In children older than 3 months and in adults, HSE is usually localized to the temporal and frontal lobes and is caused by HSV-1. Less commonly, HSV-1 may produce a brainstem encephalitis, and HSV-2 may produce a myelitis. The exact cause of encephalitis is often unknown, but the most commonly diagnosed cause is a viral infection. Encephalitis caused by HSV-1 is rare, but it has the potential to cause significant brain damage or death. The majority of cases of herpes encephalitis are caused by herpes simplex virus-1 (HSV-1), the same virus that causes cold sores. Most individuals with HSE show a decrease in their level of consciousness and an altered mental state presenting as confusion, and changes in personality.
Causes. Herpes simplex encephalitis is a complication of infection with the herpes simplex virus. In most cases, the disorder results from herpes simplex virus type I (HSV-I). Herpes simplex infection is an acute viral disease usually spread from person to person. Most viral infections in childhood are able to cause encephalitis. Herpes simplex encephalitis (HSE) is recognised worldwide as the most frequent infectious encephalitis. HSV encephalitis is caused most commonly by HSV type I. It is the most common year-round viral encephalitis.
Most new cases of genital herpes infection do not cause symptoms, and many people infected with HSV-2 are unaware that they have genital herpes. Oral herpes (herpes labialis) is most often caused by herpes simplex virus 1 (HSV-1) but can also be caused by herpes simplex virus 2 (HSV-2). Untreated, herpes encephalitis is fatal over 70 of the time. The disease is usually caused by one of several viral infections, so it’s sometimes referred to as viral encephalitis. Herpes simplex type 1 virus is one of the more common and serious causes of viral encephalitis. Herpes simplex virus type 1 (HSV-1) is one of the most common causes of sporadic viral encephalitis in adults. Herpes simplex encephalitis (HSE) may be a consequence of both primary and recurrent HSV infections, and it is characterized by focal necrosis of the medial temporal and inferior frontal lobes and, occasionally, of the insular cortex and cingulate gyrus 1, 2.
Encephalitis, Herpes Simplex
HSV remains the most common cause of severe sporadic fatal encephalitis. In adults, this necrotizing encephalitis involves the medial temporal and inferior frontal lobes; recent reports indicate that levels of cytokines and other markers of immune activation in CSF are elevated (6, 7). The various causes of acute infectious viral encephalitis are shown in table 1. In cell cultures, HSV-1 often produces rounding or ballooning of cells, whereas HSV-2 often causes infected cells to fuse. It was said that HSV-1 causes infection above the belt and HSV-2 below the belt. The most frequently encountered form of Herpes simplex encephalitis (HSE) is a severe focal destructive encephalitis with a mortality of 70 and severe neurological sequelae in survivors. Most often caused by HSV-1, herpetic gingivostomatitis presents as multiple herpetic lesions on the palate, tongue and gingivae. HSV encephalitis can result from a primary or reactivated infection. Encephalitis is the most serious neurological complication caused by HSV-1. The cerebrospinal fluid (CSF) is usually abnormal in patients with HSV-1 encephalitis. The fundamental distinguishing characteristic of herpes viruses is their establishment of latent infection with integration of viral genomic material into host chromosomes. A potentially devastating infection, most commonly caused by HSV 2 contracted during passage through the genital canal when the mother is shedding herpes virus at the time of delivery. This is the most common cause of fatal sporadic encephalitis and is lethal in 50 of patients.