Benign Essential Tremor
Benign essential tremor is a progressive neurological syndrome primarily presenting as bilateral action tremor of the arms and hands that significantly interferes with quality of life, functional activities, mood, and socialization, and can cause greater impairment than Parkinson's disease in activities like writing, eating, drinking, and reading. 1
Definition and Characteristics
- Essential tremor is the most common tremor disorder, characterized by involuntary, rhythmic oscillations involving alternating contractions of agonist and antagonist muscles 2
- It primarily presents as a postural and kinetic tremor with a frequency between 4 and 8 Hz, mainly affecting the upper extremities and head 3
- The condition has a prevalence in the US between 0.3% and 5.55% 1
- For diagnosis, bilateral action tremor must be present for at least 3 years, with absence of isolated head and voice tremor and absence of task- and position-dependent tremor 4
Clinical Presentation
- The tremor typically worsens with intentional movements and improves at rest 3
- Beyond tremor, essential tremor can involve disturbances in:
- Gait
- Speech
- Cognition
- Mood 4
- Alcohol consumption may temporarily alleviate symptoms in some patients 2
- The condition is chronic and progressive, often starting in adulthood 4
Differential Diagnosis
- Essential tremor must be distinguished from:
- Intentional tremor differs from essential tremor as it becomes more pronounced during goal-directed movements, has a "wing-beating" appearance, and is often accompanied by dysarthria and ataxic gait 1
Treatment Options
First-Line Pharmacological Treatment
- Propranolol (80-240 mg/day) and primidone are recommended as first-line treatments by the American Academy of Neurology 6, 1
- These medications are effective in up to 70% of patients 6
- Treatment should only be initiated when tremor symptoms interfere with function or quality of life 6, 1
Medication Considerations
- Beta-blockers should be avoided in patients with:
- Common adverse effects of beta-blockers include fatigue, depression, nausea, dizziness, insomnia, and cold extremities 6
- For patients with both essential tremor and hypertension, beta-blockers may provide dual benefits 6, 1
Second-Line Options
- Carbamazepine may be used as a second-line therapy, though it's generally not as effective as first-line treatments 6
- Gabapentin has limited evidence for moderate efficacy 6
Surgical Options for Refractory Cases
- When medications fail due to lack of efficacy at maximum doses or intolerable side effects, surgical options may be considered 6, 1
- Options include:
- Magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy - shows sustained tremor improvement of 56% at 4 years with lower complication rates (4.4%) 6, 1
- Deep brain stimulation (DBS) - has replaced traditional thalamotomy as the operation of choice for many patients, though it has higher complication rates (21.1%) 6, 7
- Radiofrequency thalamotomy - carries higher complication risks (11.8%) compared to MRgFUS 6
Non-Pharmacological Approaches
- Rhythm modification techniques can help control tremor:
- Superimposing alternative rhythms on existing tremor
- Gradually slowing movement to complete rest 6
- Using gross rather than fine movements can be helpful for activities like handwriting 6
- Avoiding cocontraction or tensing of muscles as this is unlikely to be helpful long-term 6
Prognosis
- Essential tremor was traditionally considered benign but is now recognized as a serious neurologic condition with life-altering repercussions 2
- The traditional view of essential tremor as a benign, familial, monosymptomatic disorder is being replaced by one of essential tremor as a disease or family of diseases with etiological, clinical, and pathological heterogeneity 8