Essential tremor is a nervous system (neurological) disorder that causes involuntary and rhythmic shaking. It can affect almost any part of your body, but the trembling occurs most often in your hands — especially when you do 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.

 

Essential tremor signs and symptoms:

• Begin gradually, usually more prominently 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

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 you use your hands. Tremors from Parkinson's disease are most prominent when your hands are at your sides or resting in your 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 your hands, head and voice. Parkinson's disease tremors usually start in your hands, and can affect your legs, chin and other parts of your body.

 

There are no medical tests to diagnose essential tremor. Diagnosing it is often a matter of ruling out other conditions that could be causing your symptoms. To do this, your health care provider may suggest the following tests:

• Neurological examination

  –In a neurological examination, your doctor tests your nervous system functioning, including checking your:
  • Tendon reflexes
  • Muscle strength and tone
  • Ability to feel certain sensations
  • Posture and coordination
  • Gait

• Laboratory tests

  –Your blood and urine may be tested for several factors, including:
  • Thyroid disease
  • Metabolic problems
  • Drug side effects
  • Levels of chemicals that may cause tremor

• Performance tests

  –To evaluate the tremor itself, your doctor may ask you to:
  • Drink from a glass
  • Hold your arms outstretched
  • Write
  • Draw a spiral

If the preceding tests leave uncertainty of whether your tremor is essential tremor or Parkinson's disease, a dopamine transporter scan can help differentiate between the two types of tremor.