Opsoclonus myoclonus ataxia syndrome in an adult with complete clinical recovery: a case report with integrative literature review

Abstract

Case Presentation: A 44-year-old previously healthy man developed a subacute neurological syndrome over approximately two weeks, characterized by upper limb dysmetria, dysarthria, and gait instability, initially misdiagnosed as peripheral vertigo without response to treatment. Neurological examination revealed opsoclonus, bilateral nystagmus, marked gait ataxia, and involuntary movements involving the head and neck. Brain magnetic resonance imaging showed no structural or inflammatory abnormalities. Cerebrospinal fluid analysis was normal, including absence of oligoclonal bands and a normal kappa free light chain index. Molecular testing for infectious agents and comprehensive autoimmune and paraneoplastic antibody panels were negative. Whole-body and brain fluorodeoxyglucose positron emission tomography did not reveal hypermetabolic lesions suggestive of malignancy or active inflammation. Empirical treatment with intravenous methylprednisolone was initiated without immediate clinical improvement. No further immunotherapy was administered. The patient achieved complete resolution of all neurological symptoms within two months. Discussion: An integrative literature review was conducted using PubMed, SciELO, and LILACS, covering the period from 2015 to 2025. Eight studies were selected for comparative analysis. The sample demonstrated a mean age of 42 years, with a predominance of males (75%). A strong association with recent viral infection was observed, particularly with severe acute respiratory syndrome coronavirus 2, accounting for 50% of reported cases. Other identified triggers included dengue, rubella, and Japanese encephalitis. Cerebrospinal fluid abnormalities were infrequent, with pleocytosis present in only three cases. Neuroimaging findings were typically normal; however, isolated reports described thalamic hyperintensity and mild cerebellar atrophy. Most patients were treated with immunomodulatory therapy, including intravenous corticosteroids (50%) and intravenous immunoglobulin (37.5%), with six patients achieving complete recovery. Final Comments: This case highlights an atypical presentation of opsoclonus myoclonus ataxia syndrome in an adult with a negative extensive workup and complete clinical recovery. The findings reinforce the role of postinfectious and immune-mediated mechanisms, the limited sensitivity of conventional diagnostic tests, and the importance of early clinical recognition in guiding management of this potentially reversible condition.