Reinders Laurien J, de Vos Cecile C
Erasmus University Medical Centre, Centre for Pain Medicine, Anaesthesiology, Dr. Molewaterplein 40, 3015 GD Rotterdam, the Netherlands.
Clin Neurophysiol Pract. 2025 May 3;10:167-171. doi: 10.1016/j.cnp.2025.04.003. eCollection 2025.
The mechanisms of spinal cord stimulation (SCS) are insufficiently understood. Conditioned pain modulation (CPM) measures how a painful stimulus is affected by a second painful stimulus. We investigated whether cortical evoked response can be used to evaluate CPM in a patient treated with burst, tonic and sham SCS.
A 40-year-old patient underwent 3 magnetoencephalography sessions (burst, tonic, sham SCS) with 1-week intervals. Painful electrical stimuli were applied to the tibial nerve before, during and after CPM (conditioning: icepack on forearm). Evoked responses were analysed in the primary somatosensory and anterior cingulate cortices.
Before CPM, the highest evoked response amplitude occurred under sham SCS, followed by tonic SCS. During CPM pain ratings remained unchanged. However, CPM reduced evoked response amplitudes in the primary somatosensory cortex under tonic and sham SCS and in the anterior cingulate cortex under all SCS paradigms.
CPM reduced evoked response amplitudes, while pain ratings were unaffected, suggesting neurophysiological measures provide additional insights into CPM effects. Tonic and burst SCS both appeared to reduce cortical capacity to attend to stimuli, with burst showing the greatest effect.
Cortical responses offer a valuable tool to assess pain pathways. Larger scale studies are needed to enhance our understanding of SCS mechanisms.
脊髓刺激（SCS）的机制尚未得到充分理解。条件性疼痛调制（CPM）测量一种疼痛刺激如何受到另一种疼痛刺激的影响。我们研究了在接受爆发式、强直性和假刺激SCS治疗的患者中，皮层诱发反应是否可用于评估CPM。
一名40岁患者接受了3次脑磁图检查（爆发式、强直性、假刺激SCS），间隔为1周。在CPM之前、期间和之后（条件刺激：在前臂放置冰袋），对胫神经施加疼痛性电刺激。在初级体感皮层和前扣带回皮层分析诱发反应。
在CPM之前，最高的诱发反应幅度出现在假刺激SCS下，其次是强直性SCS。在CPM期间，疼痛评分保持不变。然而，CPM降低了强直性和假刺激SCS下初级体感皮层以及所有SCS模式下前扣带回皮层的诱发反应幅度。
CPM降低了诱发反应幅度，而疼痛评分未受影响，这表明神经生理学测量为CPM效应提供了额外的见解。强直性和爆发式SCS似乎都降低了皮层对刺激的关注能力，爆发式表现出最大的效果。
皮层反应为评估疼痛通路提供了一种有价值的工具。需要进行更大规模的研究来加深我们对SCS机制的理解。
