Essential tremor

Overview

Essential tremor is a nervous system condition, also known as a neurological condition, that causes involuntary and rhythmic shaking. It can affect almost any part of the body, but the trembling occurs most often in the hands, especially when doing simple tasks, such as drinking from a glass or tying shoelaces.

Essential tremor is usually not a dangerous condition, but it typically worsens over time and can be severe in some people. Other conditions don't cause essential tremor, although essential tremor is sometimes confused with Parkinson's disease.

Essential tremor can occur at any age but is most common in people age 40 and older.

Symptoms

Essential tremor symptoms:

• Begin gradually, and usually are more noticeable on one side of the body.
• Worsen with movement.
• Usually occur in the hands first, affecting one hand or both hands.
• Can include a "yes-yes" or "no-no" motion of the head.
• May be aggravated by emotional stress, fatigue, caffeine or temperature extremes.

Essential tremor vs. Parkinson's disease

Many people associate tremors with Parkinson's disease, but the two conditions differ in key ways:

• Timing of tremors. Essential tremor of the hands usually occurs when using the hands. Tremors from Parkinson's disease are most noticeable when the hands are at the sides of the body or resting in the lap.
• Associated conditions. Essential tremor doesn't cause other health problems, but Parkinson's disease is associated with stooped posture, slow movement and dragging the feet when walking. However, people with essential tremor sometimes develop other neurological signs and symptoms, such as an unsteady walk.
• Parts of the body affected. Essential tremor mainly involves the hands, head and voice. Parkinson's disease tremors usually start in the hands, and can affect the legs, chin and other parts of the body.

Causes

About half the people with essential tremor appear to have an altered gene. This form is referred to as familial tremor. It isn't clear what causes essential tremor in people who don't have familial tremor.

Risk factors

Autosomal dominant inheritance pattern Enlarge image

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Autosomal dominant inheritance pattern

Autosomal dominant inheritance pattern

In an autosomal dominant disorder, the changed gene is a dominant gene. It's located on one of the nonsex chromosomes, called autosomes. Only one changed gene is needed for someone to be affected by this type of condition. A person with an autosomal dominant condition — in this example, the father — has a 50% chance of having an affected child with one changed gene and a 50% chance of having an unaffected child.

Known risk factors for essential tremor include:

• Altered gene. The inherited variety of essential tremor, known as familial tremor, is an autosomal dominant disorder. An altered gene from just one parent is needed to pass on the condition.

  Anyone who has a parent with an altered gene for essential tremor has a 50% chance of developing the condition.

• Age. Essential tremor is more common in people age 40 and older.

Complications

Essential tremor isn't life-threatening, but symptoms often worsen over time. If the tremors become severe, it might be difficult to:

• Hold a cup or glass without spilling.
• Eat without shaking.
• Put on makeup or shave.
• Talk, if the voice box or tongue is affected.
• Write legibly.