Anti-N-Methyl-D-Aspartate Receptor Encephalitis With Autonomic Instability and Focal Seizures Without Detectable Ovarian Teratoma.

Anti-N-methyl-D-aspartate receptor (anti-NMDAR) encephalitis is a severe but potentially reversible form of autoimmune encephalitis, and it typically affects young women. It can be challenging to differentiate from other conditions that cause symptoms such as seizures and psychiatric and autonomic manifestations. We present the case of a previously healthy young woman without any significant past medical history who developed acute-onset, progressive neuropsychiatric disturbance, focal impaired awareness seizures, cognitive impairment, and intermittent autonomic disturbance manifesting as sinus tachycardia. Initial investigations showed mild pleocytosis in the CSF and subtle hyperintensity involving the right insular region and adjacent subcortical white matter on MRI. Further tests detected anti-NMDAR antibodies in both serum and CSF. She was started on first-line treatment with IV methylprednisolone and IVIG, but persistent cognitive impairment prompted escalation to second-line treatment with rituximab. She also underwent an extensive workup for an underlying ovarian teratoma or other neoplasms, including pelvic ultrasound and MRI, both of which were unremarkable. The patient eventually experienced gradual neurological recovery with immunotherapy and neurorehabilitation, ultimately regaining her independence and returning home. This case highlights autonomic dysfunction as a possible feature of anti-NMDAR encephalitis and the importance of early immunotherapy, even in patients without an identifiable tumor.