Anti-NMDAR Encephalitis Caused by HSV Encephalitis: Two Different Courses and Prognosis

The recurrence of symptoms or the emergence of new clinical findings following herpes simplex virus encephalitis (HSVE) can result due to the relapse of the same viral agent, development of a new infectious encephalitis or autoimmune encephalitis. Differences in the presentation, clinical course, and electrophysiological findings of cases may be associated with variations in prognosis. In the first case of anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARE) following HSVE that we presented here, the patient exhibited epileptic seizures, and electroencephalography (EEG) revealed lateralized periodic discharges (LPDs) with plus modifiers. During the follow-up, status epilepticus developed and the patient did not respond to treatment and died. In contrast, the second case of anti-NMDARE following HSVE presented with psychiatric symptoms. EEG revealed LPDs in the form of a monomorphic blunt delta pattern. This patient responded rapidly to first-line treatments and achieved recovery with mild cognitive impairment. The pathogenic processes underlying the differences in clinical course and outcomes remain unclear, emphasizing the need for further research. Early initiation of immunotherapy is critical in patients with poor prognostic indicators after excluding HSVE relapse via polymerase chain reaction testing of cerebrospinal fluid.