There are three major categories of CJD: sporadic the most common form, in which people do not have any risk factors for the disease ; hereditary in which the person has a family member with the disease and tests positive for a genetic mutation , and acquired in which the disease is transmitted by exposure to brain and nervous system tissue, usually through certain medical procedures. Symptoms of CJD include problems with muscular coordination, personality changes including progressive and severe mental impairment, impaired vision that may lead to blindness, and involuntary muscle jerks called myoclonus.
People eventually lose the ability to move and speak and enter a coma. Tests that help in the diagnosis of CJD include electroencephalography which measures brain waves , detection of certain proteins in the fluid that surrounds the brain and spinal cord, and magnetic resonance imaging..
The first concern is to rule out treatable forms of dementia such as encephalitis or chronic meningitis. The only way to confirm a diagnosis of CJD is by brain biopsy or autopsy. In a brain biopsy, a neurosurgeon removes a small piece of tissue from the patient's brain so that it can be examined by a neurologist.
Because a correct diagnosis of CJD does not help the individual, a brain biopsy is discouraged unless it is need to rule out a treatable disorder. There is no treatment that can cure or control CJD, although studies of a variety of drugs are now in progress. Current treatment is aimed at alleviating symptoms and making the patient as comfortable as possible.
Opiate drugs can help relieve pain, and the drugs clonazepam and sodium valproate may help relieve involuntary muscle jerks.
The damage to the brain causes the mental and physical impairment associated with CJD, and eventually leads to death. Prions can survive in nerve tissue, such as the brain or spinal cord, for a very long time, even after death. The different types of CJD are all caused by a build-up of prions in the brain. But the reason why this happens is different for each type. It's not known what triggers sporadic CJD, but it may be that a normal prion protein spontaneously changes into a prion, or a normal gene spontaneously changes into a faulty gene that produces prions.
Sporadic CJD is more likely to occur in people who have specific versions of the prion protein gene. At present, nothing else has been identified that increases the risk of developing sporadic CJD.
In , a government inquiry concluded that the prion was spread through cattle that were fed meat-and-bone mix containing traces of infected brains or spinal cords. The prion then ended up in processed meat products, such as beef burgers, and entered the human food chain. Strict controls have been in place since to prevent BSE entering the human food chain, and the use of meat-and-bone mix has been made illegal. Almost all definite cases of vCJD occurred in people with a specific version MM of the prion protein gene, which affects how the body makes a number of amino acids.
It's estimated up to 4 in 10 of the UK population have this version of the gene. There have been no confirmed deaths from to Some experts believe that the food controls have worked and further cases of vCJD will continue to decline, but this doesn't rule out the possibility that other cases may be identified in the future.
It's also possible for vCJD to be transmitted by blood transfusion , although this is very rare and measures have been put in place to reduce the risk of it happening.
We don't know how many people in the UK population could develop vCJD in the future and how long it'll take for symptoms to appear, if they ever will. A study published in October that tested random tissue samples suggested around 1 in 2, people in the UK population may be infected with vCJD, but show no symptoms to date. A person cannot acquire classic CJD through food.
Here, learn more about the causes of CJD. No test can confirm a diagnosis of CJD. Only a brain biopsy can do this, and the procedure is too risky when a person is alive. These may be more reactive than usual.
Also, the muscles may be excessively toned or withered, depending on where the disease affects the brain. A vision or eye test may detect vision loss, and an EEG can reveal unusual electrical impulses that can characterize the disease.
A doctor can test spinal fluid using a lumbar puncture, also known as a spinal tap, to rule out other causes of dementia. This test can show whether there is an infection or increased pressure in the central nervous system. If the protein is present in the spinal fluid and the person has typical symptoms, this may indicate CJD.
Brain biopsies after death show that the brain tissue is spongy, with tiny holes where clumps of nerve cells have been destroyed. There is no cure for CJD, and no medications can control it or slow its progression.
Scientists are looking into several treatment options for future use. Opiate drugs can help relieve the pain. Also, clonazepam and sodium valproate may help relieve involuntary movements, such as muscle twitching. In the later stages, a carer will move the person frequently to help prevent bedsores.
Scientists continue to investigate how CJD affects the brain, in an effort to develop effective treatments. To avoid the potential transmission of TSEs to humans, most countries now have restrictions in place, including strict guidelines for managing infected cows.
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