Creutzfeldt-Jakob Disease
Creutzfeldt-Jakob disease (subacute spongiform encephalopathy) is a prion disease characterized by progressive deterioration of mental function, muscle twitching, and staggering when walking.
Creutzfeldt-Jakob disease affects 1 of 1 million people each year throughout the world. It affects adults, mainly in their late 50s and 60s.
One form of Creutzfeldt-Jakob disease results from spontaneous conversion of the normal protein molecule PrPc to a prion. Another form results from acquisition of the prion from an external source. However, doctors usually cannot determine which is the cause. In a few people, the prion has been transmitted through transplantation of contaminated corneas or possibly other tissues from affected donors. In some people, the prion has been transmitted during brain surgery using instruments previously used to operate on a person who had Creutzfeldt-Jakob disease. Routine cleansing and sterilization procedures do not destroy prions; however, bleach is effective.
The disease developed in some children who were treated with growth hormone derived from human pituitary glands. Other hormones derived from the pituitary gland have also caused Creutzfeldt-Jakob disease. These hormones are now genetically engineered rather than prepared from cadavers, so that there is no risk of Creutzfeldt-Jakob disease. There have been no reports of Creutzfeldt-Jakob disease being transmitted through blood transfusions nor through casual or even intimate contact with people who have the disease.
A new form of Creutzfeldt-Jakob disease, called variant Creutzfeldt-Jakob disease, has affected about 100 people to date. It is thought to be acquired from the consumption of contaminated beef or beef products. The variant form usually begins around age 30 in contrast to the spontaneous form of Creutzfeldt-Jakob disease, which usually begins around age 65.
Symptoms
In people who have acquired the prion from an external source, no symptoms appear for months or years after exposure. Then, symptoms of brain damage with dementia become apparent and usually progress gradually over months. Early symptoms--memory loss and confusion--may resemble those of other dementias, such as Alzheimer's disease. In people with variant Creutzfeldt-Jakob disease, the first symptoms tend to be psychiatric symptoms, rather than memory loss. Later symptoms are similar in both forms.
In about 10 to 20% of people, symptoms appear abruptly, starting with dizziness and double vision. Whether symptoms develop gradually or abruptly, mental decline progresses, often producing such symptoms as neglect of personal hygiene, apathy, and irritability. Some people tire easily and become sleepy; others cannot fall asleep.
Muscles usually begin to twitch in the first 6 months after symptoms begin. Trembling and clumsiness may also develop, and muscle coordination is lost. Walking becomes unsteady, resulting in staggering (similar to the walk of a person who is drunk). Movements may be slow. Impairment of muscle control may result in unusual postures, such as twisting of the trunk or limbs forward and sideways. Muscles may jerk when stretched. The muscles that control breathing and coughing are usually impaired, increasing the risk of pneumonia.
The person may be startled easily, and the resulting responses, such as jumping when a loud noise is heard, are exaggerated. Vision may become blurry or dim. The symptoms worsen, usually much more rapidly than in Alzheimer's disease, resulting in profound dementia.
Most people with Creutzfeldt-Jakob disease die after about 3 to 12 months of illness. About 10 to 20% of people survive for 2 years or more. Often, the cause of death is pneumonia.
Diagnosis and Treatment
Doctors consider Creutzfeldt-Jakob disease when mental function is deteriorating quickly, muscle twitching is present, walking is unsteady and staggering, and other dementias have been ruled out by routine testing. In about 70% of people with the disease, electroencephalography (EEG) detects specific abnormalities in the electrical activity of the brain (see Section 6, Chapter 77). In more than 80% of people, an unusual protein called 14-3-3 is detected in the cerebrospinal fluid. Abnormal EEG results plus the presence of the 14-3-3 protein in cerebrospinal fluid strongly support the diagnosis of Creutzfeldt-Jakob disease. The absence of the 14-3-3 protein does not rule out Creutzfeldt-Jakob disease. The definitive diagnosis of Creutzfeldt-Jakob disease is based on detecting prions in brain tissue by examination of a tissue sample under a microscope or by biochemical analysis.
Currently, Creutzfeldt-Jakob disease cannot be cured, and its progress cannot be slowed. However, certain drugs may be given to relieve symptoms. For example, the anticonvulsant valproate and the antianxiety drug clonazepam may reduce muscle jerking.
General support and care for the person and family members are important. Day care centers and respite and long-term care may be useful. Speech and occupational therapists can help with specific problems. Support groups are available.
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