Tremor is an unintentional, rhythmic, muscle movement involving to-and-fro movements of one or more parts of the body. Most tremors occur in the hands, although they can also affect the arms, head, face, voice, torso, and legs. Generally, tremor is caused by a problem in the deep parts of the brain that control movements.
Some forms of tremor are inherited and run in families, while others have no known cause. Sometimes tremor is a symptom of another neurological disorder or a side effect of certain drugs, but the most common form occurs in otherwise healthy people.
Excessive alcohol consumption or alcohol withdrawal can kill certain nerve cells, resulting in tremor, especially in the hand. Other causes include an overactive thyroid and the use of certain drugs.
Tremor may occur at any age but is most common in middle-aged and older adults.
There are several types of tremor, one of the most common of which is essential tremor (sometimes called benign essential tremor). The hands are most often affected but the head, voice, tongue, legs, and trunk may also be involved. Head tremor may be seen as a "yes-yes" or "no-no" motion. Onset is most common after age 40, although symptoms can appear at any age.
Parkinsonian tremor is caused by damage to structures within the brain that control movement. The tremor is classically seen as a "pill-rolling" action of the hands but may also affect the chin, face, lips, and legs.
Dystonic tremor occurs in individuals of all ages who are affected by dystonia, a movement disorder which causes muscles to be over-active, resulting in abnormal postures or sustained, unwanted movements.
There is no cure for most forms of tremors. The appropriate treatment depends on accurate diagnosis of the cause.
Drug treatment for parkinsonian tremor involves levodopa or dopamine-like drugs such as carbidopa.
Essential tremor may be treated with propranolol or other beta blockers (such as nadolol) and primidone, an anticonvulsant drug.
Dystonic tremor may respond to clonazepam, anticholinergic drugs, and intramuscular injections of botulinum toxin. Tranqulizers may help some people with tremor.
Surgical intervention, such as deep brain stimulation, is usually performed only when the tremor is severe and does not respond to drugs.
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 individuals.
Although tremor is not life-threatening, it can be embarrassing to some people and make it harder to perform daily tasks such as working, bathing, eating, and getting dressed. The symptoms of essential tremor usually worsen with age.
Researchers at the National Institute of Neurological Disorders and Stroke (NINDS, a unit of the National Institutes of Health) are working to better understand the underlying brain functions that casue tremor, indentify the genetic factors that make individuals more susceptible to tremor, and develop new and better treatment options.
Researchers are working to identify structural and functional changes in the brain using non-invasive neuroimating techniques. Other researchers hope to identify the genetic abnormalities in the development of essential tremor.
Additional NINDS research is investigating the impact of ethanol to determing the correct dosage amount for essential tremor and whether other medications without the side effects of ethanol can be effective.