Anti-NMDA Receptor Antibody Positivity and Presentations Without Seizure, Involuntary Movement, Hypoventilation, or Tumor: A Systematic Review of the Literature.

Patients with anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis may remain undiagnosed and untreated with immunotherapy. To investigate specific features and responses to immunotherapy of atypical anti-NMDAR antibody positivity patients, the authors reviewed and evaluated previous case reports/series including patients without seizure, involuntary movement, hypoventilation, or tumor. Of 22 patients identified, 21 responded to immunotherapy. Two patients had neurological/motor symptoms with few/no psychiatric/cognitive symptoms, and eight had both. Twelve patients presented with psychiatric/cognitive symptoms with few/no neurological/motor symptoms, and ≥1 had memory impairment, catatonia, abnormal MRI or electroencephalogram results. The authors recommend lumbar puncture and examination of anti-NMDAR antibodies for patients with these features.