Outcome of herpes simplex encephalitis in children.

Background And Purpose: Herpes simplex encephalitis (HSE) can cause high mortality and morbidity in children. Since local data of HSE in children are rare, we performed a retrospective study to evaluate the prognostic factors and outcome of HSE in Taiwan.

Methods: Children were enrolled into this study if they were diagnosed as having encephalitis and also had positive polymerase chain reaction for herpes simplex virus (HSV) from cerebrospinal fluid, and/or positive immunoglobulin M or at least four-fold elevation of immunoglobulin G against HSV type 1 or type 2 from serum during the period from December 1, 1984 to January 31, 2003.

Results: Forty patients were enrolled in this study. Twenty six patients (65%) had good outcome and 14 (35%) had poor outcome. No mortality or recurrence was found. Three-fifths of the patients were between 1 year and 6 years of age. Fever (75%) was the most common finding at admission, followed by seizures (63%), lethargy (60%), and altered consciousness (48%). Seizure and lethargy at the time of admission were more common in the poor outcome group (71% vs 58% and 64% vs 58%). Abnormal computed tomography/magnetic resonance imaging findings were found in 63% of patients in whom the examinations were performed. Abnormal electroencephalogram (EEG) findings were noted in 79% of tested patients. Acyclovir was used to treat 29 patients (73%). Abnormal neuroimaging or EEG findings were more prevalent in patients with poor outcome (75% vs 55% and 92% vs 71%), as well as delayed (>/=3 days) initiation of acyclovir therapy (92% vs 71%). There was no significant difference between the poor and good outcome groups in gender, age distribution, and clinical presentation.

Conclusion: As we cannot predict the outcome of patients with HSE in the early beginning of illness and delay of treatment may cause disaster, early diagnosis and prompt acyclovir initiation are important requirements for successful management.