Motor and cognitive changes across 2 years: a longitudinal study in early Multiple Sclerosis

Background: Functional disorders appear early in the course of the disease and develop over time, impacting participation and quality of life. However, little is known about functional deterioration assessed by clinical and instrumented tools in longitudinal studies. Methods: We included 63 PwMS with Expanded Disability Status Scale (EDSS) ≤2.5 points, disease duration ≤5 years, and age (Mean ± Standard Deviation) 38.7 ± 10.7 years. Participants were assessed at baseline and after 2 years with clinical and instrumented evaluations. Data on disability and functional disorders were collected using EDSS, Six-Minute Walk Test (6MWT), Multiple Sclerosis Walking Scale-12 (MSWS-12), Fatigue Severity Scale (FSS), and Symbol-digit modality test (SDMT), while instrumented data measuring complexity and intensity of balance disorders and gait symmetry-regularity-instability were extracted from wearable devices. Results: Clinical scales (EDSS, 6MWT, FSS, MSWS-12, and SDMT) did not show a statistically significant deterioration when baseline and 2-year follow-up were compared: EDSS (Median and min-max) from 2 (0-2.5) to 1.5 (0-4.5)points, 6MWT from 566.2 ± 80.4 to 573.9 ± 94.7m, FSS from 2.89 (0.89-7) to 2.67(1-7)points, MSWS-12 from 25 (20-65) to 25 (20-78.3) points, and SDMT from 55.34 ± 14.7 to 61.4 ± 15.5 points. We observed similar results in instrumented variables: complexity from −0.15 ± 1.06 to −0.38 ± 1.08 [au], intensity from 0.00 ± 0.69 to −0.17 ± 0.78 [au], gait regularity from 0.87 ± 0.07 to 0.88 ± 0.08 [au], gait symmetry from 80.24 ± 20.24 to 83.0 ± 8.85 [au], and gait instability from 0.67 ± 0.11 to 0.70 ± 0.13 [au]. Conclusion: We hypothesized that subtle functional deteriorations would be detectable over two years. However, our data showed a functional stability of the disease at follow-up. This held even when an instrumented assessment was added to assess subtle functional disorders.