Interaction Between the Brain Hemispheres - Key to Motor Recovery After Stroke

Rationale: Acute stroke leaves many patients with functional deficits, of which upper extremity motor impairment is one of the most disabling. Evidence from imaging and electrophysiological studies converge on the idea that impaired motor function after stroke is associated with disrupted network activity in the brain. Non-invasive brain stimulation methods, like transcranial magnetic stimulation (TMS), can be used to restore disrupted network activity and have been shown to successfully facilitate recovery of motor function in patients with stroke. Application of continuous theta burst stimulation (cTBS), an inhibitory form of TMS, to the contralesional motor cortex has been shown to improve the recovery of motor function in patients with stroke. However, responsiveness to this treatment varies considerably between stroke patients and the mechanisms through which contralesional cTBS facilitates recovery of motor function remain unclear. Objective: To determine if contralesional cTBS normalizes interhemispheric inhibition from the contralesional to ipsilesional primary motor cortex stroke patients with motor impairments. Age-matched healthy persons will serve as controls. Study design: A prospective, open-label within-subject intervention study Study population: 40 patients with first-ever ischemic stroke in one hemisphere and a unilateral paresis of the upper extremity, and 40 age-matched controls. Main endpoints: Primary endpoint: Interhemispheric inhibition from the contralesional to ipsilesional primary motor cortex. Secondary endpoints: contralesional intracortical inhibition; effect of contralesional TMS interference on finger tapping frequency.