Skip to Main Content

Amyotrophic Lateral Sclerosis (ALS)

  • A neurodegenerative disease that causes progressive muscle weakness and paralysis
  • Causes respiratory distress and trouble talking; predominantly affects arms and legs
  • There is no cure, but medications and physical therapy may slow or lessen disease severity
  • Involves neurology, ALS Program, neuromuscular medicine

Amyotrophic Lateral Sclerosis (ALS)


Before baseball player Lou Gehrig was diagnosed in 1939, few Americans knew about amyotrophic lateral sclerosis (ALS), the neurodegenerative disease which causes progressive muscle weakness and paralysis. ALS affects about 5 per 100,000 people per year in the United States. In the majority of cases, there is no known cause.

While there is no cure for ALS, patients treated at a dedicated ALS center such as the Yale Medicine ALS Program will have access to a range of specialists, treatments, and clinical trails. 

What are the symptoms of ALS?

All muscles in the body are controlled by cells called motor neurons, which deliver signals from the brain and spinal cord. When people have ALS, their motor neurons degenerate over the course of weeks, months, and years, leading to progressive muscle weakness and eventual paralysis.

Additionally, people will have respiratory distress and difficulty talking. While ALS attacks motor neurons, the disease does not typically impair cognitive function, so people with ALS are still able to think clearly and understand the world around them.

ALS predominantly affects the arms and legs, but some patients may experience early symptoms in the bulbar region and have difficulty speaking and swallowing.

How is ALS diagnosed?

There is no one test to diagnose ALS definitively. Patients suspected of having the disease undergo a series of tests to confirm that they do not have such other neuromuscular ailments as muscular dystrophy, neuropathy, or myasthenia gravis.

Magnetic resonance imaging (MRI) can rule out stroke or other brain or spine conditions that might lead to muscle weakness. Blood samples may be screened for cancers and infections that can also cause abnormal nerve function. Additionally, a diagnostic procedure called electromyography (EMG) checks for abnormal nerve and muscle function.

These tests may also reveal such other variants of motor neuron disease as primary lateral sclerosis (PLS), progressive bulbar palsy (PBP), and progressive muscular atrophy (PMA). These motor neuron disorders are similar to ALS, although the management and progression may differ.

How is ALS treated?

While there is not yet any cure for ALS, some treatments may slow its progression or lessen its neurodegenerative symptoms. A drug called Rilutek, taken in pill form twice a day, has been shown to extend the life expectancy of some patients by two to three months.

Since ALS is a disorder of the nervous system, it is important to keep muscles active to preserve the connections between the nerves and the muscles. The best treatment for this is often physical and occupational therapy, along with very mild resistance training. Properly fit orthotic devices, such as leg braces and walkers, can help keep patients mobile and walking for as long as possible.

The mere act of seeking help can have a beneficial effect, according to Babar Khokhar, MD, a neurologist. Involvement in patient networks can help mitigate depression, he says, improving quality of life and possibly even life expectancy.