Familial tremor is an involuntary shaking movement that tends to run in families. Involuntary means you shake without trying to do so.

See also:

• Drug-induced tremor
• Essential tremor
• Hand tremor
• Tremor

Tremors occur when there is a problem with the nerves supplying certain muscles. They may affect the whole body or just certain areas, such as your hand.

Familial tremor is a lot like essential tremor, except that the shaking affects more than one person in a family. The exact cause of familial tremor is unknown, but the fact that it is passed down through families (inherited) suggests that genes play a role. Familiar tremor is usually a dominant trait, which means that you only need to get the gene from one parent to develop the disorder.

The tremors usually start in early middle age, but may be seen in people who are older or younger.

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 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
• Disappear during sleep
• 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.

A familial tremor is not a dangerous condition, but some patients find the shaking annoying and embarrassing.

Severe tremors 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.

Call for an appointment with your health care provider if tremors occur and you have a family history of the condition. Also call if the tremors interfere 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, or prolonged nausea and vomiting.

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