Lymphoplasmapheresis for Refractory Anti–N‐Methyl‐D‐Aspartate Receptor Encephalitis: A Case Report

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is generally responsive to immunotherapy, but some patients remain refractory despite treatment escalation. Lymphoplasmapheresis (LPE), a modified apheresis technique that removes both plasma components and circulating lymphocytes, may offer a salvage option in selected cases. We report a 61-year-old woman with refractory anti-NMDAR encephalitis who showed limited improvement after corticosteroids, intravenous immunoglobulin, and ofatumumab. After a prolonged interval following ofatumumab induction, she remained severely impaired with persistent disease activity and elevated cerebrospinal fluid and serum anti-NMDAR IgG titers. Three sessions of LPE were performed over 5 days. Clinical improvement was observed after LPE, accompanied by a decline in antibody titers. At 5-month follow-up after LPE, she maintained sustained recovery, with a Clinical Assessment Scale in Autoimmune Encephalitis score of 6 and a modified Rankin Scale score of 2. This case supports a close temporal association between LPE and clinical and immunological improvement, although causality cannot be definitively established from a single case.