Effects of spinal cord stimulation on cortical excitability in patients with chronic neuropathic pain: a pilot study.
BACKGROUND
Despite a broad clinical use, the mechanism of action of SCS is poorly understood. Current information suggests that the effects of SCS are mediated by a complex set of interactions at several levels of the nervous system including spinal and supraspinal mechanisms.


OBJECTIVE
The study was undertaken to investigate the influence of SCS on distinct parameters of cortical excitability using single- and paired-pulse transcranial magnetic stimulation (TMS).


METHODS
Five patients with chronic neuropathic pain were examined with the SCS stimulator on and off by means of TMS. Pain was assessed using a visual-analogue scale. Electrophysiological and pain parameters of patients during this procedure were compared by means of a linear mixed effect model.


RESULTS
SCS induced a significant modulation of cortical excitability, especially by influencing the parameter "intracortical facilitation" (t=-2.657; df=8; p=0.029). A significant relationship between this parameter and "perceived pain" could be obtained (t=-4.798; df=8; p=0.002).


CONCLUSIONS
These results suggest that SCS is able to influence neurobiological processes at the supraspinal level and that clinical effects of SCS may be at least in part of cortical origin.
Schlaier
Jürgen R
JR
Department of Neurosurgery, University of Regensburg, 93053 Regensburg, Franz-Josef-Strauss-Allee 11, Germany. juergen.schlaier@klinik.uni-regensburg.de
Eichhammer
Peter
P
Langguth
Berthold
B
Doenitz
Christian
C
Binder
Harald
H
Hajak
Göran
G
Brawanski
Alexander
A
D000328:Adult; D002540:Cerebral Cortex / Q000502:physiology*; D002908:Chronic Disease; D004599:Electric Stimulation Therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009437:Neuralgia / Q000175:diagnosis / Q000628:therapy*; D010147:Pain Measurement; D010865:Pilot Projects; D013116:Spinal Cord / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation; D016896:Treatment Outcome