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Creutzfeldt-Jakob disease (CJD) is a rare, degenerative, always-fatal brain disorder. It affects about one person in every million people worldwide and about 200 people in the United States. CJD usually appears in later life and runs a rapid course. Typically, onset of symptoms occurs about age 60, and about 90% of patients die within 1 year.
There are three major categories of CJD: - Sporadic CJD. The disease appears even though the person has no known risk factors for the disease. This is by far the most common type of CJD and accounts for at least 85% of cases.
- Hereditary CJD. The person has a family history of the disease and/or tests positive for a genetic mutation associated with CJD. About 5-10% of cases of CJD in the United States are hereditary.
- Acquired CJD. The disease is transmitted by exposure to brain or nervous system tissue, usually through certain medical procedures. There is no evidence that CJD is contagious through casual contact with a CJD patient. Since CJD was first described in 1920, fewer than 1% of cases have been acquired CJD.
CJD belongs to a family of human and animal diseases known as the transmissible spongiform encephalopathies (TSEs). "Spongiform" refers to the characteristic appearance of infected brains, which become filled with holes until they resemble sponges under a microscope.
CJD is the most common of the known human TSEs. Other human TSEs include kuru, fatal familial insomnia (FFI), and Gerstmann-Straussler-Scheinker disease (GSS). Kuru was identified in people of an isolated tribe in Papua New Guinea and has now almost disappeared. Fatal familial insomnia and GSS are extremely rare hereditary diseases, found in just a few families around the world.
Other TSEs are found in specific kinds of animals. These include bovine spongiform encephalopathy (BSE), which is found in cows and often referred to as "mad cow disease"; scrapie, which affects sheep; and mink encephalopathy. Similar diseases have occurred in elk, deer, and exotic zoo animals.
Causes & Development
Some researchers believe an unusual "slow virus" or another organism causes CJD. However, they have never been able to isolate a virus or other organism in people with the disease. Furthermore, the agent that causes CJD has several characteristics that are unusual for known organisms such as viruses and bacteria. It is very difficult to kill, it does not appear to contain any genetic information in the form of nucleic acids (DNA or RNA), and it usually has a long incubation period before symptoms appear. In some cases, the incubation period may be as long as 40 years.
The leading scientific theory at this time maintains that CJD and the other TSEs are caused not by an organism but by a type of protein called a prion. Prions occur in both a normal form, which is a harmless protein found in the body's cells; and in an infectious form, which causes disease. The harmless and infectious forms of the prion protein are nearly identical, but the infectious form takes a different folded shape than the normal protein. Sporadic CJD may develop because some of a person's normal prions spontaneously change into the infectious form of the protein and then alter the prions in other cells in a chain reaction.
Once they appear, abnormal prion proteins stick together and form fibers and/or clumps called plaques that can be seen with powerful microscopes. Fibers and plaques may start to accumulate years before symptoms of CJD begin to appear. It is still unclear what role these abnormalities play in the disease or how they might affect symptoms.
About 5-10% of all CJD cases are inherited. These cases arise from a mutation, or change, in the gene that controls formation of the normal prion protein. While prions themselves do not contain genetic information and do not require genes to reproduce themselves, infectious prions can arise if a mutation occurs in the gene for the body's normal prions. If the prion gene is altered in a person's sperm or egg cells, the mutation can be transmitted to the person's offspring.
Several different mutations in the prion gene have been identified. The particular mutation found in each family affects how frequently the disease appears and what symptoms are most noticeable. However, not all people with mutations in the prion gene develop CJD. This suggests that the mutations merely increase susceptibility to CJD and that other, still-unknown factors also play a role in the disease.
While CJD can be transmitted to other people, the risk of this happening is extremely small. CJD cannot be transmitted through the air or through touching or most other forms of casual contact. Spouses and other household members of sporadic CJD patients have no higher risk of contracting the disease than the general population. However, direct or indirect contact with brain tissue and spinal cord fluid from infected patients should be avoided to prevent transmission of the disease through these materials.
