Like ALS, primary lateral sclerosis (PLS) is a progressive degenerative disease of the motor neurons. It is characterized by progressive spasticity (involuntary muscle tension and spasms) and it affects the lower limbs, trunk, upper limbs, and bulbar muscles, usually in that order. PLS usually begins with lower-extremity stiffness and pain due to spasticity.
Data on the incidence of primary lateral sclerosis (PLS) are uncertain. In contrast, data on ALS are well documented; ALS affects 2-3 individuals per 100,000 population each year. The 8 patients with PLS reported by Pringle et al in 1992 were identified over a period of 10 years among a population of 500 patients with ALS.
Physical therapy often helps prevent joint immobility. Speech therapy may be useful for those with involvement of the facial muscles.Physiotherapy treatment focuses on reducing muscle tone, maintaining or improving range of motion, increasing strength and coordination, and improving functional mobility. In PLS, stretching is thought to improve flexibility and can also reduce muscle spasticity and cramps.