Motor cortex disinhibition in acute stroke

Objectives: To test whether a disinhibition occurs in the human motor cortex after stroke. Methods: Patients with a mild to moderate hemiparesis after an acute unilateral ischemic stroke were compared with age-matched healthy controls. We used paired transcranial magnetic stimuli (TMS) to investigate intracortical inhibition and facilitation. Single TMS were applied to obtain a cortical silent period. Results: Intracortical inhibition was significantly reduced in the affected hemisphere at interstimulus intervals of 2, 3 and 4 ms. The cortical silent period was significantly prolonged when compared to the unaffected hemisphere of the patients and to the control group. Motor cortex disinhibition observed in stroke patients was associated either with minimal impairment at the onset of symptoms or with rapidly improving motor functions. Conclusions: Motor cortex disinhibition occurs in humans after stroke. We suggest that this disinhibition is indicative of compensatory mechanisms, which are involved in recovery-related reorganization.