Artikel
Antinociceptive effects of spinal cord stimulation: electrophysiology and psychophysics in chronic pain patients
Antinozizeptive Effekte nach Rückenmarkstimulation: Elektrophysiologie und Psychophysik bei chronischem Schmerz
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Autoren
Veröffentlicht: | 4. Mai 2005 |
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Gliederung
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Objective
Spinal cord stimulation (SCS) is applied for a variety of pain disorders. Due to the lack of well-documented and randomised studies, SCS remains doubted to be more than a placebo treatment. We addressed antinociceptive effects of SCS by electrophysiological and psychophysical means in chronic pain patients.
Methods
Somatosensory processing was investigated by applying laser-evoked cortical potentials (LEP) and quantitative sensory testing (QST) in patients suffering from traumatic ulnar nerve lesion (n=1), traumatic peroneal and tibial nerve lesions (n=1), or chronic sciatica (n=4). Thermal and mechanical stimuli were applied to the painful test area and the corresponding contralateral healthy area (upper arm, thigh, lower leg, foot). QST consisted of warm, cold, cold pain, and heat pain thresholds determination by a computer controlled Peltier type thermode (TSAII, Medoc, Israel). Mechanical detection and pain thresholds were determined by von Frey filaments and pinprick stimulators. Phasic radiant heat stimuli of an infrared thulium-YAG laser (Baasel Lasertech, Germany) elicited pricking painful sensations and cortical potentials. LEP were recorded by surface EEG electrodes at sites Fz, Cz, Pz, T3, and T4 according to the 10-20-system. Patients participated in two experimental sessions before and after SCS implantation.
Results
All patients indicated analgesic effects of SCS with at least 50% pain reduction. Painful laser stimuli did evoke no LEP (5/6) or pathological LEP (1/6) on the painful side in patients without SCS. After implantation, LEP recovered in one patient with chronic sciatica. Three patients showed pathologically increased cold, cold pain, and heat pain thresholds before SCS. Under SCS, heat pain threshold improved in two patients, cold and cold pain thresholds in one patient each. Raised mechanical thresholds on painful side, partly recovered in three out of five patients under SCS.
Conclusions
Beside the subjective pain reduction after SCS implantation, LEP and QST documented partial or total recovery of somatosensory dysfunction in four out of six chronic pain patients. The results indicate objective antinociceptive effects of SCS.