Essential tremor is the most common type of tremor. In general, tremors occur when there is a problem with the nerves supplying certain muscles. The specific cause for essential tremor is unknown. However, some research suggests that the cerebellum, the part of the brain that controls muscles movements, does not work correctly in patients with essential tremor.

Essential tremors can occur at any age but are most common in people older than 65. There are several different types of essential tremor, including:

• Essential tremor with head tremor
• Young-onset essential tremor (essential tremors that start at an earlier-than-usual age)

If an essential tremor occurs in more than one member of a family, it is called a familial tremor .

The tremors are usually most obvious in the hands, but may affect the arms, head, eyelids, or other muscles. The tremors rarely affect the legs or feet. People with essential tremors 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.

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

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. 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 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 control 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.

An essential tremor is not a dangerous condition, but some patients find the tremors annoying and embarrassing.

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

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.

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.

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