Muscular Dystrophy: 9 types of muscle disorders

Definition of Muscular Dystrophy

Muscular dystrophy, or MD, is really the name of nine groups of inherited disorders that impact muscle strength and the connections between muscles and nerves. Some begin in childhood while others impact mostly adults; some lead to early death while other people cause only mild disabilities. What they have in typical is progressive weakening of the skeletal muscles. Some types of MD also impact the muscular tissue of the heart.

Duchenne muscular dystrophy. Named for Guillaume Duchenne (1806-1875), the French physician who first described it in the 1860s, Duchenne muscular dystrophy will be the most typical form, accounting for half of all cases of MD. It's gender-linked, affecting mostly boys, and is usually diagnosed in childhood. Muscle wasting begins in the muscles of the legs and pelvis, then moves to the arms and neck. Boys with Duchenne MD have frequent falls, breathing difficulties and heart problems, and are usually confined to a wheelchair by age twelve. Most patients die before age twenty.

Becker muscular dystrophy. This really is a milder type of MD but affects exactly the same muscles as Duchenne muscular dystrophy. Patients are usually diagnosed at age eleven but usually remain independent longer than patients with Duchenne MD and live into middle age.

Congenital MD. This is a group of muscular dystrophies that affects both boys and girls and is usually diagnosed before age two. Some children with these disorders die in infancy while other people live into adulthood.

Emery-Dreifuss MD. This form of MD primarily affects boys; symptoms appear at any point from age ten to twenty-five. Contractures in the ankles, knees, and other joints occur before the muscles begin to weaken. Nearly all patients create heart problems by age thirty.

Facioscapulohumeral MD. This form of muscular dystrophy affects the muscles of the face, shoulders, and upper arms before other parts of the physique. Signs and symptoms may begin at any age from the late teens via age forty. Patients frequently create a pouting or masklike expression as the muscles of the face deteriorate.

Limb-girdle MD. This type of MD affects both boys and girls. Muscle weakness is usually noticed first around the hips before spreading towards the shoulders, legs, and neck. Individuals with this type of MD develop a waddling gait, fall often, and are unable to run.

Distal MD. This type of the illness doesn't seem till patients are forty to sixty years old. It affects the muscles of the hands, forearms, lower legs, and feet.

Myotonic MD. This is probably the most typical type of adult-onset MD, appearing between twenty and thirty years of age. It affects both men and women. Also known as Steinert’s illness, this type of MD is characterized by stiffness; the patient cannot relax the muscles voluntarily following tightening then. In addition to weakening the patient’s muscles, myotonic MD affects the central nervous system along with other organs, including the heart, adrenal glands and thyroid, the eyes, and also the digestive tract. Individuals with myotonic MD may also create cataracts in the eyes.

Oculopharyngeal MD. This form of muscular dystrophy typically begins when the patient is in his or her forties or fifties. It also affects both men and women. It is most common in people of French Canadian descent and some Hispanics living in New Mexico. Muscle weakness first affects the eyelids and throat muscles, causing difficulty swallowing as well as interfering with vision. Most patients will ultimately lose the ability to walk.

Causes and symptoms of Muscular Dystrophy

The basic cause of the various forms of MD is really a genetic mutation that affects the production of proteins essential to maintain the structure of muscle cells. In the case of Duchenne MD and Becker MD, the affected gene is known as the DMD gene and is situated on the X chromosome. The gene is responsible for the production of a protein known as dystrophin, which is needed to maintain the cell membrane of muscle cells.

In Duchenne MD, there is no dystrophin produced; in Becker MD, there is some dystrophin, but not sufficient to protect the muscle fibers from gradually weakening. In Emery-Dreifuss MD, the defective gene on the X chromosome is known as the EMD gene. It is responsible for producing a protein called emerin, which is important for the functioning of skeletal and heart muscles. Myotonic dystrophy is caused by a defect in a gene on chromosome 19. The defect interferes using the production of a protein called myosin, which is involved in the movement of muscles. Although you will find some variations among the nine kinds of muscular dystrophy, probably the most typical symptoms of the illness include:

Muscle weakness that gets worse more than time
Contractures
Loss of balance and coordination
Wasting (loss of muscle tissue, replaced by fat in some instances)
Scoliosis (curvature of the spine)
Difficulty walking
Frequent falls
Clumsiness; eventual loss of the ability to write
Gradual weakening of the heart and breathing muscles
Eventual difficulty in swallowing

Diagnosis of Muscular Dystrophy

Since the symptoms of MD appear in different patients at different ages, depending on the particular kind of disease that the patient has, diagnosis begins having a physical examination and taking a history of the patient’s signs and symptoms. Subsequent, the patient may be sent to a neurologist (a specialist in diagnosing and treating disorders of the nervous system) for tests of the reflexes, balance, and other functions in order to rule out exposures to toxins or other illnesses that may be causing the patient’s symptoms. The third step is really a series of laboratory and imaging tests:

Blood and urine tests. These are used to measure the levels of various enzymes in the patient’s body fluids that result from the breakdown of muscle tissue or that leak out of damaged muscle. A blood test can also be performed for genetic testing.
Physical exercise tests. These can be carried out at the patient’s bedside. They measure the strength of the muscles, particularly the muscles involved in breathing.
Ultrasound imaging. Ultrasound imaging can detect abnormalities in the patient’s muscles even in early stages of MD. Magnetic resonance imaging (MRI) can also be used to search for changes in muscle tissue and to monitor the progression of the disease.
Muscle biopsy. Taking a sample of the patient’s muscle tissue allows the doctor to distinguish in between MD along with other illnesses that affect the muscles and nerves.
Electromyography. Electromyography is a technique in which the physician inserts a thin electrode through the skin into a muscle. As the patient tightens and relaxes the muscle, the electrode measures the patterns of electrical activity in the muscle.
Electrocardiogram (ECG). This test is done to evaluate the functioning of the patient’s heart.
Pulmonary function test. The doctor might order this test for patients whose breathing muscles are showing signs of weakness. It measures the patient’s lung capacity.

Treatment of Muscular Dystrophy

There's no cure for muscular dystrophy. Treatment consists of keeping the patient mobile and comfortable so long as feasible. Specific therapies may include medicines to delay the loss of muscle tissue and function or to relax tightened muscles; surgery to minimize problems caused by contractures or scoliosis; physical therapy to keep the muscles as powerful and flexible as feasible; and occupational therapy to teach the patient the skills that are essential for self-care.

Some patients with breathing difficulties might be placed on an artificial respirator, while those with heart problems might have a pacemaker implanted. Most patients with MD eventually require assistive devices, from canes, braces, and walkers to wheelchairs and motorized scooters. These devices can help to maintain patients independent as well as slow the development of contractures. It is important for patients with MD to stay as active as feasible, as bed rest or inactivity can speed up the deterioration of the muscles.

Prognosis

The prognosis of muscular dystrophy depends on the particular kind, although all kinds are incurable. Patients with Duchenne MD rarely reside beyond age twenty, while those with congenital MD may die in childhood, and patients with one of the adult-onset dystrophies may reside into their sixties. Contemporary medical and surgical care permits most patients a better high quality of life than they would otherwise have, but the outcome is still premature death, generally from heart failure.

Prevention

There is no known method to prevent all of the various kinds of MD. Genetic counseling is advised, nevertheless, when there is a family history of muscular dystrophy. Ladies may have no symptoms but still carry the gene for the disorder, and Duchenne muscular dystrophy could be detected by genetic tests during pregnancy.