Encephalitis is a term usually used to describe an inflammatory condition of the brain. Herpes simplex encephalitis is one of the most common infectious causes of encephalitis. A complicating situation after completion of the acyclovir treatment is the development of neurological relapses or worsening of deficits, reported to occur in 5–26% of cases. There are number of possibilities for such presentation including autoimmune etiologies.

75 year old woman presented with three days history of confusion, formed visual hallucinations and intermittent dizziness. she was found to have HSV encephalitis. Patient completed three weeks course of Acyclovir treatment. hospital course was complicated by atonic bladder. one week later, patient presented with decrease responsiveness and right arm choreiform movement. CSF showed significant protein elevation with elevated nucleated cells (protein 186, nucleated cells 44, lymphocyte 90%, glucose 47). Autoimmune post herpes encephalitis especially anti NMDAR was suspected, and patient was started on five days trial of methylprednisolone 1 gram daily with significant improvement within 24-48 hours. An antibody against unknown antigen was recognized on initial CSF; however, a repeat CSF testing done after clinical improvement showed absence of previously recognized pleocytosis and repeated autoimmune panel was also negative.

These findings support the concept of transient synthesis of neuronal antibodies that subsequently becomes undetectable as well as the role of steroids in the management of inflammatory immune mediated complications in HSE. Another interesting finding in our case was of urinary retention due to atonic bladder. 

our case emphasized the importance of an organized approach in evaluation of patients with persistent encephalopathy after treatment with acyclovir for HSE.