Artikel
Neurophysiological investigation of patient with postherpetic neuralgia treated with Spinal Cord Stimulation (SCS)
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Veröffentlicht: | 8. Juni 2016 |
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Gliederung
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Objective: Spinal Cord Stimulation is an evidence based neuromodulatory procedure for the treatment of chronic pain disorders. Results of few previously published investigations on the effect of SCS on the somatosensory system have been inconclusive. Moreover, none of the recent studies have evaluated whether SCS is able to quantitatively reduce the hyperalgesic area of pain patients.
Method: We performed a sensory mapping using pricking stimuli in a 67-year old female patient with a cervical Spinal Cord Stimulation (octapolar lead, lower cervical spine) because of post herpetic neuralgia C4-C8 on the left side. We used quantitative sensory testing (QST) to assess somatosensory effects of SCS. The patient was examined twice, during her “off” phase and one hour after switching on the stimulator.
Results: SCS reduced pain by 33% (VAS) and the hyperalgesic area noticeably by approximately 40%. SCS increased both, the thermal detection thresholds and the mechanical detection thresholds of the affected area, while the reverse was observed at the contralateral (control) side. Unexpectedly, we found a mild increase of pain sensitivity to pricking stimuli within the affected area when the stimulator was switched “on”. Paradoxical heat sensations were abolished by SCS, but dynamic mechanical allodynia remained unaffected. SCS had no significant effects on pressure pain thresholds and only slightly reduced vibration detection thresholds.
Conclusions: QST is a reliable tool to quantitatively assess SCS effects on evoked pain. We suggest including sensory mapping and a comprehensive quantitative sensory testing battery as standard measures for SCS patients to ameliorate selection procedures and to assess long-term effects of SCS.