Essential Tremor (ET)

What is Essential Tremor(ET)

Essential tremor is a tremor without a known cause.

A tremor is trembling or shaking that you cannot control. Most tremors affect the hands or arms. Tremors can also affect the head, vocal cords, face, and other parts of the body.

Essential tremor is a neurologic disease characterized by action tremor of the hands in the absence of any identifiable causes, such as drugs or toxins.

Other types of tremors, such as isolated head and voice tremors, are also expressions of ET.

It is estimated that ET affects at least 5 million Americans.

Characterized by action-postural tremor of the hands and arms, ET may be asymmetric at onset and have a kinetic component.

Patients with severe forms of ET may display tremor at rest.

ET is presumably transmitted by an autosomal dominant gene with variable expression.

A tremor is an oscillatory movement of a body part. Essential tremor is a predominantly postural and action tremor that is bilateral and tends to progress slowly over the years in the absence of other neurologic abnormalities.

Synonyms

• Benign essential tremor
• Familial tremor

How common is Essential Tremor?

Essential tremor is one of the most prevalent neurologic diseases. It affects nearly 7 million persons in the U.S. It is the most common movement disorder.

Can begin at any age, but incidence increases after age 40 yr. Prevalence is 6% to 9% for those >60 yr of age.

Positive family history is found in 50% of patients. No gender or racial predominance.

What are the causes?

Essential tremor has no known cause.

Often an inherited disease in an autosomal dominant pattern. Sporadic cases without a family history can occur.

What increases the risk?

You may be at greater risk of essential tremor if:

• You have a family member with essential tremor.
• You are age 40 or older.
• You take certain medicines.

What are the symptoms of Essential tremor?

The main sign of a tremor is uncontrolled and unintentional rhythmic shaking of a body part.

• You may have difficulty eating with a spoon or fork.
• You may have difficulty writing.
• You may nod your head up and down or side to side.
• You may have a quivering voice.

Your tremors:

• May get worse over time.
• May come and go.
• May be more noticeable on one side of your body.
• May get worse due to stress, fatigue, caffeine, and extreme heat or cold.

Physical Findings & Clinical Presentation

•Essential tremor is characterized by a bilateral action tremor of 6 to 12 Hz that tends to be more prominent one side of the body than the other. In approximately 50% of patients, the tremor also worsens with intention, specifically at the termination of a goal-directed movement. This can be seen at the very end of the finger-to-nose maneuver or while drinking from a glass. The tremor can be found in the upper extremities (90%-95%), head (30%), legs (10%-15%), or voice (20%), and is usually absent when the affected body part is at rest.

•In addition to the action tremor, a postural tremor may be seen when the patient holds the body part against gravity. The postural tremor is usually most noticeable at the wrist and is usually of lower amplitude than the action tremor.

•Patients with essential tremor may also have gait ataxia on tandem walk and may report a history of increased falls or near falls.

•No other neurologic abnormalities are found on examination.

•Symptoms worsen with emotional distress, fatigue, or the use of caffeine or other stimulants and improve with intake of small amounts of alcohol.

How is Essential tremor diagnosed?

Your health care provider can diagnose essential tremor based on your symptoms, medical history, and a physical examination. There is no single test to diagnose an essential tremor. However, your health care provider may perform a variety of tests to rule out other conditions. Tests may include:

• Blood and urine tests.
• Imaging studies of your brain, such as:
  • CT scan.
  • MRI.
• A test that measures involuntary muscle movement (electromyogram).

Essential tremor is a clinical diagnosis. Review of medications is essential.

•All imaging studies (MRI, CT) are unnecessary unless other neurologic abnormalities are present.

•Obtain TSH to rule out hyperthyroidism and ionized calcium to rule out calcium abnormalities.

•In patients younger than 40 yr old with other neurologic abnormalities, send ceruloplasmin, serum copper, and 24-hr urine copper to evaluate for Wilson disease.

How is Essential tremor treated?

Your tremors may go away without treatment. Mild tremors may not need treatment if they do not affect your day-to-day life. Severe tremors may need to be treated using one or a combination of the following options:

• Medicines. This may include medicine that is injected.
• Lifestyle changes.
• Physical therapy.

Follow these instructions at home:

• Take medicines only as directed by your health care provider.
• Limit alcohol intake to no more than 1 drink per day for nonpregnant women and 2 drinks per day for men. One drink equals 12 oz of beer, 5 oz of wine, or 1½ oz of hard liquor.
• Do not use any tobacco products, including cigarettes, chewing tobacco, or electronic cigarettes. If you need help quitting, ask your health care provider.
• Take medicines only as directed by your health care provider.
• Avoid extreme heat or cold.
• Limit the amount of caffeine you consume as directed by your health care provider.
• Try to get eight hours of sleep each night.
• Find ways to manage your stress, such as meditation or yoga.
• Keep all follow-up visits as directed by your health care provider. This is important. This includes any physical therapy visits.

Treat essential tremor when it is functionally impairing. Treatments are up to 75% effective.

