Supplementary sensorimotor area epilepsy in adults.
Based on stimulation studies, observation of seizure phenomena in patients with epilepsy, and diagnostic studies documenting SSMA anatomic and functional abnormalities, there is evidence that epileptic involvement of the SSMA results in a set of clinical phenomena that include asymmetric tonic posturing of the extremities, abduction and elevation of the contralateral upper extremity, and speech arrest with preserved consciousness. Auras and vocalization occur less frequently. These seizures tend to be brief and to have an abrupt onset and cessation. They are more common during sleep than during wakefulness, and they tend to occur multiple times per night. The abolition of seizures following a resection limited to the SSMA provides conclusive evidence that the SSMA is the epileptogenic zone in some patients with this type of seizure. On the other hand, there is variation in seizure phenomena among patients whose seizures originate in the SSMA. In addition, there are patients with seizures suggestive of SSMA involvement whose seizures originate in a broad epileptogenic zone that includes the SSMA, other patients whose seizures originate outside the SSMA and spread to the SSMA, and still other patients whose seizures originate outside the SSMA and remain outside the SSMA. To better understand the phenomena associated with SSMA seizure onset and to determine the specificity of certain phenomena to SSMA involvement, additional data are needed from structural and functional imaging studies, video and EEG monitoring studies with noninvasive and invasive electrodes, and pathologic and surgical outcome studies. Since one cannot be certain at this time of the specificity of seizure phenomena to SSMA involvement, and because localization for possible surgery is the primary rationale for detailed study of these patients, we recommend that the term SSMA seizure refer only to those seizures that originate in the SSMA and that SSMA epilepsy refer only to epilepsies in which the patient's seizures originate in the SSMA. Since the present classification of epileptic seizures is not of value in describing the major phenomena of a partial seizure or in localization of the site of onset, a descriptive classification is needed to improve communication concerning seizure phenomena and to provide clues to localization.
King
D W
DW
Department of Neurology, Medical College of Georgia, Augusta 30912, USA.
Smith
J R
JR
D000328:Adult; D004558:Electric Stimulation; D004827:Epilepsy / Q000175:diagnosis / Q000503:physiopathology*; D006801:Humans; D009044:Motor Cortex / Q000503:physiopathology*; D012640:Seizures / Q000503:physiopathology; D013003:Somatosensory Cortex / Q000503:physiopathology*