Tremor is an unintentional, somewhat rhythmic, muscle movement involving to-and-fro movements (oscillations) of one or more parts of the body. It is the most common of all involuntary movements and can affect the hands, arms, head, face, vocal cords, trunk, and legs. Most tremors occur in the hands.
Tremor may occur at any age but is most common in middle-aged and older persons. It may be occasional, temporary, or occur intermittently. Tremor affects men and women equally.
Tremor is generally caused by problems in parts of the brain that control muscles throughout the body or in particular areas, such as the hands. The most common form of tremor occurs in otherwise healthy people. However, in some people a tremor is a symptom of another neurological disorder or condition, including:
Other causes include the use of some drugs (such as amphetamines, corticosteroids, and drugs used for certain psychiatric disorders), alcohol abuse or withdrawal, mercury poisoning, overactive thyroid, or liver failure. Some forms of tremor are inherited and run in families, while others have no known cause.
Characteristics may include:
Some tremors may be triggered by or become exaggerated during times of stress or strong emotion, when the individual is physically exhausted, or during certain postures or movements.
Although tremor is not life-threatening, it can be embarrassing to some people and make it harder to perform daily tasks.
A useful way to understand and describe tremors is to define them according to the following types:
Tremor is most commonly classified by clinical features and cause or origin. Some of the better known forms of tremor are:
There is no cure for most tremors. The appropriate treatment depends on accurate diagnosis of the cause. Some tremors respond to treatment of the underlying condition. For example, in some cases of psychogenic tremor, treating the patient’s underlying psychological problem may cause the tremor to disappear.
Symptomatic drug therapy is available for several forms of tremor. Eliminating tremor “triggers” such as caffeine and other stimulants from the diet is often recommended. Physical therapy may help to reduce tremor and improve coordination and muscle control for some patients. Surgical intervention such as thalamotomy and deep brain stimulation may ease certain tremors. These surgeries are usually performed only when the tremor is severe and does not respond to drugs.