Centre for Pain Medicine, Swiss Paraplegic Centre, Nottwil, Switzerland.
Department of Anesthesiology and Intensive Care, University Medical Centre Mannheim, University of Heidelberg, Heidelberg, Germany.
PLoS One. 2022 Jul 14;17(7):e0271327. doi: 10.1371/journal.pone.0271327. eCollection 2022.
We explored whether increased C-nociceptor excitability predicts analgesic effects of topical lidocaine in 33 patients with mono- (n = 15) or poly-neuropathy (n = 18). Excitability of C-nociceptors was tested by transcutaneous electrical sinusoidal (4 Hz) and half sine wave (single 500 ms pulse) stimulation delivered to affected and non-affected sites. Analgesic effects of 24 hrs topical lidocaine were recorded. About 50% of patients reported increased pain from symptomatic skin upon continuous 4 Hz sinusoidal and about 25% upon 500 ms half sine wave stimulation. Electrically-evoked half sine wave pain correlated to their clinical pain level (r = 0.37, p < 0.05). Lidocaine-patches reduced spontaneous pain by >1-point NRS in 8 of 28 patients (p < 0.0001, ANOVA). Patients with increased pain to 2.5 sec sinusoidal stimulation at 0.2 and 0.4 mA intensity had significantly stronger analgesic effects of lidocaine and in reverse, patients with a pain reduction of >1 NRS had significantly higher pain ratings to continuous 1 min supra-threshold sinusoidal stimulation. In the assessed control skin areas of the patients, enhanced pain upon 1 min 4 Hz stimulation correlated to increased depression scores (HADS). Electrically assessed C-nociceptor excitability identified by slowly depolarizing electrical stimuli might reflect the source of neuropathic pain in some patients and can be useful for patient stratification to predict potential success of topical analgesics. Central neuronal circuitry assessment reflected by increased pain in control skin associated with higher HADS scores suggest central sensitization phenomena in a sub-population of neuropathic pain patients.
我们探讨了在 33 名患有单神经病（n = 15）或多神经病（n = 18）的患者中，C 伤害感受器兴奋性增加是否预示着局部利多卡因的镇痛效果。通过经皮正弦（4 Hz）和半正弦波（单个 500 ms 脉冲）刺激传递到受影响和未受影响的部位来测试 C 伤害感受器的兴奋性。记录了 24 小时局部利多卡因的镇痛效果。约 50%的患者报告说，在持续 4 Hz 正弦波和大约 25%在 500 ms 半正弦波刺激下，症状性皮肤的疼痛增加。电诱发的半正弦波疼痛与他们的临床疼痛水平相关（r = 0.37，p < 0.05）。利多卡因贴片在 28 名患者中的 8 名中减轻了自发性疼痛超过 1 个 NRS 点（p < 0.0001，ANOVA）。在 0.2 和 0.4 mA 强度下对 2.5 秒正弦波刺激增加疼痛的患者对利多卡因的镇痛效果明显更强，相反，疼痛减轻超过 1 NRS 的患者对持续 1 分钟阈上正弦波刺激的疼痛评分明显更高。在患者的评估对照皮肤区域中，1 分钟 4 Hz 刺激时疼痛增加与抑郁评分（HADS）升高相关。通过缓慢去极化电刺激评估的 C 伤害感受器兴奋性可能反映了一些患者的神经病理性疼痛的来源，并且可以用于患者分层以预测局部镇痛剂的潜在成功。与更高的 HADS 评分相关的对照皮肤中疼痛增加反映了中枢神经元电路评估，提示神经病理性疼痛患者的亚群存在中枢敏化现象。
