Herpes simplex encephalitis: CT findings in the neonate and young infant.

The computed tomographic (CT) findings in six cases of neonatal herpes simplex encephalitis (HSE) are reviewed and compared with previous reports. The diagnoses were made on the basis of isolation of the virus from a brain biopsy specimen in one case, from cerebrospinal fluid in two cases, from tracheal aspirate in one case, and on clinical grounds in two cases. Five infants survived; all had significant neurologic deficits. CT showed bilateral cerebral involvement with relative sparing of the lower neuraxis in all cases. Bilateral patchy low-density zones involving the periventricular white matter more than the cortical gray matter were seen initially in four of the six infants. Hemorrhage and/or calcifications in the thalamus, insular cortex, periventricular white matter, and along the corticomedullary junction were present in five infants. Severe cerebral necrosis eventually resulted in all six infants. Unlike older patients, only one infant had predominantly temporal lobe involvement. These findings agree with the CT descriptions reported by others.