[Herpetic meningoencephalitis in the elderly. Apropos of 13 cases].

In a retrospective analysis of 13 cases of Herpes simplex encephalitis (mean age: 67.2 +/- 6.4 years; ten women, three men), the authors conclude that this infection is more often due to Herpes simplex virus 1 in the elderly. Diagnosis is difficult at an early stage, and must be suspected in case of confusion (9/13), especially feverish (11/13), associated with neurological signs (10/13), and particularly epilepsy (5/13). It requires a lumbar puncture which collect a clear and lymphocytic fluid. Prognosis of this encephalitis depends on early diagnosis and an presumptive therapy with acyclovir. EEG is helpful showing periodic activity (10/13). CT scan and MRI can show unspecific abnormalities, but often too late. Laboratory findings will secondarily confirm the diagnosis quite frequently, using new Elisa methods. Polymerase chain reaction allows earlier diagnosis. Geriatric cases seem more often due to reinfection or to endogen virus reactivation rather than to primary infection.