Herpes simplex encephalitis in North West India.

All patients admitted with provisional diagnosis of an encephalitic illness over a period of 30 months, were studied. Special investigations included CSF analysis, EEG, CT scan and MRI. Herpes simplex virus (HSV) antibody estimation in CSF and blood was done simultaneously using ELISA. Patients with diagnosis of cerebral venous thrombosis, cerebral malaria, tubercular meningitis etc, who resembled herpes simplex encephalitis (HSE), were excluded systematically with relevant investigations. 28 patients showed electroencephalographic, serologic and/or neuroradiological evidence of herpes simplex encephalitis. Males were affected more than females. Age ranged from 4 years to 65 years. Main clinical features included altered sensorium (100%) and seizures (89%). Serological test for HSV antibody in CSF and blood was positive in 14 patients. Fronto-temporal localisation was seen in EEG of 18 patients. CT and MRI were fairly characteristic with bilateral asymmetric fronto-temporal lesions. Patients with mild disease and who reported earlier responded well to treatment with acyclovir. Mortality was higher if treatment was delayed or if the disease was severe. Delayed treatment even in less severe cases produced neurological deficit in many survivors. Despite limitations of non-availability of CSF-PCR and serial estimation of HSV antibodies, the study is an attempt to highlight the value of high index of suspicion of HSE on clinical grounds, systematically excluding cases with different aetiologies resembling HSE and planning early antiviral therapy to reduce both mortality and morbidity associated with this fatal disease.