Background: Transcranial direct current stimulation (tDCS) seems to facilitate and/or inhibit neural activity and improve motor function in neurological patients. However, it is important to confirm such improvements as well as determine the association between neurophysiological changes and the enhancement of motor control.
Research question: Does the improvement of motor control in neurological patients after transcranial direct current stimulation translate into changes in the motor evoked potential?
Methods: A systematic electronic search strategy was employed to identify studies indexed in the PubMed, BIREME, and COCHRANE databases using a combination of search terms adapted to each database: transcranial direct current stimulation; evoked potential motor; and motor control. Relevant data was extracted from each selected article and methodological quality was assessed using the PEDro scale. Standard mean differences with 95% confidence intervals were pooled using a random-effects model. Moreover, standard methods were employed for assessment of the heterogeneity of the studies.
Results: Thirteen articles were included in this review. Anodal tDCS was found to increase the amplitude and diminish the latency of the MEP, which correlated positively with improvements in motor control. However, the improvement in MEP did not persist over time.
Significance: Despite the paucity of studies, positive effects are found when combining anodal tDCS and a therapeutic intervention, such as an improvement in MEP and better motor control in neurological patients. Future studies should include neurophysiological measures other than MEP and consider a homogenous analysis.
Keywords: Cortical excitability; Motor control; Motor evoked potential; Motor function; Transcranial direct current stimulation.
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