In a few very rare cases, CJD has spread to other people from grafts of dura mater (a tissue that covers the brain), transplanted corneas, implantation of inadequately sterilized electrodes in the brain, and injections of contaminated pituitary growth hormone derived from human pituitary glands taken from cadavers. Since 1985, all human growth hormone used in the United States has been synthesized by recombinant DNA procedures, which eliminates the risk of transmitting CJD by this route.
The appearance of a new variant of CJD (nv-CJD or v-CJD) in several younger than average people in Europe has led to concern that BSE can be transmitted to humans through consumption of contaminated beef. Although laboratory tests have shown a strong similarity between the prions causing BSE and v-CJD, there is no direct proof to support this theory. The importation of cattle and beef from countries with BSE has been banned in the United States since 1989 to reduce the risk.
Many people are concerned that it may be possible to transmit CJD through blood and related blood products such as plasma. Some animal studies suggest that contaminated blood and related products may transmit the disease, although this has never been shown in humans. If there are infectious agents in these fluids, they are probably in very low concentrations. Scientists do not know how many abnormal prions a person must receive before he or she develops CJD, so they do not know whether these fluids are potentially infectious or not. They do know that, even though millions of people receive blood transfusions each year, there are no reported cases of someone contracting CJD from a transfusion. Even among hemophiliacs, who sometimes receive blood plasma concentrated from thousands of people, there are no reported cases of CJD. This suggests that, if there is a risk of transmitting CJD through blood or plasma, it is extremely small.
Signs & Symptoms
The first symptoms of Creutzfeldt-Jakob disease typically include failing memory, dementia (personality changes together with impaired memory, judgment, and thinking), visual disturbances and problems with muscular coordination. People with the disease also may experience insomnia, depression, or unusual sensations. CJD does not cause a fever or other flu-like symptoms.
As the illness progresses, the patients' mental impairment becomes severe. They often develop involuntary muscle jerks called myoclonus, and they may go blind or lose bladder control. They eventually lose the ability to move and speak and enter a coma. Pneumonia and other infections often occur in these patients and can lead to death.
There are several known variants of CJD. These variants differ somewhat in the symptoms and course of the disease. For example, a variant form of the disease (nv-CJD or v-CJD), described in Great Britain and some other parts of Europe, begins primarily with psychiatric symptoms, affects younger patients than other types of CJD, and has a longer-than-usual duration from onset of symptoms to death. Another variant, called the panencephalopathic form, occurs primarily in Japan and has a relatively long course, with symptoms often progressing for several years. Scientists are trying to learn what causes these variations in symptoms.
Some symptoms of CJD can be similar to symptoms of other progressive neurological disorders, such as Alzheimer's or Huntington's disease. However, CJD causes unique changes in brain tissue which can be seen at autopsy. It also tends to cause more rapid deterioration of a person's abilities than Alzheimer's disease or most other types of dementia.
Diagnosis & Tests
At the time of writing there is no single diagnostic test for CJD. When a doctor suspects CJD, the first concern is to rule out treatable forms of dementia such as encephalitis (inflammation of the brain) or chronic meningitis.
A neurological examination will be performed or the doctor may seek consultation with other physicians. Standard diagnostic tests will include a spinal tap to rule out more common causes of dementia and an electroencephalogram (EEG) to record the brain's electrical pattern, which can be particularly valuable because it shows a specific type of abnormality in CJD.
Computerized tomography of the brain can help rule out the possibility that the symptoms result from other problems such as stroke or a brain tumor. Magnetic resonance imaging (MRI) brain scans also can reveal characteristic patterns of brain degeneration that can help diagnose CJD.
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 neuropathologist. This procedure may be dangerous for the patient, and the operation does not always obtain tissue from the affected part of the brain. Because a correct diagnosis of CJD does not help the patient, a brain biopsy is discouraged unless it is needed to rule out a treatable disorder. In an autopsy, the whole brain is examined after death.
Scientists are working to develop laboratory tests for CJD. One such test is performed on a person's cerebrospinal fluid and detects a protein marker that indicates neuronal degeneration. This can help diagnose CJD in people who already show the clinical symptoms of the disease. This test is much easier and safer than a brain biopsy. The false positive rate is about 5-10%. Scientists are working to develop this test for use in commercial laboratories. There have been reports of other ways of diagnosing the disease, including tonsil biopsies, which may lead to other tests.
