Post-Herpes Simplex Virus (HSV) Autoimmune Encephalitis: A Case Series and Novel Immunological Findings (P1.292)

OBJECTIVE: To describe the clinical and immunological characteristics of a case series with post-HSV autoimmune encephalitis. BACKGROUND: Autoimmune encephalitides are diseases of children and adults associated with autoantibodies against synaptic antigens. They present with a variety of symptoms, including psychosis, cognitive and memory disrurbances, seizures and abnormal movements. It has been recently reported that HSV can trigger brain autoimmunity, as up to 20[percnt] of patients with HSV-encephalitis relapse, developing autoimmune NMDAR encephalitis. METHODS: Patient sera and CSF were tested for anti-NMDAR, GABAbR, AMPAR, LGI1, CASPR2 and DDPX antibodies using cell-based assays. RESULTS: Three patients developed autoimmune-encephalitis following HSV-encephalitis. A 33 year-old woman continued having symptoms after 2 weeks of anti-HSV therapy and developed anti-NMDAR antibodies in serum, and anti-GABAbR antibodies in both serum and CSF. Following immunotherapy, she fully recovered but her anti-NMDAR and anti-GABAbR seropositivity persists 22 months later. Another, a 58 year-old woman, recovered fully with anti-HSV therapy but upon discharge she was tested positive for anti-NMDAR antibodies. She remained asymptomatic for 6 months when she relapsed with generalized seizures. Her CSF was positive for anti-NMDAR antibodies. A third case, a 9-month old infant, was successfully treated with anti-HSV therapy but 2 days after discharge she was re-admitted with typical NMDAR encephalitis symptoms including choreoathetotic movements and seizures. Her serum and CSF tested positive for anti-NMDAR antibodies even though a previously obtained CSF sample, 7 days before her relapse, was anti-NMDAR-negative. CONCLUSIONS: From this series we conclude that: HSV can trigger autoimmune encephalitis in adults and infants associated not only with anti-NMDAR but also anti-GABAbR antibodies; like anti-NMDAR, anti-GABAbR antibodies can also persist in the serum, even without associated symptoms for a long time. However, relapses are associated with antibody presence in the CSF, which may be intrathecally produced (or detected) even within 7 days before a relapse. Disclosure: Dr. Alexopoulos has nothing to disclose. Dr. Kouremenos has nothing to disclose. Dr. Akrivou has nothing to disclose. Dr. Naoumis has nothing to disclose. Dr. Antonopoulou has nothing to disclose. Dr. Vlachoyiannopoulos has nothing to disclose. Dr. Dalakas has received personal compensation for activities with Baxter, Novartis, Grifols, CSL, Octapharma, and Dysimmune Diseases Foundation as a member of their Scientific Advisory Board or speaking honoraria and for activities with Therapath as a co