Herpes simplex virus encephalitis in children: analysis of cerebrospinal fluid and progressive neurodevelopmental deterioration.

In this retrospective study of six patients (five infants and one child) with herpes simplex virus (HSV) encephalitis, we report the results of developmental evaluations and assays of cerebrospinal fluid (CSF) that were performed more than one month after the onset of disease. Two infants had recurrence or worsening of disease immediately after completing parenteral therapy. Two other infants had late developmental deterioration of previously attained abilities, which was associated with pleocytosis and/or elevation of the protein concentration in CSF during the year after acute HSV encephalitis. Three of the five infants had severe neurological and developmental impairment, and all of them had late CSF pleocytosis and/or elevated protein concentrations. Two infants were treated with oral acyclovir after completing parenteral therapy; they had mild neurological impairment and no further CSF abnormalities. Periodic activation of latent virus may be the cause of inflammatory responses of the CSF that lead to continued or intermittent neurological and developmental damage. Our data suggest that HSV encephalitis in infants may result in late persistent or recurrent disease of the central nervous system.