Thermal Integrative Stimuli for Assessment of Neuropathic Pain after SCI

描述(由申请人提供)： 慢性神经性疼痛是脊髓损伤(SCI)的一个特别麻烦的继发性后果，大约40%的SCI患者受到影响。尽管与脊髓损伤相关的神经性疼痛的发病率很高，并对康复工作产生了影响，但目前对这种类型的疼痛的治疗往往无效。中枢神经性疼痛的更成功的干预措施的发展受到以下事实的限制：导致这种类型疼痛的机制还不清楚，而且还没有建立明确的诊断和结果工具。定量感觉测试(QST)允许对受试者的躯体感觉处理机制进行非侵入性评估，最近被认为是研究神经病理性疼痛的潜在关键工具，包括帮助确认持续疼痛的评级，评估治疗效果，以及成功地将研究从动物模型转化为临床治疗范例。拟议的试点项目的目标是研究特定的QST措施的效用，这些措施旨在评估热和疼痛综合感觉处理的完整性，用于评估脊髓损伤患者的神经病理性疼痛特征。由于在这项先导研究中采用的方法在非常有限的出版物中得到了报道，所以进行这项先导项目的基本原理是为下面概述的假说提供初步支持，这些假说将指导设计一项完整的研究方案，以彻底验证这些治疗脊髓损伤神经病理性疼痛的QST技术。目的：探讨脊髓损伤患者热伤害性刺激的空间整合程度与神经病理性疼痛的关系。刺激-反应关系将通过让受试者评估不同温度的热刺激产生的疼痛强度，使用一个热探头(面积为9cm2)和两个并排的热探头(总面积为18cm2)。空间总和将通过比较受试者之间小刺激区(一个探测器)和大刺激区(两个探测器)的疼痛强度评级的差异来评估。我们假设，与没有疼痛的脊髓损伤参与者相比，有脊髓损伤和神经病理性疼痛的参与者在两种刺激大小(一个探头和两个探头)之间的疼痛评级会出现更大的差异(即，更大的空间总和)，这表明有神经病理性疼痛的人在空间上加强了有害输入的整合。目的：比较脊髓损伤伴神经病理性疼痛和无疼痛的脊髓损伤患者对“热烧烤”刺激的知觉反应。热烧烤刺激将用于评估热和疼痛整合过程。热烤架通常由多个相互交错的热(40摄氏度)和冷(20摄氏度)刺激棒同时呈现，当呈现给具有完整体感功能的人的皮肤时，会产生一种自相矛盾的“灼痛”感觉。这种由热烤架引起的疼痛在神经病理性疼痛的患者中被认为是不正常的。在拟议的试点研究中，将在有脊髓损伤和神经病理性疼痛的人以及没有神经病理性疼痛的脊髓损伤患者中获得热烤产生的痛阈值。据推测，患有神经病理性疼痛的参与者的热烧烤阈值将显著高于没有神经病理性疼痛的参与者，这表明那些患有神经病理性疼痛的人对来自温暖和凉爽感觉通路的信息的正常整合受到干扰。拟议的先导性研究的结果将深入了解可能与神经病理性疼痛经验相关的特定躯体感觉系统机制，并将为未来旨在充分验证这些QST技术用作脊髓损伤神经病理性疼痛的潜在诊断和结果测量的研究提供支持。

DESCRIPTION (provided by applicant): Chronic neuropathic pain is a particularly troublesome secondary consequence of spinal cord injury (SCI) which affects approximately 40% of persons with SCI. Despite the high prevalence of SCI-related neuropathic pain and its impact on rehabilitation efforts, current treatments for this type of pain are often ineffective. The development of more successful interventions for central neuropathic pain is limited by the fact that the mechanisms responsible for this type of pain are not clearly understood, and definitive diagnostic and outcome tools have yet to be established. Quantitative sensory testing (QST), which allows for noninvasive evaluation of somatosensory processing mechanisms in human subjects, has recently been advocated as a potentially critical tool for the investigation of neuropathic pain, including aiding in the validation of ratings of ongoing pain, in the evaluation of treatment efficacy, and in the successful translation of research from animal models to clinical treatment paradigms. The goal of the proposed pilot project is to examine the utility of specific QST measures, which are aimed at assessing the integrity of thermal and pain integrative sensory processing, for the assessment of neuropathic pain characteristics in persons with SCI. Because the methods to be employed in this pilot study have been reported in a very limited number of publications, the rationale for conducting this pilot project is to provide initial support for the hypotheses outlined below, which will guide the design of a full research protocol to thoroughly validate these QST techniques for neuropathic pain in SCI. Objective 1: Examine the relationship between the degree of spatial integration of thermal noxious stimulation and the presence of neuropathic pain in persons with SCI. Stimulus-response relationships will be measured by asking subjects to rate the intensity of pain produced by thermal stimuli of varying temperatures delivered using one thermal probe (9cm2 area) and those delivered using two thermal probes side-by-side (18cm2 total area). Spatial summation will be assessed by comparing the differences in pain intensity ratings for the small stimulus area (one probe) and the large stimulus area (two probes) across subjects. We hypothesize that greater differences in pain ratings between the two stimulus sizes (one probe vs. two probes) will occur in participants with SCI and neuropathic pain (i.e., greater spatial summation) compared to participants with SCI who do not have pain, suggesting enhanced integration of noxious inputs across space in persons who have neuropathic pain. Objective 2: Compare perceptual responses to the "thermal grill" stimulus between persons with SCI and neuropathic pain and persons with SCI who do not have pain. A thermal grill stimulus will be used to assess thermal and pain integration processes. The thermal grill, which is typically composed of a number of interlaced warm (40oC) and cool (20oC) stimulus bars presented simultaneously, produces a paradoxical "burning pain" sensation when presented to the skin of a person with intact somatosensory function. This experience of pain due to the thermal grill has been suggested to be abnormal in persons with neuropathic pain. In the proposed pilot study thermal grill-produced pain thresholds will be obtained in persons with SCI and neuropathic pain and in persons with SCI who do not have neuropathic pain. It is hypothesized that the thermal grill threshold for participants with neuropathic pain will be significantly higher than for participants without neuropathic pain, suggesting that the normal integration of information from warm and cool sensory pathways is disrupted in those with neuropathic pain. Results from the proposed pilot studies will yield insight regarding the specific somatosensory system mechanisms that may be related to the experience of neuropathic pain, and will provide support for future studies aimed at fully validating the use of these QST techniques as potential diagnostic and outcome measures for neuropathic pain in SCI.