2019 年 35 巻 1 号 p. 50-55
Neonatal herpes simplex encephalitis (HSE) is a devastating disorder, although it can be treated. Early diagnosis and antiviral therapy are essential. In this study, we report on a female neonate with HSE, whose brain MRI was of diagnostic value. She exhibited lethargy, poor suckling, seizure, and central apnea on day 13 after birth (day 1). An examination of her cerebrospinal fluid (CSF) on day 2 showed mild pleocytosis with lymphocytic predominance. On day 3, multiple high signal lesions were found on diffusion-weighted images (DWI) in brain MRI in the bilateral corticospinal tracts, bilateral frontal and right parietal cortices, bilateral thalami and pallidums, left cerebellar white matter, and pons. Although a traditional polymerase chain reaction (PCR) did not detect herpes simplex virus (HSV) in the CSF on day 2, acyclovir administration was not discontinued, because MRI showed corticospinal tract lesions, which have recently been reported to be preferentially affected in neonatal HSE. Real-time PCR thereafter detected HSV from the CSF on day 2. It is important to recognize that the negative results of the first HSV–PCR do not exclude neonatal HSE, if DWI shows a characteristic lesion distribution in early stages of the illness.