Filingeri Davide, Chaseling Georgia, Hoang Phu, Barnett Michael, Davis Scott L, Jay Ollie
Thermal Ergonomics Laboratory, Faculty of Health Sciences, University of Sydney, Sydney, NSW, Australia.
Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, UK.
Exp Physiol. 2017 Aug 1;102(8):887-893. doi: 10.1113/EP086320. Epub 2017 May 23.
What is the central question of this study? Between 60 and 80% of multiple sclerosis (MS) patients experience transient worsening of symptoms with increased body temperature (heat sensitivity). As sensory abnormalities are common in MS, we asked whether afferent thermosensory function is altered in MS following exercise-induced increases in body temperature. What is the main finding and its importance? Increases in body temperature of as little as ∼0.4°C were sufficient to decrease cold, but not warm, skin thermosensitivity (∼10%) in MS, across a wider temperature range than in age-matched healthy individuals. These findings provide new evidence on the impact of heat sensitivity on afferent function in MS, which could be useful for clinical evaluation of this neurological disease. In multiple sclerosis (MS), increases in body temperature result in transient worsening of clinical symptoms (heat sensitivity or Uhthoff's phenomenon). Although the impact of heat sensitivity on efferent physiological function has been investigated, the effects of heat stress on afferent sensory function in MS are unknown. Hence, we quantified afferent thermosensory function in MS following exercise-induced increases in body temperature with a new quantitative sensory test. Eight relapsing-remitting MS patients (three men and five women; 51.4 ± 9.1 years of age; Expanded Disability Status Scale score 2.8 ± 1.1) and eight age-matched control (CTR) subjects (five men and three women; 47.4 ± 9.1 years of age) rated the perceived magnitude of two cold (26 and 22°C) and two warm stimuli (34 and 38°C) applied to the dorsum of the hand before and after 30 min cycling in the heat (30°C air; 30% relative humidity). Exercise produced similar increases in mean body temperature in MS [+0.39°C (95% CI: +0.21, +0.53) P = 0.001] and CTR subjects [+0.41°C (95% CI: +0.25, +0.58) P = 0.001]. These changes were sufficient to decrease thermosensitivity significantly to all cold [26°C stimulus, -9.1% (95% CI: -17.0, -1.5), P = 0.006; 22°C stimulus, -10.6% (95% CI: -17.3, -3.7), P = 0.027], but not warm, stimuli in MS. Contrariwise, CTR subjects showed sensitivity reductions to colder stimuli only [22°C stimulus, -9.7% (95% CI: -16.4, -3.1), P = 0.011]. The observation that reductions in thermal sensitivity in MS were confined to the myelinated cold-sensitive pathway and extended across a wider (including milder and colder) temperature range than what is observed in CTR subjects provides new evidence on the impact of rising body temperature on afferent neural function in MS. Also, our findings support the use of our new approach to investigate afferent sensory function in MS during heat stress.
本研究的核心问题是什么？60%至80%的多发性硬化症（MS）患者会随着体温升高（热敏感性）出现症状短暂恶化。由于感觉异常在MS中很常见，我们询问在运动引起体温升高后，MS患者的传入热感觉功能是否发生改变。主要发现及其重要性是什么？体温仅升高约0.4°C就足以降低MS患者对冷刺激而非热刺激的皮肤热敏感性（约10%），且该温度范围比年龄匹配的健康个体更宽。这些发现为热敏感性对MS传入功能的影响提供了新证据，这可能有助于对这种神经系统疾病进行临床评估。在多发性硬化症（MS）中，体温升高会导致临床症状短暂恶化（热敏感性或Uhthoff现象）。尽管已经研究了热敏感性对传出生理功能的影响，但热应激对MS传入感觉功能的影响尚不清楚。因此，我们采用一种新的定量感觉测试方法，对运动引起体温升高后的MS患者的传入热感觉功能进行了量化。八名复发缓解型MS患者（三名男性和五名女性；年龄51.4±9.1岁；扩展残疾状态量表评分为2.8±1.1）和八名年龄匹配的对照（CTR）受试者（五名男性和三名女性；年龄47.4±9.1岁）在热环境（30°C空气；30%相对湿度）中骑行30分钟前后，对施加于手背的两种冷刺激（26°C和22°C）和两种热刺激（34°C和38°C）的感知强度进行评分。运动使MS患者的平均体温升高幅度与CTR受试者相似[分别为+0.39°C（95%CI：+0.21，+0.53），P = 0.001]和[+0.41°C（95%CI：+0.25，+0.58），P = 0.001]。这些变化足以使MS患者对所有冷刺激的热敏感性显著降低[26°C刺激，-9.1%（95%CI：-17.0，-1.5），P = 0.006；22°C刺激，-10.6%（95%CI：-17.3，-3.7），P = （此处原文有误，应为0.027）]，但对热刺激无影响。相反，CTR受试者仅对较冷刺激的敏感性降低[22°C刺激，-9.7%（95%CI：-16.4，-3.1），P = 0.011]。MS患者热敏感性降低局限于有髓鞘的冷敏感通路，且扩展到比CTR受试者更宽（包括更温和和更冷）的温度范围，这一观察结果为体温升高对MS传入神经功能的影响提供了新证据。此外，我们的研究结果支持使用我们的新方法来研究热应激期间MS患者的传入感觉功能。
