State of intracortical inhibitory interneuron activity in patients with chronic stroke

ObjectivesFew studies have assessed short intracortical inhibition (SICI) in the affected hemisphere (AH) in a large number of patients with chronic stroke. In this study, SICI was assessed in chronic stroke patients with severe hemiparesis, and its relationship to clinical parameters was examined.MethodsThe participants were 72 patients with chronic hemiparetic stroke. SICI of both the AH and the unaffected hemisphere (UH) was assessed. The relationships between SICI and the location of lesion, time from onset, and finger function were studied. Motor function of the paretic finger was assessed with the Stroke Impairment Assessment Set (SIAS) and the Fugl-Meyer test upper extremity motor score. To compare the results with those of healthy subjects, SICI was assessed in seven age-matched control subjects.ResultsMEPs of the UH were evoked in all 72 subjects, and MEPs of the AH were evoked in 24 subjects. SICI of the AH was inversely correlated with paretic finger motor function and time from stroke onset. SICI of the UH was not correlated with either one. SICI of the UH was higher in the cortical lesion group than in the control group.ConclusionsThe state of intracortical inhibitory neuron activity depends on the state of motor function and lesion site even in chronic stroke patients with severe hemiparesis.SignificanceThe inhibitory system of the AH is involved in functional recovery of the paretic hand even in the chronic stage of stroke.

► Relationships between short intracortical inhibition (SICI) and lesion site, time from onset, and motor function were studied in chronic stroke patients with severe to moderate upper extremity paresis. ► Affected-side SICI had inverse correlations with paretic finger motor function and time from onset. ► The state of intracortical inhibitory neuron activity depends on the state of motor function and lesion site even in chronic stroke patients with severe hemiparesis.