Characteristics of Disease Relapses and Their Relationships with Weather Conditions in Patients with Multiple Sclerosis.

Background: The aim of the study was to analyze the clinical characteristics and circumstances of relapses in the patients with relapsing-remitting multiple sclerosis (MS). Objectives: The eighty patients with clinically definite MS and relapsing-remitting course were enrolled in the retrospective study. Methods: The calendar of documented recurrences was analyzed, looking for any patterns across years, warm and cold periods, and seasons and months. Results: In the years 2015-2020 the majority of relapses occurred in March, June-July, and October; with regard to seasons, the relapse rate peaked during spring and summer. In 2021-2023 there was significant increase in relapses in May and in February. In these years, most cases occurred in spring, and the least in autumn. The most significant coincidences were found for sensory symptoms in January, optic neuritis in March, motor deficit with pyramidal signs in May and June, cerebellar symptoms in March and July, and spinal cord involvement signs in August. Conclusions: Observation of seasonal occurrence of relapses revealed periods with high temperature, low humidity, and variable atmospheric pressure as potential contributors. Better recognition of these issues within future investigations could be considered in the complex approach to the management of MS outcomes.