Neonatal herpes simplex type 2 encephalitis: its appearances on ultrasound and CT.

We report the ultrasound findings in a 28-day-old infant with encephalitis due to herpes simplex type 2. To date less than ten such cases have appeared in the world literature. Asymmetric ventricular dilatation was seen sonographically with widespread parenchymal hyperechoic areas which corresponded to areas of low attenuation on CT. Cranial ultrasound has a distinctive appearance which, if recognised, and suggested, can lead to an early definitive diagnosis.