Clinical and radiologic differences between early onset, late onset, and very late onset adult multiple sclerosis

Background: Previous studies suggested possible differences in clinical and radiologic characteristics between early-onset multiple sclerosis (EOMS) and late-onset MS (LOMS). However, differences between LOMS and very late onset MS (VLOMS) are largely unknown.Methods: We performed a retrospective review of medical records of patients diagnosed with MS between 8/1/ 2017 and 3/1/2022 at the comprehensive MS center of the Froedtert and Medical College of Wisconsin. We included adult patients with MS diagnosis who were 60 years or older VLOMS, 50-59 years old at diagnosis - LOMS, or were 18-30 years old at diagnosis - EOMS and had complete imaging and clinical records. Clinical presentation and location of demyelinating lesions at the onset of diagnosis were extracted and compared using the chi-square test, p<0.05.Results: A total of 246 newly diagnosed patients were identified. Of which 54 were EOMS, 29 were LOMS, and 35 were VLOMS. The sex ratio was not different between groups. EOMS had a higher percentage of patients who self-identified as black, while LOMS had a higher percentage of patients who self-identified as white. LOMS and VLOMS showed significant differences in the presence of tremors and lesion distribution at the onset. Older onset patients were more likely to present with motor symptoms, sphincter dysfunction, fatigue, and tremor. EOMS was more likely to present with cerebellum and occipital lobe lesions, and lesions were more likely to show contrast enhancement on MRI at diagnosis. Conclusion: Our findings revealed novel clinical and imaging characteristics differences between VLOMS and LOMS. The current classification of LOMS may benefit from revision to better align with chronological age classification for old age >60 instead of the current standard in the literature of >50 years.