Electroencephalography as an Adjunct in the Diagnosis of HSV Encephalitis in Preterm Twins.

Neonatal herpes simplex virus (HSV) infections are rare, with an estimated 1500 cases diagnosed annually in the United States.1 Intrapartum exposure to HSV in vaginal secretions leads to 85% of neonatal HSV infections, while intrauterine and postpartum infection accounts for 5% and 10% of infections, respectively.2 Irrespective of the route of exposure, neonatal HSV infection can cause devastating disease if not recognized and treated early.3 Primary maternal HSV infections carry a considerably higher risk of vertical transmission compared with reactivated latent infection or asymptomatic viral shedding because of the higher titer of virus found in the maternal genital track and the lack of transplacental transfer of protective IgG to the fetus.2 Other important risk factors for transmission include prolonged rupture of membranes, which increases the likelihood of ascending infection, and the use of intrapartum fetal scalp monitoring.2 Neonatal disease is classified as cutaneous/mucosal, central nervous system (CNS; with an encephalitic presentation), or disseminated disease involving multiple organs with or without CNS involvement.3 CNS and disseminated disease have the highest risk of morbidity and mortality, and favorable clinical outcomes are more likely if intravenous acyclovir is started promptly.2,3 However, treatment is frequently delayed because the presenting symptoms of neonatal HSV infection are often nonspecific. Despite decades of research there has not been a significant shortening of the time to institution of therapy.3 Because of the potentially devastating consequences of neonatal HSV infection, many researchers have evaluated screening of pregnant women for HSV infection and third trimester prophylaxis of HSV-positive women. Unfortunately, serological screening of pregnant women is of little use in preventing neonatal HSV infection because seropositivity does not predict the presence of infectious virus in the genital secretions of pregnant women at the time of parturition.4 Likewise, antenatal surveillance cultures to detect HSV in maternal genital secretions had poor correlation with the presence of infectious virus at the time of delivery.5 Third trimester prophylaxis has been demonstrated to reduce the incidence of genital lesions in pregnant women at delivery, the detection of HSV in genital secretions, and the rate of Caesarean delivery; however, the evidence is insufficient to support a recommendation for prophylaxis of pregnant women.6 It should be kept in mind as well that Caesarean delivery does not eliminate the risk of neonatal HSV infection, and in the setting of premature or prolonged rupture of membranes may provide little benefit.7 Because of the diagnostic uncertainty and the lack of effective preventive measures, some researchers support the use of acyclovir along with empiric broad-spectrum antibiotics for infants undergoing a rule out sepsis workup, though to date no standard of care has been defined.1 The cases described here illustrate the diagnostic uncertainty posed by neonatal HSV encephalitis. We propose an evidence-based application of routine electroencephalography (EEG) to aid in the workup of equivocal cases.