Involvement of the healthy hemisphere in recovery from aphasia and motor deficit in patients with cortical ischemic infarction: A transcranial Doppler study

Activation of areas of the healthy hemisphere seems to play a role in functional recovery from stroke. We studied cerebral blood flow changes during motor and mental activity in patients with cortical ischemic lesions. We simultaneously measured blood flow velocity in the two middle cerebral arteries of 45 patients with single cortical ischemic lesions and good functional recovery and of 16 healthy controls by means of bilateral transcranial Doppler ultrasonography during a 2-minute sequential thumb-to- finger opposition task, alternately performed with the right and left hands, and during a 1-minute word-fluency task. Twenty-five patients had left cortical lesions, 12 with previous motor deficit alone and 13 with associated motor deficit and Broca's aphasia. Twenty patients had right cortical lesions with previous motor deficit. With respect to baseline values, the increase of flow velocity in the middle cerebral artery contralateral to the hand performing the motor task was comparable in controls and patients, regardless of the side of the lesion and the hand (normal or recovered) involved in the task. During movement of the recovered hand, the increase of flow velocity in the ipsilateral middle cerebral artery was significantly greater (p <0.001, two-way ANOVA) than the increase during movement of the normal hand in both controls and patients. During performance of the word-fluency task, the increase of flow velocity in the left middle cerebral artery was comparable in controls and patients. In patients with left lesions and previous aphasia, the increase of flow velocity in the right middle cerebral artery was significantly higher than in controls (p = 0.02, one-way ANOVA), patients with right cortical lesions (p = 0.01), and patients with left lesions but no previous aphasic problem (p = 0.001). These data suggest a contribution of the undamaged hemisphere to the functional recovery of patients with cortical ischemic lesions.