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

Background: Both cerebral hemispheres seem to contribute to motor recovery after stroke. We studied the effect of motor activity on cerebral blood flo w in both hemispheres at different stages of stroke evolution. Methods: Thi rty 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 oppo sition task while blood flow velocities in both middle cerebral arteries we re measured with transcranial Doppler ultrasonography (TCD). Results: Contr alateral movement caused a higher increase in blood flow velocity than ipsi lateral movement in controls (p < 0.0001). On the healthy side, patients sh owed a striking increase with ipsilateral movement (affected hand), which w as similar to the increase with contralateral movement (normal hand) at all stages. On the damaged side, the increase with contralateral movement (aff ected hand) was low and was similar to the increase with ipsilateral moveme nt (normal hand) at T1 and T2; however, at T3 the increase with contralater al movement was higher and the pattern of response was similar to that foun d in controls. Conclusions: TCD can trace the evolution of brain motor outp ut following stroke. Compensatory activation of the healthy side of the bra in may be already present soon after stroke, whereas function of the damage d side may improve during several months.