Adult-onset opsoclonus-myoclonus syndrome (OMS) is a rare condition caused by paraneoplastic encephalitis from ANNA-2 antibody associated with breast cancer. OMS has been associated with other neurological symptoms such as encephalopathy, cranial nerve palsies, vertigo, ataxia, behavioral changes, but not seizure.

A 69 year-old-female presented with new onset refractory status epilepticus.  Three years prior to presentation, she developed OMS in the setting of high titer of ANNA-2 antibody leading to a diagnosis of metastatic breast cancer. OMS resolved with surgical resection and immunosuppression.  Diagnostic evaluation for the NORSE was unremarkable, including brain MRI, serology and infectious work up. CSF analysis revealed pleocytosis with lymphocytic predominance and repeat ANNA-2 antibody testing showed high titer. She was then treated with multiple intravenous antiepileptic drugs, corticosteroids and immunoglobulin with favorable results.

Paraneoplastic ANNA-2 associated encephalitis should be considered as a possible cause of new onset refractory status epilepticus.