Transcutaneous electrical nerve stimulation(TENS) is assuming increasing clinical importance as a nonpharmacological method of pain relief. The mechanism of their analgesic action remains obscure, and it is not known how they affect sensory
processing
in general.
This study was carried out to assess whether transcutaneous electrical nerve stimulation gates somatosensory evoked potentials(SEPs) peripherally or centrally, and which afferent fibers and sensory nuclei mediate this effect.
The N9, N13, N19 potentials were recorded after stimulation of the median nerve at wrist and these potentials were conditioned by high and low frequency TENS delivered to the median nerve. The latencies of N9, N13, N19 potentials were not
affected
by
TENS. The amplitudes of N9, N13 were slightly affected, but that of N19 was significantly reduced by TENS. It is concluded that TENS may gate the somatosensory volley centrally at the level of the cuneatus nucleus or thalamocortical level.
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