Essential Tremor
Essential tremor is one of the most common movement disorders in adults and can affect both children and adults.
Updated UKMLA guide to essential tremor, which covers: causes, risk factors, symptoms, diagnosis, and management.
Causes and Risk Factors
The exact underlying cause and pathophysiology remain unclear. Instead of a single disease entity, it is defined as a syndrome with heterogeneous causes. [Ref]
Risk factors: [Ref]
- Strong family history (~50% of patients have a +ve family history)
- Bimodal age of onset
- Early onset group: <24 y/o
- Older onset group: >46 y/o
- Males
- Conversely, females are at higher risk for developing specific tremor locations (e.g. head and vocal tremor)
- Parkinson’s disease (5-10x risk)
Clinical Features
Clinical features by body part: [Ref]
| Body part | Presentation |
|---|---|
| Limb tremor | Upper limbs are primarily affected
Upper limb tremor often improves with:
Lower limbs may also be affected, where they develop kinetic or intention tremor in the legs |
| Hand and neck tremor | More common in older patients and females
Typically manifests as
Head tremors often subside upon lying supine |
| Vocal tremor | More common in females, often starting in their 70s
|
Patients may also experience non-motor symptoms [Ref]
- Balance and gait impairment
- High-frequency sensorineural hearing loss
- Eye movements affected
- Cognitive impairment (esp. affecting attention, working memory, executive function)
- Psychiatric comorbidities (e.g. depression, anxiety, fatigue, sleep disturbances)
Investigation and Diagnosis
Essential tremor is primarily a clinical diagnosis [Ref]
- No single test can be used to confirm the disease
- All patients should be tested for thyroid function to exclude thyrotoxicosis
- Imaging (e.g. MRI and DaTscan) can be useful to exclude differential diagnoses (e.g. Parkinson’s disease, and those with other neurological symptoms)
Diagnostic criteria: [Ref]
- Bilateral action tremor (or tremor in other location – see above) for at least 3 years, AND
- NO other neurological signs (e.g. parkinsonism, dystonia, ataxia)
If an isolated tremor has been present for <3 years, this is termed isolated tremor
Differential Diagnosis
High-yield tremor differential:
| Condition / cause of tremor | Clinical clues |
|---|---|
| Essential tremor |
|
| Parkinson’s disease |
Presence of other features like bradykinesia, cogwheel rigidity Parkinson’s disease and essential tremor can co-exist |
| Thyrotoxicosis |
Presence of other features like sweating, anxiety, palpitations |
| Medication-induced tremor (e.g. beta-2 agonist) |
Tremor is worse right after the dose + other signs of sympathetic activity (e.g. tachycardia, palpitations, headache) |
Management
Reassure patients
- Remind the patient that it is common and rare to become disabling
- Strategic alcohol consumption (small amount) maybe consisdered (e.g. having an alcoholic beverage prior to a social situation)
- Use of weighted device (e.g. pen, mouse) to reduce amplitude of the tremor
- Clarify that essential tremor is different from Parkinson’s disease (if excluded)
If symptoms are troublesome, consider pharmacological management:
- 1st line oral medications:
- Propranolol modified release, or
- Primidone (few patients tolerate it due to sedation)
- 2nd line options:
- Topiramate
- Gabapentin
- Clonazepam
Interventional therapies include (under specialist guidance): [Ref]
- Botulinum toxin injection
- DBS – typically targeting the ventral intermediate nucleus of the thalamus
- MRI-guided high intensity focused ultrasound