J Korean Acad Rehabil Med.  2001 Feb;25(1):85-90.

Effect of Isometric Muscle Contraction on the Somatosensory Evoked Potentials

• Sohn MK
• Kim YK
• Song JY
• Bok SK
• Cho KH
• Kim BO

Abstract

OBJECTIVE
To investigate the association of the muscle contraction with gating of the sensory input at central and peripheral levels according to the intensity of muscle contraction and location of the muscles, somatosensory evoked potentials (SSEPs) studies were evaluated at different levels of isometric contraction in the different muscles. METHOD: Median nerve SSEPs were recorded at Erb's point and scalp in the ten healthy adult subjects with isometric contraction of ipsilateral abductor pollicis brevis (APB), ipsilateral abductor digiti minimi (ADM) and contralateral APB. Median nerve SSEPs were recorded in each of these conditions during precontraction, weak contraction, strong contraction and 4 minutes after contraction.
RESULTS
1) N9 amplitudes of median SSEPs recorded at Erb's point were augumented during weak contraction and these amplitude augumentations were statistically significant in the ipsilateral APB contraction (p<0.05). 2) N20 amplitudes recorded at scalp were inhibited during strong isometric contraction and these amplitude inhibitions were statistically significant in the ipsilateral APB contraction (p<0.05). 3) The latencies of N9 and N20 potentials were not significantly changed during isometric contraction.
CONCLUSION
Therefore peripheral nervous system as well as central nervous system is responsible for gating, so the subject should be asked for the best relaxation possible for higher reliability of SSEPs.

Keyword

Isometric muscle contraction; Somatosensory evoked potentials; Gating

MeSH Terms

Adult
Central Nervous System
Evoked Potentials, Somatosensory*
Humans
Isometric Contraction
Median Nerve
Muscle Contraction*
Muscles
Peripheral Nervous System
Relaxation
Scalp