Loss of interhemispheric inhibition on the ipsilateral primary sensorimotor cortex in patients with brachial plexus injury: fMRI study.

This functional magnetic resonance imaging study verified an antagonistic pattern in which a concomitant deactivation of ipsilateral primary sensorimotor (SM1) was coupled to the contralateral SM1 activation in healthy controls during unimanual hand grasping. Of note, dramatic reduction of ipsilateral SM1 deactivation (loss of antagonistic pattern) was observed during movement of intact hands by patients with unilateral brachial plexus injury. We propose that the disappearance of the antagonistic pattern of SM1 activities in the patients with brachial plexus injury reflects a reduction of interhemispheric inhibition, which may mirror an adaptive mechanism to functional status.