The nociceptive flexion reflex (NFR) is a spinally mediated withdrawal response and is used as an electrophysiological marker of descending modulation of spinal nociception. Chemical and pharmacological modulation of nociceptive neurotransmission at the spinal level has been evidenced by direct effects of neurotransmitters and pharmacological agents on the NFR. Largely unexplored are, however, the effects of nonpharmacological noninvasive conservative interventions on the NFR. Therefore, a systematic review and meta-analysis was performed and reported following the PRISMA guidelines to determine whether and to what extent spinal nociception measured through the assessment of the NFR is modulated by conservative therapy in patients and healthy individuals. Five electronic databases were searched to identify relevant articles. Retrieved articles were screened on eligibility using the predefined inclusion criteria. Risk of bias was investigated according to Version 2 of the Cochrane risk-of-bias assessment tool for randomized trials. The evidence synthesis for this review was conducted in accordance with the Grading of Recommendations Assessment, Development and Evaluation. Thirty-six articles were included. Meta-analyses provided low-quality evidence showing that conservative therapy decreases NFR area and NFR magnitude and moderate-quality evidence for increases in NFR latency. This suggests that conservative interventions can exert immediate central effects by activating descending inhibitory pathways to reduce spinal nociception. Such interventions may help prevent and treat chronic pain characterized by enhanced spinal nociception. Furthermore, given the responsiveness of the NFR to conservative interventions, the NFR assessment seems to be an appropriate tool in empirical evaluations of treatment strategies.

PROSPERO registration number: CRD42020164495.

伤害性屈曲反射 (NFR) 是一种脊髓介导的退缩反应，被用作脊髓伤害性下行调节的电生理标志。神经递质和药物对 NFR 的直接影响已经证明了脊髓水平伤害性神经传递的化学和药理学调节。然而，非药物非侵入性保守干预措施对 NFR 的影响很大程度上尚未被探索。因此，根据 PRISMA 指南进行了系统回顾和荟萃分析并进行了报告，以确定通过 NFR 评估测量的脊柱伤害感受是否以及在多大程度上受到患者和健康个体保守治疗的调节。检索了五个电子数据库以识别相关文章。使用预定义的纳入标准对检索到的文章进行资格筛选。根据随机试验的 Cochrane 偏倚风险评估工具第 2 版对偏倚风险进行了调查。本次审查的证据综合是根据建议评估、制定和评价的分级进行的。收录了三十六篇文章。荟萃分析提供了低质量的证据，表明保守治疗减少了 NFR 面积和 NFR 幅度，并提供了中等质量的证据，表明 NFR 潜伏期增加。这表明保守干预可以通过激活下行抑制通路来减少脊髓伤害感受，从而发挥直接的中枢作用。此类干预措施可能有助于预防和治疗以脊髓伤害感受增强为特征的慢性疼痛。此外，考虑到 NFR 对保守干预措施的反应性，NFR 评估似乎是治疗策略实证评估的合适工具。

PROSPERO 注册号：CRD42020164495。