 |
 |
 |
|
Muscular dystrophy is one of a number of muscular diseases (myopathies) characterized by progressive muscle weakness and loss of muscle tissue. It is caused by an inherited genetic abnormality whereas other myopathies, such as polymositis, can be caused by an abnormality of the immune system. These disorders can develop at any time from birth through adulthood.
There are many types of muscular dystrophy (MD). These diseases are classified according to the muscle groups involved and the age of onset. Some of these muscular dystrophies result in premature death; others may allow the person to live for decades with varying degrees of disability.
MD includes many inherited disorders such as: - Becker's muscular dystrophy
- Duchenne muscular dystrophy
- facioscapulohumeral muscular dystrophy
- limb-girdle muscular dystrophy
- Emery-Dreifuss muscular dystrophy
- myotonic dystrophy
- myotonia congenita
These disorders are distinguished from each other by the type of inheritance (sex-linked, dominant gene, recessive gene), the age when symptoms appear, and the types of symptoms that develop.
Myotonic dystrophy
Also known as Steinert's disease, this is the most common adult form of muscular dystrophy. Its name underscores an unusual symptom found only in this form of dystrophy - myotonia - which is similar to a spasm or stiffening of muscles after use.
Myotonic dystrophy results from a gene flaw on chromosome 19. The gene containing the defect is for an enzyme named myotonin protein kinase. Some researchers believe the defect may affect other nearby genes.
The disease causes muscle weakness and affects the central nervous system, heart, gastrointestinal tract, eyes (causing cataracts) and endocrine (hormone-producing) glands. Although muscle weakness progresses slowly, this symptom can vary greatly, even among members of a single family. Most often muscle weakness doesn't hamper daily living for many years after symptoms first occur.
Many people with myotonic dystrophy seem to require more sleep than the average person. Mild mental retardation is present in some people with the disease, and a peculiar emotional and mental "indifference" has also been found to accompany myotonic dystrophy in some patients.
Duchenne muscular dystrophy
The most common childhood form of muscular dystrophy, early signs usually occur between the ages of 2 and 6 and include frequent falling, difficulty getting up from a sitting or lying position, and a waddling gait. Another hallmark is the apparent enlargement of the calf and sometimes other muscles, which is really due to an accumulation of fat and connective tissue in the muscle. A blood sample shows a very high level of creatine kinase (CK), an enzyme that leaks out of damaged muscle. Posture changes as the child grows.
Progression varies somewhat from child to child. The use of orthopedic devices and physical therapy can prolong the ability to walk. Frequently, however, a wheelchair will be needed by age 12. Mild mental retardation has been noted in some (by no means all) boys with Duchenne dystrophy.
Breathing becomes affected during the later stages of Duchenne, leading to respiratory infections. These are often successfully treated with antibiotics and respiratory therapy. Severe respiratory and heart problems mark the disease's final stages, usually in the child's teens or early 20s.
Risk Factors
Because these are inherited disorders, risk factors include a family history of muscular dystrophy.
Signs & Symptoms
MD is characterized by muscle weakness in various parts of the body, depending on its type. Muscle weakness worsens over time; initial symptoms usually develop gradually.
People with muscular dystrophy might have some of the following symptoms, which arise from the atrophy that takes place:- Delayed development of muscle skills
- Problems walking (frequent falls)
- Joint contracture - shortening of muscles around a joint - are common. This causes abnormal positioning of the joint, along with possible pain. Shortening of the muscle fibers, fibrosis of the connective tissue and scarring slowly destroy muscle function. Some types of MD involve the heart muscle, causing cardiomyopathy or arrhythmias.
- Muscular deformities, such as clubfoot or clawhand
- Skeletal deformities, often scoliosis (curved spine)
- Drooling
- Drooping eyelids ("ptosis")
- Mental retardation is also possible
- Hypotonia (poor muscle tone)
As the disease progresses, it may lead to: - Heart Trouble
- Lung Ailments
- Lung Infections, such as Pneumonia
- Choking
- Collapsed Lung
- Respiratory Failure
Treatment & Prevention
There are no known cures for the various muscular dystrophies. Treatment is aimed at controlling symptoms to maximize the quality of life. Physical therapy may help people with this disorder to maintain muscle strength and function. Orthopedic appliances such as braces and wheelchairs can improve mobility and self-care abilities. In some cases, surgery on the spine or lower extremities may help improve function and slow deterioration.
Prognosis; Complications
The outcome varies with the type of muscular dystrophy. All types of MD progressively worsen, but the speed of decline and extent of disability they cause varies widely. Some types are fatal.
Complications include: deformities, scoliosis, joint contractures, permanent and progressive disability, decreased mobility, decreased ability to care for self, mental impairment (varies), cardiomyopathy, respiratory failure.
|
|
 |
|
 |
Signs, symptoms & indicators of Muscular Dystrophy:
Conditions that suggest Muscular Dystrophy:
Recommendations and treatments for Muscular Dystrophy: | | | | | Habits |  Aerobic Exercise | Activity is encouraged to the degree tolerated. |
|
Physical Medicine |
Not recommended:
 Rest| | Complete inactivity (such as bedrest) can worsen the disease. |
|
Vitamins |
Vitamin E| | Severe deficiency results in muscular dystrophy-like symptoms. Some cases have shown improvement. |
|
| | | | |
KEY | | Strong or generally accepted link |  | | Proven definite or direct link | | | May do some good | | | Reasonably likely to cause problems |
GLOSSARY
Arrhythmia (Arrhythmias)
A condition caused by variation in the regular rhythm of the heartbeat. Arrhythmias may cause serious conditions such as shock and congestive heart failure, or even death.
Cataract (Cataracts)
A steadily worsening disease of the eye in which the lens becomes cloudy as a result of the precipitation of proteins. Most cataracts are caused by the functions of the body breaking down. Eye trauma, such as from a puncture wound, may also result in cataracts.
Central Nervous System (CNS)
A collective term for the brain, spinal cord, their nerves, and the sensory end organs. More broadly, this can even include the
neurotransmitting hormones instigated by the CNS that control the chemical nervous system, the endocrine glands.
Contracture (Contractures)
An abnormal, often permanent shortening, as of muscle or scar tissue, that results in distortion or deformity, especially of a joint of the body.
Enzymes (Enzyme)
Specific protein catalysts produced by the cells that are crucial in chemical reactions and in building up or synthesizing most compounds in the body. Each enzyme performs a specific function without itself being consumed. For example, the digestive enzyme amylase acts on carbohydrates in foods to break them down.
Gastrointestinal (GI, GI Tract)
Pertaining to the stomach, small and large intestines, colon, rectum, liver, pancreas, and gallbladder.
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.
Hypotonia
Lessened tension; arterial relaxation.
Immune System (Immune Response, Immunity)
A complex that protects the body from disease organisms and other foreign bodies. The system includes the humoral immune response and the cell-mediated response. The immune system also protects the body from invasion by making local barriers and inflammation. The process may involve acquired immunity (the ability to learn and remember a specific infectious agent), or innate immunity (the genetically programmed system of responses that attack, digest, remove, and initiate inflammation and tissue healing).
Lung (Lungs, Pulmonary)
Organ of the body, located in the chest cavity which is designed to bring oxygen from the air into the blood stream, while also expelling carbon dioxide and other waste gases out of the body. Pulmonary: Related to the lungs.
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.
Spasm
Involuntary contraction of one or more muscle groups.
Last updated: Jul 19, 2008
|
 |
|
|
