In a retrospective study of children with viral encephalitis admitted to the University Paediatric Unit, Queen Mary Hospital, Hong Kong, during the past 10 years, 57 satisfied the diagnostic criteria. The presumed viral etiology was determined in 15 (26%) patients of whom 9 had post-infectious encephalitis (mumps-4, measles-1, rubella-1, influenza A-2, influenza B-l). The viruses isolated were: influenza (3 cases), Coxsackie (2), adenovirus (2), mixed adenovirus and cytomegalovirus (1), and herpes simplex (1). Presenting neurologic features included focal signs (33%), convulsion (30%), headache (25%), drowsiness (18%), nuchal rigidity (10%), and coma (9%). Seven (12%) who developed status epilepticus within 24 hrs of admission died subsequently. A total of 16 (28%) died, and 5 were less than 1 year old. Indicators of a poor outcome were an onset in infancy and rapid deterioration in the level of consciousness.
Recovery was complete in 76% of 41 survivors; focal neurological deficits remained in 29% and epilepsy in 4% of 31 with sequelae. Eight children with suspected herpes simplex encephalitis on admission were treated with Acyclovir and none died; one in whom the diagnosis was confirmed developed spastic quadriplegia, mental retardation, and infantile spasms. 
COMMENT. Unlike previous reports from the USA and Scandinavia which have emphasized herpes simplx virus (HSE) as a major cause of acute sporadic viral encephalitis, only 1 case was identified in this study and none of the 16 patients who died had histological evidence of herpes simplex infection. Brain biopsy, a controversial diagnostic test, was not performed. A consensus panel of the Jrnl of Pediatric Infectious Disease has recommended early brain biopsy as a prerequisite for diagnosis and treatment of HSE. This view is supported by Hanley et al, Johns Hopkins Hospital, but is considered invalid by Fishman RA, Univ of California, San Francisco . Brett EM, at the Hospital for Sick Children, Great Ormond Street, London, has spoken against routine diagnostic brain biopsy for suspected HSE in children . Noninvasive magnetic resonance imaging (MRI) may provide early diagnosis without the immediate risks of biopsy and its later complications.