Opsoclonus-myoclonus syndrome (OMS) is a rare neurological syndrome characterized by involuntary, arrhythmic, chaotic, multidirectional saccades with horizontal, vertical, and torsional components commonly accompanied by myoclonic jerks in the limbs and trunk, cerebellar ataxia, tremor, and encephalopathy.1 Although the circuitry and exact mechanism of opsoclonus remain unclear, findings of neuropathological examination and functional magnetic resonance imaging studies suggest that disinhibition of the fastigial nucleus of the cerebellum is involved.1 Evidence suggests an autoimmune origin of OMS, but no specific associated autoantibody has been described and the mechanisms of OMS are still unknown.2 Opsoclonus-myoclonus syndrome can occur with many different contexts such as infections, toxic-metabolic disorders, or systemic cancer. In children, the disorder is related to the presence of a neuroblastoma in about 50% of cases.2 In adults, the tumors most commonly involved include small cell lung carcinoma or breast carcinoma, but an idiopathic origin seems more frequent. Some differences in treatment response and outcome may exist between adults and children with OMS, but only small series or case reports of adult patients have been reported.
Honnorat J. New Findings in Adult Opsoclonus-Myoclonus Syndrome. JAMA Neurol. 2016;73(4):381-382. doi:10.1001/jamaneurol.2015.4757