The experience of thermal environments and skin thermal perception in multiple sclerosis patients

Temperature sensitivity phenomenon is a unique condition in multiple sclerosis (MS) disease. In temperature sensitivity MS patients experience the worsening of their symptoms when their body temperature changes. It can occur when they exercise when they have hot baths or experience weather changes. This worsening of the MS symptoms is temporary and remains as long as the body temperature stays out of its normothermic levels. As a result, MS patients experience significant challenges in maintaining appropriate physical activity levels which affect their daily life. Even though the traditional view postulates that changes in the core body temperature are necessary to elevate the symptoms, there is little evidence that shows they occur with skin temperature changes alone. Thus, the symptoms worsening might be triggered during sauna use or exposure to environmental changes and maybe humidity, for which the skin and not the core body temperature change. In addition, MS patients are challenged with thermoregulatory impairment and they cannot control their body temperature within a homeostatic range. This is mainly due to lesions in the hypothalamus and surrounding subcortical brain areas. One of the thermoregulatory functions that assist in controlling body temperature is the function of the thermoreceptors under the skin, which seems to be disrupted in MS due to the demyelination in the central nervous system (CNS). Therefore, the process of determining the temperature and wetness of items might be affected.

This thesis has identified important gaps in the literature. One such gap is that the information about the temperature sensitivity in MS is lacking. It remained unclear whether temperature sensitivity is encountered in MS with changes only in skin temperature; it was still unknown what the impact and the implications are in the symptom worsening in MS patients. Another research gap was that information was lacking as to whether people with MS who experience temperature sensitivity are challenged with thermoregulatory dysfunction manifested with wetness and thermal abnormalities on the skin. Such information would explain how the patients behaviourally thermoregulate while, for example, they hold and lift objects; or why they drop them, especially when these objects are wet.

The main aims of the thesis were to increase the understanding of temperature sensitivity and thermoregulatory dysfunction on the skin in MS. The main objectives were to assess the impact in temperature sensitivity and quantify the thermoregulatory dysfunction by focusing on thermal and wetness perception in MS in heat and cold conditions.

The findings revealed that the MS participants were greatly impacted in heat and cold conditions. An online survey and two focus groups showed the plethora of triggers, symptoms, and strategies to ameliorate the effect of temperature sensitivity; and how important the relationship between clinicians and patients is to feel supported during those challenges. Furthermore, the experimental studies showed that temperature sensitivity can occur with changes in the patients’ skin temperature alone. From all the MS symptoms investigated in the experimental studies, the wetness and thermal perception abnormalities emerged as general MS symptoms, which worsened in heat and cold conditions. The findings increased the understanding of the patients’ claims that temperature sensitivity occurs without changes in core body temperature and that it is not an outcome of negative anticipations. The main aims and objectives of the thesis were successfully accomplished.

These findings are described in detail in the thesis Chapters and provide useful insights for neurologists, clinicians, and patients to understand the temperature sensitivity and thermoregulatory dysfunction in MS. In addition, it derives from all the Chapters, that the subjective experience of temperature sensitivity is equally important as the objective measurements during assessments. Both types of information have shown that each MS patient is unique and requires treatment tailored to his or her needs. Hopefully, these results may inform the development of novel and effective management plans and therapeutic interventions to assist during those challenging times in MS.