Opsoclonus‑myoclonus‑ataxia syndrome (OMAS), or “dancing eye-dancing feet” syndrome, is a very rare but critical neurologic condition that may present in the emergency department. OMAS can often be attributed to serious underlying pathology such as neuroblastoma in children or malignancy in adults. A detailed understanding of this condition can facilitate prompt recognition by emergency medicine (EM) residents, thus accelerating diagnosis and improving patient outcomes.
OMAS classically presents as a triad of opsoclonus, myoclonus, and ataxia. Opsoclonus consists of involuntary, rapid, multidirectional saccadic eye movements. Myoclonus refers to sudden, arrhythmic jerks of the limbs or trunk. Ataxia typically refers to gait disturbance and incoordination. Other symptoms may include behavioral regression, irritability, and sleep disturbance in children, or encephalopathy and prominent motor dysfunction in adults.
The syndrome is primarily immune-mediated, with autoantibodies targeting cerebellar and brainstem structures. In children, approximately half of OMAS cases are associated with neuroblastoma, particularly in those under age 3. Adults more often have an underlying malignancy such as small cell lung cancer, breast cancer, or ovarian teratoma. OMAS can also follow viral infections, such as West Nile virus, Epstein-Barr virus, and SARS‑CoV‑2.
Diagnosis is primarily clinical but can be supported by workup to identify underlying causes. The hallmark features of OMAS distinguish it from many other neurologic conditions with similar presentations. Cerebellar stroke may cause ataxia but usually lacks opsoclonus and myoclonus. Toxic-metabolic syndromes and postictal states may involve tremor or confusion, but not the full triad. Infectious encephalitis can have some overlap but is usually accompanied by fever or diffuse neurologic signs.
Initial ED evaluation should include basic labs, such as CBC, CMP, TSH, and inflammatory markers which can help rule out metabolic and infectious causes that may be on the list of differential diagnoses. Brain imaging, preferably an MRI, would be helpful to exclude structural or ischemic lesions. If encephalitis is suspected, lumbar puncture may show mild pleocytosis or elevated protein.
Once OMAS is suspected, urgent imaging to identify underlying malignancy should be obtained. In children, abdominal MRI and MIBG scans help identify neuroblastoma. In adults, CT of the chest, abdomen, and pelvis can screen for occult malignancy. ED providers should prioritize early neurology and oncology consults to streamline further evaluation and initiation of treatment.
Management in the ED is largely supportive. Patients should be monitored closely for airway compromise, seizures, and worsening encephalopathy. Sedating medications should be avoided unless absolutely necessary, as they may interfere with one’s ability to perform a good neurological exam. Immunotherapy is not typically started in the ED, although early involvement of consultants can facilitate swift initiation after hospital admission.
Prognosis can vary, and is primarily influenced by etiology and time to treatment. Children with neuroblastoma‑associated OMAS may show neurologic improvement after tumor resection and immunotherapy, but many experience persistent cognitive or motor delays. Adults with paraneoplastic OMAS often experience relapsing or chronic symptoms unless the malignancy is successfully treated. In contrast, post‑infectious OMAS may completely resolve over weeks to months.
For EM residents, the key is recognition. A patient with new-onset chaotic eye movements, limb or truncal jerks, and gait instability warrants consideration of OMAS. In a young child with behavioral regression and ataxia, the syndrome should prompt immediate evaluation for neuroblastoma. In adults, look for subtle signs of malignancy or recent infection. While OMAS may seem rare and complex, its early identification in the ED can be life‑altering. When faced with an unusual movement disorder and unexplained neurologic findings, don’t overlook the possibility of this rare but revealing diagnosis.
References
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