404 - Autoimmune Encephalitis: A Case Report

Case Diagnosis: 32 year old male with autoimmune encephalitis.

Case Description: Patient is a 32 year old male without significant past medical history who presented with altered mental status, gait instability and generalized weakness, worse in the lower extremities. MRI brain revealed diffuse leptomeningeal enhancement concerning for infectious vs inflammatory etiology. EEG was consistent with encephalopathy and subclinical seizure was also noted early on in his course. Lumbar puncture performed was consistent with lymphocytic pleocytosis with elevated protein. West Nile virus, IgM, IgG, autoimmune panel, and CSF cultures were negative. GFAP antibody was positive. Patient was treated with plasmapheresis and steroids. Patient spent 2.5 weeks in inpatient rehab, and progressed from moderate assistance with ambulation to minimal assistance on day of discharge, walking 170 feet with rolling walker. On follow up 6 months later, patient was back to his baseline and asymptomatic. Repeat MRI brain showed improvement in his myelitis.

Discussions: Literature regarding autoimmune encephalitis is unfortunately limited. It is a relatively rare disease (prevalence of 13.7 per 100,000 people). An aggressive course of the disease is common, with a reported mortality rate of 8–18.45%. Many patients require long-term immunomodulatory therapy with prednisone and also nonsteroidal immunosuppressive medications. This is an especially interesting case given the patient’s robust recovery without long term medical management.

Conclusions: Autoimmune encephalitis is a rare and potentially deadly diagnosis. Treatment involves steroids, plasmapharesis, and aggressive rehabilitation.