What Is Asterixis (Flapping Hand Tremor)?

Medically Reviewed by Christopher Melinosky, MD on March 07, 2024
3 min read

Asterixis is a disorder in which a person loses motor control of some parts of the body. It is commonly called flapping hand tremor because the muscles in the fingers and the wrists are typically affected. ‌A person with asterixis loses muscle control and experiences irregular jerking movements in the hands. If you have asterixis, the movement of your hands may resemble the flapping of a bird's wings.  This motion is why asterixis is also known as flapping hand tremor. ‌

Flapping hand tremor is associated with some liver conditions and may also be referred to as liver flap. Although the connection between liver disease and asterixis was recognized some decades ago, we still do not know exactly how or why it happens. ‌Some experts believe the disorder results from improper functioning in specific brain regions that control your posture and muscle movement. These areas are called diencephalic motor centers. ‌Another theory is that Alzheimer's type II astrocytes, brain cells that have a hyperactive metabolism and enlarged size, swell up due to fluid shifts in the brain.

As a result, the body's blood-brain barrier (BBB) is compromised, The BBB regulates the movement of substances between the blood and the brain. Scientists do not yet have a clear understanding of how these changes lead to flapping tremors. Other causes of asterixis are still unknown or have not yet been explained in detail. ‌

The most notable symptom of asterixis is the flapping tremor of the hands, fingers, and wrists. This flapping is involuntary, which means it is not under your control. ‌While hand tremors are most common, asterixis can also affect other parts of your body. Also, additional symptoms may be present stemming from the underlying disease that caused the asterixis. ‌Depending on whether liver, kidney, heart, or metabolic conditions are affecting the brain, these additional symptoms may vary.‌

Since flapping hand tremor is a neurological disorder, everything that impacts the brain negatively can be a risk factor for the disease. ‌

Stroke. A stroke happens when blood flow to the brain is blocked. Stroke can result from an injury to a blood vessel or from a blood clot. If the brain does not get oxygen for a long time, many areas can get damaged beyond repair. ‌

Liver disease. People with liver disease are at a high risk of hepatitis and cirrhosis. The liver undergoes scarring in both of these conditions. Scarring makes the liver less effective at removing toxins, and increases the risk of flapping hand tremor. ‌

Wilson disease.  If you have this condition, your liver does not process copper properly. A copper buildup in the body can damage the brain. The disorder is rare, affecting one in every 30,000 people. Common symptoms of Wilson disease are asterixis, personality changes, and muscle stiffness. ‌

A doctor diagnoses flapping tremors using lab tests and a physical exam. A person with asterixis will flap their wrists involuntarily when told to flex their wrists and spread their fingers. ‌Your doctor may also check for asterixis at your hip joint. To do so, they will ask you to lie on your back with your face up, knees bent outwards, and feet flat. A flapping movement indicates asterixis. To determine the extent of brain damage, your doctor will use an imaging scan or test. A CT scan or MRI are tests your doctor may request to see brain areas that appear damaged.

Asterixis treatment depends on the underlying cause of the disease. For example, if your flapping hand tremor is due to liver or kidney encephalopathies (diseases that affect the brain), your doctor may recommend that you:

  • Limit your alcohol intake to reduce strain on your kidneys. 
  • Take laxatives to remove toxins from the body.
  • Plan for a kidney or liver transplant if the encephalopathy is severe.‌

The treatment for Wilson disease involves taking drugs that prevent the body from absorbing the copper in the food you eat. Your doctor may also prescribe penicillamine or other chelating agents that remove copper from body tissues.