Essential tremor

Definition

Essential tremor is a type of involuntary shaking movement in which no cause can be identified. Involuntary means you shake without trying to do so.

See also:

• Drug-induced tremor
• Tremor

Alternative Names

Tremor - essential; Familial tremor; Tremor - familial

Causes, incidence, and risk factors

Essential tremor is the most common type of tremor. In general, tremors occur when there is a problem with the nerves supplying certain muscles. However, everyone has some essential tremor but the movements are usually so small that they can't be seen.

The specific cause for essential tremor is unknown. Some research suggests that the cerebellum, the part of the brain that controls muscles movements, does not work correctly in patients with essential tremor.

Noticeable essential tremors can be seen at any age but are most common in people older than 65.

Essential tremor can also occur with other neurological conditions, including dystonia, parkinsonism, and certain inherited nerve conditions such as Charcot-Marie-Tooth disease.

If an essential tremor occurs in more than one member of a family, it is called a familial tremor. This type of essential tremor is passed down through families (inherited), which suggests that genes play a role in its cause.

Familial tremor is usually a dominant trait, which means that you only need to get the gene from one parent to develop the disorder. It usually starts in early middle age, but may be seen in people who are older or younger.

Symptoms

The tremor is usually most obvious in the hands, but may affect the arms, head, eyelids, or other muscles. The tremor rarely affects the legs or feet. People with essential tremor may have trouble holding or using small objects such as silverware or a pen.

The shaking usually involves small, rapid movements -- more than 5 times a second.

Specific symptoms may include:

• Head nodding
• Shaking or quivering sound to the voice if the tremor affects the voice box
• Difficulty writing, drawing, drinking from a cup, or using tools if the tremor affects the hands

The tremors may:

• Occur when you move (action-related tremor), and may be less noticeable with rest
• Come and go, but generally get worse as you age
• Get worse with stress, caffeine, and certain medications
• Not affect both sides of the body the same way

Signs and tests

Your doctor can make the diagnosis by performing a physical exam and asking questions about your medical and personal history.

A physical exam will show shaking with movement, usually small movements that are faster than 5 times per second. There are usually no problems with coordination or mental function.

Further tests may be needed to rule out other reasons for the tremors. Other causes of tremors may include:

• Alcohol withdrawal
• Cigarette smoking
• Hyperthyroidism
• Pheochromocytoma
• Too much caffeine
• Use of certain medications
• Wilson's disease

Blood tests and imaging studies (such as a CT scan of the head, brain MRI, and x-rays) are usually normal.

Treatment

Treatment may not be necessary unless the tremors interfere with your daily activities or cause embarrassment.

Medicines may help relieve symptoms. How well medicines work depend on the individual patient.

Two medications used to treat tremors include:

• Propranolol, a drug that blocks the action of stimulating substances called neurotransmitters, particularly those related to adrenaline
• Primidone, an antiseizure drug that also controls the function of some neurotransmitters

The drugs can have significant side effects.

Side effects of propranolol include:

• Fatigue
• Nose stuffiness
• Shortness of breath (people with asthma should not use this drug)
• Slow heart beat

Side effects of primidone include:

• Drowsiness
• Difficulty concentrating
• Nausea
• Problems with walking, balance, and coordination

Other medications that may reduce tremors include:

• Antiseizure drugs such as gabapentin and topiramate
• Mild tranquilizers such as alprazolam or clonazepam
• Blood pressure drugs called calcium-channel blockers such as flunarizine and nimodipine

Botox injections, given in the hand, have been used to reduce tremors by weakening local muscles.

In severe cases, surgery to implant a stimulating device in the brain may be an option.

Expectations (prognosis)

An essential tremor is not a dangerous condition, but some patients find the tremors annoying and embarrassing. In some cases, it may be dramatic enough to interfere with work, eating, or drinking.

Complications

Severe essential tremor can interfere with daily activities, especially fine motor skills such as writing. Sometimes the tremors affect the voice box, which occasionally leads to speech problems.

Calling your health care provider

Call for an appointment with your health care provider if essential tremor interferes with your ability to perform daily activities.

Call your health care provider if you are being treated for this condition and have side effects from the medication, such as fainting, very slow heart rate, confusion or changes in alertness, lack of coordination, problems walking, and prolonged nausea or vomiting.

Prevention

Stress and caffeine can make tremors worse. Avoid caffeinated drinks such as coffee, tea, and soda, and other stimulants. Exercise and counseling to reduce emotional stress may also help.

Alcoholic beverages in small quantities may decrease tremors but can lead to alcohol dependence and alcohol abuse, especially if you have a family history of such problems. How alcohol helps relieve tremors is unknown.

References

Jankovic J. Movement disorders. In: Goetz CG. Textbook of Clinical Neurology. 3rd ed. St. Louis, Mo: WB Saunders; 2007: chap. 34.