The onset of ALS is gradual. The first sign is usually weakness in one limb, often a hand. Weakness later spreads to the forearms and legs, and twitching or cramps may occur. There are no unusual changes in feeling or sensations. There is often an event, such as an unexplained fall, that alerts the person to the fact that something is wrong.
Paralysis usually occurs as the disease progresses.
The disease does not usually affect mental abilities. Swallowing may become difficult. The person may tend to inhale food or saliva. Death usually results from lung infections. During the early stages, treatment focuses on quality of life.