Primary lateral sclerosis (PLS) causes weakness in your voluntary muscles, such as those you use to control your legs, arms and tongue. Primary lateral sclerosis is a type of motor neuron disease that causes muscle nerve cells to slowly break down, causing weakness. Primary lateral sclerosis can happen at any age, but it usually occurs between ages 40 and 60.
The incidence rate for PLS is difficult to determine. One study puts it at 500 individuals. However, many researchers feel this is inaccurate, and that the actual incidence rate is closer to 2000. The issue is further complicated by the fact that researchers also believe a good portion of those initially diagnosed with PLS may actually have ALS or HSP.
Treatment for individuals with PLS is symptomatic. Muscle relaxants such as baclofen, tizanidine, and the benzodiazepines may reduce spasticity. Other drugs may relieve pain and antidepressants can help treat depression. Physical therapy, occupational therapy, and rehabilitation may prevent joint immobility and slow muscle weakness and atrophy.