Familial tremor is a neurologic disorder that tends to run in families, which results in shaking (tremor) that gets worse during movement or activity.

Tremors can affect people at any age, but they are most common in older people. Familial tremors affect more than one person in a family. The condition causes a rhythmic, moderately rapid tremor (shaking) of voluntary muscles.

Purposeful movements may make the tremors worse. People with familial tremors may have trouble holding or using small objects, such as silverware or a pen. Emotional stress may also increase the tremors.

Over time, the tremors may affect the hands, arms, head, voice box, eyelids, or other muscles. The tremors 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 passed down through families (inherited) suggests that genes play a role. Familiar tremor is usually a dominant trait, which means that about 50% of a patient's children will also have the tremors. If you inherit one copy of the gene from either parent, you will have the disorder.

See also: Essential tremor

The tremors may come and go. They typically affect the head, hands, arms, eyelids, or voice. Less commonly, a tremor may affect the lower body. Tremors may not affect both sides of the body equally.

The tremors:

• Get worse with voluntary movement and emotional stress
• Disappear during sleep
• May improve when drinking alcohol

Diagnosis is usually made on the basis of the patient's history and an examination that reveals tremors on voluntary movement with no changes in gait or coordination. There are usually no other problems or changes in mental status or brain function.

No other tests may be required. However, testing may be used to rule out other causes of tremors such as excessive caffeine intake, alcohol withdrawal, medication use, hyperthyroidism, pheochromocytoma, Wilson's disease, or other disorders. Laboratory tests and a head CT scan, MRI, x-rays, angiography, or other tests are usually normal.