There is overlap between essential tremor, which may occur as an isolated case but may also run in families, and familial tremor, which affects more than one person in a family. Tremors can affect people at any age, but they are most common in older people.

A familial tremor is usually a relatively benign condition, affecting movement or voice quality but seldom having any other effects. It involves a rhythmic, moderately rapid tremor (shaking) of voluntary muscles.

Purposeful movements may make the tremors worse. There may be difficulty holding or using small objects (such as eating or writing utensils). Emotional stress may also increase the tremors.

Over time, the tremors may affect the hands, arms, head, voice box (larynx), eyelids, or other muscles, but they rarely involve the legs or feet. In children, these tremors are usually limited to the hands and rarely require treatment.

The exact cause is unknown, but the fact that it is inherited suggests a genetic cause. It is usually dominant, which means about 50% of an affected person's children will be affected.

If you inherit one copy of the gene from either parent, you will have the disorder.

• Tremors
  • Occasional (sporadic), temporary (episodic), or ceasing at intervals (intermittent)
  • A rate of about 6 to 10 per second (when tremors are occurring)
  • Affecting the head, hands, arms, eyelids or voice
  • Less commonly affect the lower body
  • May not affect both sides of the body equally
• Tremors that worsen with voluntary movement and emotional stress
• Tremors that disappear during sleep
• Tremors that may improve with alcohol

Call your health care provider if tremors occur and there is a family history of tremors or if a familial tremor is interfering with ability to perform daily activities.

Call your health care provider if side effects of medications occur, such as fainting, very slow heart rate, confusion or changes in alertness, or prolonged nausea/vomiting.