Bihemispheric contribution to motor recovery after stroke: A longitudinal study with transcranial doppler ultrasonography.

Both cerebral hemispheres seem to contribute to motor recovery after stroke. We studied the effect of motor activity on cerebral blood flow in both hemispheres at different stages of stroke evolution. Thirty patients with hemiplegic stroke and 30 controls were included. Patients were examined within the first week (T1), 1 month (T2) and 6 months after stroke (T3). All subjects performed a 2-min sequential thumb-to-finger opposition task while blood flow velocities in both middle cerebral arteries were measured with transcranial Doppler ultrasonography (TCD). Contralateral movement caused a higher increase in blood flow velocity than ipsilateral movement in controls (p < 0.0001). On the healthy side, patients showed a striking increase with ipsilateral movement (affected hand), which was similar to the increase with contralateral movement (normal hand) at all stages. On the damaged side, the increase with contralateral movement (affected hand) was low and was similar to the increase with ipsilateral movement (normal hand) at T1 and T2; however, at T3 the increase with contralateral movement was higher and the pattern of response was similar to that found in controls. TCD can trace the evolution of brain motor output following stroke. Compensatory activation of the healthy side of the brain may be already present soon after stroke, whereas function of the damaged side may improve during several months.