NMDAr Antibody Positivity Without Encephalitis in a Case of Isolated Neurosarcoidosis
Usama Khan1, Kasyap Kondury1, Jerilyn Summay1, Stefanie Rodenbeck1
1Indiana University School of Medicine
Objective:
We describe a case demonstrating the presence of NMDA receptor antibodies in the cerebrospinal fluid (CSF) of a patient with neurosarcoidosis.
Background:
Sarcoidosis involves the nervous system in 5-10% of cases. Neurosarcoidosis has variable presentations including multiple cranial neuropathies, meningitis, and myelopathy. Neurosarcoidosis can be associated with multiple CSF biomarkers including elevated protein, increased IL-2r, and lymphocyte-predominant pleocytosis. While nearly 20% of patients with neurosarcoidosis have a concurrent autoimmune disorder, there are no cases in the literature of comorbid NMDAr-encephalitis.
Results:
A 63-year-old female presented with a one-year history of increasing gait instability, bilateral lower extremity weakness, and diplopia. She had a remote history of renal cell carcinoma with negative surveillance imaging. MRIs of the neuroaxis showed extensive leptomeningeal enhancement of the superior cerebellum, brainstem, and spinal cord with intrathecal nerve root thickening. CSF analysis revealed lymphocytic pleocytosis, elevated protein, elevated ACE, and elevated IL-2r; NMDAr antibody was also positive. Infectious work up, cytology, and flow cytometry were negative.
Dural biopsy was performed which was notable for non-necrotizing granulomatous inflammation. Despite high suspicion for isolated neurosarcoidosis, as NMDAr-antibody mediated disease can be paraneoplastic and given history of renal cell carcinoma, PET-CT was obtained which revealed enlarged subcarinal lymph node. Fine needle aspiration revealed benign pathology.
Based on this comprehensive workup and as she did not have any features of encephalopathy or behavioral changes to suggest NMDAr-antibody mediated disease, a diagnosis of neurosarcoidosis was made. The patient was initiated on high-dose corticosteroid and infliximab with improvement in symptoms.
Conclusions:
Despite biopsy favoring neurosarcoidosis, NMDAr antibodies in CSF were unexpected. Since NMDAr antibody testing in the CSF has significant specificity and antibodies can present with paraneoplastic syndromes, PET-CT was completed to rule out malignancy recurrence. Careful interpretation of clinical presentation, imaging, and CSF analysis is critical when diagnosing neuroinflammatory disease.
Generative AI Usage
No, did not use generative AI in the drafting or editing in this abstract.
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