Primary Lateral Sclerosis

What is Primary Lateral Sclerosis?

Primary lateral sclerosis (PLS) is a rare neuromuscular disease with slowly progressive weakness in voluntary muscle movement. PLS belongs to a group of disorders known as motor neuron diseases. In motor neuron diseases, the nerve cells that control voluntary muscle movement degenerate and die. In PLS, the corticospinal motor neurons (often called “upper motor neurons”) in the brain are affected. There is no evidence of degeneration of lower motor neurons in the spinal cord or brainstem and there is little muscle wasting (what doctors call “amyotrophy”). Symptoms include weakness, muscle stiffness and spasms (spasticity), clumsiness, slowing of movement, and problems with balance. Onset of PLS usually occurs after age 40. The symptoms often begin with problems in the legs, but may also start with hand clumsiness or changes in speech. PLS progresses gradually over a number of years, or even decades. Scientists do not believe PLS has a simple hereditary cause. There are similar, but rare, hereditary childhood disorders termed “juvenile PLS.” The diagnosis of PLS requires extensive testing to exclude other diseases. When symptoms begin, PLS may be mistaken for amyotrophic lateral sclerosis or ALS (Lou Gehrig’s disease) and the diagnosis of PLS can be delayed for several years.

Is there any treatment?

Treatment for individuals with PLS is symptomatic. Baclofen and tizanidine may reduce spasticity. Quinine or phenytoin may decrease cramps. Physical therapy helps prevent joint immobility and maintain muscle strength. Speech therapy may be useful for those with involvement of the facial muscles.

What is the prognosis?

PLS is not fatal. There is no cure and the progression of symptoms varies. Some people may retain the ability to walk without assistance, but others eventually require wheelchairs, canes, or other assistive devices.

What research is being done?

The NINDS conducts a broad range of research on neuromuscular disorders such as PLS. This research is aimed at developing techniques to diagnose, treat, prevent, and ultimately cure these devastating diseases.

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