Objective:

To present a case of overlap between AQP4-IgG-positive NMOSD and anti-NMDAR encephalitis, highlighting diagnostic challenges.

Approach:

• Case Presentation: A 47-year-old woman presented with anorexia, dizziness, nausea, and vomiting. Initial MRI suggested Wernicke encephalopathy, but symptoms progressed to cognitive decline and neuropsychiatric symptoms.
• Diagnostic Evaluation: MRI findings included lesions in the hypothalamic region and cerebellum. CSF analysis showed AQP4-IgG positivity and low titer anti-NMDAR1 IgG.
• Treatment: The patient was treated with high-dose intravenous methylprednisolone, followed by oral prednisone and inebilizumab.

Key Findings:

• Persistent vomiting with lesions in the diencephalon may indicate brain-predominant AQP4-IgG-positive NMOSD.
• CSF anti-NMDAR1 IgG positivity in AQP4-IgG-positive NMOSD may suggest overlap rather than definitive anti-NMDAR encephalitis.
• Correlation of clinical course, MRI findings, and antibody results is crucial for diagnosis in autoimmune overlap syndromes.

Interpretation:

The case illustrates the importance of correlating clinical symptoms, MRI findings, and antibody results for accurate diagnosis.

Limitations:

• The case is based on a single patient, limiting generalizability.
• Low titer of anti-NMDAR1 IgG may complicate interpretation of results.

Conclusion:

Early recognition and treatment of autoimmune overlap syndromes may improve patient outcomes.