Treatment & Prevention
There is no treatment that can cure or control Creutzfeldt-Jakob disease. Researchers have tested many drugs, including amantidine, steroids, interferon, acyclovir, antiviral agents, and antibiotics. However, none of these treatments has shown any consistent benefit.
Current treatment for CJD is aimed at alleviating symptoms and making the patient as comfortable as possible. Opiate drugs can help relieve pain if it occurs, and the drugs clonazepam and sodium valproate may help relieve myoclonus. During later stages of the disease, changing the person's position frequently can keep him or her comfortable and helps prevent bedsores. A catheter can be used to drain urine if the patient cannot control bladder function, and intravenous fluids and artificial feeding also may be used.
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Risk factors for Creutzfeldt-Jakob Disease:
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GLOSSARY
Alzheimer's Disease (Alzheimer's)
A progressive disease of the middle-aged and elderly, characterized by loss of function and death of nerve cells in several areas of the brain, leading to loss of mental functions such as memory and learning. Alzheimer's disease is the most common cause of dementia.
Antiviral
Any of a number of herbs, drugs or agents capable of destroying viruses or inhibiting their growth or multiplication until the body is capable of destroying the virus itself. Most antiviral agents are members of the antimetabolite family.
Bacteria (Bacterial, Bacterium)
Microscopic germs. Some bacteria are "harmful" and can cause disease, while other "friendly" bacteria protect the body from harmful invading organisms.
Biopsy
Removal of a sample of tissue from a living being for diagnosis. A pathologist later uses a microscope to look for certain features, such as cancer cells, in the sample. A fine-needle aspiration biopsy involves inserting a thin needle to remove a small amount of tissue, sometimes using CT or ultrasound to guide the needle. A core biopsy involves obtaining a sample of tissue with a thick needle or by inserting a thin, lighted tube (laparoscope) into a small incision in the abdomen. Another biopsy method is to remove tissue during an operation.
Chronic (Chronicity)
Usually referring to chronic illness: Illness extending over a long period of time.
Dementia (Senile Dementia)
An acquired progressive impairment of intellectual function. Marked compromise exists in at least three of the following mental activity spheres: memory, language, personality, visuospatial skills, and cognition (i.e. abstraction and calculation).
DNA
Deoxyribonucleic acid, the large molecule that is the main carrier of genetic information in cells. DNA is found mainly in the chromosomes of cells.
Gland (Glands)
The glandular system is one of the most important and complicated systems of the body. Gland tissue can be either an organ or general tissue that secretes chemicals and there are two types of gland: exocrine and endocrine. Those glands which secrete chemicals through tubules or ducts are called exocrine and include sweat, tear and salivary glands. Ductless glands - part of the endocrine system - secrete special chemicals (hormones) directly into the blood.
Hormones (Hormone)
Chemical substances secreted by a variety of body organs that are carried by the bloodstream and usually influence cells some distance from the source of production. Hormones signal certain enzymes to perform their functions and, in this way, regulate such body functions as blood sugar levels, insulin levels, the menstrual cycle, and growth. These can be prescription, over-the-counter, synthetic or natural agents. Examples include adrenal hormones such as corticosteroids and aldosterone; glucagon, growth hormone, insulin, testosterone, estrogens, progestins, progesterone, DHEA, melatonin, and thyroid hormones such as thyroxine and calcitonin.
Interferon
A protein formed by the cells of the immune system in the presence of a virus, etc. It prevents viral reproduction, and is capable of protecting noninfected cells from viral infection. Several kinds of interferon exist including alpha, beta, and gamma.
Magnetic Resonance Imaging (MRI)
A technique used in diagnosis that combines radio waves and magnetic forces to produce detailed images of the internal structures of the body.
Nervous System
A system in the body that is comprised of the brain, spinal cord, nerves, ganglia and parts of the receptor organs that receive and interpret stimuli and transmit impulses to effector organs.
