English Timothy, Barton Joshua, Vargas Nicole, Barnett Michael, Jay Ollie
Heat and Health Research Centre, Faculty of Medicine and Health, University of Sydney, Sydney, Australia.
Beach Brain, Southern Cross University Hospital, Birtinya, Australia.
Eur J Appl Physiol. 2025 Jun 11. doi: 10.1007/s00421-025-05838-7.
To determine if reductions in whole-body thermal sensation (WBTS) with localised skin cooling mitigate heat-induced visual performance decrements in people with multiple sclerosis (MS), optic neuritis, and heat-sensitive visual symptoms, independent of core temperature increases.
Thirteen participants (7 relapsing-remitting MS (MS) patients with unilateral (left) optic neuritis and heat-sensitive visual symptoms; 6 controls) underwent visual performance testing on each eye at baseline and during passive heating (0.6℃ rise in gastrointestinal temperature (ΔT) via a hot water-perfused suit) under two counterbalanced crossover ordered conditions: 1) cold packs (0℃-CLD) or 2) hot packs (50℃-HOT) applied to the lower back. WBTS, visual symptoms, multifocal visual evoked potentials (mf-VEPs) amplitude/latency, and contrast sensitivity were assessed.
ΔT was consistent across trials (p = 0.213; η = 0.21). WBTS was only marginally lower (p = 0.017; η = 0.42) in CLD than HOT for MS (CLD: 5.8 ± 0.9 a.u.; HOT: 6.4 ± 0.7 a.u.) and controls (CLD: 5.0 ± 0.9 a.u.; HOT: 5.9 ± 0.7 a.u.). Passive heating worsened (p = 0.027; η = 0.59) visual symptoms in the affected eye similarly (p = 0.356; η = 0.14) for HOT and CLD conditions. Heating reduced mf-VEPs amplitude in the left (affected) eye (p = 0.007; η = 0.50) similarly (p = 0.332; η = 0.09) across groups and conditions. For the unaffected (right) eye, reductions in mf-VEPs amplitude were greater in MS than controls (p = 0.031; η = 0.36), with no difference between conditions (p = 0.339; η = 0.08). mf-VEPs latency and contrast sensitivity were unaffected by heating.
Localised skin cooling during passive heating to a moderate core temperature produces only a modest reduction in WBTS and does not mitigate heat-induced visual performance decrements. The limited perceptual difference achieved suggests the localised skin cooling was insufficient to meaningfully isolate the effects of skin temperature from core temperature.
确定局部皮肤冷却引起的全身热感觉（WBTS）降低是否能减轻多发性硬化症（MS）、视神经炎和有热敏感视觉症状患者因热导致的视觉性能下降，而不受核心体温升高的影响。
13名参与者（7名复发缓解型MS患者，单侧（左侧）视神经炎且有热敏感视觉症状；6名对照者）在两种平衡交叉有序条件下，于基线和被动加热期间（通过热水灌注套装使胃肠道温度升高0.6℃（ΔT））对每只眼睛进行视觉性能测试：1）在 lower back 应用冷敷袋（0℃ - CLD）；2）在 lower back 应用热敷袋（50℃ - HOT）。评估 WBTS、视觉症状、多焦视觉诱发电位（mf - VEPs）振幅/潜伏期和对比敏感度。
各试验中的ΔT一致（p = 0.213；η = 0.21）。对于MS患者（CLD：5.8 ± 0.9任意单位；HOT：6.4 ± 0.7任意单位）和对照者（CLD：5.0 ± 0.9任意单位；HOT：5.9 ± 0.7任意单位），CLD组的WBTS仅略低于HOT组（p = 0.017；η = 0.42）。被动加热使患眼的视觉症状恶化（p = 0.027；η = 0.59），HOT和CLD条件下相似（p = 0.356；η = 0.14）。加热使左侧（患）眼的mf - VEPs振幅降低（p = 0.007；η = （此处原文似乎有误，推测应为0.50）），各分组和条件下相似（p = 0.332；η = 0.09）。对于未受影响（右侧）眼，MS患者的mf - VEPs振幅降低幅度大于对照者（p = 0.031；η = 0.36），不同条件之间无差异（p = 0.339；η = 0.08）。mf - VEPs潜伏期和对比敏感度不受加热影响。
在被动加热至适度核心体温期间进行局部皮肤冷却，仅使WBTS有适度降低，并未减轻热诱导的视觉性能下降。所实现的有限感知差异表明，局部皮肤冷却不足以有效区分皮肤温度和核心温度的影响。
