Artikel
Effects of spinal cord stimulation (SCS) on cortical excitability in patients with chronic pain syndromes
Einflüsse der rückenmarksnahen Stimulation (SCS) auf die kortikale Exzitabilität bei Patienten mit chronischen Schmerzsyndromen
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Autoren
Veröffentlicht: | 4. Mai 2005 |
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Gliederung
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Objective
Although spinal cord stimulation (SCS) has been successfully applied in neuropathic pain syndromes for many years the mechanisms how SCS reduces pain are not completely understood. The aim of our study was to investigate the effect of spinal cord stimulation on cortical excitability measured by Transcranial Magnetic Stimulation (TMS).
Methods
The study was approved by the local ethics committee. Written informed consent was obtained from all participants. We investigated 5 patients with permanently implanted SCS devices due to neuropathic pain syndromes. TMS measurements were conducted in three cycles: stimulation “on”, stimulation “off”, stimulation “on”. Cortical excitability was evaluated by measuring motor threshold (MT) divided into resting (RMT) and active motor threshold (AMT), cortical silent period and intracortical inhibition and facilitation. Pain intensities were documented on a visual analogue scale.
Results
We found a distinct increase of intracortical facilitation after deactivation of the spinal cord stimulation, corresponding to an increased cerebral excitability. Reactivation of the stimulation reduced the amount of intracortical facilitation, which was correlated to pain intensities on the visual analogue scale. The cortical silent period increased after deactivation of the SCS and showed an additional increase after reactivation of the system. Resting and active motor thresholds did not change significantly with or without SCS.
Conclusions
Spinal cord stimulation seems to reduce pain induced cerebral hyperexcitability by up-regulation of inhibitory cortical and subcortical mechanisms.