Modulation of Human Somatosensory Cortical Excitability by Repetitive Peripheral Nerve Stimulation

ABSTRACT

OBJECTIVE: To investigate whether the somatosensory cortical excitability could be modulated by repetitive electrical stimulation (RES) on the tibial nerve at human ankle joint. METHOD: The subjects were 10 healthy volunteers. The study was composed of 3 sessions first session, baseline evaluation; second session, RES with a intensity for proprioceptive stimulation on tibial nerve at the right ankle for 3 different duration of 30 minutes, 1 hour, and 2 hours; third session, repeat of baseline evaluation after RES (post- RES evaluation). The baseline evaluation include somatosensory evoked potential study with stimulation of right tibial nerve and compound muscle action potential (CMAPs) of tibial nerve recorded at abductor hallucis and H reflex. The amplitude of each study were measured and compared between baseline evaluation and post-RES evaluation using Kruscal-Wallis test. RESULT: There was no significant change in amplitudes of SSEP, CMAP and H reflex between baseline evaluation and post-RES evaluation of 30 minutes, 1 hour and 2 hours. CONCLUSION: This study suggests that chronic repetitive proprioceptive afferent nerve stimulations could not modulate primary somatosensory cortex in healthy subjects. However, we could not rule out the limitations of sensitivity of somatosensory evoked potential study.