Primary lateral sclerosis (PLS) is a rare neuromuscular disease characterized by progressive muscle weakness in the voluntary muscles. PLS belongs to a group of disorders known as motor neuron diseases. According to modern views, PLS is considered to be part of the range of motor neuron diseases consisting of primary lateral sclerosis, amyotrophic lateral sclerosis (ALS), and progressive spinal muscular atrophy (PSMA).
PLS incidence has been estimated at approximately 0.5 percent of that of ALS. Further, PLS has not been considered to shorten life expectancy and has been observed in males between ages 40-60 years.A conservative estimate is that no more than 500 people with PLS currently are living. PLS has not been considered to shorten life expectancy and has been observed in males between ages 40-60 years.
No treatments are currently available to prevent, stop, or reverse PLS. Treatment is focused on symptom relief, such as medication to reduce spasticity; physical therapy and exercise to help maintain flexibility, strength, and range of motion; assistive devices and communications aids; and supportive therapy and other modalities.