Creutzfeldt-Jakob disease

(CJD); a progressive neurologic disorder, one of the subacute spongiform encephalopathies caused by prions

Description
Clinical features of CJD include a progressive cerebellar syndrome, including ataxia, abnormalities of gait and speech, and dementia. In most patients, these symptoms are followed by involuntary movements (myoclonus) and the appearance of a typical diagnostic electroencephalogram tracing (burst suppression, consisting of intermittent sharp and slow wave complexes on a flat background). The average survival is less than 1 year after onset of symptoms. Changes in the cerebrospinal fluid are absent or nonspecific. Mild cortical atrophy and ventricular dilation may be grossly evident. On microscopic examination, the distinctive finding is spongiform encephalopathy in gray matter throughout the brain and spinal cord. Severe neuronal loss and gliosis are also present and mild demyelination may occur. Ultrastructural changes include formation of intracytoplasmic vacuoles, the basis for the spongy appearance. CJD occurs worldwide at a rate of about 1–2 cases per million population per year; most cases are sporadic, but 10–12% are inherited. The peak incidence is between 55 and 65 years of age; the disease is rare before age 30. Cases of iatrogenic CJD have been associated with corneal transplants, electrode implants, dura mater grafts, and administration of human growth hormone. CJD is caused by a prion protein (an abnormal isoform of amyloid protein) that serves as a nucleating factor, inducing abnormalities in other proteins. This protein is detectable by Western blot early in the course of clinical disease. Prion diseases besides CJD include Gerstmann-Sträussler-Scheinker syndrome, fatal familial insomnia, and kuru in humans; scrapie in sheep and goats; bovine spongiform encephalopathy (BSE, mad cow disease) in cattle; and similar encephalopathies and wasting syndromes in other species. All these diseases have been shown to be transmissible in laboratory animals. See bovine spongiform encephalopathy. A variant of CJD can be transmitted by transfusion.