Primary lateral sclerosis (PLS) is a progressive degenerative motor neuron disease, meaning that nerve cells in the body gradually die off. PLS affects only some of the nerve cells in the body--those that control voluntary movement of muscles. It is not known why it occurs, or exactly how the nerve cells are destroyed. Primary lateral sclerosis seems to begin between 35 and 65 years of age. It is not known how many people in the world are affected by primary lateral sclerosis, although it does seem to be rare.
The loss of the nerve cells causes muscles to become stiff and difficult to move. Typically, the muscle problems start in the legs, and move up the body to the trunk, arms, and muscles in the face and neck. The disease progresses slowly, usually over a few years.
There is no specific test for primary lateral sclerosis, so most of the time the diagnosis occurs as the result of eliminating other possible causes of the symptoms. Because amyotrophic lateral sclerosis (ALS, or Lou Gehrig's disease) is more common, primary lateral sclerosis is often confused with it. However, primary lateral sclerosis does not produce muscle wasting throughout the body as ALS does, and therefore does not affect the respiratory muscles.
There is no specific treatment or cure for primary lateral sclerosis, so treatment focusing on relieving its symptoms. Medications can reduce pain and muscle spasms. Physical therapy can also help reduce spasms and provide devices to help with walking, talking, and eating. Support groups such as the Spastic Paraplegia Foundation can help individuals and their families adapt to the physical changes the disease brings. Primary lateral sclerosis brings progressive disability and loss of function but does not affect the mind or shorten the life span directly.
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