Evolution of clinically isolated syndrome to pediatric-onset multiple sclerosis and a review of the literature.

Background: Clinically isolated syndrome (CIS) may be the first presentation of pediatric onset multiple sclerosis (POMS). We retrospectively evaluated the clinical and laboratory data of pediatric CIS (pCIS) patients who were diagnosed with POMS upon followup for any predictive variables. We also reviewed the literature concerning the management of pCIS.

Methods: This single-center study involved patients who had pCIS in childhood that converted to POMS during followup between 2011 and 2021. Sixteen patients were included in the study. The data were evaluated retrospectively and analyzed with descriptive statistics.

Results: The majority of the pCIS patients were female (F/M: 10/6, 62/38%), and the first pCIS attack was at 13.3 ± 2.6 years old (mean ± SD). Mean follow-up was 3.1 ± 1.4 years; 6 of the patients relapsed within 1 year and 6 within 2 years. The time from the first pCIS attacks of the patients to the diagnosis of POMS was 15.75 ± 11.07 months. The annualized relapse rate (ARR) was 0.9 ± 0.7. The majority (68%) of the patients had a monosymptomatic onset, optic neuritis (ON) being the most common initial presentation (44%). Cerebrospinal fluid (CSF) oligoclonal bands (OCBs) were found in 9/12 (75%) and the immunoglobulin G index (IgG index) was elevated in 5/11 (45%). An autoimmune disorder was reported in the 1st or 2nd degree relatives of 6 patients: four (25%) MS, one ulcerative colitis, and one Hashimoto's thyroiditis. Our pCIS patients did not receive any disease-modifying treatment (DMT) for their first attack. When the diagnosis changed to POMS, most (68%) were started on interferons. The Expanded Disability Status Scale (EDSS) increased in one patient during follow-up (EDSS: 3) while in the others it was 0 at the last visit. The literature is reviewed in order to compare results for suggestions regarding the management of pCIS.

Discussion: The presence of OCBs in the initial episode, MS in the family, and monosymptomatic onset may increase the possibility of developing POMS. Whether DMTs given at the pCIS stage are effective in preventing relapses and disability needs to be evaluated in longitudinal follow-up of large cohorts.