M. Hoshiyama et R. Kakigi, After-effect of transcutaneous electrical nerve stimulation (TENS) on pain-related evoked potentials and magnetic fields in normal subjects, CLIN NEU, 111(4), 2000, pp. 717-724
Objectives: The after-effect of transcutaneous electrical nerve stimulation
(TENS) on pain-related brain responses was investigated using electroencep
halography (EEG) and magnetoencephalography (MEG).
Methods: We studied 13 healthy volunteers for the main experiment and 7 for
the control experiment. The pain-related evoked cerebral potentials (PREP)
at Cz and magnetic cortical fields (PRCF) on both hemispheres following pa
inful electrical finger stimulation were simultaneously recorded before and
after TENS on the right forearm of the median nerve territory at 50 Hz for
30 min. PREP and PRCF were similarly recorded without TENS in the control
experiment.
Results: The PREP components, N150 and P220, were significantly attenuated
after TENS, compared to those before TENS (P < 0.01, two-way repeated ANOVA
). However, there was no consistent change of the PRCF components. Eleven o
f 13 subjects reported no change of pain sensation after TENS. There was no
change of PREP in control experiment without TENS.
Conclusions: The results indicated that TENS reduced PREP following painful
electrical stimulation, and that the origin of PREP was, at least partiall
y, different from that of PRCF which was not changed after TENS. An after-e
ffect of TENS significantly affected the generation process of PREP, but it
was not enough to relieve the subjective painful feeling. (C) 2000 Elsevie
r Science Ireland Ltd. All rights reserved.