The role of cooling strategies to mitigate Uhthoff’s phenomenon in adults with Multiple Sclerosis

Abstract

Up to 80% of people with MS experience Uhthoff’s phenomenon, whereby heat exposure drives a transient worsening of existing MS symptoms and physical disability. MS advocacy bodies recommend cooling strategies to protect people with MS from the debilitating effects of heat exposure, however the effectiveness and practicality of many recommendations is questionable. The aims of this thesis were to a) systematically review the literature examining the efficacy of cooling strategies for alleviating the effects of Uhthoff’s phenomenon, and b) to examine the effectiveness of a practical cooling strategy for mitigating heat-related decrements in physical performance and symptom severity in people with MS during exercise in hot conditions. Chapter 2 is a systematic review of the literature examining the effectiveness of cooling interventions for mitigating the effects of Uhthoff’s phenomenon. The available data indicates that cooling may enhance exercise tolerance in ambient temperatures up to 30°C, however, the effects of cooling on heat-related symptom worsening was remains unclear, due to scarcity of data and methodological limitations.

Chapter 3 is an experimental trial of 4°C water skin dousing for improving physical performance and symptom severity in people with MS during exercise in hot conditions (35°C, 40% relative humidity). Preliminary findings are that cold water skin dousing may attenuate heat-related worsening of postural sway following exercise and reduce MS symptom severity during exercise in the heat. These improvements were observed without parallel reductions in core temperature. However, exercise performance and hand-grip strength remained un-altered.

In conclusion, cooling may enhance physical performance in hot ambient conditions. Moreover, heat-related symptoms may be ameliorated by cooling. This thesis provides emerging evidence that cooling the skin surface may attenuate some of the effects of Uhthoff’s phenomenon without reducing core temperature.