A progressive neurologic disorder, one of the subacute spongiform encephalopathies caused by prions. 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 electroencephalogram pattern (burst suppression, consisting of intermittent sharp and slow wave complexes on a flat background). The average survival time is less than 1 year after onset of symptoms. Changes in the CSF 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, which account 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, and 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 tesing early in the course of clinical disease. Other prion diseases include Gerstmann-Sträussler-Scheinker (GSS) syndrome, fatal familial insomnia, and kuru in humans; scrapie in sheep and goats; and bovine spongiform encephalopathy (BSE, mad cow disease) in cattle. Similar encephalopathies and wasting syndromes are found in other species. All these diseases have been shown to be transmissible in laboratory animals.
An unusual number of cases of CJD were reported in young people in Great Britain during the 1990s. These patients displayed ataxia, memory impairment, dementia, and myoclonus. Besides the characteristic spongiform changes of CJD, autopsy specimens showed unusual amyloid plaques with dense eosinophilic centers extensively distributed throughout the cerebrum and cerebellum. These plaques, visible with routine staining methods, had not previously been noted in CJD, but did resemble plaques seen in kuru. In addition, these patients did not display the EEG changes characteristic of classical CJD. The development of this variant CJD in human beings has been traced to consumption of beef products contaminated with central nervous system tissues of cows infected with BSE. An epizootic of BSE killed more than 150,000 cattle in Britain between 1986 and 1996. The discovery late in 2003 of a single dairy cow infected with BSE in the western U.S. state of Washington prompted a revision of screening procedures and a tightening of restrictions on the use of meat products as human food. SEE ALSO bovine spongiform encephalopathy.
Reference: Stedman's Medical Dictionary