Though it’s a progressive disease, there are no officially-defined stages of ALS. Not everyone experiences the same symptoms in exactly the same order, and the disease progresses more slowly in some people than others.
In general, though, the progression of ALS can be divided up into three stages: early, middle, and late.
The early stages of ALS are usually marked by muscle weakness, tightness, cramping, and/or twitching. These muscular issues may cause the patient to drop things, trip and fall, or have difficulty doing common physical movements such as buttoning clothes.
The muscle weakness can start in any part of the body, and progress on to any other part. In the majority of cases, though, the symptoms appear first in the arms or legs. And if muscle weakness occurs in one arm or one leg, the other arm or leg is usually the next part of the body to be effected.
In the middle stages of ALS, the muscle weakness becomes widespread throughout the body. Some muscles become paralyzed. There is a loss of muscle mass, and some unused muscles may become permanently shortened. These shortened muscles, known as contractures, prevent joints (such as elbows) from fully straightening.
Some ALS patients also experience bouts of uncontrollable laughter or crying, even though they may not feel that anything is particularly funny or sad. These symptoms are known as pseudobulbar palsy.
As the disease progresses to its final stages, almost all voluntary muscles will become paralyzed. As the mouth and throat muscles become paralyzed, it becomes impossible to talk, eat, or drink normally. Eating and drinking is done via a feeding tube.
As the muscles that control breathing become weaker, it becomes harder to bring in enough oxygen for the body’s needs. Respiratory failure is by far the most common cause of death for ALS patients, though some deaths result from malnutrition, heart problems, or pneumonia.
Unfortunately, there is currently no cure for ALS; all cases are eventually fatal. On average, ALS patients live two to five years after diagnosis, but some live far longer—in rare cases, for decades.