Essential tremor (ET) is a progressive, neurological disorder characterized by tremor, most often of the hands or arms. A tremor is an involuntary, rhythmic, movement of a body part. Tremor may be seen as involuntary shaking or trembling of the affected area. In individuals with ET, other motor symptoms may be present including an unsteady manner of walking due to an inability to coordinate voluntary movements (ataxia). In some cases, affected individuals may also develop a variety of non-motor symptoms including cognitive impairment or personality changes. ET can occur in childhood or adulthood. The exact, underlying cause of ET is not fully understood. In some cases, the disorder runs in families; in others, it occurs in individuals with no previous family history. The cause of ET is most likely multifactorial, which means that several factors, such as genetic and environmental ones, all play a role in the development of the disorder.
Traditionally, ET was viewed as a relatively benign disorder characterized by one symptom, tremor. However, ET can be associated with a variety of psychosocial issues and it can potentially significantly disrupt daily activities and social interactions. Consequently, the term benign was dropped from the name. In addition, researchers have determined that additional non-motor symptoms can be associated with the disorder. Some researchers now believe that essential tremor may actually represent a group of similar, yet distinct, disorders sharing the common trait of kinetic tremor.

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.

About half of essential tremor cases appear to result from altered DNA. This form is referred to as familial tremor. It isn't clear what causes essential tremor in people who don't have familial tremor.

Some people with essential tremor don't require treatment if their symptoms are mild. But if your essential tremor is making it difficult to work or perform daily activities, discuss treatment options with your doctor.

Medications

• Beta blockers. Typically used to treat high blood pressure, beta blockers such as propranolol (Inderal, InnoPran XL, Hemangeol) help relieve tremors in some people. Beta blockers may not be an option if you have asthma or certain heart problems. Side effects may include fatigue, lightheadedness or heart problems.
• Anti-seizure medications. Epilepsy drugs, such as primidone (Mysoline), may be effective in people who don't respond to beta blockers. Other medications that might be prescribed include gabapentin (Gralise, Neurontin, Horizant) and topiramate (Topamax, Qudexy XR, others). Side effects include drowsiness and nausea, which usually disappear within a short time.
• Tranquilizers. Doctors may use benzodiazepine drugs such as clonazepam (Klonopin) to treat people for whom tension or anxiety worsens tremors. Side effects can include fatigue or mild sedation. These medications should be used with caution because they can be habit-forming.

• OnabotulinumtoxinA (Botox) injections. Botox injections might be useful in treating some types of tremors, especially head and voice tremors. Botox injections can improve tremors for up to three months at a time.

  However, if Botox is used to treat hand tremors, it can cause weakness in the fingers. If Botox is used to treat voice tremors, it can cause a hoarse voice and difficulty swallowing.

Therapy

Doctors might suggest physical or occupational therapy. Physical therapists can teach you exercises to improve your muscle strength, control and coordination.

Occupational therapists can help you adapt to living with essential tremor. Therapists might suggest adaptive devices to reduce the effect of tremors on your daily activities, including:

• Heavier glasses and utensils
• Wrist weights
• Wider, heavier writing tools, such as wide-grip pens

Nerve stimulation devices

A wearable electronic peripheral nerve stimulation device (Cala Trio) is a newer treatment option for people with essential tremor. The device, which can be worn as a wristband for 40 minutes twice a day, works by stimulating peripheral nerves and muscles to create a muscle response that reduces tremors. Studies have found that the device can bring some improvement for tremors.

Autosomal dominant inheritance pattern Open pop-up dialog box Close Autosomal dominant inheritance pattern Autosomal dominant inheritance pattern

In an autosomal dominant disorder, the altered gene is a dominant gene located on one of the nonsex chromosomes (autosomes). You need only one altered gene to be affected by this type of disorder. A person with an autosomal dominant disorder — in this case, the father — has a 50% chance of having an affected child with one altered gene (dominant gene) and a 50% chance of having an unaffected child with two typical genes (recessive genes).

Known risk factors for essential tremor include:

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

  If you have a parent with an altered gene for essential tremor, you have a 50% chance of developing the disorder yourself.

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