Are you temperature sensitive?
In my experience the vast majority of pwMS are affected by changes in temperature; typically it is hot or cold temperature that triggers changes in central nerve conduction velocity that brings on old symptoms. One of my patients reports becoming paralysed if sits outdoors in the sunshine for as little as 30 minutes in the middle of summer. Other report worsening of their cognitive fatigue with relatively minor changes in temperature. Women post-ovulation raise their body temperatures by about 0.5C; in some woman this enough to incapacitate them. I call this catamenial temperature-related fatigue and it often responds to non-steroidal anti-inflammatories and maybe the reason why aspirin has been shown to improve MS-related fatigue.
This Korean study below is fascinating. They show that short-term exposure to wide diurnal temperature ranges (DTRs), which have become increasingly common as a result of climate change, is associated with an increased risk of visits to A&E (emergency departments). The was an ~9% change in the odds ratio per 1 °C increase in the diurnal temperature range. If this data is reproduced then it will have a major impact on how we manage patients with MS as global warming ramps up. I suspect the many exacerbations triggered by hot weather may prove to be pseudo-relapses. I suspect this may be the ideal use of serum neurofilament levels; to differentiate relapses from pseudorelapses. Sorting out this old problem may prevent unnecessary MRI scans and more importantly reduce the use of corticosteroids use for possible relapse.
Please be aware that it is not only the ambient temperature that is important, fever can also result in worsening of symptoms. With the COVID-10 pandemic in full swing, I suspect many more pwMS will be monitoring their temperatures as an indicator of infection. I wonder how many of you are doing this? And if yes was it advised by any HCP?
Byun et al. Association between diurnal temperature range and emergency department visits for multiple sclerosis: A time-stratified case-crossover study. Sci Total Environ. 2020 Feb 25;720:137565. doi: 10.1016/j.scitotenv.2020.137565.
Although multiple sclerosis (MS) has been the leading cause of neurologically-induced disability in young adults, risk factors for the relapse and acute aggravation of MS remain unclear. A few studies have suggested a possible role of temperature changes on the relapse and acute aggravation of MS. We investigated the association between short-term exposure to wide diurnal temperature ranges (DTRs) and acute exacerbation of MS requiring an emergency department (ED) visit. A total of 1265 patients visited EDs for acute aggravation of MS as the primary disease in Seoul between 2008 and 2014 from the national emergency database. We conducted a conditional logistic regression analysis of the time-stratified case-crossover design to compare DTRs on the ED visit days for MS and those on control days matched according to the day of the week, month, and year. We examined possible associations with other temperature-related variables (ambient temperature, between-day temperature change, and sunlight hours). Short-term exposure to wide DTRs immediately increased the risk of ED visits for MS. Especially, 2-day average (lag0-1) DTR levels on the day of and one day prior to ED visits exhibited the strongest association (an 8.81% [95% CI: 3.46%-14.44%] change in the odds ratio per 1 °C increase in the DTR). Other temperature-related variables were not associated with MS aggravation. Our results suggest that exposure to wider DTR may increase the risk of acute exacerbation of MS. Given the increasing societal burden of MS and the increasing temperature variability due to climate change, further studies are required.