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Fibrillation vs. Fasciculation: What's the Difference?

Edited by Janet White || By Harlon Moss || Published on February 7, 2024
Fibrillation is irregular, rapid heart muscle contractions, while fasciculation refers to small, involuntary muscle twitches under the skin.

Key Differences

Fibrillation involves the rapid, irregular, and often unsynchronized contraction of muscle fibers, particularly in the heart. This can be life-threatening if it affects the heart's rhythm. Fasciculation, on the other hand, is the twitching of small groups of muscle fibers, often visible under the skin, and is usually benign.
Atrial and ventricular fibrillation are types of fibrillation that affect different parts of the heart. They can lead to serious health issues like stroke or cardiac arrest. Fasciculations are generally localized, affecting muscle groups like eyelids, arms, or legs, and are often caused by fatigue, stress, or neurological disorders.
Fibrillation, especially in the heart, requires immediate medical attention and can be a symptom of underlying heart conditions. It is diagnosed using electrocardiograms (ECG). Fasciculation, while sometimes unsettling, is typically not a medical emergency and may not require extensive diagnostics.
Treatment for fibrillation may involve medication, electrical cardioversion, or surgery, depending on its severity and cause. Fasciculation is often treated by addressing its underlying cause, such as electrolyte imbalance or stress management, and may not always need direct medical intervention.
Fibrillation can be a chronic condition, affecting individuals’ long-term heart health and requiring ongoing management. Fasciculations, while they can be persistent, are usually transient and less likely to signify a serious health condition.

Comparison Chart


Irregular, rapid muscle contractions, in heart
Small, involuntary muscle twitches under the skin

Commonly Affected Area

Heart (atrial or ventricular)
Skeletal muscles (eyelids, limbs)

Medical Severity

Can be life-threatening
Usually benign

Diagnostic Method

Electrocardiogram (ECG)
Often diagnosed by symptoms, rarely needs tests


Medication, cardioversion, surgery
Addressing underlying cause, sometimes no treatment

Fibrillation and Fasciculation Definitions


Fibrillation causes inefficient blood pumping by the heart.
Ventricular fibrillation is a medical emergency requiring immediate attention.


It often occurs in small muscle groups like eyelids or fingers.
The constant fasciculation in her hand was distracting but harmless.


Fibrillation is a rapid, uncoordinated series of muscle contractions, often in the heart.
The patient was diagnosed with atrial fibrillation after experiencing heart palpitations.


These twitches can be a symptom of neurological disorders.
The neurologist checked for fasciculation as part of the examination.


This condition can be chronic, affecting long-term heart health.
Managing fibrillation often involves lifestyle changes and medication.


Fasciculations are usually benign and can be caused by muscle fatigue.
After a long run, he experienced fasciculation in his calf muscles.


Fibrillation is detectable through an electrocardiogram.
The ECG showed signs of fibrillation, prompting further cardiac assessment.


Fasciculation is the involuntary twitching of muscle fibers visible under the skin.
He noticed fasciculation in his eyelid after several days of stress.


It refers to an abnormal heart rhythm due to disorganized electrical impulses.
Fibrillation can significantly increase the risk of stroke.


Fasciculation is often transient and resolves without treatment.
She experienced temporary fasciculation due to electrolyte imbalance.


The forming of fibers.


A form of involuntary muscular contraction that is more intense than fibrillation, consisting of simultaneous twitching of adjacent groups of muscle fibers.


Fine, rapid twitching of individual muscle fibers with little or no movement of the muscle as a whole.


An arrangement of fasciculi.


Rapid uncoordinated twitching movements that replace the normal rhythmic contraction of the heart and may cause a lack of circulation and pulse.


An involuntary muscle twitch, usually localised and temporary, but that may be intensified and prolonged fatally by particular poisons and venoms such as acetylcholinesterase inhibitors.


The rapid, irregular, and unsynchronized contraction of the muscle fibers of the heart.


A cluster of fascicules.


The state of being reduced to fibers.


Muscular twitching of contiguous groups of muscle fibers


Muscular twitching involving individual muscle fibers acting without coordination


Act or process of forming fibrils


What causes fibrillation?

It can be caused by heart disease, hypertension, or electrolyte imbalances.

How is atrial fibrillation treated?

With medications, lifestyle changes, and sometimes procedures like ablation.

Can stress cause fibrillation?

Yes, stress can be a contributing factor to fibrillation episodes.

Can dehydration cause fasciculations?

Yes, electrolyte imbalances due to dehydration can lead to fasciculations.

Is fasciculation common after exercise?

Yes, it's common due to muscle fatigue.

Can fibrillation be cured?

Treatment can manage symptoms, but some forms may be chronic.

Do fasciculations require medical testing?

Usually not, unless accompanied by other neurological symptoms.

Are fasciculations always harmless?

While often benign, they can indicate neurological issues in some cases.

Does caffeine affect fibrillation?

Yes, caffeine can trigger or worsen fibrillation in some people.

Is fibrillation a type of heart attack?

No, but it can lead to serious complications like heart failure or stroke.

Is exercise safe for someone with fibrillation?

It depends on the type and severity; consulting a doctor is important.

Can fibrillation lead to other heart conditions?

Yes, it can increase the risk of stroke and heart failure.

Are fasciculations more common in any specific muscle groups?

They frequently occur in the eyelids, arms, and legs.

Are fasciculations a sign of ALS?

They can be a symptom but are also common in healthy individuals.

How long do fasciculations last?

They can last from a few seconds to several days or longer.

Can anxiety cause fasciculations?

Yes, stress and anxiety can trigger muscle twitches.

Are there different types of fibrillation?

Yes, including atrial fibrillation and ventricular fibrillation.

Can vitamin deficiency cause fasciculations?

Deficiencies in certain vitamins like B12 can contribute to fasciculations.

What lifestyle changes help with fibrillation?

Healthy diet, regular exercise, and avoiding triggers like alcohol.

Is there a link between fasciculations and sleep disorders?

Poor sleep can exacerbate fasciculations, but a direct link is not well-established.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.

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