The limbic system and the localisation of herpes simplex encephalitis.

The selective destruction of temporal and frontal lobe structures by herpes simplex encephalitis has been explained as a consequence of the proximity of those regions to the point of entry of the virus in the encephalon, through olfactory pathways or meningeal branches of the trigeminal nerves. An alternative hypothesis is presented: that the encephalitis is due to a special affinity of the herpes simplex Type 1 virus for the limbic cortices, that is, that distinctive neuroanatomical, neurochemical and neuroimmunological properties of those cortices permit the virus to manifest its destructive behaviour, regardless of the route of entry to the CNS, possibly during altered immunological states. The study of the neurochemical and neuroimmunological properties of the limbic cortices may be a useful approach to the enigma of why and when herpes simplex Type 1 causes encephalitis.