Novaes Isabela C, Ardestani Soraya S, Nascimento Allen Matheus S, Conti Paulo C R, Bonjardim Leonardo R, Svensson Peter, Exposto Fernando G, Costa Yuri M
Department of Biosciences, Universidade Estadual de Campinas (UNICAMP), Faculdade de Odontologia de Piracicaba (FOP), Piracicaba, Brazil.
Department of Prosthetic Dentistry, Bauru School of Dentistry, University of Sao Paulo, Bauru, Sao Paulo, Brazil.
Sci Rep. 2025 Jan 2;15(1):308. doi: 10.1038/s41598-024-83312-8.
This study compared the degree of secondary hyperalgesia and somatosensory threshold changes induced by topical capsaicin between spinal and trigeminal innervation. This crossover clinical trial included 40 healthy individuals in which 0.25 g of 1% capsaicin cream was randomly applied for 45 minutes to a circular area of 2 cm to the skin covering the masseter muscle and forearm in 2 different sessions, separated by at least 24 hours and no more than 72 hours (washout period). The main outcome variables were the area of allodynia and pinprick hyperalgesia, as well as electrical and mechanical pain thresholds within the area of pinprick hyperalgesia. Mixed ANOVA models and McNemar tests were applied to the data (p = 0.050). The occurrence of allodynia and pinprick hyperalgesia was higher in the forearm than in the masseter (p < 0.050). Additionally, the areas of pinprick hyperalgesia and allodynia were larger in the forearm compared to the masseter (p < 0.050). The electrical and mechanical pain thresholds demonstrated a loss of somatosensory function following capsaicin application to the masseter (p < 0.050). However, no significant somatosensory threshold changes were observed at the forearm after capsaicin (p > 0.050). In conclusion, these findings indicate potential differences compatible with central sensitization related to secondary hyperalgesia between trigeminal and spinal innervation.
本研究比较了辣椒素局部应用于脊髓和三叉神经支配区域所诱导的继发性痛觉过敏程度和体感阈值变化。这项交叉临床试验纳入了40名健康个体，在两个不同的时间段中，将0.25克1%的辣椒素乳膏随机涂抹于覆盖咬肌和前臂皮肤的2厘米圆形区域，持续45分钟，两个时间段间隔至少24小时且不超过72小时（洗脱期）。主要结局变量为痛觉过敏区域和针刺性痛觉过敏区域，以及针刺性痛觉过敏区域内的电痛阈和机械痛阈。对数据应用了混合方差分析模型和 McNemar 检验（p = 0.050）。前臂出现痛觉过敏和针刺性痛觉过敏的发生率高于咬肌（p < 0.050）。此外，与咬肌相比，前臂针刺性痛觉过敏和痛觉过敏区域更大（p < 0.050）。对咬肌应用辣椒素后，电痛阈和机械痛阈显示体感功能丧失（p < 0.050）。然而，对前臂应用辣椒素后未观察到明显的体感阈值变化（p > 0.050）。总之，这些发现表明三叉神经和脊髓神经支配在继发性痛觉过敏方面与中枢敏化相关的潜在差异。
