NeurologyTier 1Disease (DEADMAN)

Tremor

Description

Rhythmic, involuntary oscillation of a body part - classified by the state in which it occurs, since this localises the cause

Classification by activation condition

Type	When it occurs	Classic cause
Rest tremor	Limb fully supported, at rest; reduces with action	Parkinson's disease
Postural tremor	Maintaining a position against gravity (arms outstretched)	Essential tremor, physiological, drug-induced, thyrotoxicosis
Kinetic/action tremor	Throughout voluntary movement	Essential tremor
Intention tremor	Worsens on approach to target (finger-nose testing)	Cerebellar disease

Essential tremor - commonest pathological tremor, prevalence rises with age, often familial (autosomal dominant pattern in many)
Parkinsonian rest tremor - see Parkinson's disease note
Physiological tremor - universal, exaggerated by anxiety, caffeine, fatigue, thyrotoxicosis, drugs

By type

Rest tremor - basal ganglia dopaminergic pathway dysfunction (Parkinson's disease, parkinsonism)
Postural/kinetic (essential) tremor - cerebello-thalamo-cortical circuit dysfunction; genetic in a substantial proportion
Intention tremor - cerebellar or cerebellar outflow (dentate/superior cerebellar peduncle) pathway lesion - MS, stroke, alcohol, tumour, degenerative ataxia
Enhanced physiological tremor - thyrotoxicosis, anxiety, caffeine/stimulants, alcohol withdrawal, beta-agonists, valproate, lithium
Task-specific/other - orthostatic tremor (legs, standing), dystonic tremor, functional (psychogenic) tremor

History and examination - the tremor "decoder"

Frequency: essential tremor typically faster (6-12Hz) than parkinsonian rest tremor (4-6Hz)
Distribution: essential tremor - bilateral hands, may involve head/voice; Parkinson's - typically starts unilateral, asymmetric
Alleviating/aggravating factors: essential tremor characteristically improves transiently with alcohol; both worsen with anxiety/stress
Associated signs: bradykinesia/rigidity/postural instability (Parkinson's); dysmetria, dysdiadochokinesia, ataxic gait (cerebellar)
Family history - strong in essential tremor
Medication and substance review - valproate, lithium, beta-agonists, SSRIs, alcohol withdrawal, caffeine
Functional tremor clues: variable frequency/amplitude, distractibility, entrainment to an examiner-set rhythm, abrupt onset/remission

Investigations

Largely clinical; TFTs to exclude thyrotoxicosis in new postural tremor
MRI brain if cerebellar signs, asymmetry, or atypical features suggest a structural cause
DaTscan (dopamine transporter imaging) - distinguishes Parkinson's/parkinsonism from essential tremor when clinically equivocal

By type - treatment targets the tremor category, not a generic "tremor drug"

Essential tremor

Propranolol or primidone - first-line, roughly equal efficacy; choice by comorbidity (avoid propranolol in asthma/bradycardia, primidone sedating especially early)
Topiramate - alternative if first-line agents fail/contraindicated
Botulinum toxin for focal/head/voice tremor refractory to medication
Deep brain stimulation (thalamic - VIM nucleus) or MR-guided focused ultrasound thalamotomy for severe, disabling, drug-refractory tremor

Parkinsonian rest tremor

Treated as part of Parkinson's disease management (levodopa, dopamine agonists) - see Parkinson's disease note; tremor can be the most treatment-resistant motor feature

Cerebellar/intention tremor

Treat underlying cause where possible; tremor itself is notoriously difficult to treat pharmacologically - clonazepam sometimes tried; DBS in severe cases

Enhanced physiological/secondary tremor

Remove/treat the cause (correct thyrotoxicosis, cease/reduce offending drug, manage anxiety, address alcohol withdrawal)

Functional tremor

Multidisciplinary approach - explanation of diagnosis, physiotherapy, psychology input; avoid unnecessary escalating pharmacotherapy

Essential tremor - slowly progressive over decades, can become functionally disabling (writing, eating, drinking) but not life-shortening
Parkinsonian tremor - part of a progressive neurodegenerative course (see Parkinson's disease note)
Cerebellar tremor - prognosis follows the underlying cause
Psychosocial impact often underestimated - embarrassment and functional limitation drive presentation more than the movement itself

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