Essential Tremor

A tremor is unintentional, rhythmic shaking or trembling. Essential tremor is a tremor whose cause is unknown. However, some evidence suggests the cause could be an abnormality of the cerebellum.

This tremor, once called benign or senile tremor, affects up to 1 out of 5 people over 65. The tremor often begins in young adulthood and slowly becomes more obvious as people age. However, the tremor may begin much later in life. Some forms of essential tremor run in families and are sometimes called familial tremor.

In many people, essential tremor remains mild, although it may be troublesome and embarrassing. However, the tremor often gradually worsens over time, eventually resulting in disability.

Essential tremor affects the arms most often and the legs rarely. Because it occurs during movement, such as writing or using eating utensils, it is considered an action tremor. Essential tremor also occurs when the limbs are held out from the side. The tremor usually stops when the arms or legs are at rest. Usually, essential tremor affects both sides of the body, but one side is affected more than the other.

Sometimes essential tremor affects the head, causing it to tremble and bob, and the vocal cords, causing the voice to shake.

Diagnosis

The diagnosis is usually based on characteristics of the tremor. Doctors ask the person to describe the tremor, including when it started, when it usually occurs, which parts of the body it affects, and whether other symptoms also occur. Doctors observe the person while moving, resting, and holding different positions. Sometimes if the diagnosis is uncertain, electromyography (EMG, which records electrical activity in muscles) is done. Or the speed and range of the tremor may be measured with a device called an accelerometer, which is attached to the finger.

Usually, blood tests are done to determine whether the tremor is caused by an overactive thyroid gland (hyperthyroidism) rather than essential tremor.

Treatment

Treatment depends on how troublesome the tremor is. Certain simple precautions can enable many people to continue their normal daily activities. For example, objects should be grasped firmly but comfortably and held close to the body. Specially designed utensils (such as rocker knives and utensils with large handles) and electrical appliances (such as can openers and toothbrushes) can make daily activities easier. Cylinders of foam can be placed around handles to make them easier to hold. Other helpful measures include using straws, button hooks, Velcro fasteners, zipper pulls, and shoe horns.

Drinking small amounts of alcohol may reduce the tremor. But stopping drinking can make the tremor worse. Avoiding caffeine may help.

If the tremor interferes with daily activities or work, drugs may help. A beta-blocker (used to treat high blood pressure), such as propranolol, is most commonly prescribed. If a beta-blocker does not help, primidone, an anticonvulsant, is often tried. However, this drug may cause confusion, nausea, unsteadiness, and excessive drowsiness in older people. Other choices include gabapentin and topiramate (anticonvulsants) and clozapine (a sedative and an antipsychotic).

If a tremor is severe and disabling and drugs are ineffective, brain surgery may be done. There are two types of surgery. In a thalamotomy, parts of the thalamus are destroyed. The thalamus, a cluster of nerve cells, relays nerve signals through the brain. Thus, the pathways that produce the tremor are interrupted. In thalamic stimulation, an electrical probe is placed inside the thalamus. The probe continuously stimulates the thalamus. The tremor is usually reduced. Such procedures are available only at special centers.

See the sidebar When People Tremble.