Long-lasting effects of paired associative stimulation in hemiparetic stroke patients

Purpose: To establish whether motor point stimulation paired with repetitive transcranial magnetic stimulation (rTMS) produces a lasting modulation of the primary motor cortex in persons with hemiparetic stroke. Methods: Subjects were nine hemiparetic patients after stroke, all right-handed. The mean days from onset were 80 days. Repeated measurements of the motor evoked potential (MEP) in the affected first dorsal inter osseous (FDI) muscle in all subjects were performed. For determination of baseline, a single measurement of the MEPs was given before intervention stimulation. Subjects received 30 min of just suprathreshold motor point stimulation of the affected abductor pollicis brevis (APB) muscle paired every 10 s with TMS over the motor cortex. After intervention stimulation, measures of MEPs were taken immediately (0 min) and at 10, 20 and 30 min. Results: The MEPs significantly increased in amplitude immediately after pairing stimulation and recovered to baseline after 30 min in amplitude. Conclusions: In stroke hemiparetic patients, as well as healthy subjects, paired stimulation increases the corticomotor excitability for short periods after stimulation. This finding might have potential therapeutic implications for stroke rehabilitation.