High-Resolution EEG in Poststroke Hemiparesis Can Identify Ipsilateral Generators During Motor Tasks

Abstract

Background and Purpose —Multimodal neuroimaging with positron emission tomography (PET) scanning or functional MRI can detect and display functional reorganization of the brain’s motor control in poststroke hemiplegia. We undertook a study to determine whether the new modality of 128-electrode high-resolution EEG, coregistered with MRI, could detect changes in cortical motor control in patients after hemiplegic stroke. Methods —We recorded movement-related cortical potentials with left and right finger movements in 10 patients with varying degrees of recovery after hemiplegic stroke. All patients were male, and time since stroke varied from 6 to 144 months. All patients were right-handed. There was also a comparison group of 20 normal control subjects. Results —Five of 8 patients with left hemiparesis had evidence of ipsilateral motor control of finger movements. There were only 2 cases of right hemiparesis; in addition, 1 patient had a posteriorly displaced motor potential originating behind a large left frontal infarct (rim). Conclusions —Reorganization of motor control takes place after stroke and may involve the ipsilateral or contralateral cortex, depending on the site and size of the brain lesion and theoretically, the somatotopic organization of the residual pyramidal tracts. Our results are in good agreement with PET and functional MRI studies in the current literature. High-resolution EEG coregistered with MRI is a noninvasive imaging technique capable of displaying cortical motor reorganization.