Physical Examination Assessment of Tremor ("Shakes")
Systematically characterize the tremor by observing it at rest, with posture holding, and during movement, while specifically checking for asterixis, tremor frequency/amplitude, and associated neurological signs to distinguish between essential tremor, parkinsonian tremor, and other causes.
Core Examination Sequence
1. Activation Condition Assessment (Most Critical Step)
Determine when the tremor occurs 1, 2, 3:
Rest tremor: Observe with limbs completely relaxed and supported against gravity (e.g., hands resting in lap while seated). Parkinsonian tremor appears here and diminishes with voluntary movement 1, 3
Postural tremor: Have patient hold arms outstretched in front with fingers spread. Essential tremor is most prominent here 1, 2
Kinetic tremor: Observe during finger-to-nose testing or when reaching for objects. Cerebellar tremor worsens as the target is approached (intention tremor) 2, 4
2. Specific Maneuvers to Perform
Asterixis testing (critical for metabolic causes): Have patient hyperextend wrists with fingers separated, or squeeze your fingers rhythmically. Look for sudden loss of postural tone causing "flapping" movements. This indicates hepatic encephalopathy, uremia, or other metabolic derangements 5
Entrainment testing (distinguishes functional from organic): Ask patient to tap contralateral hand at a specific rhythm while observing the tremor. Functional tremor will entrain to the voluntary rhythm or disappear; organic tremor persists unchanged 6, 2
Distraction techniques: Engage patient in cognitive tasks (serial 7s, months backward) while observing tremor. Functional tremor decreases or disappears with distraction 7, 2
3. Tremor Characteristics to Document
Frequency: Essential tremor is typically 4-12 Hz; parkinsonian tremor is 4-6 Hz; cerebellar tremor is <4 Hz 1, 2, 8
Amplitude: Note if fine or coarse
Distribution: Unilateral (suggests Parkinson's disease) vs bilateral and symmetric (suggests essential tremor) 1, 3
Body parts affected: Hands, head (isolated head tremor suggests dystonia, not essential tremor), voice, legs 9
4. Associated Neurological Signs
Check systematically for:
Parkinsonian features: Bradykinesia, rigidity (cogwheel), masked facies, shuffling gait, reduced arm swing 1, 2
Cerebellar signs: Dysmetria, dysdiadochokinesia, ataxic gait, nystagmus 2, 4
Dystonic postures: Abnormal limb positioning, torticollis 9
Hyperreflexia and Babinski sign: May indicate hepatic encephalopathy or structural lesions 5
Key Diagnostic Patterns
Essential tremor: Bilateral postural/action tremor, may have head tremor, family history common, improves with alcohol 1, 2
Parkinson's disease: Asymmetric rest tremor (4-6 Hz "pill-rolling"), improves with movement, accompanied by rigidity and bradykinesia 1, 3
Enhanced physiologic tremor: Fine, rapid (8-12 Hz) postural tremor, exacerbated by anxiety, caffeine, fatigue, or medications (beta-agonists, valproate, lithium) 1, 2
Cerebellar tremor: Intention tremor during goal-directed movements, associated with ataxia 2, 4
Functional/psychogenic tremor: Abrupt onset, variable characteristics, entrainment with voluntary movements, extinction with distraction 1, 3
Critical Pitfalls to Avoid
- Don't assume all tremors are essential tremor—rest tremor indicates Parkinson's disease until proven otherwise 1
- Asterixis is NOT a true tremor but negative myoclonus; its presence demands metabolic workup 5
- Isolated head tremor is more likely dystonic than essential tremor 9
- Tremor that changes character or disappears with distraction suggests functional etiology 2, 3
- Cocontraction (patient tensing muscles to suppress tremor) is common but unhelpful long-term and should be noted 6
Orthostatic Vital Signs
Measure heart rate and blood pressure supine and after 3 minutes standing, as orthostatic changes can cause tremulousness and must be distinguished from true tremor 10