[Cognitive Impairment in Patients with Bacterial Meningitis and Encephalitides]

Cognitive impairments, including dementia, can present as first symptoms at the acute stage, and/or as sequelae in the chronic stages, in some patients with bacterial meningitis (BM) or encephalitides. BM and encephalitides are lifethreatening neurological emergencies, and early recognition, efficient decision-making, and rapid commencement of therapy can be lifesaving. Empirical therapy should be initiated promptly whenever BM or encephalitides are a probable diagnosis. In this article cognitive impairments, including dementia, presenting in patients with BM, Herpes simplex virus encephalitis (HSVE), Human herpesvirus-6 (HHV-6) encephalitis, and Anti N-methyl-d-aspartate (NMDA) receptor encephalitis are reviewed. In the above mentioned diseases, cognitive impairment without fever might be observed at the time of disease onset. cognitive impairment has been also noted in some aged or immunocompromised patients at the onset of BM. Immediate memory disturbance as one of the first symptoms of HHV-6 encephalitis presented in 74% of patients with this disease. Cognitive impairment, including dementia as sequela, was also found in 10-27% of patients with BM, 54-69% of patients with HSVE, 33% of HHV-6 encephalitis patients, and 39% of patients with anti-NMDA receptor encephalitis. Suitable therapeutic management of these diseases at the acute stage is thus required in order to avoid these sequelae.