Pituitary (Pituitary Gland)
The pituitary gland is a small (half-inch), bean-shaped organ that hangs down from the lower center of the brain on a stalk attached to another gland, the hypothalamus. Weighing less than one gram, the pituitary gland is often called the "master gland" since it controls the secretion of hormones by other endocrine glands. It regulates many body activities, and is partitioned into front and back lobes. The front lobe is stimulated by the hypothalamus, and produces any one of six different hormones that in turn stimulate the thyroid, adrenal and reproductive glands, and also breast milk production.
Pneumonia (Pneumonitis)
Inflammation, usually infectious, of the lungs. Unless the result of only moderate chemical or smoke irritation, it is a potentially life-threatening condition. There are so many defenses against an infection this deep in the body that the very presence of pneumonia signals a pathogen of great virulence or impaired or exhausted immunity, or all three. Pneumonitis: Inflammation of the lungs, from whatever cause. It may be concurrent with pneumonia or pleurisy.
Protein (Proteins)
Compounds composed of hydrogen, oxygen, and nitrogen present in the body and in foods that form complex combinations of amino acids. Protein is essential for life and is used for growth and repair. Foods that supply the body with protein include animal products, grains, legumes, and vegetables. Proteins from animal sources contain the essential amino acids. Proteins are changed to amino acids in the body.
RNA
A ribonucleic acid found in plant and animal cells; a complex protein chemical. Important in the coding of genetic information with DNA carrying information from the nucleus of the cell into the cytoplasm.
Smooth Muscle (Involuntary Muscle)
The human body contains 2 types of muscle - smooth muscle and striated (skeletal) muscle. Smooth muscle is found in our internal organs such as stomach, intestines, blood vessels, or uterus (womb) and causes them to contract. These muscles are involuntary - that is, we don't control their movement.
Sodium
An essential mineral that our bodies regulate and conserve. Excess sodium retention increases the fluid volume (edema) and low sodium leads to less fluid and relative dehydration. The adult body averages a total content of over 100 grams of sodium, of which a surprising one-third is in bone. A small amount of sodium does get into cell interiors, but this represents only about ten percent of the body content. The remaining 57 percent or so of the body sodium content is in the fluid immediately surrounding the cells, where it is the major cation (positive ion). The role of sodium in the extracellular fluid is maintaining osmotic equilibrium (the proper difference in ions dissolved in the fluids inside and outside the cell) and extracellular fluid volume. Sodium is also involved in nerve impulse transmission, muscle tone and nutrient transport. All of these functions are interrelated with potassium.
Spinal Tap (Lumbar Puncture)
Despite the discomfort felt by many over this procedure, spinal taps are actually very simple procedures from the doctor's standpoint. Because the fluid that coats and flows through the brain also flows down into the spinal cord, the spinal fluid reflects what is occurring in the brain. A spinal tap involves: numbing the skin over the lower part of the spine with an injection or cream; sterilizing the area; having the patient curl up on his side while being held securely; passing a needle through the skin at a large space in between two of the lower vertebrae (the needle does NOT pass through bone); slowly advancing the needle until it "pops" through the lining of the spinal canal into an area of spinal fluid (the needle does NOT go into the spinal cord where the nerves are because the spinal cord stops further up the spine: the bottom of the spine simply contains a reservoir of spinal fluid); spinal fluid will flow out through the needle and the doctor will collect it and send it to the lab. Once the needle is pulled out, the hole seals up rapidly.
Steroid (Steroids)
Any of a large number of hormonal substances with a similar basic chemical structure containing a 17-carbon 14-ring system and including the sterols and various hormones and glycosides.
Stroke (Stroke-Type Event)
A sudden loss of brain function caused by a blockage or rupture of a blood vessel that supplies the brain, characterized by loss of muscular control, complete or partial loss of sensation or consciousness, dizziness, slurred speech, or other symptoms that vary with the extent and severity of the damage to the brain. The most common manifestation is some degree of paralysis, but small strokes may occur without symptoms. Usually caused by arteriosclerosis, it often results in brain damage.
Virus (Viri, Viruses)
Any of a vast group of minute structures composed of a protein coat and a core of DNA and/or RNA that reproduces in the cells of the infected host. Capable of infecting all animals and plants, causing devastating disease in immunocompromised individuals. Viruses are not affected by antibiotics, and are completely dependent upon the cells of the infected host for the ability to reproduce.
Last updated: Jun 08, 2008
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