Essential Tremor

Tremor is an involuntary, repetitive movement of a body part. The most common types are essential tremor, Parkinson’s disease, and enhanced physiological tremor. Essential tremor is the most common adult-onset movement disorder — an autosomal dominant disorder with variable penetrance, 2–5% prevalence. Frequency 4–12Hz; in severe cases a resting tremor can also occur.

Assessment

History:

• Pattern: occurs with attempted hand use, usually bilateral but often starts in one hand; onset is usually from age 45 in sporadic essential tremor (the more common form), or from age 25 or younger in familial essential tremor.
• Aggravating factors: caffeine, stress, fatigue, anxiety.
• Relieving factors: alcohol often helps; absent during sleep.
• Family history is common.
• Screen for causative medications/conditions (e.g. salbutamol, hyperthyroidism).
• Can progress to interfere with writing, using cups/spoons, and speech.

Examination:

• Ask the patient to demonstrate the movement, and to hold their hands out — a tremor reproduced this way is less likely Parkinson’s, more likely essential tremor (postural, not resting).
• Normal arm swing/gait (distinguishing it from Parkinson’s shuffling gait/reduced arm swing).
• Frequency 8–13Hz (slows with age); usually regular; fine amplitude; normal neurological exam otherwise.

Investigations: aim to exclude other tremor causes — baseline bloods and TSH.

Tremor-type differential

Type	Frequency	Occurrence	Associations
Rest	Low–medium (3–6Hz)	Limb supported against gravity, muscles inactive	Parkinson’s disease, drug-induced, vascular midbrain lesions; less commonly atypical parkinsonism (MSA, PSP)
Action/postural	Medium–high (4–12Hz)	Voluntary contraction / limb held against gravity	Physiological, essential tremor, thyrotoxicosis, hypoglycaemia, Cushing syndrome, alcohol withdrawal, neuropathy, drugs
Intention	Variable (3–10Hz)	Increases approaching a target	Cerebellar lesions (MS, stroke, mass lesion), drugs, chronic alcoholism
Isometric/task-specific	Low–variable	Muscle contraction against a stationary object, or specific tasks	Essential tremor, dystonic tremor (e.g. primary writing tremor, musician’s tremor)

Management

Non-pharmacological

• Mild tremor without functional disturbance needs no treatment — reassure the patient it isn’t a more sinister cause.
• Avoid aggravating factors.
• General measures: heavier utensils/cups, use a computer rather than handwriting, wrist weights, yoga/exercise.
• Monitor for anxiety/depression related to embarrassment or disability.

Pharmacological

Reserve for tremor causing significant dysfunction. Provide driving advice if grip/fine manipulation is impaired.

• First-line: propranolol 10mg PO BD, increasing slowly over several weeks to a maximum of 160mg/day in 2–3 divided doses.
• Second-line: primidone 62.5mg PO nocte, increasing slowly over several weeks to a maximum of 250mg nocte.
• Both can be combined; if initial therapy fails, refer for expert advice.
• Atenolol and sotalol are also effective but should be used cautiously outside their usual indications.
• Benzodiazepines, gabapentin or topiramate are specialist-guided options.
• Refractory cases: referral to a movement disorder unit for botulinum toxin injection or deep brain stimulation.