The difficulties in diagnosis in 6 children aged 13 days to 9 years with herpes simplex encephalitis (HSE) are stressed in a report from the Departments of Child Health and Pathology, University Hospital of Wales, Cardiff. The original diagnoses in 3 cases were post-traumatic epilepsy, bacterial meningitis and febrile convulsion. Fever was absent in 2 cases and the CT was normal in 2. All cases had abnormal EEG findings with encephalitic changes in 5. Brain biopsy was diagnostic in 2. The outcome was poor in all 6. The authors stress that the absence of fever at presentation and a normal CT scan should not discourage the use of acyclovir for children presenting with focal seizures and altered consciousness. 
COMMENT. Mikati MA and colleagues at the Children’s Hospital and Massachusetts General Hospital, Boston have shown that the EEG is a sensitive test that may be superior to radiologic procedures in the early diagnosis of neonatal herpes simplex encephalitis. The multifocal periodic pattern in the presence of CSF pleocytosis is highly suggestive of the diagnosis. The CT and ultrasound studies may be normal when the EEG is abnormal during the first few days of the infection. An MRI with T2 weighted images may be more revealing than the CT and will show multiple small disseminated lesions (see Progress in Pediatric Neurology, 1991, p. 423, PNB Publishers).