Intrathecal Rituximab as a Rescue Therapy in Refractory Pure CSF Positive, Non-Teratomatous Type Anti-NMDAR Encephalitis

NMDAR antibody encephalitis is the most common autoimmune encephalitis characterized by a myriad of neuropsychiatric symptoms. It predominantly affects females and is associated with ovarian teratoma (58%). Nineteen percent do not respond to treatment and are left with serious neurological deficits. A subset of NMDAR encephalitis with antibody positivity in CSF alone without ovarian teratoma is often found to be refractory to treatment. We name them Pure CSF positive, non-teratomatous type anti-NMDAR encephalitis. We report two such cases who responded to intrathecal rituximab, to highlight a novel treatment as a rescue therapy to prevent long-term disability and improve clinical outcomes.