Other Viral Encephalitis

00:00 So what are some other types of viral encephalitis? We talked about herpes encephalitis or herpes zoster virus encephalitis, which is the prototypical viral encephalitis, but we see others. Varicella zoster is an uncommon cause, this results from reactivation of this virus from the sensory ganglia. It infects many areas of the brain and in the cerebrospinal fluid, the subarachnoid space but particularly the vascular endothelial cells and can lead to a vasculopathy. Patients with varicella zoster encephalitis can present with strokes. And the strokes occur secondary to this vasculitic process. Patients with herpes encephalitis and varicella zoster encephalitis are often treated with acyclovir potentially with steroids if there is a prominent inflammatory vasculitis. West Nile virus is something that we typically hear.

00:51 We commonly test but is uncommon. Less than 1% of patients who have West Nile virus will have neuroinvasive disease. Complications of West Nile encephalitis or CNS infections include an acute flaccid paralysis where the entire body becomes weak, this is a peripheral motor neuron disorder where patients become weak with reduced reflexes and it can be quite debilitating, or a chorioretinitis. Both the infection and the inflammatory response that occurs after the infection can affect the nervous system. So we need to think of the virus, but after the virus we can see post infectious encephalitides both after an infection and after a vaccine. These tend to present with diffuse neurologic dysfunction affecting the brain and maybe even the spinal cord. And some common syndromes that we see are acute demyelinating encephalomyelitis or ADEM. This is an acute onset condition where there is diffuse demyelination and neurologic dysfunction that affects the brain (encephalo) and spinal cord (myelo) myelitis and it's an infection. There is also an even hyperacute form of this condition called acute hemorrhagic leukoencephalitis or Hurst's encephalitis, which can be particularly debilitating.