Sometimes associated with malignancy. Often responds to drug therapy. Sometimes involves swallowing muscles. More common in men than women. Lung tumor is sometimes present.
Progression varies with success of drug therapy and treatment of any malignancy.
Varies in severity, and weakness can fluctuate. Some muscle wasting. Stiffness and muscle cramps common. Weakness and atrophy of muscles of hands and lower legs, with foot deformities and some loss of sensation in feet. Slow but variable progression among individuals.