How common is primary lateral sclerosis?

a rare disease that causes progressive weakness in voluntary muscles such as in the legs, hands, and tongue. PLS is one of the diseases, along with amyotrophic lateral sclerosis, that are grouped...

Diagnosis is based on the observance of the muscle weakness and the progressive worsening of the weakness. The diagnosis can be delayed because the disease is mistaken for ALS.

Motor neuron diseases like primary lateral sclerosis develop because the nerve cells that normally control the movement of voluntary muscles degenerate and die.

PLS affects a part of the neuron called the cell body (or soma). Specifically, it is the cell bodies of upper motor neurons that are affected.

PLS is not fatal, and people with the disorder can usually maintain mobility with the use of canes or other assistance.