Opsoclonus-myoclonus syndrome is extremely uncommon in adults with an autoimmune pathophysiology. Because of the rarity of the syndrome, international recognition of opsoclonus-myoclonus-ataxia syndrome needs to be improved urgently. Therefore, the goal of this study was to raise the awareness of the opsoclonus-myoclonus-ataxia syndrome and help doctors in better diagnosing and using immunotherapy. Methods: We present a case study of an adult-onset case of idiopathic opsoclonus-myoclonus syndrome characterized by spontaneous arrhythmic multidirectional conjugate eye movements, myoclonus, ataxia, sleep disorders, and intense fear. Additionally, we conduct a literature search and summarize the pathophysiology, clinical presentation, diagnosis, and treatment of opsoclonus-myoclonus-ataxia syndrome. Results: Immunotherapies successfully treated the patient's opsoclonus, myoclonus, and ataxia. Further, the article also includes an update summary of the opsoclonus--myoclonus-ataxia syndrome. Conclusion: The prevalence of residual sequela in adults with opsoclonus-myoclonus-ataxia syndrome is low. Early diagnosis and treatment may result in a better prognosis. Furthermore, combined immunotherapy is expected to reduce the incidence of refractory and reoccurring opsoclonus-myoclonus-ataxia syndrome.