Amyotrophic lateral sclerosis (ALS) is a progressive neurological disease characterized by the destruction of nerve cells (neurons) that are responsible for controlling voluntary muscle movement. Examples of voluntary muscle movement include chewing, walking, talking and breathing.
In general, ALS progression may be divided into three distinct stages: early, middle, and late. The following section offers information about the characteristic symptoms associated with each stage.
Early stage ALS
Early symptoms of ALS are usually characterized by muscle weakness, tightness (spasticity), cramping, or twitching (fasciculations). This stage is also associated with muscle loss or atrophy.
Symptoms at this stage are generally limited to a particular part of the body, and often first begin in the arms or hands, making daily tasks, such as buttoning clothes or opening a can of food, difficult to execute. Alternatively, they may first appear in a leg — in either case, disease that begins in the arms or legs is often called “limb onset” ALS. The muscular issues may cause people to experience fatigue, poor balance, slurred words, loss of grip strength, or to trip or fall when walking.
Middle stage ALS
During the middle stages of ALS, muscle weakness and atrophy spreads to other parts of the body. Some muscles become paralyzed, while others lose strength. Some infrequently used muscles may become permanently shortened, causing contractures in which joints (e.g., elbows) are no longer able to fully straighten.
People may also develop problems in walking, and in swallowing (dysphagia) and chewing food, which increases the risk of choking. Other problems associated with increasing muscle weakness include difficulty in speaking and breathing (dyspnea), and possibly uncontrollable and inappropriate laughing or crying, a reaction called the pseudobulbar affect.
Most ALS patients retain higher mental and reasoning abilities, and are aware of their progressive loss of muscular function.
Late stage ALS
As ALS progresses, most voluntary muscles become paralyzed. As the muscles of the mouth and throat, and those involved in breathing, become paralyzed, eating, speaking, and breathing is compromised. During this stage, eating and drinking are usually require a feeding tube. Breathing is assisted via a ventilator.
Most people with ALS die due to respiratory failure, and the prognosis is usually three to five years after the first symptoms appear. Less common causes of death may result from malnutrition, pulmonary embolism (obstruction of a lung artery), heart arrhythmias (the heart beating faster or slower than normal, or irregularly), and pneumonia due to aspiration (which occurs when food or water gets into the lungs).
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