A tremor is a type of involuntary shaking movement. Involuntary means you shake without trying to do so. A tremor is often most noticeable in your hands, but may affect any body part (even your head or voice).

There are three main types of tremors:

• Resting or static tremors occur when your hand or affected body part is at rest.
• Kinetic and intention tremors occur when you are moving your hand or affected body part, and disappear at rest.
• Postural tremors occur when you are holding your hand or affected body part in a particular position for a period of time.

Tremors can happen at any age but tend to be more common in older people.

You can develop a tremor from fatigue, stress, anxiety, or even rage. However, an ongoing tremor that is not associated with a change in your emotional state may be a sign of an underlying medical condition and should be evaluated. You may learn, as many do, that your tremors are perfectly normal, but eliminating medical reasons for the shaking is important.

It is especially important to have tremors evaluated if body parts other than the hands are involved, like your tongue or head, or if you have other types of involuntary movements other than shaking.

Essential tremor is common in older people. Essential tremor is rarely present when the hands are not being used. It becomes most apparent when the affected person is trying to do something, like reaching for an object or writing. It is not caused by an underlying disease.

Another common type of tremor is called familial tremor which, as the name implies, tend to run in families.

Both essential and familial tremors may be suppressed by drinking alcohol. This is a useful fact for making the diagnosis, but alcohol is not a desirable treatment.

Tremors may be caused by:

• Too much coffee or other caffeinated drink
• Excessive alcohol consumption, alcoholism, or alcohol withdrawal
• Stress, anxiety, or fatigue -- these can cause a postural tremor
• Normal aging
• A variety of drugs and prescription medicines
• Low blood sugar
• Parkinson's disease -- this is the classic cause of a resting tremor and is often accompanied by slowness of movement, muscle rigidity, and an abnormal gait
• Multiple sclerosis -- can cause an intention tremor
• Over active thyroid -- can cause a postural tremor

For tremors caused by stress, try relaxation techniques like meditation, deep relaxation, or breathing exercises. For tremors of any cause, avoid caffeine and get enough sleep.

For tremors caused by a medication, consult with your doctor about stopping the drug, reducing the dosage, or switching medications. DO NOT change or stop medications on your own.

For tremors caused by alcohol abuse, seek treatment and support to help you avoid alcohol.

Severe tremors may interfere with your ability to perform daily activities. Assistance with these activities may be necessary. Precautions should be taken to avoid injury during activities such as walking or eating.

Call your doctor if:

• Your tremor is worse at rest and gets better with movement, like when you reach for something.
• Your tremor is prolonged, severe, or interfere with your life.
• Your tremor occurs with other symptoms, like headache, weakness, abnormal tongue motion, or other types of involuntary movements.

Your doctor will perform a physical examination, including a detailed neurologic examination. The following medical history questions may help your doctor evaluate the cause of your tremors:

• Is your tremor regular or irregular?
• Does it occur with activity, at rest, or when you have been holding your hand (or other body part) in a particular position for a long time?
• Are the movements small (fine) or large (coarse)?
• Are both hands affected? To the same degree on both sides?
• Are other body parts affected, including your voice or head?
• Does the tremor impair your ability to use your hands or other body parts?
• Does emotional stress or excitement make it worse?
• Does drinking an alcoholic beverage make the tremor better or worse?
• Do you have any other symptoms?

• Blood tests such as CBC, blood differential, thyroid function tests, and glucose test
• Urine tests
• Head CT scan
• MRI of the head
• EMG or nerve conduction studies

Once a cause of the tremor has been determined, the appropriate treatment for the disease will be prescribed.

For certain types of tremors, like essential tremor and familial tremor, medications such as beta-blockers, gabapentin, primidone, and others may be an option. If medication doesn't work, your doctor may even consider surgery. Botox injections, given in the hand, have been used to treat essential hand tremors.

Fahn S. Hypokinesia and Hyperkinesia. In: Goetz, CG. Textbook of Clinical Neurology. 3rd ed. St. Louis, Mo: WB Saunders; 2007: chap 16.