Amyotrophic lateral sclerosis, ALS, is a collective name for a group of neurodegenerative diseases that lead to the death of motor neurons in the spinal cord and in the brain. As the signals from the motor neurons to the muscles diminish, the muscles get weaker, start wasting and eventually get paralyzed. Usually, the disease starts in a single body part and then gradually spreads to the remaining skeletal muscles in the body.
In a third of those afflicted by ALS, the disease starts by weakness and/or muscle wasting in a hand or an arm. The first symptom can be e.g., trouble opening screw caps or brushing one’s teeth. Some patients may discover that they have developed a pit between the thumb and index finger as a result of wasting of the muscles in the hand.
About a third first discovers weakness and/or muscle wasting in a leg, and the first symptoms may include bad balance, increased tripping, or difficulty climbing stairs.
In a slightly smaller group (a little less than a third) the disease starts with weakness in mouth, neck, or facial muscles, and the first symptom is difficulty articulating (dysarthria), that eventually leads to development of a montonous, hoarse voice (dysphonia), and difficulty swallowing (dysphagia).
It is rare, but sometimes the disease starts with symptoms from the back, abdominal or respiratory muscles. Typical symptoms are extreme fatigue, shortness of breath, and back pain.
Some patients experience fasciculations (involuntary twitching of an individual muscle) and spasticity (stiff or rigid muscles). It is important to keep in mind that involuntary twitching is a common occurance also in healthy individuals. Muscle twitching can be triggered by stress, sleep deprivation, lack of magnesium, several hormonal diseases, and other diseases of the nervous system. Muscle twitching is usually not the first symptom to occur in ALS.
The muscle symptoms vary depending on the speed at which the disease is developing and on how the damage is distributed between the motorneurons in the cortex of the brain, and those in the brainstem and spinal cord. Patients with damage to the motorneurons in the brain become stiff (spastic) in the afflicted muscles and their movements become clumsy. If mainly motorneurons in the brain are afflicted, the muscle wasting is usually slower.
Patients with damage mainly to the motorneurons of the brainstem or spinal cord present with flaccid muscle weakness and paralysis, and obvious muscle wasting. Muscle twitching can be very evident in these patients. In most ALS patients, a combination of damage to the motorneurons of the brain and spinal cord occurs, but the symptoms may present to a varying extent during the disease progression.
It is very important to keep in mind that there are many different types of ALS disease and that the disease course varies heavily. Usually, the disease progresses evenly – more aggressively in some patients, and slower in some. However, the end stage is generally the same. When the respiratory muscles are affected, the patient fails to exhale carbon dioxide from the lungs. This means that not enough oxygen can be inhaled, and the lack of oxygen causes increase fatigue and lack of energy. The patient commonly dies in their sleep, or due to pneumonia. While the average survival time is three years, a fifth of patients live with ALS for five years, 10 percent will live for ten years, and approximately 5 percent will live for 20 years or longer.
