Abstract Details

Title Adult-onset Opsoclonus-Myoclonus-Ataxia Post- West Nile Virus Infection: Diagnostic Challenges and Recovery with Immunotherapy

Topic Movement Disorders

Presentation(s) P4 - Poster Session 4 (8:00 AM-9:00 AM)

Poster/Presentation
Number 16-002

Objective To report a case of adult-onset opsoclonus-myoclonus-ataxia syndrome (OMAS) following West Nile virus infection, highlighting the diagnostic dilemma and recovery with immunotherapy.

Background

Opsoclonus-myoclonus-ataxia syndrome (OMAS) is an uncommon autoimmune-mediated movement disorder characterized by multidirectional saccadic intrusions, generalized myoclonus, cerebellar ataxia, and encephalopathy. In adults, OMAS is most often paraneoplastic or idiopathic. Post-infectious etiologies, including West Nile virus (WNV), are rarely reported and may pose significant diagnostic challenges.

Design/Methods We retrospectively reviewed the clinical presentation, diagnostic workup, and hospital course of a 69-year-old woman presenting with acute encephalopathy, abnormal ocular movements, and generalized myoclonus. Diagnostic evaluation included neuroimaging, cerebrospinal fluid analysis, and serologic testing. Management strategies and clinical response to immunotherapy were documented.

Results Neurologic examination demonstrated multidirectional opsoclonus, diffuse myoclonus, severe truncal and gait ataxia, and encephalopathy. Brain MRI revealed no acute pathology, and cerebrospinal fluid showed mild lymphocytic pleocytosis. Given the absence of structural findings, functional neurologic disorder was initially considered. Subsequent testing confirmed serum and CSF positivity for WNV IgM, establishing WNV neuroinvasive disease as the underlying etiology. The patient required ICU-level care for agitation and delirium. Treatment with high-dose intravenous methylprednisolone followed by intravenous immunoglobulin led to gradual improvement in opsoclonus, myoclonus, and mental status. At transfer to inpatient rehabilitation, she had persistent cognitive-linguistic deficits, urinary retention, and residual ataxia, but demonstrated progressive functional recovery.

Conclusions WNV-associated OMAS represents a rare but important post-infectious autoimmune encephalopathy in adults. This case illustrates the diagnostic dilemma posed by initial consideration of functional disorder and highlights the role of immunotherapy in promoting neurological recovery. Clinicians should maintain a broad differential for adult-onset OMAS, including infectious etiologies, to ensure timely recognition and management.

Authors/Disclosures
Mostafa Razavi, MD (University of South Dakota) PRESENTER	Dr. Razavi has nothing to disclose.
Mahika Khurana, MD, MBBS	Dr. Khurana has nothing to disclose.
Mariel Kalkach Aparicio, MD	Mariel Kalkach Aparicio, MD has nothing to disclose.
Xiyan Yi, MD	Dr. Yi has nothing to disclose.
Nessim Amin, MD (USD Sanford Medical Center)	Dr. Amin has nothing to disclose.

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