Neuromuscular disorders are conditions that affect the nerve, muscle, or neuromuscular
junction (where the nerve talks to the muscle). Muscular dystrophy is a group of inherited
diseases that causes weakness. They also cause wasting away of muscle tissue. There
are multiple types of muscular dystrophy. Each type leads to loss of strength, increasing
disability, and possible deformity.
The most common muscular dystrophy is Duchenne muscular dystrophy. The next most common
is Becker muscular dystrophy.
Listed below are nine major types of muscular dystrophy. Each type differs in the
muscles affected, the age of onset, and its rate of progression. The following are
named for the affected muscles:
|
Type
|
Age at onset
|
Symptoms, rate of progression, and life expectancy
|
|
Becker
|
Teen to early adulthood
|
Symptoms are almost the same as Duchenne, but less severe. It progresses more slowly
than Duchenne. Survival goes into middle age. Becker disease is almost always limited
to males. This is the same as with Duchenne.
|
|
Congenital
|
Birth
|
Symptoms include general muscle weakness and possible joint deformities. The disease
progresses slowly. It causes a shortened life span.
|
|
Duchenne
|
Ages 2 to 6
|
Symptoms include general muscle weakness and wasting. It affects the pelvis, upper
arms, and upper legs. Over time, it includes all voluntary muscles. Survival beyond
the 20s is rare. It happens mostly in boys. Very rarely it can affect women, who have
much milder symptoms and a better prognosis.
|
|
Distal
|
Ages 40 to 60
|
Symptoms include weakness and wasting of muscles of the hands, forearms, and lower
legs. Progression is slow. It rarely leads to total disability.
|
|
Emery-Dreifuss
|
Childhood to early teens
|
Symptoms include weakness and wasting of shoulder, upper arm, and shin muscles. Joint
deformities are common. progression is slow. Sudden death may occur from cardiac problems.
|
|
Facioscapulohumeral
|
Childhood to early adults
|
Symptoms include facial muscle weakness and weakness with some wasting of shoulders
and upper arms. Progression is slow with periods of rapid deterioration. Life span
may be many decades after onset.
|
|
Limb-Girdle
|
Late childhood to middle age
|
Symptoms include weakness and wasting, affecting shoulder girdle and pelvic girdle
first. Progression is slow. Death is usually due to cardiopulmonary complications.
|
|
Myotonic
|
Ages 20 to 40
|
Symptoms include weakness of all muscle groups and delayed relaxation of muscles after
contraction. It affects the face, feet, hands, and neck first. Progression is slow,
sometimes spanning 50 to 60 years. An infantile form causes more severe problems.
|
|
Oculopharyngeal
|
Ages 40 to 70
|
Symptoms affect muscles of eyelids and throat causing weakening of throat muscles.
Over time, this causes inability to swallow and severe weight loss from lack of food.
Progression is slow.
|