Essential Tremor

Essential tremor is one of the most common movement disorders, characterized by involuntary, rhythmic shaking that typically affects the hands but can also involve the head, voice, and other body parts. While often confused with Parkinson's disease, essential tremor is a distinct neurological condition that can significantly impact daily activities and quality of life.

Medical Disclaimer: This information is for educational purposes only and should not replace professional medical advice. Always consult with a qualified healthcare provider for diagnosis and treatment of medical conditions.

Overview

Essential tremor (ET) is a neurological disorder that causes involuntary and rhythmic shaking. It is the most common form of tremor and one of the most prevalent movement disorders, affecting approximately 1% of the general population and up to 5% of people over age 65. Despite its prevalence, essential tremor remains poorly understood and is often misdiagnosed or undertreated.

The tremor typically begins gradually and worsens over time. It most commonly affects the hands and arms but can also involve the head (causing a "yes-yes" or "no-no" motion), voice (leading to a shaky sound), trunk, and rarely, the legs and feet. Unlike the resting tremor seen in Parkinson's disease, essential tremor typically occurs during voluntary movement, such as when reaching for an object or holding a position against gravity.

While essential tremor is sometimes called "benign essential tremor," this term is increasingly considered inappropriate because the condition can cause substantial disability. Many people with essential tremor experience difficulty with daily activities such as eating, drinking, writing, or performing their job duties. The psychological impact can also be significant, with many individuals experiencing embarrassment and social isolation due to their visible symptoms.

Symptoms

Essential tremor symptoms can vary significantly between individuals in terms of severity, body parts affected, and progression over time. The hallmark feature is a rhythmic shaking that occurs during voluntary movement or when maintaining a position against gravity.

Primary Symptoms

  • Abnormal involuntary movements - rhythmic shaking, typically 4-12 Hz frequency
  • Hand tremor - often bilateral, affecting both hands, worse with action
  • Head tremor - nodding "yes-yes" or shaking "no-no" movements
  • Hoarse voice or voice tremor - quavering quality when speaking
  • Problems with movement - difficulty with fine motor tasks

Associated Symptoms

Characteristic Features

Essential tremor has several distinguishing characteristics:

  • Action tremor: Worsens with voluntary movement
  • Postural tremor: Occurs when holding a position against gravity
  • Bilateral involvement: Usually affects both sides of the body
  • Alcohol responsiveness: Often temporarily improves with small amounts of alcohol
  • Stress sensitivity: Worsens with stress, fatigue, or caffeine

Causes

The exact cause of essential tremor remains unknown, but research suggests it involves abnormal electrical brain activity that originates in the thalamus, cerebellum, and other motor control regions. Multiple factors likely contribute to the development of this complex neurological disorder.

Genetic Factors

Essential tremor has a strong genetic component, with approximately 50-70% of cases showing a familial pattern. When inherited, it follows an autosomal dominant pattern, meaning a child has a 50% chance of developing the condition if one parent is affected. Several genetic loci have been identified, though no single gene accounts for all cases. The variability in genetic expression explains why symptoms can differ significantly even within the same family.

Neurological Mechanisms

Research indicates that essential tremor involves dysfunction in the cerebello-thalamo-cortical circuits that control movement. Abnormalities have been found in:

  • Cerebellar Purkinje cells - showing degenerative changes
  • Olivocerebellar pathways - exhibiting abnormal oscillatory activity
  • GABAergic dysfunction - reduced inhibitory neurotransmission
  • Increased cerebellar blood flow during tremor episodes

Environmental Triggers

While genetics play a major role, environmental factors may trigger or worsen symptoms:

  • Certain medications (lithium, valproate, some antidepressants)
  • Metabolic conditions (hyperthyroidism, hypoglycemia)
  • Heavy metal exposure (lead, mercury)
  • Excessive caffeine consumption
  • Physical or emotional stress

Risk Factors

Several factors increase the likelihood of developing essential tremor:

Age

Essential tremor can begin at any age but shows two peak periods of onset:

  • Late adolescence to early 20s
  • Late 50s to early 60s
  • Prevalence increases with age, affecting up to 20% of people over 80

Family History

  • Having a parent with essential tremor gives a 50% chance of inheritance
  • Earlier onset often seen in familial cases
  • Multiple affected family members increase risk

Other Risk Factors

  • Gender: Slightly more common in males
  • Ethnicity: Higher prevalence in Caucasian populations
  • Certain medications: Some drugs can unmask or worsen tremor
  • Stress and anxiety: Can trigger or exacerbate symptoms

Diagnosis

Diagnosing essential tremor is primarily clinical, based on medical history and physical examination. There is no specific test for essential tremor, so diagnosis involves ruling out other causes of tremor and identifying characteristic features of the condition.

