Spontaneous muscle twitching can be an early symptom of ALS and a sign that motor neurons are damaged. But other causes can also contribute to muscle twitching. Consulting a doctor can help identify the cause.

Amyotrophic lateral sclerosis (ALS) is a disease of the nervous system that causes progressive loss of muscle strength and control. Among the common early symptoms of ALS (aka Lou Gehrig’s disease) is muscle twitching, also known as fasciculations.

Muscle twitching can also occur for reasons other than ALS. Fasciculations that occur with other classic ALS symptoms, such as progressive muscle weakness, cramps, or fatigue, could be indications of a serious neurological disorder.

Still, it’s important to see a doctor about recurrent or persistent fasciculations — whether they occur with or without other symptoms.

Fasciculations occur when motor neurons — the cells in your nervous system that control muscle movement — become excited and release electrical impulses spontaneously.

ALS can cause muscle twitching because the disease damages the motor neurons and interferes with their ability to function. Eventually, motor neurons in muscles throughout your body begin to die off, so those muscles can no longer twitch or move at all.

The ALS Association reports that muscle twitching is often, but not always, an early symptom of ALS.

The gradual weakening of one or more muscles is the most common early symptom of ALS. These changes usually occur in the arms, hands, legs, and feet but may also affect the muscles involved with swallowing and speech.

Other early ALS symptoms can include:

Not all people with ALS will experience the same symptoms, especially early on. The timetable for symptoms to progress also varies from one person to the next.

While muscle twitching can be an early indicator of ALS, evolving changes in fasciculations may help doctors understand how the disease is progressing or affecting a particular muscle group, according to a 2020 study.

Muscle twitching in ALS feels like persistent but visible muscle jumps under the skin or contractions of a muscle or muscles.

Fasciculations usually aren’t painful, but they can be annoying and frustrating. They can also interfere with sleep.

Muscle twitching doesn’t always indicate ALS. Benign fasciculation syndrome (BFS) causes muscle twitching without an underlying medical condition and usually occurs without any other symptoms.

Muscle twitching usually feels the same, regardless of what triggers it. But when ALS is the cause, several muscles or muscle groups are likely involved. For example, you may feel muscle twitching in your arms and legs at the same time.

BFS differs from ALS in that BFS usually causes one muscle at a time to twitch. The same is true when muscle twitching is the result of other temporary and relatively minor factors, such as:

  • caffeine (or other stimulants)
  • intense exercise
  • lack of sleep
  • stress

There’s no cure for muscle twitching in ALS.

However, certain medications, such as muscle relaxants or nerve blockers, may help ease the frequency and intensity of your fasciculations.

Physical therapy or occupational therapy may also help.

When to contact a doctor

Occasional muscle twitching is usually a benign symptom that doesn’t require a medical evaluation. But it’s important to see a doctor if you notice fasciculations or muscle cramps that linger or come and go for several weeks.

It’s also important to see a doctor if you notice changes in how you walk, in your muscle strength and coordination, and even slight changes in your ability to speak, chew, or swallow.

However, if you have experienced muscle twitching without other muscle-related symptoms for years, there’s probably no rush to see a doctor. Some people are simply more likely to experience chronic muscle twitching.

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Do ALS fasciculations stop with movement?

While fasciculations associated with BFS or other benign causes often stop while you deliberately move the affected muscles, this isn’t always the case with ALS. Movement may have no impact, and as ALS progresses, you may have a tougher time intentionally moving certain muscles affected by fasciculations.

When should I worry about muscle twitching?

Muscle twitching usually isn’t a sign of anything serious. But if you notice your muscles becoming unusually fatigued or weak while also experiencing fasciculations, it’s important to seek a medical evaluation.

What are the first warning signs of ALS?

Muscles that become tired quickly or are noticeably weaker in recent weeks or months may be signs of ALS or another motor neuron disease.

Muscles in the arms and legs are usually among the first parts of the body to be affected by ALS. Changes in the muscles involved in speech and swallowing may also be among the first warning signs of ALS.

How long can you have ALS without knowing it?

According to 2020 research, doctors typically diagnose ALS 10–16 months after symptoms first appear.

Muscle twitching is sometimes the first ALS symptom a person notices or is at least among the first few symptoms of the disease. But twitching doesn’t necessarily indicate ALS. It’s a rare disease, with about 5,000 new U.S. cases each year, according to the Centers for Disease Control and Prevention.

To know if your muscle twitching isn’t a symptom of ALS or another serious condition, pay attention to when your muscle twitching and any other symptoms started. Tell a doctor if symptoms linger or you notice a sudden progression of any problems related to your muscle strength and motor control.