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ValtteriKaasinen

Essential Tremor

Symmetrical tremor of upper extremities or of the head, accentuated by movement and in raised arms. Psychological stress also intensifies tremor.
Often familial
Diagnosis is based on physical examination and patient history.
Important to differentiate from Parkinson's disease and from other diseases causing tremor on the basis of the clinical picture
Beta-blockers, either as needed or continuously, are the most common treatment.

Essential tremor is more common than tremor caused by Parkinson's disease Parkinson's Disease, with a general prevalence of approx. 0.5-1% and in people over 65 years of age 5-6%.
Strongly hereditary, but the detection of genetic defects causing the disease has turned out to be difficult. Several genetic defects increasing the risk have been reported.
The pattern of inheritance is probably autosomal dominant, i.e., about half of the children may inherit the susceptibility for tremor. The patient's first-degree relatives' risk of developing the condition is 4-5-fold compared to the general population.

Tremor is manifested during muscle activation (action tremor) and is rarely present at rest.
It is most intense in a static sustentained position, e.g. in extended arms.
Tremor usually occurs in both arms quite symmetrically.
Tremor may also be seen in the trunk, in the voice and in the head where it is often expressed as turning from side to side ("no-no"-movement; not Parkinson's disease).
Psychological stress intensifies tremor which is worst in social situations, e.g. when holding a cup of tea or coffee.
Tremor is intensified when skilled acts should be performed (e.g. signature) and is often relieved by ingestion of small amounts of alcohol.
Tremor can be quite incapacitating.

There are no symptoms typical to Parkinson's disease, such as
- hypokinesia
- rigidity.
In essential tremor
- the patient's face is expressive
- speed of movements is normal
- muscular tone is normal
- gait is typically normal or slightly atactic.
It may be more difficult to differentiate essential tremor clinically from enhanced physiological tremor Tremor.
Differential diagnosis as regards ataxia Ataxia and dystonic tremor should be taken into account.
- In head tremor, differential diagnosis from cervical dystonia (see Involuntary Movements) may be difficult.
- Risk of Parkinson's disease is slightly higher in these persons, and sometimes both types of tremor are concomitant.
Remember the possibility of hyperthyroidism as the underlying cause of tremor (TSH, free T4).

The treatment is symptomatic.
Non-pharmacological treatments
- Reduction of coffee consumption (ample consumption of coffee worsens tremor)
- Adaptation of practices, as applicable, related to home, hobbies and work.
Disturbing symptoms may be reduced by pharmacotherapy
- Medications can be used as needed, but in the most severe cases continuous use is often required.
- Non-selective beta-blockers
  - Propranolol 20-80 mg × 2-3 Beta-Blockers for Essential Tremor; or as a depot preparation (may require special license)
  - In selected cases
    - Primidone: initial dose 30 mg (1/8 of a 250 mg tablet), may be increased up to 500 mg per day, taken usually in the evening (may require special license)
    - Benzodiazepines, such as alprazolam
  - Combination of propranolol and primidone
  - In the absence of treatment response or in the case of adverse effects, gabapentin or topiramate may be used as alternativesTopiramate for Essential Tremor.
  - As reserve drugs (less researched): clonazepam, alprazolam (caution: avoid long-term use!), sotalol, atenolol
Botulinum injections are used in some cases (tremor of the head and voice).
- The decision should be made after careful assessment within specialized care.
Neurosurgery (thalamic deep brain stimulation [DBS] or thalamotomy) may be considered in drug-resistant and incapacitating cases.
- Thalamic stimulator may be inserted bilaterally.
- Assessment in specialized clinics.

Sepúlveda Soto MC, Fasano A. Essential tremor: New advances. Clin Park Relat Disord 2020;3:100031. [PubMed]