Herpes simplex encephalitis
Herpes simplex encephalitis | |
---|---|
Other names | Herpes encephalitis, Herpesviral encephalitis |
Coronal T2-weighted MR image shows high signal in the temporal lobes including hippocampal formations and parahippogampal gyrae, insulae, and right inferior frontal gyrus. A brain biopsy was performed and the histology was consistent with encephalitis. PCR was repeated on the biopsy specimen and was positive for HSV | |
Specialty | Infectious diseases |
Herpes simplex encephalitis (HSE), or simply herpes encephalitis, is encephalitis due to herpes simplex virus. It is estimated to affect at least 1 in 500,000 individuals per year,[1] and some studies suggest an incidence rate of 5.9 cases per 100,000 live births.[2]
About 90% of cases of herpes encephalitis are caused by herpes simplex virus-1 (HSV-1), the same virus that causes
Two-thirds of HSE cases occur in individuals already
The most common cause for encephalitis in children and adults is HSV-1. However, encephalitis found in newborns and immunocompromised individuals is mainly caused by HSV-2.[5]
Signs and symptoms
Most individuals with HSE show a decrease in their level of consciousness and an altered mental state presenting as
Definite diagnosis requires testing of the cerebrospinal fluid (CSF) by a lumbar puncture (spinal tap) for presence of the virus. The testing takes several days to perform, and patients with suspected Herpes encephalitis should be treated with
Associated conditions
Herpesviral encephalitis can serve as a trigger of anti-NMDA receptor encephalitis.[8] About 30% of HSE patients develop this secondary immunologic reaction,[9] which is associated with impaired neurocognitive recovery.[10]
Epidemiology
The annual incidence of herpesvial encephalitis is from 2 to 4 cases per 1 million population.[11]
Pathophysiology
HSE is thought to be caused by the transmission of virus from a peripheral site on the face following HSV-1 reactivation, along a nerve
Diagnosis
Brain CT scan (with/without contrast). Complete prior to lumbar puncture to exclude significantly increased ICP, obstructive hydrocephalus, mass effect[14]
Brain MRI—Increased T2 signal intensity in frontotemporal region → viral (HSV) encephalitis[15]
Treatment
Herpesviral encephalitis can be treated with high-dose intravenous
Earlier treatment (within 48 hours of symptom onset) improves the chances of a good recovery. Rarely, treated individuals can have relapse of infection weeks to months later. There is evidence that aberrant inflammation triggered by herpes simplex can result in granulomatous inflammation in the brain, which responds to steroids.[16] While the herpes virus can be spread, encephalitis itself is not infectious. Other viruses can cause similar symptoms of encephalitis, though usually milder (Herpesvirus 6, varicella zoster virus, Epstein-Barr, cytomegalovirus, coxsackievirus, etc.).[17][11]
References
- ^ PMID 16675036.
- S2CID 9632498.
- PMID 16926356.
- ^ S2CID 5980017.
- PMID 32491575, retrieved 2023-10-02
- ^ "Encephalitis, Herpes Simplex - Symptoms, Causes, Treatment | NORD". rarediseases.org. Retrieved 2023-10-02.
- ^ Gupta, Harsh; Malhotra, Samira; Batra, Amit (2019-04-15). "An Unusual Stroke-Like Presentation of HSV Encephalitis". The Journal of the Arkansas Medical Society. 115 – via ResearchGate.
- S2CID 197464804.
- PMID 23280840.
- PMID 27497810.
- ^ PMID 32491575.
- PMID 7437807.
- PMID 19456260.
- ^ "Herpes Meningoencephalitis". Johns Hopkins Medicine. 19 November 2019. Retrieved 13 July 2021.
- ^ "Encephalitis". The Lecturio Medical Concept Library. Retrieved 13 July 2021.
- S2CID 12859405.
- ^ "Encephalitis". Mayo Foundation for Medical Education and Research (MFMER). Retrieved 13 July 2021.
External links
- Kumar M, Hill JM, Clement C, Varnell ED, Thompson HW, Kaufman HE (December 2009). "A double-blind placebo-controlled study to evaluate valacyclovir alone and with aspirin for asymptomatic HSV-1 DNA shedding in human tears and saliva". Investigative Ophthalmology & Visual Science. 50 (12): 5601–5608. PMID 19608530.
- Kaufman HE, Azcuy AM, Varnell ED, Sloop GD, Thompson HW, Hill JM (January 2005). "HSV-1 DNA in tears and saliva of normal adults". Investigative Ophthalmology & Visual Science. 46 (1): 241–247. PMID 15623779.
- Hill JM, Zhao Y, Clement C, Neumann DM, Lukiw WJ (October 2009). "HSV-1 infection of human brain cells induces miRNA-146a and Alzheimer-type inflammatory signaling". NeuroReport. 20 (16): 1500–1505. PMID 19801956.<ref>