Motor, cognitive, affective, and communication outcomes in patients with sustained remission of opsoclonus-myoclonus-ataxia syndrome

Background: Opsoclonus-myoclonus-ataxia syndrome (OMS) is a rare pediatric immune-mediated disorder characterized by motor and behavioral disturbances, often with regression of previously acquired skills. While aggressive immunotherapy has improved motor outcomes, long-term cognitive and affective sequelae remain present. Objective: To evaluate long-term motor, cognitive, affective, and communication outcomes in patients with sustained OMS remission treated with a unified immunotherapy protocol, with a specific focus on the presence and trajectory of Cerebellar Cognitive Affective Syndrome (CCAS). Methods: Sixteen patients with OMS and ≥4 years of sustained remission were evaluated using standardized neurological, cognitive, and behavioral assessments. CCAS severity was assessed retrospectively at onset and categorized at outcome based on neuropsychological and behavioral data. Correlational analyses explored associations between clinical variables and functional outcomes. Results: All patients demonstrated OMS remission; however, 50 % exhibited residual, mild motor symptoms. Cognitive impairments were present in 37.5 % of patients, with 25 % showing moderate to severe intellectual disability. Communication difficulties were reported in 37 %, and 50 % screened positive for anxiety. CCAS features were identified in all patients at onset and persisted in 50 % at outcome. Worse cognitive and motor outcomes were significantly associated with delayed treatment initiation, higher relapse frequency, and greater CCAS severity at onset. Conclusions: Despite remission of core motor symptoms, many OMS patients experience persistent CCAS-related cognitive, affective, and communication deficits. Our findings support the use of early CCAS assessment as a prognostic indicator, the development of an age-appropriate CCAS assessment tool for young children, and the inclusion of CCAS features in OMS diagnostic criteria.