Center for Interdisciplinary Research in Rehabilitation and Social Integration (CIRRIS), Quebec City, Quebec, Canada.
Laval University, Quebec City, Quebec, Canada.
Neurorehabil Neural Repair. 2020 Nov;34(11):997-1008. doi: 10.1177/1545968320962497. Epub 2020 Oct 3.
Neuropathic pain is a major problem following spinal cord injury (SCI). Central mechanisms involved in the modulation of nociceptive signals have been shown to be altered at the chronic stage, and it has been hypothesized that they might play a role in the development of chronic pain.
This prospective longitudinal study aimed to describe the evolution of pain modulation mechanisms over time after SCI, and to explore the relationships with the presence of clinical (neuropathic and musculoskeletal) pain.
Patients with an SCI were assessed on admission (n = 35; average of 38 days postinjury) and discharge (n = 25; average of 131 days postinjury) using the International Spinal Cord Injury Pain Basic Data Set. Conditioned pain modulation was assessed using the cold pressor test (10 °C; 120 s) as the conditioning stimulus and tonic heat pain, applied above the level of injury, as the test stimulus (120 s). Heat pain threshold was also assessed.
A marked decrease in the efficacy of conditioned pain modulation was observed over time, with 30.2% of inhibition at admission and only 12.9% at discharge on average ( = .010). This decrease was observed only in patients already suffering from neuropathic pain at admission and was not explained by a general increase in sensitivity to thermal nociceptive stimuli.
These results suggest that the presence of neuropathic pain leads to a decrease in conditioned pain modulation over time, rather than supporting the hypothesis that inefficient conditioned pain modulation mechanisms are leading to the development of neuropathic pain.
神经性疼痛是脊髓损伤（SCI）后的一个主要问题。已经表明，在慢性阶段，涉及疼痛信号调制的中枢机制发生了改变，并且有人假设它们可能在慢性疼痛的发展中起作用。
本前瞻性纵向研究旨在描述 SCI 后疼痛调制机制随时间的演变，并探讨其与临床（神经性和肌肉骨骼性）疼痛存在的关系。
在入院时（n = 35；平均伤后 38 天）和出院时（n = 25；平均伤后 131 天），使用国际脊髓损伤疼痛基本数据集评估患有 SCI 的患者。使用冷加压测试（10°C；120 秒）作为条件刺激，并在上肢损伤水平上方施加持续热痛作为测试刺激（120 秒），评估条件性疼痛调制。还评估了热痛阈值。
随着时间的推移，条件性疼痛调制的效果明显下降，入院时的抑制率为 30.2%，出院时平均为 12.9%（ =.010）。这种下降仅发生在入院时已经患有神经性疼痛的患者中，并且不能用热伤害性刺激敏感性的普遍增加来解释。
这些结果表明，神经性疼痛的存在导致条件性疼痛调制随时间的降低，而不是支持无效的条件性疼痛调制机制导致神经性疼痛发展的假设。
