A-165 Selective Mutism in Pediatric Opsoclonus-Myoclonus Syndrome: A Case Study

Abstract

Abstract Objective: Opsoclonus-Myoclonus Syndrome (OMS) is an extremely rare (1 per 5 million estimated incidence), subacute movement disorder characterized by myoclonus and/or ataxia, opsoclonus, and behavioral disturbance with or without neuroblastoma. Many pediatric patients will experience long-term cognitive, behavioral, and motor sequelae. This case study describes deficits associated with a rare course of OMS and will present a poly-etiologic hypothesis for the observed profile. Improved understanding of the phenotypic variance in atypical OMS may promote diagnostic clarity and subsequent intervention for a rare presentation that is scientifically underserved. Method: Patient presented with viral infection at 2 years of age that led to loss of motor and speech functioning and ultimately a diagnosis of OMS. Patient exhibited typical features of cerebellar mutism syndrome (mutism, emotional lability, motor impairment), with rapid recovery of gross motor skills. Patient’s mutism has persisted for several years despite immunomodulatory treatment and normal neuroimaging findings. Results: Neuropsychological results indicated below average performance across intellectual, language, motoric, and academic domains. Functional and adaptive impairments secondary to social anxiety and separation distress were also exhibited. Diagnostic criteria for Selective Mutism and Social Anxiety Disorder were met. Significant anxiety, post-event stress, attachment needs, altered speech/language development, and personal temperament are all probable contributors to her prolonged mutism. Conclusions: This case study examines OMS with prolonged mutism. Mutism, while not uncommon in some cerebellar disorders or post surgically, is not well documented in the OMS literature and may represent a rare outcome. These findings add to the phenotypic variability, developmental course, and profile of atypical cerebellar presentations.