creation date: 2026-06-05 18:55
tags: Workups
Tremor
Background
Tremor is an involuntary, rhythmic, and oscillatory movement of a body part. It is the most common movement disorder.
Pathophysiology
Tremors occur due to synchronous or antagonistic muscle contractions. The cause of the contractions vary based on condition, and includes exaggeration of physiological tremor.
Differential Diagnosis
Rest tremors
- Idiopathic Parkinson disease
- Tremor-dominated Parkinson disease (PD with tremor as only or most prominent sign)
- Isolated rest tremor (SWEDD: scans without evidence of dopaminergic deficit) - appearing like PD but without evolution to PD later
- Drug-induced parkinsonism (dopamine receptor antagonists)
Action tremors
- Physiologic tremor - high frequency, low amplitude; made detectable by:
- Medications (eg. beta-adrenergic agonist, isoproterenol, epinephrine, amphetamines, SSRIs, TCAs, levodopa, nicotine, xanthines)
- High adrenergic state (eg. anxiety, excitement, fright, alcohol/opioid withdrawal, thyrotoxicosis)
- Drug-induced tremor (eg. lithium, antidepressants, corticosteroids, sodium valproate, bromides, mercury, lead, arsenic)
- Essential tremor
- Primary writing tremor - large amplitude supination-pronation movement during writing
- Orthostatic tremor - leg and trunk when standing
- Cerebellar tremor - due to cerebellar outflow system disorder
- Rubral tremor (cerebellar subtype involving midbrain, thalamic, cerebellar, or pontine injury)
- Neuropathic tremor (eg. hereditary neuropathies, recovery phase of Guillain-Barre syndrome, chronic inflammatory demyelinating polyneuropathy)
- Dystonia with tremor
Functional tremors
Previously psychogenic tremor.
Initial Evaluation
History
Key components of the history are:
- Rest versus action
- If action, during the motion does it:
- Occur during voluntary movement (kinetic tremor)
- Remain the same (simple kinetic tremor)
- Increases in intensity as the part approaches the target (intention tremor)
- Occur during a specific task (task-specific kinetic tremor)
- Occur in specific position or posture (postural tremor)
- Occur during contraction against a stationary object (isometric tremor)
- Occur during voluntary movement (kinetic tremor)
- Tremor frequency (<4, 4-8, 8-12, >!2 Hz)
- Body distribution
- Focal: only one body region (eg. voice, head, jaw, one limb)
- Segmental (two or more contiguous body part)
- Hemitremor (one side of the body)
- Generalized (upper and lower body)
- Other neurologic signs (syndromes)
Physical Exam
Exam includes:
- Neurologic exam
- Focused exam of tremor
- Limbs at rest
- Limbs with posture (elevated against gravity)
- Test for distractability or entrainment while outstretched
- Finger-to-nose and heel-to-shin movements
- Writing sample and spirals
- Pouring water
Investigations
Laboratory evaluations may include:
- Thyroid function
- Wilson disease workup and heavy metal screening
- Glucose (for hypoglycemia)
Brain imaging is typically not indicated in cases of essential tremor, PD, enhanced physiologic tremor, or drug-induced tremor.