Creutzfeldt-Jakob disease (CJD) is a rare, relentlessly progressive, dementing illness caused by an "infectious" protein particle known as a prion. Infection results in spongiform degeneration of cortical and subcortical gray matter, and less commonly cerebellum, thalamus, and basal ganglia. Inflammation is absent. Sporadic occurence accounts for 85-90% of cases with an incidence of about 1 per million. Patients classically present with rapidly progressive dementia, myoclonus, and ataxia, though confusion and sensory disturbances may also be seen. Antemortem diagnosis may be difficult; characteristic findings on EEG and CSF analysis are often suggestive of the diagnosis, but pathologic examination of brain tissue is frequently required. Ninety percent of patients succumb to their illness within 2 years of the onset of symptoms.

Conventional CT and MR imaging has generally been considered unhelpful in establishing the diagnosis. Diffusion-weighted imaging has been reported to demonstrate characteristic patterns of diffusion abnormality in the cortex and basal ganglia, with or without corresponding T2-hyperintensity. Atrophy may be observed late in the disease. MR Spectroscopy may demonstrate decreased concentrations of N-acetylaspartate, a non-specific finding.