Herpes simplex virus encephalitis update.

PURPOSE OF REVIEW: HSV is the most frequently identified cause of infectious encephalitis, in Western countries. This article is an update on the topic based on a review of recent studies from 2017 to 2018.

RECENT FINDINGS: Acyclovir is still the first line treatment, and no new drugs are currently available for clinical use. The major considerations for HSV encephalitis are as follows: point one, clinical evaluation remains the most important factor, as though CSF HSV PCR has a good sensitivity, in a small proportion of patients the initial testing might be negative. MRI brain is the first line imaging test, and mesial temporal lobe involvement and other typical findings are important for diagnosis; point 2, there should be emphasis on sequela, short-term, and long-term outcomes, and not just case fatality rated in future studies and clinical management. Auto-immune encephalitis can be triggered by HSV, and should be considered in patients who are not responding to treatment; point 3, future studies should be on better management of sequela, and better treatment regimens including those targeting the immune response.

SUMMARY: Autoimmune encephalitis is a clearly identified complication of HSV encephalitis. Inflammatory mechanisms are linked to the clinical presentation as well as severity and poor outcome. Initial corticosteroid therapy has to be evaluated in order to prevent complications.