A case of immunotherapy-responsive eastern equine encephalitis with diffusion-weighted imaging

Abstract

Eastern equine encephalitis (EEE) is the most severe of the mosquito-borne encephalitides, associated with 30% mortality. Age over 40, rapid progression to coma, severe hyponatremia, and CSF white blood cell count >500 at symptom onset have all been correlated with poor outcome.1,2⇓ We report a patient with poor prognostic signs in whom apparent diffusion coefficient (ADC) images revealed vasogenic edema without ischemia. He made a complete recovery after treatment with steroids and IV immunoglobulin (IVIg). A 69-year-old man from southeastern Massachusetts developed a frontal headache, fever, and mild right upper extremity weakness precipitating admission to a local hospital. The following day, he developed fever to 104 °F, rapidly progressive flaccid paraparesis, and acute respiratory failure. A CT brain scan without contrast was normal. A lumbar puncture revealed 1196 white blood cells (WBC) (80% neutrophils, 2% lymphocytes), 12 red blood cells/cubic millimeter, total protein 140 mg/dL, and glucose 74 mg/dL (serum glucose of 121 mg/dL) without organisms on Gram stain or detection of cryptococcal antigen. Serum chemistries were normal except …