About DMD

The following is information about Duchenne Muscular Dystrophy. (from Wikipedia)

Overview

Duchenne muscular dystrophy (DMD) (also known as muscular dystrophy - Duchenne type) is an inherited disorder characterized by rapidly progressive muscle weakness which starts in the legs and pelvis and later affects the whole body. Duchenne muscular dystrophy (DMD) is the most common form of muscular dystrophy. It usually affects only males, but in rare cases it can also affect females. It is an X-linked recessive inherited disease. A milder form of this disease is known as Becker's muscular dystrophy (BMD). In Becker muscular dystrophy, most of the symptoms are similar to Duchenne, but the onset is later and the course is milder.

DMD is named after the French neurologist Guillaume Benjamin Amand Duchenne (1806-1875), who first described the disease in the 1860s. It is due to mutations in the dystrophin gene, which encodes a cell membrane protein in myocytes (muscle cells). One third of the cases are known to be caused by development of spontaneous mutations in the gene, while the remainder are inherited. Boys with DMD develop weak muscles because the muscle fibers that were present at birth are destroyed. Symptoms result in death by age 30 and respiratory failure usually results in a life expectancy of 20 years. A 1996 study found that early detection of the disease does not improve life-expectancy, and the most common cause of death is respiratory failure.

Symptoms

The main symptom of Duchenne muscular dystrophy is rapidly progressive muscle weakness associated with muscle wasting with the proximal muscles[citation needed] being first affected, especially the pelvis and calf muscles. Muscle weakness also occurs in the arms, neck, and other areas, but not as severely or as early as in the lower half of the body. Symptoms usually appear before age 6 and may appear as early as infancy. Generalized weakness and muscle wasting first affecting the muscles of the hips, pelvic area, thighs and shoulders. Calves are often enlarged. The other physical symptoms include; awkward Gait, rapidly progressive, frequent falls, difficulty with motor skills (running, hopping, jumping), progressive difficulty walking, ability to walk is usually lost by the age of 12, fatigue, mild mental retardation (in approx. 30% of Duchenne's patients), Skeletal deformities (including scoliosis in some cases), Muscle deformities, pseudohypertrophy of tongue and calf muscles. The enlarged muscle tissue is eventually replaced by fat and connective tissue, muscle contractures of heels and legs, rendering them unusable because the muscle fibers shorten and fibrosis occurs in connective tissue.

Signs and tests

Muscle wasting begins in the legs and pelvis, then progresses to the muscles of the shoulders and neck, followed by loss of arm muscles and respiratory muscles. Calf muscle enlargement (pseudohypertrophy) is quite obvious. Cardiomyopathy may occur, but the development of congestive heart failure or arrhythmias (irregular heartbeats) is rare.

A positive Gower's sign, which reflects the more severe impairment of the lower extremities muscles. The child helps himself to get up with upper extremities: first by rising to stand on his arms and knees, and then "walking" his hands up his legs to stand upright. The ability to walk is usually lost by the age of 12.

Treatment

There is no known cure for Duchenne muscular dystrophy. Treatment is aimed at control of symptoms to maximize the quality of life. Physical activity is encouraged. Inactivity (such as bed rest) can worsen the muscle disease. Physical and occupational therapy may be helpful to maintain muscle strength and function. Orthopaedic appliances (such as braces and wheelchairs) may improve mobility and the ability for self-care.

Prognosis

Duchenne muscular dystrophy eventually affects all voluntary muscles, and the heart and breathing muscles. Survival is rare beyond the early 30s. Death typically occurs from respiratory failure (suffocation) or heart disorders.

Mechanical Ventilatory Assistance: Volume Ventilators

Modern "volume ventilators," which deliver a preset volume (amount) of air to the person with each breath, are valuable in the treatment of people with muscular dystrophy related respiratory problems. Ventilator treatment usually begins in childhood when the respiratory muscles begin to fail.

When the vital capacity has dropped below 40 percent of normal, a volume ventilator may be used during sleeping hours, a time when the person is most likely to be underventilating ("hypoventilating"). Hypoventilation during sleep is determined by a thorough history of sleep disorder with an oximetry study and a capillary blood gas. The ventilator requires a nasal or facemask for connection to the airway. The masks are constructed of comfortable plastic with Velcro straps to hold them in place during sleep.

As the vital capacity declines to less than 30 percent of normal, a volume ventilator may also be needed during the day for more assistance. The person gradually will increase the amount of time using the ventilator during the day as needed. A mouthpiece can be used in the daytime and a nasal or facemask can be used during sleep. The machine can easily fit on a ventilator tray on the bottom of a power wheelchair.

There may be times such as during a respiratory infection when a person needs to rest his/her respiratory muscles during the day even when not yet using full-time ventilation. The versatility of the volume ventilator can meet this need, allowing tired breathing muscles to rest and also allowing aerosol medications to be delivered.

Prevention & Cure

There is presently no cure for DMD. Genetic counseling is advised if there is a family history of the disorder. Duchenne Muscular Dystrophy can be detected with about 95% accuracy by genetic studies performed during pregnancy.