Multiple Sclerosis Functional Composite as a Measure of the Effects of Heat in Multiple Sclerosis

Heat sensitivity is a common feature of multiple sclerosis (MS), and heat has been found to impair MS patients’ physical and cognitive functioning. There is, however, no simple and specific measurement tool to evaluate the possible effects of heat on these functions. The aim of this study was to evaluate the compatibility of the multiple sclerosis functional composite (MSFC) to demonstrate the effects of heat on functioning in patients with MS. A total of 22 heat-sensitive MS patients and 19 healthy controls (HCs) were considered for the analysis. Moderate heat exposure took place in a Finnish sauna. Functioning was measured with the MSFC, which consists of two physical (the Nine Hole Peg test and the 25-foot timed walk test) and one cognitive (the PASAT-3) measure, before, during and one hour after the heat exposure. In the MS group the average MSFC scores were -0.48 (SD 0.79) at baseline, -0.99 (SD 1.97) during heat exposure and -0.68 (SD 1.58) after a one-hour delay. The average MSFC scores of the HC group were 0.58 (SD 0.42) at baseline, 0.66 (SD 0.43) during heat exposure and 0.68 (SD 0.41) after a one-hour delay. The MS group had significantly lower MSFC scores than the HC group (P = 0.01). The MS patients’ score deteriorated during the heat exposure, whereas that of the controls did not (P = 0.00). The results suggest that the MSFC could be used as a simple tool to detect the negative effects of heat in patients with MS.