A disease characterized by the dysfunction in the nerve cells in the brain and spinal cord that control muscle movement. resulting in progressive loss of movement, paralysis, and death. It is sometimes referred to as Lou Gehrig’s disease, after a famous baseball player who had the condition.
ALS attacks the nerve cells used in voluntary muscle actions, actions that a healthy body can control such as the arms, legs, and face. The targeted cells are called motor neurons. As it progresses, these cells degenerate and die. They stop sending messages to muscles and the brain can no longer control voluntary movement. Over time, the muscles weaken and degenerate.
Amyotrophic lateral sclerosis (ALS), also known as motor neuron disease (MND) or (in the United States) Lou Gehrig's disease (LGD), is a rare, terminal neurodegenerative disorder that results in the progressive loss of both upper and lower motor neurons that normally control voluntary muscle contraction. ALS is the most common form of the motor neuron diseases. ALS often presents in its early stages with gradual muscle stiffness, twitches, weakness, and wasting. Motor neuron loss typically continues until the abilities to eat, speak, move, and, lastly, breathe are all lost. While only 15% of people with ALS also fully develop frontotemporal dementia, an estimated 50% face at least some minor difficulties with thinking and behavior. Depending on which of the aforementioned symptoms develops first, ALS is classified as limb-onset (begins with weakness in the arms or legs) or bulbar-onset (begins with difficulty in speaking or swallowing).
| Amyotrophic lateral sclerosis | |
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| Parts of the nervous system affected by ALS, causing progressive symptoms in skeletal muscles throughout the body | |
| Specialty | Neurology |
| Symptoms | Early: Stiff muscles, muscle twitches, gradual increasing weakness Later: Difficulty in speaking, swallowing, and breathing; respiratory failure; 10–15% experience frontotemporal dementia |
| Complications | Falling (accident); Respiratory failure; Pneumonia; Malnutrition |
| Usual onset | 45–75 years |
| Causes | Unknown (about 85%), genetic (about 15%) |
| Risk factors | Genetic risk factors; age; male sex; heavy metals; organic chemicals; smoking; electric shock; physical exercise; head injury |
| Diagnostic method | Clinical diagnosis of exclusion based on progressive symptoms of upper and lower motor neuron degeneration in which no other explanation can be found. Supportive evidence from electromyography, genetic testing, and neuroimaging |
| Differential diagnosis | Multifocal motor neuropathy, Kennedy's disease, Hereditary spastic paraplegia, Nerve compression syndrome, Diabetic neuropathy, Post-polio syndrome, Myasthenia gravis, Multiple sclerosis |
| Treatment | Walker (mobility); Wheelchair; Non-invasive ventilation; Feeding tubes; Augmentative and alternative communication; symptomatic management |
| Medication | Riluzole, Edaravone, Sodium phenylbutyrate/ursodoxicoltaurine, Tofersen, Dextromethorphan/quinidine |
| Prognosis | Life expectancy highly variable but typically 2–4 years after diagnosis |
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Most cases of ALS (about 90–95%) have no known cause, and are known as sporadic ALS. However, both genetic and environmental factors are believed to be involved. The remaining 5–10% of cases have a genetic cause, often linked to a family history of the disease, and these are known as familial ALS (hereditary). About half of these genetic cases are due to disease-causing variants in one of four specific genes. The diagnosis is based on a person's signs and symptoms, with testing conducted to rule out other potential causes.
There is no known cure for ALS. The goal of treatment is to slow the disease progression, and improve symptoms. FDA-approved treatments that slow the progression of ALS include riluzole and edaravone. Non-invasive ventilation may result in both improved quality and length of life. Mechanical ventilation can prolong survival but does not stop disease progression. A feeding tube may help maintain weight and nutrition. Death is usually caused by respiratory failure. The disease can affect people of any age, but usually starts around the age of 60. The average survival from onset to death is two to four years, though this can vary, and about 10% of those affected survive longer than ten years.
Descriptions of the disease date back to at least 1824 by Charles Bell. In 1869, the connection between the symptoms and the underlying neurological problems was first described by French neurologist Jean-Martin Charcot, who in 1874 began using the term amyotrophic lateral sclerosis.
