In adults with HSV-1, the most common early symptoms are headache and fever. Additional symptoms include intellectual impairment, aphasia, meningeal signs, seizures, and paresthesias. Early treatment is crucial to a good outcome, and empirical acyclovir therapy can be initiated before a definitive diagnosis is established.
The virus cannot be cultured routinely from CSF, though lymphocytic pleocytosis and elevations in protein concentrations are observed. CSF viral cultures are positive for HSV in fewer than 5% of patients. Anti-HSV antibodies often do not appear until 1-3 weeks after symptom onset; therefore, antibody culture is helpful only in retrospective diagnosis.
EEG also can reveal focal temporal abnormalities, which are seen in 80% of patients; a normal EEG is believed to exclude the diagnosis. Periodic lateralized epileptiform discharges also support the diagnosis, but this finding is nonspecific. Historically, a brain biopsy provided