[The diagnosis of herpes encephalitis--a case-based update].

Herpes simplex virus encephalitis (HSVE) is a rare and life-threatening infection. The clinical signs are diverse and often misleading regarding the aetiology. However, focal seizure with fever and typical CT/MRI finding should always raise the possibility of HSVE as early diagnosis and antiviral therapy is crucial. Before the advent of molecular techniques and high-tech imaging histological examination from multiple brain biopsies were often necessary. Although nowadays PCR and other molecular methods may provide an aetiological diagnosis some cases need neuropathological verification. Due to the high IgG seropositivity rate in the population the plasma IgG titer is not diagnostic and elevation of its plasma level requires several weeks. We report the case of a 25-years old male patient who initially presented with epileptic seizures. There was no final diagnosis and no causal treatment in the district general hospital. The patient was admitted to our institution in comatose state on day 9; the initiated diagnostic tests and therapy could not save the patient who died next day. The autopsy and subsequent neuropathological examination revealed HSVE. We present a flowchart on diagnostic work-up and special techniques to aid diagnosis in suspected viral encephalitis.