RESUMO
INTRODUCTION: Herpetic encephalitis (HE) is the commonest cause of acute sporadic encephalitis in the United States and Europe. In 20% of cases, the clinical course is atypical and this may lead to delay in diagnosis and treatment. CLINICAL CASE: A 24 year old patient presented with aseptic meningitis, which had been present for the previous 10 days and which then became complicated by fever and aphasia. The cerebrospinal fluid (CSF) showed marked pleocytosis and increased protein. Cerebrospinal puncture was found to be positive for DNA of the herpes simplex virus. Magnetic resonance (MR) imaging showed a temporal lesion with intense uptake of contrast. Treatment was started with acyclovir and the patient improved over the days following this. CONCLUSIONS: At present the diagnosis of herpetic encephalitis is based on polymerase chain reaction (PCR) studies of the CSF and MR imaging. The correlation between patients with HE with cerebrospinal puncture showing positive for herpes and alterations on MR is 89%. In view of the 20% of atypical forms, a high degree of clinical suspicion is necessary to try to obtain early diagnosis and treatment.