Area postrema syndrome and longitudinally extensive transverse myelitis masquerading as leptomeningeal carcinomatosis.

backgroundNeuromyelitis optica spectrum disorder (NMOSD) is a severe autoimmune demyelinating disease of the central nervous system commonly associated with aquaporin-4 (AQP4) antibodies. Area postrema syndrome (APS), characterized by intractable nausea, vomiting, and hiccups, is a core clinical feature but is frequently misdiagnosed as a gastrointestinal disorder, leading to delays in diagnosis and treatment. CASE PRESENTATION: A 63-year-old woman with a history of treated breast cancer presented with one week of intractable nausea, vomiting, progressive left lower extremity weakness, and sensory changes. Initial evaluation was unrevealing. MRI demonstrated longitudinally extensive transverse myelitis and an enhancing dorsal medullary lesion consistent with APS, along with diffuse leptomeningeal enhancement raising concern for neoplastic or inflammatory etiologies. Cerebrospinal fluid analysis showed lymphocytic pleocytosis and elevated protein. The patient developed respiratory failure requiring intensive care support. Empiric treatment with high-dose intravenous methylprednisolone and plasma exchange was initiated. AQP4-IgG serology returned positive, confirming NMOSD. Following treatment, nausea and mental status improved, with partial neurological recovery, although significant residual left leg weakness and neurogenic bladder persisted. The patient was discharged to rehabilitation with plans for long-term immunosuppressive therapy.

conclusionThis case highlights APS as an important early manifestation of NMOSD that may mimic gastrointestinal or neoplastic conditions, particularly in patients with complex medical histories. Early recognition of APS and prompt immunotherapy are critical to prevent severe neurological disability and improve outcomes.