ALS

Amyotrophic lateral sclerosis
Other names	Motor neurone disease (MND) Lou Gehrig's disease Charcot's disease[1]
Parts of the nervous system affected by ALS, causing progressive symptoms in skeletal muscles throughout the body[2]
Specialty	Neurology
Symptoms	Early: Stiff muscles, muscle twitches, gradual increasing weakness[3] Later: Difficulty in speaking, swallowing, and breathing; respiratory failure[3] 10–15% experience frontotemporal dementia[2]
Complications	Falling (accident); Respiratory failure; Pneumonia; Malnutrition
Usual onset	45–75 years[2]
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[2]
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[4]
Treatment	Walker (mobility); Wheelchair; Non-invasive ventilation;[5] Feeding tube; 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[6]
Frequency	Incidence: 1.6/100,069 individuals per year[6] Prevalence: 4.4/100,000 living individuals[6] Lifetime risk: 1 in 400 individuals[7]

Amyotrophic lateral sclerosis (ALS), also known as motor neurone disease (MND) or Lou Gehrig's disease in the United States, is a rare but terminal neurodegenerative disorder that results in the progressive loss of both upper and lower motor neurons that normally control voluntary muscle contraction.^[3] ALS is the most common form of the motor neuron diseases.^[8] ALS often presents in its early stages with gradual muscle stiffness, twitches, weakness, and wasting.^[3] Motor neuron loss typically continues until the abilities to eat, speak, move, and, lastly, breathe are all lost.^[3] 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.^[9] 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).^[10]

Most cases of ALS (about 90% to 95%) have no known cause, and are known as sporadic ALS.^[3][11] However, both genetic and environmental factors are believed to be involved.^[12] The remaining 5% to 10% of cases have a genetic cause, often linked to a history of the disease in the family, and these are known as familial ALS (hereditary).^[6][13] About half of these genetic cases are due to disease-causing variants in one of four specific genes.^[14] The diagnosis is based on a person's signs and symptoms, with testing conducted to rule out other potential causes.^[3]

There is no known cure for ALS.^[3] The goal of treatment is to slow the disease progression, and improve symptoms.^[9] Treatments that slow ALS include riluzole (extends life by two to three months) and sodium phenylbutyrate/ursodoxicoltaurine (extends life by around seven months).^[15][16] Non-invasive ventilation may result in both improved quality, and length of life.^[5] Mechanical ventilation can prolong survival but does not stop disease progression.^[17] A feeding tube may help maintain weight and nutrition.^[18] Death is usually caused by respiratory failure.^[19] The disease can affect people of any age, but usually starts around the age of 60.^[19] 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.^[20]

Descriptions of the disease date back to at least 1824 by Charles Bell.^[21] 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.^[21]