Development of movement-related intracortical inhibition in acute to chronic subcortical stroke

Objective:A prospective longitudinal cohort study in stroke patients was performed to better understand the role of -aminobutyric acid-dependent intracortical inhibition (ICI) for recovery after stroke.Methods:Patients with acute first-ever subcortical stroke and hand paresis were recruited, and motor function as well as ICI were measured up to 1 year after stroke. Motor recovery was defined as the change in hand motor function from the acute to the chronic stage ( = recovery over 1 year). Primary outcome measures for hand motor function were the recovery of grip strength (GS) and finger-tapping speed (FT). Using double-pulse transcranial magnetic stimulation, we studied ICI in the ipsilesional primary motor cortex during the preparation of a movement with the paretic hand at different time points during recovery (first week, 7 weeks, 3 months, and 1 year after stroke).Results:Eleven patients were enrolled (mean age 62.9 3.8 years). The results of a multiple regression analysis showed a significant association of movement-related ICI in the acute stage only (first week) with motor recovery over 1 year (GS: R-2 = 0.75, F = 17.6, p = 0.006; FT: R-2 = 0.55, F = 7.3, p = 0.035). More disinhibition of ICI in the acute phase of stroke predicted more improvement in GS ( = -0.86, p = 0.006) and FT ( = -0.74, p = 0.035), independent of the initial motor deficit.Conclusions:Movement-related ICI one week after a subcortical stroke is associated with better outcome of hand motor function. Disinhibition in the ipsilesional primary motor cortex could be a mechanism of how the brain attempts to promote motor recovery after stroke.