What are muscular dystrophy and neuromuscular diseases?
Muscular dystrophy (MD) is a group of rare neuromuscular diseases that cause weakness, wasting away of muscles, and permanent loss of muscle tissue. MD is a progressive disease and symptoms get worse over time. Muscles degenerate, causing communication problems between the muscles and nerves that control movement. MD can also cause spasms, twitching, and pain, as well as heart and lung problems.
Most types of MD are caused by a new mutation (change) in your genes, or a mutation that’s inherited from your parents. Some forms of MD develop in infancy or childhood; others appear in middle age or later. Medications and therapy can help manage symptoms, slow the disease’s progression, help maintain mobility, and lengthen lifespan.
Are there different types of muscular dystrophy?
There are more than 30 types of MD. Each type can differ according to which muscles are affected, the extent of muscle weakness, age of onset, rate of progression, and if they’re inherited.
The most commonly occurring types are:
Duchenne MD develops primarily in boys between ages 2 to 6. Survival beyond the 20s is rare because of the diseases’ rapid progression. Most boys can no longer walk by age 12, and later need a respirator to breathe. Girls in these families have a 50% chance of inheriting the defective gene and passing it to their children. Duchenne is the most common type of MD, and includes general muscle weakness, and muscle wasting that initially affect the pelvis, upper arms and legs. It can affect a child’s heart and lungs. Eventually all voluntary muscles are affected.
Becker MD, the second most common MD, develops between the ages of 5 and 60, but usually in the teen years. It affects the hip, thigh and shoulder muscles, and eventually the heart. Symptoms are the same as Duchenne but milder, and it progresses more slowly than Duchenne. Most patients diagnosed young can survive to middle age.
Congenital MD is present at birth. Symptoms can include muscle weakness, a curved spine, joints that are too stiff or too loose, learning disabilities, seizures and vision problems. It progresses slowly, and can shorten life span.
Distal MD develops between ages 40 to 60. Symptoms include weakness and muscle wasting of the hands, forearms, and lower legs. It progresses slowly and rarely causes total disability.
Emery-Dreifuss MD develops in childhood to adolescence. Symptoms include weakness and wasting of shoulder, upper arm, and calf muscles. The heart is also affected, and joint deformities are common. It progresses slowly, but heart problems can cause sudden death.
Facioscapulohumeral MD can develop in childhood to early adulthood. Symptoms, which usually appear before age 20, include muscle weakness in the face, shoulder blades, legs, and upper arms. Muscle wasting occurs in the shoulders and upper arms. Disease progression is slow, and symptoms can range from mild to disabling.
Limb-Girdle MD can develop between pre-teenage to middle age. The symptoms first include weakness and wasting of the shoulders and pelvic area. Progression is slow; death is usually due to heart-lung complications.
Myotonic MD, the most common adult form of MD, develops between the ages of 20 to 40, primarily in people of European descent. All muscle groups become weak. Muscle relaxation is delayed after each contraction. It also causes muscle spasms, cataracts, heart/lung problems, and endocrine disturbances. Muscles of the face, feet, hands, and neck are first affected, causing a long, thin face, drooping eyelids and a swan-like neck. Disease progression is slow and lifespan is shortened.
Oculopharyngeal MD is rare and develops between ages 40 to 70. Muscles of the eyelids and throat are affected, causing weakening of throat muscles. Patients lose the ability to swallow and lose weight, but the progression is slow.
Are there different types of other neuromuscular diseases?
There are many types of neuromuscular diseases, including: