Hand Tremors

What is tremor?
Tremor is an involuntary, rhythmic muscle contraction leading to shaking movements in one or more parts of the body. It is a common movement disorder that most often affects the hands but can also occur in the arms, head, vocal cords, torso, and legs. Tremor may be intermittent (occurring at separate times, with breaks) or constant. It can occur sporadically (on its own) or happen as a result of another disorder.

Tremor is most common among middle-aged and older adults, although it can occur at any age. The disorder generally affects men and women equally.

Tremor is not life threatening. However, it can be embarrassing and even disabling, making it difficult or even impossible to perform work and daily life tasks.

What causes tremor?
Generally, tremor is caused by a problem in the deep parts of the brain that control movements. Most types of tremor have no known cause, although there are some forms that appear to be inherited and run in families.

Tremor can occur on its own or be a symptom associated with a number of neurological disorders, including:

multiple sclerosis
stroke
traumatic brain injury
neurodegenerative diseases that affect parts of the brain (e.g., Parkinson's disease).
Some other known causes can include:

the use of certain medicines (particular asthma medication, amphetamines, caffeine, corticosteroids, and drugs used for certain psychiatric and neurological disorders)
alcohol abuse or withdrawal
mercury poisoning
overactive thyroid
liver or kidney failure
anxiety or panic.


What are the symptoms of tremor?
Symptoms of tremor may include:

a rhythmic shaking in the hands, arms, head, legs, or torso
shaky voice
difficulty writing or drawing
problems holding and controlling utensils, such as a spoon.
Some tremor may be triggered by or become worse during times of stress or strong emotion, when an individual is physically exhausted, or when a person is in certain postures or makes certain movements.



How is tremor classified?
Tremor can be classified into two main categories:

Resting tremor occurs when the muscle is relaxed, such as when the hands are resting on the lap. With this disorder, a person’s hands, arms, or legs may shake even when they are at rest. Often, the tremor only affects the hand or fingers. This type of tremor is often seen in people with Parkinson’s disease and is called a “pillrolling” tremor because the circular finger and hand movements resemble rolling of small objects or pills in the hand.

Action tremor occurs with the voluntary movement of a muscle. Most types of tremor are considered action tremor. There are several sub-classifications of action tremor, many of which overlap.

Postural tremor occurs when a person maintains a position against gravity, such as holding the arms outstretched.
Kinetic tremor is associated with any voluntary movement, such as moving the wrists up and down or closing and opening the eyes.
Intention tremor is produced with purposeful movement toward a target, such as lifting a finger to touch the nose. Typically the tremor will become worse as an individual gets closer to their target.
Task-specific tremor only appears when performing highly-skilled, goal-oriented tasks such as handwriting or speaking.
Isometric tremor occurs during a voluntary muscle contraction that is not accompanied by any movement such as holding a heavy book or a dumbbell in the same position.


What are the different categories or types of tremor?
Tremor is most commonly classified by its appearance and cause or origin. There are more than 20 types of tremor. Some of the most common forms of tremor include:

Essential tremor

Essential tremor (previously also called benign essential tremor or familial tremor) is one of the most common movement disorders. The exact cause of essential tremor is unknown. For some people this tremor is mild and remains stable for many years. The tremor usually appears on both sides of the body, but is often noticed more in the dominant hand because it is an action tremor.

The key feature of essential tremor is a tremor in both hands and arms, which is present during action and when standing still. Additional symptoms may include head tremor (e.g., a “yes” or “no” motion) without abnormal posturing of the head and a shaking or quivering sound to the voice if the tremor affects the voice box. The action tremor in both hands in essential tremor can lead to problems with writing, drawing, drinking from a cup, or using tools or a computer.

Tremor frequency (how “fast” the tremor shakes) may decrease as the person ages, but the severity may increase, affecting the person’s ability to perform certain tasks or activities of daily living. Heightened emotion, stress, fever, physical exhaustion, or low blood sugar may trigger tremor and/or increase its severity. Though the tremor can start at any age, it most often appears for the first time during adolescence or in middle age (between ages 40 and 50). Small amounts of alcohol may help decrease essential tremor, but the mechanism behind this is unknown.

About 50 percent of the cases of essential tremor are thought to be caused by a genetic risk factor (referred to as familial tremor). Children of a parent who has familial tremor have greater risk of inheriting the condition. Familial forms of essential tremor often appear early in life.

For many years essential tremor was not associated with any known disease. However, some scientists think essential tremor is accompanied by a mild degeneration of certain areas of the brain that control movement. This is an ongoing debate in the research field.

Dystonic tremor

Dystonic tremor occurs in people who are affected by dystonia—a movement disorder where incorrect messages from the brain cause muscles to be overactive, resulting in abnormal postures or sustained, unwanted movements. Dystonic tremor usually appears in young or middle-aged adults and can affect any muscle in the body. Symptoms may sometimes be relieved by complete relaxation.

