From the Guidelines
HSV-1 encephalitis is associated with the development of anti-N-methyl-D-aspartate (NMDA) receptor encephalitis in a significant proportion of cases, with approximately 24.5% of patients developing detectable CSF antibodies within 3 months of initial diagnosis. This association is supported by a recent prospective study of 49 patients with HSV encephalitis, which found that NMDAR antibodies were absent at the initial diagnosis but developed in nearly a quarter of patients by 3 months 1. The development of anti-NMDA receptor encephalitis following HSV-1 encephalitis is thought to be a post-infectious complication, where the initial viral infection triggers a subsequent autoimmune response.
Key Points
- HSV-1 encephalitis and anti-NMDA receptor encephalitis are two distinct conditions with different causes, but can be related in some cases
- HSV-1 encephalitis is caused by direct infection of the brain by herpes simplex virus type 1, requiring immediate treatment with intravenous acyclovir
- Anti-NMDA receptor encephalitis is an autoimmune disorder where antibodies attack NMDA receptors in the brain, treated with immunotherapy such as corticosteroids, intravenous immunoglobulin, or plasma exchange
- The development of anti-NMDA receptor encephalitis following HSV-1 encephalitis can lead to a relapse of neurological symptoms, requiring a different treatment approach
Treatment Implications
- Patients with HSV-1 encephalitis should be monitored for the development of anti-NMDA receptor encephalitis, particularly in the first 3 months after initial diagnosis
- Treatment of anti-NMDA receptor encephalitis may involve immunotherapy, such as corticosteroids, intravenous immunoglobulin, or plasma exchange, and may require long-term immunosuppression in some cases 1
- Early recognition and treatment of anti-NMDA receptor encephalitis are crucial to improve clinical outcomes and prevent long-term neurological sequelae.
From the Research
Association between HSV-1 Encephalitis and Anti-NMDA Receptor Encephalitis
- There is evidence to suggest that Herpes Simplex Virus type 1 (HSV-1) encephalitis is associated with anti-N-methyl-D-aspartate (NMDA) receptor encephalitis 2, 3, 4, 5, 6.
- Studies have reported cases of patients developing anti-NMDA receptor encephalitis after HSV-1 encephalitis, with symptoms including neuropsychiatric and cognitive deficits 2, 3, 4, 5, 6.
- The onset of anti-NMDA receptor encephalitis can occur within a few days to several months after HSV-1 encephalitis 2, 3, 4, 5, 6.
Clinical Presentation and Diagnosis
- Patients with anti-NMDA receptor encephalitis after HSV-1 encephalitis often present with symptoms such as paranoid delirium, Capgras and Cotard syndromes, and cognitive deficits 2, 3, 4, 5, 6.
- Diagnosis of anti-NMDA receptor encephalitis is often delayed, and it is essential to search for anti-NMDA-R antibodies in cerebrospinal fluid of patients with unexpected evolution of HSV-1 encephalitis 3, 4, 5, 6.
Treatment and Prognosis
- Treatment of anti-NMDA receptor encephalitis after HSV-1 encephalitis typically consists of immunosuppressive therapy, such as steroids, plasma exchange, and rituximab 2, 3, 4, 5, 6.
- Prognosis is often favorable, but some symptoms may persist, and patients may require ongoing treatment and follow-up 2, 3, 4, 5, 6.