Clinical Evaluation

The diagnostic process typically includes:

  • Detailed tremor history: Onset, progression, triggering factors, family history
  • Physical examination: Assessment of tremor characteristics during rest, posture, and action
  • Neurological examination: Testing reflexes, muscle tone, gait, and coordination
  • Functional assessment: Evaluating impact on daily activities (writing, drinking, eating)

Diagnostic Criteria

Essential tremor diagnosis requires:

  • Bilateral action tremor of hands and forearms (may include head tremor)
  • Absence of other neurological signs (except mild cogwheel phenomenon)
  • Duration of at least 3 years
  • May have positive family history

Differential Diagnosis

Conditions to rule out include:

  • Parkinson's disease - resting tremor, bradykinesia, rigidity
  • Hyperthyroidism - check thyroid function tests
  • Medication-induced tremor - review drug history
  • Cerebellar tremor - intention tremor, ataxia
  • Psychogenic tremor - variable frequency, distractibility

Diagnostic Tests

While no test confirms essential tremor, the following may help exclude other conditions:

  • Blood tests: Thyroid function, liver function, copper levels
  • EMG (Electromyography): Can characterize tremor frequency and pattern
  • Brain imaging: MRI or DaTscan to rule out other conditions
  • Accelerometry: Objective measurement of tremor characteristics

Treatment Options

Treatment for essential tremor is individualized based on symptom severity, functional impairment, and patient preferences. While there is no cure, various treatments can significantly reduce tremor amplitude and improve quality of life. Treatment typically begins when tremor interferes with daily activities or causes social embarrassment.

Medications

First-line Medications

  • Propranolol (Beta-blocker):
    • Reduces tremor amplitude by 50-70% in responsive patients
    • Typical dose: 60-320 mg daily
    • Contraindicated in asthma, heart block
  • Primidone (Anti-seizure):
    • Effective in 50-70% of patients
    • Start low (25 mg) and titrate slowly
    • Common side effects: sedation, nausea initially

Second-line Medications

  • Topiramate: Anti-seizure medication, moderate efficacy
  • Gabapentin: May help with associated anxiety
  • Alprazolam: For situational use, risk of dependence
  • Botulinum toxin: Injections for head or voice tremor

Surgical Options

Deep Brain Stimulation (DBS)

  • Most effective treatment for severe, medication-resistant tremor
  • Electrodes placed in ventral intermediate nucleus of thalamus
  • Can reduce tremor by 80-90%
  • Reversible and adjustable

Focused Ultrasound Thalamotomy

  • Non-invasive procedure using MRI-guided ultrasound
  • Creates lesion in thalamus without surgery
  • Typically done unilaterally
  • Immediate tremor reduction in treated limb

Lifestyle Modifications

  • Adaptive devices: Weighted utensils, button hooks, card holders
  • Occupational therapy: Techniques for daily activities
  • Stress management: Relaxation techniques, meditation
  • Avoid triggers: Limit caffeine, manage fatigue
  • Physical therapy: Improve coordination and strength

Prevention

Since essential tremor has a strong genetic component and unknown exact causes, primary prevention is not currently possible. However, several strategies can help prevent symptom worsening and maintain quality of life.

Lifestyle Strategies

  • Stress reduction: Regular exercise, yoga, meditation
  • Sleep hygiene: Adequate rest reduces tremor severity
  • Limit stimulants: Reduce caffeine and nicotine intake
  • Moderate alcohol: While temporarily helpful, avoid dependence
  • Maintain general health: Control blood sugar, thyroid function

Early Intervention

  • Seek treatment when tremor first interferes with activities
  • Regular monitoring for progression
  • Genetic counseling for families with strong history
  • Avoid medications known to worsen tremor when possible

When to See a Doctor

Schedule an appointment if you experience:

  • New onset of tremor at any age
  • Worsening tremor that interferes with daily activities
  • Tremor affecting work performance or social interactions
  • Difficulty with eating, drinking, or writing due to tremor
  • Voice changes or head shaking

Seek immediate medical attention if tremor is accompanied by:

  • Sudden onset of severe tremor
  • One-sided tremor with weakness or numbness
  • Confusion, speech problems, or vision changes
  • Loss of consciousness or seizures
  • Severe dizziness or balance problems

Consider neurologist referral for:

  • Uncertain diagnosis
  • Poor response to initial treatments
  • Consideration of advanced therapies (DBS, focused ultrasound)
  • Significant functional impairment

Related Conditions

References

  1. Bhatia KP, Bain P, Bajaj N, et al. Consensus Statement on the classification of tremors from the task force on tremor of the International Parkinson and Movement Disorder Society. Mov Disord. 2018;33(1):75-87.
  2. Haubenberger D, Hallett M. Essential Tremor. N Engl J Med. 2018;378(19):1802-1810.
  3. Shanker V. Essential tremor: diagnosis and management. BMJ. 2019;366:l4485.
  4. Elias WJ, Lipsman N, Ondo WG, et al. A Randomized Trial of Focused Ultrasound Thalamotomy for Essential Tremor. N Engl J Med. 2016;375(8):730-739.
  5. International Essential Tremor Foundation. Essential Tremor: The Facts. 2023. Available at: www.essentialtremor.org
  6. Louis ED, Ferreira JJ. How common is the most common adult movement disorder? Update on the worldwide prevalence of essential tremor. Mov Disord. 2010;25(5):534-541.