The prevalence, predictors, and clinical significance of electrographic seizures (ESz) or periodic epileptiform discharges (PEDs) recorded during continuous electroencephalographic monitoring in critically ill patients with CNS infections were evaluated in a study at Columbia University Medical Center, New York, NY. Of 42 patients (mean age 39 years; range 0-82) identified between 1996 and 2007, 27 (64%) had viral infection, 8 (18%) bacterial, and 7 (17%) fungal or parasitic infections. Electrographic seizures were recorded in 14 (33%) patients and PEDs in 17 (40%). Either ESz or PEDs were recorded in 20 (48%) patients. Five (36%) of the 14 patients with ESz had clinical seizures. PEDs and viral infection were independently associated with ESz (P=0.001 and 0.02, respectively). ESz (P=0.02) and PEDs (P=0.01) were independently associated with poor outcome at discharge. Thirteen (31%) patients had severe disability, 3 were in coma or persistent vegetative state, and 5 died. 
COMMENT. Continuous EEG monitoring should be considered in patients with CNS infections and especially viral infection. Since electrographic seizures (ESz), recorded in 33% of the patients in this study, are associated with poor outcome, further studies are required to determine whether the ESz should be treated. The neurotropism and more extensive parenchymal damage after viral encephalitis compared to bacterial meningitis may explain the higher incidence of ESz with CNS viral infections.