Introduction: Environmental factors appear to play an important role in the development and course of Multiple Sclerosis (MS). Seasonal variability in disease activity has been described and it is postulated that it may vary according to geographical area. The aim of this study is to analyse the monthly distribution of activity observed on Magnetic Resonance Imaging (MRI) and to look for a possible relationship with climate in patients with relapsing remitting MS.
Material and methods: Retrospective observational study, carried out in the population of one hospital on the Spanish Mediterranean coast. A total of 238 MRI scans of 51 patients were evaluated. Climatological data were obtained from the Spanish State Meteorological Agency from 2012 to 2016. Activity was defined as contrast-enhancing lesions.
Results: The distribution of gadolinium-enhancing lesions was found to be non-uniform across months (p = 0.008). Visual inspection suggests higher activity in July and August. Regarding weather, tropical nights (defined as days with a minimum temperature above 20 °C) were associated with increased risk of MRI activity (OR = 1.06, p = 0.001).
Conclusion: These findings suggest a non-uniform monthly distribution of gadolinium-enhancing lesions and an association between warmer nights and increased MRI activity, pointing to a potential impact of environmental factors on multiple sclerosis activity in neuroimaging.
Keywords: Hot temperature; MRI; Multiple sclerosis; Seasons; Tropical nights.
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