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Updated: Aug 20, 2026

Fiber Connections of the Supplementary Motor Area Revisited: Methodology of Fiber Dissection, DTI, and Three Dimensional Documentation
Published on: May 23, 2017
Propagation of tonic posturing in supplementary motor area (SMA) seizures
Shinji Ohara1, Akio Ikeda, Takeharu Kunieda
1Human Brain Research Center, Graduate School of Medicine, Kyoto University, Shogoin, Sakyo, Kyoto 606-8507, Japan.
Abstract:
We analyzed ictal motor symptoms in 10 patients diagnosed to have supplementary motor area (SMA) seizures based on ictal encephalographic (EEG) findings and ictal clinical semiology. Inclusion criteria were (1) EEG seizure pattern in the vertex for the scalp recording or in the area over and/or adjacent to SMA for epicortical recording and (2) ictal motor semiology characterized, as previously reported, by sudden and a brief tonic posturing of extremities and trunk mainly occurring during sleep without loss of consciousness. In 50% (5/10) of the patients, tonic posturing began in one part of the body and moved to other part(s) in 5-10s. Unlike Jacksonian march seen in seizures involving the primary sensorimotor area (S1-M1), it spread in no accordance with the somatotopy in S1-M1. The sequential propagation of tonic posturing may represent the somatotopic organization within the SMA proper.
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