Nonpharmacologic Therapy

• •Stress management.
• •Minimization of caffeine use if consumption is correlated with worsened symptoms.
• •Wrist weights and use of weighted utensils may be helpful in reducing tremor amplitude during feeding.
• •Consumption of small quantities of alcohol at social functions, although the symptom relief may be short in duration and may be followed by tremor rebound.
• •A recent trial using MRI-guided focus ultrasound thalamotomy found it effective in reducing hand tremor in patients with essential tremor. Side effects included sensory and gait disturbances.

Acute General Rx

Propranolol (20-40 mg) may be used in preparation for specific event.

Chronic Rx

First-line agents:

• •Propranolol: Typical starting dose of 40 mg BID titrating to 60 mg BID.
• •Propranolol LA: Typical starting dose is 30 mg/day. The usual therapeutic dose is 160 mg/day. Although not contraindicated, this medication must be used with caution in those with asthma, depression, cardiac disease, and diabetes. Atenolol or sotalol are also effective.
• •Primidone: Typical starting dose is 12.5 to 25 mg qhs. Increase by 12.5 to 25 mg/day every week. Usual therapeutic dose is between 62.5 and 750 mg daily (assuming side effects are tolerated). Sedation and nausea are common at treatment initiation.
• •Topiramate: 25 mg qhs, may titrate up to by 25 mg per week in BID dosing to maximum of 400 mg (200 mg BID).

Other (second-line) agents:

• •Gabapentin: Typical starting dose is 300 mg tid. Usual therapeutic dose is 1200 to 3600 mg daily in three divided doses
• •Benzodiazepines (i.e., alprazolam): 0.125 to 3 mg daily in divided doses
• •Focal botulinum toxin injections

Surgical Rx

Thalamic deep brain stimulation (or possibly thalamotomy) contralateral to side of tremor isreserved for resistant tremor or for patients who do not tolerate drug therapy. Surgical ablation of the neutral intermediate nucleus or the thalamus with use of magnetic resonance-guided focused ultrasound was recently FDA approved.

Disposition

Patients should be reassured that the condition is not associated with other neurologic disabilities; however, it can become quite functionally disabling over time.

Referral

This is a condition that usually can be treated by the primary care physician; however, if patient fails first-line therapies, the patient should be referred to a neurologist for other drug trials and discussion of possible surgical options.

 Pearls & Considerations

• •Essential tremor is the most common of all movement disorders. It is characterized by an action tremor that increases at the end of goal-directed movement.
• •In addition to motor dysfunction, essential tremor can cause significant psychological impact on patients in social situations.

Contact a health care provider if:

• You experience any changes in the location or intensity of your tremors.
• You start having a tremor after starting a new medicine.
• You have tremor with other symptoms such as:
  • Numbness.
  • Tingling.
  • Pain.
  • Weakness.
• Your tremor gets worse.
• Your tremor interferes with your daily life.

Differential Diagnosis

• •Parkinson disease: The tremor is usually asymmetric, especially early on in the disease, and is predominantly a resting tremor. Patients with Parkinson disease will also have increased tone, decreased facial expression, slowness of movement, and shuffling gait.
• •Cerebellar tremor: This is an intention tremor that increases steadily right before arriving at the target during a goal-directed movement (such as finger to nose testing). Other associated neurologic abnormalities include ataxia, dysarthria, dysmetria, wide-based gait, and difficulty with tandem gait.
• •Drug-induced: Many drugs enhance normal, physiologic tremor. These include caffeine, nicotine, lithium, levothyroxine, β-adrenergic bronchodilators, amiodarone, valproate, and SSRIs.
• •Wilson disease: This is often characterized by a wing-beating tremor that is most pronounced with shoulders abducted, elbows flexed, and fingers pointing toward each other. Usually there are other neurologic abnormalities including dysarthria, dystonia, and Kayser-Fleischer rings on ophthalmologic examination.
• •Physiologic tremor.

Overlapping Features of Various Types of Tremor

From Remmel KS et al: Handbook of symptom-oriented neurology, ed 3, St Louis, 2002, Mosby.

Feature	Parkinson Syndrome	Cerebellar Tremor	Essential Tremor
Present at rest	Yes	No	No
Increased tone	Yes	No	No
Decreased tone	No	Yes	No
Postural abnormality	Yes	Yes	No
Head involvement	Yes	Yes	Yes
Intentional component	No	Yes	Yes
Incoordination	No	Yes	No

References

1. Abboud H., et al.: Essential tremor: choosing the right management plan for your patient. Cleve Clin J Med 2011; 78: pp. 821.
2. Elias W.J., et al.: A randomized trial of focused ultrasound thalamotomy for essential tremor. N Engl J Med 2016; 375: pp. 730-739.
3. Elias W.S., Shah B.B.: Tremor. JAMA 2014; 311 (9): pp. 948-954.
4. Louis E.: Tremor. Continuum 2019; 25 (4): pp. 959-975.