Case Presentation: A 41-year-old gentleman with history of spinal trauma status post several spinal surgeries and chronic arachnoiditis presented to the emergency department reporting vertigo, generalized weakness, headache, and fever developing over the past two days. On exam he was alert and oriented, with irregularly irregular tachycardia, tachypnea, and a temperature of 39.2°C. Additionally and noted on video, he had pronounced truncal ataxia and multidirectional saccadic eye movements. There were no changes in sensation or strength, and no meningismus or rash. Initial labs were unremarkable. ECG indicated new onset of atrial fibrillation. MRI of the brain and spine was notable for spinal fluid collections consistent with his previous studies without new abnormality. Based on this presentation, the diagnosis of opsoclonus myoclonus syndrome was made, and levetiracetam was initiated for symptom management. The investigation for an underlying etiology was initially complicated by inability to obtain CSF; multiple attempts at lumbar puncture under imaging guidance were unsuccessful, and the patient declined cervical puncture. As a result, he was treated empirically for meningitis with a ten day course of ceftriaxone and acyclovir. A serum paraneoplastic panel and PET CT was unrevealing for malignancy. Viral studies ultimately demonstrated West Nile Virus (WNV) infection, with positive serum WNV IgG and IgM. The patient underwent successful cardioversion for his new atrial fibrillation, and was treated with 2g/kg IVIG, which was administered over the course of three days; steroids were withheld due to concern for ongoing infection. The patient experienced significant improvement in his disabling symptoms which were also documented on video.

Discussion: There have been nearly 44,000 cases of West Nile Virus (WNV) reported in the United States since 1991. Only a quarter of those infected develop symptoms, typically presenting with fever, headache, myalgias, and rash. About 1% develop neuroinvasive disease, characterized by encephalitis, meningitis, and flaccid paralysis. WNV infection is rarely associated with myocarditis which can present as atrial fibrillation; this has only been described in a few cases and autopsy reports. Opsoclonus myoclonus syndrome (OMS) is a rare condition with an estimated 1 case per 10 million population. The characteristic ataxia (dancing feet) and random horizontal and vertical saccades (dancing eyes) are thought to be due to autoimmune attack on omnipause neurons in the cerebellum. OMS most commonly presents in children with neuroblastoma but can also occur as a paraneoplastic or parainfectious syndrome in adults. Treatment typically includes IVIG or plasmapheresis with high dose steroids. There have been only 4 reported cases of OMS occurring in patients with WNV. Our patient represents an extremely rare case of WNV-associated OMS as well as cardiac involvement from WNV.

Conclusions: As the incidence of WNV rises, it will be increasingly important to consider WNV in the differential for patients presenting with sepsis and unusual neurologic and cardiac findings.