Aftereffects of 2 noninvasive brain stimulation techniques on corticospinal excitability in persons with chronic stroke: a pilot study.

Background And Purpose: Noninvasive brain stimulation, including repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS), have gained popularity in the stroke rehabilitation literature. Little is known about the time course and duration of effects of noninvasive brain stimulation on corticospinal excitability in individuals with stroke. We examined the aftereffects of a single session of high-frequency rTMS (5 Hz) and anodal tDCS on corticospinal excitability in the same sample of participants with chronic stroke.

Methods: Ten individuals with chronic stroke participated in this randomized cross-over study. Participants received 1 session of rTMS and 1 session of tDCS, with 1 week between sessions. During the rTMS session, 5-Hz rTMS (total of 1200 stimuli) was administered to the ipsilesional primary motor cortex (M1). For anodal tDCS, 1 mA of direct current was delivered to the ipsilesional M1 for 20 minutes. Motor evoked potentials were measured before and after (immediately, 15 minutes, 30 minutes, and 60 minutes) each stimulation session.

Results: Both 5-Hz rTMS and anodal tDCS significantly increased corticospinal excitability for 30 to 60 minutes after stimulation. There was no statistically significant difference between the 2 stimulation techniques in their effects on motor evoked potentials. No changes in measures of motor or cognitive performance were observed.

Discussion And Conclusion: Both 5-Hz rTMS and anodal tDCS induced effects on corticospinal excitability in persons with chronic stroke lasting at least 1 hour after stimulation. In the absence of concurrent motor practice, neither form of stimulation applied in a single session was associated the changes in motor performance. These approaches to increased cortical excitability may be of value as adjuncts to training.

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