We present the case of a patient with acute flares of two overlapping autoimmune conditions: neuromyelitis optica spectrum disorder (NMOSD) and systemic lupus erythematosus (SLE) who was initially presumed to have bacterial meningitis given obscure presentation and CSF analysis. We aim to highlight the potential spectrum of CSF abnormalities in this patient population.

NMOSD/SLE overlap syndrome is well recognized. Limited information is available for CSF parameters in overlapping cases, along with treatment guidelines and overall prognosis.

27-year-old female who presented with fever, headaches, nausea/vomiting, and neck/shoulder pain. Diagnosed with lupus based on renal dysfunction, positive antibodies, and low complement levels. CSF revealed pleocytosis (1382/cumm; 92% neutrophilic), elevated protein (211mg/dl), and low glucose (24mg/dl). She was presumed to have bacterial meningitis, treated with antibiotics, however continued to worsen and eventually developed urinary retention, weakness in all extremities, and hyperreflexia. MRI brain revealed T2 hyperintense lesions in the area postrema bilaterally. MRI cervical/thoracic spine revealed longitudinally extensive T2 hyperintense signal from C3 to conus medullaris. Negative CSF cultures and PCR panels. Positive aquaporin-4 antibodies. Treated with methylprednisolone, plasmapheresis, cyclophosphamide, and rituximab with an excellent recovery.

In NMOSD, CSF pleocytosis is predominantly lymphocytic but both neutrophilic and eosinophilic pleocytosis can be seen. Number of cells range from < 10 to a few hundred cells, with an average < 50 cells/cumm. Our patient had a cell count in the thousands, which could indicate highly active disease or overlapping disease state. Very low glucose is also atypical for NMOSD, overall favoring an infectious etiology. Treatment guidelines are not well established for patients with overlapping NMOSD and SLE, as 4 biologic medications have been approved for NMO but none were studied in NMOSD/SLE overlap. Our patient made an excellent recovery with cyclophosphamide and rituximab. More research is warranted regarding standardized treatment guidelines for these cases.