Neuromyelitis Optica Spectrum Disorder Following Pituitary Tumor Resection: A Rare but Critical Differential in Neurosurgical Practice.

Neuromyelitis optica spectrum disorder (NMOSD) is a rare, immune-mediated astrocytopathy disorder that predominantly affects adults. Postoperative cases are scarcely reported. A 75-year-old woman underwent uncomplicated endoscopic resection of a nonfunctional pituitary macro-adenoma. Seven days postoperatively, she developed encephalopathy without focal deficits. Magnetic resonance imaging (MRI) revealed extensive confluent T2 and fluid attenuated inversion recovery (FLAIR) hyperintensities in the corpus callosum, periventricular white matter, and cervical spinal cord, absent preoperatively. Metabolic, infectious, and structural etiologies were excluded. Despite high-dose corticosteroids and intravenous immunoglobulin (IVIG) administration, she deteriorated with brainstem involvement, respiratory failure, and fatal arrhythmias. This exceptionally rare case emphasizes NMOSD as a critical differential in postoperative neurological decline, particularly after CNS procedures. Clinicians must prioritize early recognition to guide timely intervention. Future studies should investigate surgical stress, pituitary dysfunction, and immune activation in demyelination pathogenesis.