What is amyotrophic lateral sclerosis (ALS)?
Amyotrophic lateral sclerosis (ALS), once called Lou Gehrig’s disease after the baseball player diagnosed with it, is a progressive neurodegenerative disease that affects nerve cells in the spinal cord (lower motor neurons) and brain (upper motor neurons). Over time, ALS leads to the degeneration and death of motor neurons, which control voluntary muscle movements. As the disease progresses, the muscles they control weaken and atrophy, causing difficulty speaking, swallowing, breathing, and ultimately paralysis. Most ALS patients die from respiratory failure, usually within 3 to 5 years of symptom onset. There is no cure, and treatment focuses on symptom management, slowing progression, and improving quality of life.
Approximately 1 in 400 people will develop ALS in their lifetime, and around 30,000 people are living with ALS in the U.S. About 85% of cases are sporadic with no family history; the remaining 15% are familial. ALS affects all races, ages, and genders.
Causes of ALS
ALS is a nervous system disease affecting people of all races and ethnicities. About 15% of cases are familial, involving inherited gene mutations. Sporadic ALS makes up the other 85% with no known family history or linked genetic mutation.
The most common familial mutation is in the C9orf72 gene, accounting for 30–40% of familial cases. Other risk factors include:
- Age: most common between 60 and mid-80s
- Sex: slightly more men than women develop ALS before age 65 (difference disappears after age 70)
- Smoking: may increase risk, especially in postmenopausal women
- Military service: higher risk observed among veterans
ALS diagnosis
There is no single test for ALS, making diagnosis challenging. Early and accurate diagnosis by a neurologist is important, as treatments are most effective when started soon after symptom onset. Diagnosis typically involves a physical exam, medical history review, and symptom evaluation, plus some of the following tests:
- Electrodiagnostic tests (EMG and NCS) to assess muscle and motor neuron function
- Magnetic resonance imaging (MRI) to image the brain and spinal cord
- Laboratory tests including blood, urine, and thyroid function
- Spinal tap (lumbar puncture) to analyze cerebrospinal fluid
- Muscle biopsy to rule out other muscle diseases
Further research is needed to understand ALS mechanisms, genetic influences, identify earlier biomarkers, and develop new treatments.
ALS symptoms
Initial symptoms vary but often begin in the hands, feet, arms, or legs and then spread. Possible symptoms include:
- Muscle weakness in arms or legs
- Slurred speech
- Difficulty swallowing (bulbar-onset ALS)
- Muscle twitching (fasciculations)
- Muscle cramps
- Dropping objects
- Tripping, falling, or difficulty walking
- Uncontrolled crying or laughing
As ALS progresses, loss of voluntary movement control extends to walking, talking, chewing, and breathing.
ALS treatment
Treatment cannot reverse existing damage but can slow progression, improve quality of life, and extend survival.
Medications
- Rilutek (riluzole): oral medication shown to extend life by 2–3 months
- Radicava (edaravone): IV infusions that may preserve muscle function when started early
- Relyvrio (sodium phenylbutyrate/taurursodiol): oral drug approved in 2022 to block nerve cell stress signals
- Qalsody (tofersen): spinal injection for patients with SOD1 gene mutation, under ongoing study
Physical therapy
Low-impact exercises (walking, swimming, stationary bike) and range-of-motion routines help reduce fall risk, maintain muscle strength, and preserve independence.
Occupational therapy
Assists with daily living activities and recommends adaptive devices for bathing, grooming, and feeding to support independence.
Speech therapy
Helps with clear speech techniques and alternative communication methods such as speech synthesizers or alphabet boards.
Nutritional support
Dietitians guide patients on easy-to-swallow foods and nutrient intake. When eating becomes difficult, a feeding tube may be recommended.
Resources
- Elman LB, et al. Clinical features of amyotrophic lateral sclerosis and other forms of motor neuron disease. UpToDate. Accessed Apr. 18, 2024.
- Just what is ALS? ALS Association. https://www.als.org/understanding-als/what-is-als. Accessed Apr. 18, 2024.
- Dharmadasa T, et al. Genetic testing in motor neuron disease. Practical Neurology. 2022. doi:10.1136/practneurol-2021-002989.
- Amyotrophic lateral sclerosis (ALS) fact sheet. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Amyotrophic-Lateral-Sclerosis-ALS-Fact-Sheet. Accessed Apr. 18, 2024.