muscle-twitchingFasciculations, or involuntary muscle twitches, happen to about 70% of people. While it’s typically benign, the condition can become a cause for concern when it starts happening frequently. Amyotrophic lateral sclerosis (ALS, often referred to as Lou Gehrig’s disease) and benign fasciculation syndrome (BFS) are two separate disorders that can cause these symptoms.

It’s important to understand the distinction between these two medical conditions, though, and the distinctions in the treatment paths.

Why Does ALS Cause Muscle Twitching?

ALS is a progressive neurological disease that causes degeneration in the motor neurons that extend from the brain to the spinal cord, then reach out to other muscles within the body. 

As those motor neurons die, the brain loses its ability to communicate with and control the movement of muscles. That affects voluntary muscle action to the point where individuals with ALS start losing the ability to perform functions like moving, breathing, speaking, and eating.¹

The effects of ALS vary. Some people may have more advanced symptoms depending on the motor neurons affected. One common symptom is twitching and cramping within your muscles, including places like your legs and shoulders. 

Symptoms often start in the limbs, known as limb onset ALS, move to the feet and hands, and then spread to other body parts (as opposed to bulbar onset ALS, when symptoms begin with trouble swallowing or speaking).²

Other symptoms that often appear in ALS patients include:

  • Slurred speech
  • Problems swallowing
  • Twitching in the arms and tongue
  • Changes in behavior
  • Cognitive difficulties

ALS affects all age groups, though it typically appears when people reach middle age. The first signs include spasticity in one of a person’s limbs. 

Individuals usually consult with a physician about the possibility of having ALS if the condition persists.³


Why Does BFS Lead to Muscle Twitching?

Benign fasciculation syndrome can be diagnosed when individuals start to experience constant muscle tingling, numbness, or twitching. The symptoms may appear when the person is at rest, then fade away once they start moving. People may experience fasciculation, or muscle twitching, for many reasons. Such twitches are often referred to as eye spasms when they appear in the eyelid.⁴

Fasciculations can be a result of many conditions. Those associated with BFS usually occur in a person’s calves and thighs, though the tremors may also show up in other body parts. The twitching may happen only occasionally or become a frequent occurrence.

BFS is thought to occur because of muscle nerves becoming overactive, though the actual cause of the condition is currently unknown. Certain studies have found a tie between BFS and other medical issues like:

  • Depression
  • Anxiety
  • Fatigue
  • Consumption of alcohol or caffeine
  • Cigarette smoking
  • Viral infections
  • Strenuous exercise
  • Trauma
  • Stress

How Does ALS Muscle Twitching Differ From BFS Muscle Twitching?

The main difference between BFS vs. ALS muscle twitching is that the muscle contractions associated with ALS are caused by a deterioration of the muscles over time. That may manifest as a loss of mobility or weakness in the body.⁵ BFS is a benign condition that does not cause any damage to the muscles or nerves, and is caused by a sometimes temporary stimulus.

Anyone who becomes concerned about persistent muscle twitching should consult with a neurologist. Doctors will typically conduct an exam to help them determine whether they believe there is a reason to be worried about the possibility of ALS or whether the spasms are connected to another condition like BFS. The doctor may order additional bloodwork to determine if the symptoms are benign or associated with a more serious health problem.⁶


How to Cope With Muscle Twitching

Patients diagnosed with ALS who experience constant twitching of the muscles may worry that their disease is progressing rapidly. However, the severity of muscle spasms does not necessarily correlate to ALS severity.⁷ One thing that both ALS and BFS have in common is that there is currently no known cure for either condition.


Potential Relief for ALS Symptoms

Some patients have been able to use the following options to ease the effects of some ALS symptoms or make them feel more comfortable. 

  • Medications to help with side effects like muscle cramps and excessive saliva
  • Nutritional counseling
  • Dietary options to help when swallowing becomes difficult
  • Use of special medical devices to facilitate independent movement


BFS Treatment

There are no specific treatments available to address issues associated with BFS. However, a doctor may recommend other therapies to manage the side effects of muscle twitching if the twitching adversely impacts a patient’s daily life. Exercising and massage may also provide some relief.⁴



  1. 1. “What is ALS?” ALS Association,
  2. 2. “Amyotrophic lateral sclerosis ALS)” Mayo Clinic,
  3. 3. “Amyotrophic Lateral Sclerosis (ALS) : Signs and Symptoms”, MDA | Muscular Dystrophy Association,
  4. 4. “What Is Benign Fasciculation Syndrome?”,,
  5. 5. Daniels, A.: What is causing that twitching in your muscles? Baltimore Sun (2018)
  6. 6. “Annoying Muscle Twitch? When to Seek Help” Rush,
  7. 7. “What Do Fasciculations or Muscle Twitching Mean?”, ALS Association,

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