Congenital herpes simplex virus encephalitis (brain MRI)

The patient was a 17-day-old boy whose symptoms included lethargy, fever, and right-sided clonic seizures. PCR for herpes simplex virus-2 was positive in the CSF and blood. The patient received high-dose parenteral acyclovir for 21 days, followed by oral acyclovir for 6 months. At follow-up, the patient had global developmental delay. MRI scans of the brain were obtained during the acute phase, on hospital day 2 (panels A-D), and during the chronic phase, at age 8 months (panels E and F). (A) Gadolinium administration reveals pial enhancement (arrow) in the left temporal-parietal region. (B) T1-weighted image reveals subtle focal hypointensity (arrow) in the region corresponding to the pial enhancement. (C) T2-weight image reveals focal hyperintensity (arrow) in the same region. (D) In the left temporal-parietal region, there is marked diffusion restriction (arrow). (E and F) Follow-up MRI scan at age 8 months reveals cystic encephalomalacia (arrows) in the same region in which abnormal signal was evident during the acute phase. (Contributed by Dr. Daniel Bonthius.)