Correlations of flow velocity changes during mental activity and recovery from aphasia in ischemic stroke

Mean flow velocity in the middle cerebral arteries (MCAs) during a rest period and during execution of a word-fluency task were measured by means of bilateral transcranial Doppler ultrasonography in 26 stroke patients with Broca's aphasia and in 25 healthy controls. Changes in flow velocity were calculated as percentage of increase from rest to mental activity. In patients, the evaluation was made within 21 days from onset of symptoms and after 2 months of speech therapy, when they were classified into two groups on the basis of extent of recovery from aphasia: absent or slight recovery (group 1, 10 patients) and good recovery (group 2, 16 patients). During the word-fluency task in the first evaluation, the increase in flow velocity in the left MCA was similar in controls and in group 2 patients. In both groups the increase was higher than in group 1 patients (p < 0.0001). Changes in mean flow velocity on the right side were slight and comparable in the three groups of study subjects. After speech therapy, group 1 patients showed a hemodynamic pattern on both sides similar to that observed in the first examination. In group 2 patients, comparison between values of the first and second evaluations showed that the increase of flow velocity in the left MCA was similar. On the right side, the increase was higher in the second than in the first examination (p < 0.01). These data further support the involvement of cerebral areas contralateral to the lesion in functional recovery after stroke. Moreover, the presence of an activation of areas in the lesioned hemisphere, soon after stroke onset, seems to be a predictor of recovery from aphasia.