Supplementary motor seizures mimicking pseudoseizures: some clinical differences
Kanner, A.M.; Morris, H.H.; Lüders, H.; Dinner, D.S.; Wyllie, E.; Medendorp, S.V.; Rowan, A.J.
Neurology 40(9): 1404-1407
1990
ISSN/ISBN: 0028-3878 PMID: 2392226 Document Number: 362651
Supplementary motor seizures (SMS) are among the group of frontal lobe seizures that may often be misdiagnosed as pseudoseizures (PS). We designed this study to determine the value of clinical phenomena in distinguishing between the two. In a series of patients with SMS, we identified those with signs and symptoms mimicking PS and compared the clinical phenomena with those of clinically similar PS. We found that SMS are short in duration, stereotypic, tend to occur in sleep, and often present with a tonic contraction of the upper extremities in abduction. This sign was specific for SMS, particularly when occurring at the onset. Conversely, PS are long in duration, nonstereotypic, and occur in the awake state. We conclude that clinical phenomena may be useful in distinguishing PS from SMS, although the final diagnosis must be documented by neurophysiologic means.