MRI and encephalography in fatal eastern equine encephalitis.

Eastern equine encephalitis (EEE) is the most severe of the mosquito-borne encephalitides, with a case fatality rate estimated at 36%. We describe 2 fatal cases of seropositive EEE in men. In both patients, EEG monitoring revealed periodic 0.25to 0.5-Hz transients with lower voltages (;20–40 mV) than typically seen in herpes encephalitis (;100–500 mV), and MRI revealed a symmetric pattern of T2 hyperintensity in the lentiform nuclei, as previously noted (figure). Considered together, these MRI and EEG findings suggest a distinctive pattern that may be pathognomonic for EEE in the appropriate clinical context.