Supplementary motor seizures mimicking pseudoseizures: Some clinical differences

A. M. Kanner, H. H. Morris, H. Luders, D. S. Dinner, E. Wyllie, S. Q. Medendorp, A. J. Rowan

Research output: Contribution to journalArticlepeer-review

120 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)1404-1407
Number of pages4
Issue number9
StatePublished - Sep 1990
Externally publishedYes

ASJC Scopus subject areas

  • Clinical Neurology


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