Although some of the symptoms are similar, dystonic tremor differs from essential tremor in some ways. The dystonic tremor:

is associated with abnormal body postures due to forceful muscle spasms or cramps
can affect the same parts of the body as essential tremor, but also—and more often than essential tremor—the head, without any other movement in the hands or arms
can also mimic resting tremor, such as the one seen in Parkinson’s disease.
Also, the severity of dystonic tremor may be reduced by touching the affected body part or muscle, and tremor movements are “jerky” or irregular instead of rhythmic.
Cerebellar tremor

Cerebellar tremor is typically a slow, high-amplitude (easily visible) tremor of the extremities (e.g., arm, leg) that occurs at the end of a purposeful movement such as trying to press a button. It is caused by damage to the cerebellum and its pathways to other brain regions resulting from a stroke or tumor. Damage also may be caused by disease such as multiple sclerosis or an inherited degenerative disorder such as ataxia (in which people lose muscle control in the arms and legs) and Fragile X syndrome (a disorder marked by a range of intellectual and developmental problems). It can also result from chronic damage to the cerebellum due to alcoholism.

Psychogenic tremor

Psychogenic tremor (also called functional tremor) can appear as any form of tremor. It symptoms may vary but often start abruptly and may affect all body parts. The tremor increases in times of stress and decreases or disappears when distracted. Many individuals with psychogenic tremor have an underlying psychiatric disorder such as depression or post-traumatic stress disorder (PTSD).

Physiologic tremor

Physiologic tremor occurs in all healthy individuals. It is rarely visible to the eye and typically involves a fine shaking of both of the hands and also the fingers. It is not considered a disease but is a normal human phenomenon that is the result of physical properties in the body (for example, rhythmical activities such as heart beat and muscle activation).

Enhanced physiologic tremor

Enhanced physiological tremor is a more noticeable case of physiologic tremor that can be easily seen. It is generally not caused by a neurological disease but by reaction to certain drugs, alcohol withdrawal, or medical conditions including an overactive thyroid and hypoglycemia. It is usually reversible once the cause is corrected.

Parkinsonian tremor

Parkinsonian tremor is a common symptom of Parkinson’s disease, although not all people with Parkinson’s disease have tremor. Generally, symptoms include shaking in one or both hands at rest. It may also affect the chin, lips, face, and legs. The tremor may initially appear in only one limb or on just one side of the body. As the disease progresses, it may spread to both sides of the body. The tremor is often made worse by stress or strong emotions. More than 25 percent of people with Parkinson’s disease also have an associated action tremor.

Orthostatic tremor

Orthostatic tremor is a rare disorder characterized by rapid muscle contractions in the legs that occur when standing. People typically experience feelings of unsteadiness or imbalance, causing them to immediately attempt to sit or walk. Because the tremor has such a high frequency (very fast shaking) it may not visible to the naked eye but can be felt by touching the thighs or calves or can be detected by a doctor examining the muscles with a stethoscope. In some cases the tremor can become more severe over time. The cause of orthostatic tremor is unknown.



How is tremor diagnosed?
Tremor is diagnosed based on a physical and neurological examination and an individual’s medical history. During the physical evaluation, a doctor will assess the tremor based on:

whether the tremor occurs when the muscles are at rest or in action
the location of the tremor on the body (and if it occurs on one or both sides of the body)
the appearance of the tremor (tremor frequency and amplitude).
The doctor will also check other neurological findings such as impaired balance, speech abnormalities, or increased muscle stiffness. Blood or urine tests can rule out metabolic causes such as thyroid malfunction and certain medications that can cause tremor. These tests may also help to identify contributing causes such as drug interactions, chronic alcoholism, or other conditions or diseases. Diagnostic imaging may help determine if the tremor is the result of damage in the brain.

Additional tests may be administered to determine functional limitations such as difficulty with handwriting or the ability to hold a fork or cup. Individuals may be asked to perform a series of tasks or exercises such as placing a finger on the tip of their nose or drawing a spiral.

The doctor may order an electromyogram to diagnose muscle or nerve problems. This test measures involuntary muscle activity and muscle response to nerve stimulation.



How is tremor treated?
Although there is no cure for most forms of tremor, treatment options are available to help manage symptoms. In some cases, a person’s symptoms may be mild enough that they do not require treatment.

Finding an appropriate treatment depends on an accurate diagnosis of the cause. Tremor caused by underlying health problems can sometimes be improved or eliminated entirely with treatment. For example, tremor due to thyroid hyperactivity will improve or even resolve (return to the normal state) with treatment of thyroid malfunction. Also, if tremor is caused by medication, discontinuing the tremor-causing drug may reduce or eliminate this tremor.