A 45-year-old man presents with progressive clumsiness, stat…
A 45-year-old man presents with progressive clumsiness, stating he often drops objects and recently has had difficulty performing tasks requiring fine motor coordination, such as hammering a nail. He also reports that his speech has become slurred, and his legs occasionally feel weak. He denies visual or cognitive changes. A chronic degenerative disease of the central nervous system involving predominantly motor neurons is suspected. Which of the following is the most likely diagnosis?