to confirm their diagnosis, to improve our understanding of the diagnosis of stiff-man syndrome, and to define reproducible clinical and neurophysiologic criteria for the stiff-man syndrome. These patients had the following features of this syndrome: (1) continuous muscle activity that varied with awake and sleep states, posture, passive and active movements, and medications; (2) superimposed intermittent generalized contractions while awake, which continued into drowsiness and interfered with onset of sleep; and (3) abnormal cocontractions of antagonistic muscles. The characteristic findings in the stiff-man syndrome can be recorded by using video-electroencephalographic-surface electromyographic techniques, a useful application of equipment already available in most electroencephalography laboratories. Neurophysiologic techniques can help in elucidating the clinical findings in the stiff-man syndrome. Further systematic study in patients before and during treatment is needed to identify common diagnostic criteria for this syndrome.