Encephalitis caused by the Herpes simplex virus (HSV) is very serious disease, which may end up with a significant brain damage or even death. This condition, more specifically HSV type 2, may affect newborn babies causing neonatal herpes and generalized infection of the brain. The other type of this disease is known to affect children over 3 months and adult people. In this case, HSV type 1 affects only temporal and frontal lobes of the brain.
HSV remains dormant in the nervous system (the neurons) and in rare occasions it gets transported through peripheral neurons to the brain (central nervous system), provoking encephalitis. HSV encephalitis is considered to be medical emergency, as this is the most serious complication of the HSV infection that exists.
How HSV Affects the Brain?
Doctors still don’t know everything about this virus and the way it causes encephalitis. However, neurons get destroyed very quickly in this disease, especially those located in the medical temporal and inferior frontal lobes. In rare cases HSV encephalitis can affect some other parts of the brain, such as cerebellum, basal ganglia or the brainstem. Brain cells get damaged directly because of the virus and also because of the immune system of the body, responding to infection. Viral infection spreads through the brain, from one side to the other, provoking necrosis of the cells and inflammation.
About 30% of all herpes encephalitis (HSE) is caused directly because of the primary HSV infection, while other cases are usually associated with some preexisting HSV infection and its reactivation.
What to Expect from HSE Diagnosis?
Herpes encephalitis is potentially fatal neurological disease and for that reason it must be treated. In untreated patients, HSE is a progressive problem and usually ends lethally after a week or two in some 70% of cases. Those who survive untreated HSV encephalitis may expect serious neurologic problems.
Acyclovir and vidarabine are drugs recommended for the treatment of this condition. However, doctors usually prefer acyclovir because of the studies which revealed just 19% (or 6 to 11%, depending on the studies) mortality rate. These results are much better than in patients treated with vidarabine. After the treatment with acyclovir, some 38% of the patients had no or just mild neurological deficits, 9% had moderate and 53% experienced severe neurological problems.
Neonatal HSE is quite often fatal medical problem. About 6% of babies suffering from isolated HSE and some 31% of those with disseminated HSV infection in the brain have fatal consequences.
Prognosis is also found to be much better for non-comatose patients, especially in those younger than 30 years of age, while coma usually means bad prognosis.