Factors Related to the Progression of Clinically Isolated Syndrome to Multiple Sclerosis: A Retrospective Study in Lithuania

Background and Objectives: Multiple sclerosis (MS) is a demyelinating disease which usually manifests as clinically isolated syndrome (CIS). Approximately 70% of patients with CIS progress to MS. Therefore, there is a pressing need to identify the most accurate predictive factors of CIS developing into MS, some of which could be a clear clinical phenotype of early MS as well as lesions in magnetic resonance imaging (MRI), pathological findings in cerebrospinal fluid (CSF) and evoked potentials (EP) tests. The problem is of outstanding importance since early MS diagnosis and treatment prevents long-term disability. The aim of our study is to analyze the factors that could influence the progression of CIS to MS. Materials and Methods: This study is a retrospective data analysis which included patients with their primary CIS diagnosis between 1st January 2015 and 1st January 2020. The prevalence and predictive value of clinical symptoms, MRI lesions, pathological CSF and EP findings were evaluated in accordance with the final diagnosis and compared between the sexes and age groups. Results: Out of 138 CIS patients, 49 (35.5%) patients progressed to MS. MS patients were more likely to have a diminished sense of vibration and proprioception (χ(2) = 9.033, p = 0.003) as well as spinal cord MRI lesions (χ(2) = 7.209, p = 0.007) in comparison with the non-MS group. Positive oligoclonal bands (OCBs) in CSF (χ(2) = 34.859, p ≤ 0.001) and pathological brainstem auditory evoked potential (BAEP) test findings (χ(2) = 10.924, p ≤ 0.001) were more prevalent in the MS group. Diminished sense of vibration and proprioception increased the risk for developing MS by 13 times (p = 0.028), whereas positive OCBs in CSF increased the risk by 100 times (p < 0.001). MS patients that were older than 50 years were more likely to exhibit positive Babinski’s reflex (χ(2) = 6.993, p = 0.03), decreased muscle strength (χ(2) = 13.481, p = 0.001), ataxia (χ(2) = 8.135, p = 0.017), and diminished sense of vibration and proprioception (χ(2) = 7.918, p = 0.019) in comparison with both younger age groups. Conclusions: Diminished sense of vibration and proprioception, spinal cord MRI lesions, positive OCBs and pathological BAEP test findings were more common among patients that developed MS. Diminished sense of vibration and proprioception along with positive CSF OCBs are predictors of CIS progressing to MS. Older patients that develop MS have more symptoms in general, such as positive Babinski’s reflex, decreased muscle strength, ataxia, and diminished sense of vibration and proprioception.