Tremor

Physiologic tremor is the normal tremor that everyone has to some degree. For example, most people's hands, when held outstretched, usually tremble slightly. Such slight, rapid tremor reflects the precise moment-by-moment control of muscles by nerves. In most people, the tremor is barely noticeable. However, a normal tremor may become more noticeable under certain conditions and may worry people. For example, the tremor may be more noticeable when people

• Feel stressed or anxious

• Are deprived of sleep

• Stop drinking alcohol or taking a sedative (such as a benzodiazepine) or an opioid

• asthma and chronic obstructive pulmonary disease [COPD]), corticosteroids, or illicit drugs (such as or amphetamines)

• Have certain disorders, such as an overactive thyroid gland (hyperthyroidism) that is causing other symptoms

Essential tremor results from a problem in the nervous system, but people with this tremor rarely have any other symptoms of nervous system dysfunction (neurologic symptoms). The cause is unclear, but the tremor often runs in families.

Essential tremor usually begins during early adulthood but can begin at any age. The tremor slowly becomes more noticeable as people age. Thus, it is sometimes incorrectly called senile tremor. The tremor usually involves the arms and hands and sometimes affects the head. When it affects the head, people may look as if they are nodding yes or shaking their head no. These tremors are usually worsened by holding a limb outstretched (against gravity) or by moving a limb.

Usually, essential tremor remains mild. However, it can be troublesome and embarrassing. It can affect handwriting and make using utensils difficult. In some people, the tremor gradually worsens over time, eventually resulting in disability. Symptoms may resemble those of Parkinson disease, and sometimes essential tremor is misdiagnosed as Parkinson disease. Rarely, people have Parkinson disease and essential tremor.

Resting tremor occurs when muscles are at rest. An arm or a leg shakes even when a person is completely relaxed. The tremor becomes less noticeable or disappears when the person moves the affected muscles. Resting tremors are often slow and coarse.

These tremors develop when nerve cells in the part of the brain called the basal ganglia are disturbed. The basal ganglia help initiate and smooth out intended (voluntary) muscle movements. Such disturbances usually result from

• Parkinson disease or disorders that cause the same symptoms as Parkinson disease (parkinsonism)

However, resting tremors can also result from use of medications or other substances that can affect basal ganglia, such as antipsychotic medications and some medications used to relieve nausea.

Resting tremors may be socially embarrassing, but because they go away when people try to do something (such as drinking a glass of water), they typically do not interfere with daily activities.

This tremor occurs during a purposeful movement, as when reaching for an object with the hand. People may miss the object because of the tremor. Intention tremors worsen as people get closer to the targeted object. These tremors are relatively slow and wide (coarse).

Intention tremors may result from damage to the cerebellum, the part of the brain responsible for balance and coordination.

Common causes of intention tremor include

• Certain hereditary disorders that affect the cerebellum (called spinocerebellar ataxias)

• Multiple sclerosis

Other disorders and drugs can also cause the cerebellum to malfunction, resulting in an intention tremor. They include

• Stroke

• A tumor

• Alcohol use disorder

• Overuse of sedatives or antiseizure medications

Postural tremors are most obvious when a limb is held in a position that requires resisting the pull of gravity, as when people hold their arms outstretched.

The most common postural tremors are

• Essential tremor

• Physiologic (normal) tremor

Complex tremor is a tremor that has features of more than one type of tremor.

Common causes of complex tremors are

• Psychologic factors

• Widespread nerve damage such as that caused by diabetes or Guillain-Barré syndrome

The following symptoms are cause for concern:

• Tremors that start abruptly

• Tremors in people who are under 50 years old and have no relatives who have had essential tremors

• Other neurologic symptoms, such as a change in mental status, muscle weakness, changes in the way a person walks, and difficulty speaking

• A rapid heart rate and agitation

People with warning signs should see a doctor immediately.

People without warning signs should see a doctor as soon as possible.

If people are under 50 years old and do not have a family history of essential tremors, they should see a doctor soon. Being evaluated by a doctor is important to make sure that the cause is not another disorder, a drug, or another substance.

Doctors first ask questions about the person's symptoms and medical history and then do a physical examination. What doctors find during the history and physical examination often suggests a cause and the tests that may need to be done (see table Some Causes and Features of Tremor).

Doctors ask about the tremor:

• When the tremor started

• Whether the tremor began gradually or suddenly

• Which body parts are affected

• What triggers it (such as movement, rest, or standing)

If the tremor began suddenly, doctors ask about events that may have triggered it (such as a recent injury or use of a new drug).

Doctors review the person's past medical history, looking for conditions associated with tremor

Doctors do a physical examination, paying particular attention to the neurologic examination (including the way the person walks). Doctors note which body parts are affected by the tremor. They observe how fast the shaking movements are in various situations:

• When the affected body parts are at rest and when they are fully supported (for example, hands in the person's lap)

• While the person maintains certain positions (such as holding the arms outstretched)

• While the person is walking or doing tasks with the affected body part

The quality of the person's voice may be observed when holding a long note.

Doctors can usually identify the type of tremor based on its characteristics and results of the medical history and physical examination—for example,

• Tremors that develop gradually: Usually physiologic or essential tremor

• A tremor that starts suddenly: Possibly psychologic factors, a poison, a disorder (such as hyperthyroidism), stopping use of alcohol or another drug (such as a sedative), or use of a drug known to cause tremor

Brain imaging with magnetic resonance imaging (MRI) or computed tomography (CT) is done if

• The person has other neurologic symptoms that suggest a brain disorder, such as a stroke, a tumor, or multiple sclerosis.

• The tremor started suddenly or progresses rapidly.

Blood tests may be done to check for possible causes when the cause is unclear. Tests may include

• Measurement of blood sugar

• Tests to evaluate how well the thyroid and parathyroid glands, liver, and kidneys are functioning

Electromyography (stimulating muscles and recording their electrical activity) is rarely done. But if the cause is thought to be nerve damage, it may be done. This test can help distinguish tremor from other disorders, such as disorders of the peripheral nerves.

If many daily activities (such as using utensils and drinking from a glass at mealtime) become difficult or if the person's work requires steady hands, medications may help.

beta-blocker) may help.

For some people, drinking alcohol in moderation may lessen the tremor, but doctors do not recommend this tactic as a treatment. Heavy drinking followed by suddenly stopping makes the tremor worse.

Benzodiazepines may be used to treat essential tremor if other medications are ineffective. However, they should be taken for only a short time if at all.

Intention tremors are difficult to treat, but if the condition causing it can be corrected, the tremor may resolve.

If the condition cannot be corrected, a therapist may put wrist and ankle weights on the affected limb to reduce the tremor. Or people may be taught to brace the limb during activity. These measures sometimes help.

For deep brain stimulation , tiny electrodes are placed in the area of the brain involved in tremors—the basal ganglia (collections of nerve cells that help smooth out muscle movements—see figure Locating the Basal Ganglia). The electrodes send small amounts of electricity to the specific area of the basal ganglia responsible for the tremors and thus help relieve symptoms.

Deep brain stimulation is sometimes done when medications cannot control a severe, disabling tremor. Sometimes essential tremors or tremors due to Parkinson disease or another disorder require such treatment. Such treatments are used only when medications have been tried and have been not been effective. These treatments are available only at special centers.