What is the workup for a unilateral hand tremor?

Workup for Unilateral Hand Tremor

Begin by determining whether the tremor occurs at rest or with action/posture, as this single distinction immediately narrows the differential diagnosis and directs the entire workup. 1

Initial Clinical Assessment

Tremor Characterization

• Resting tremor (present when hand is fully supported against gravity, disappears with voluntary movement) strongly suggests Parkinson's disease, which typically begins asymmetrically and unilaterally 1, 2
• Action/postural tremor (occurs during tasks like holding objects or maintaining posture) indicates essential tremor or enhanced physiologic tremor 1, 3
• Variable frequency, amplitude, and direction with sudden onset in context of stress suggests functional/conversion tremor 1, 4

Key Historical Features to Elicit

• Timing of tremor onset: Gradual onset favors Parkinson's disease or essential tremor; sudden onset suggests functional tremor 1
• Family history: Positive family history points toward essential tremor rather than Parkinson's disease 1
• Medication review: Identify potentially causative drugs (stimulants, antipsychotics, valproate) that must be discontinued before further workup 1
• Associated symptoms: Bradykinesia, rigidity, or postural instability support Parkinson's disease 5

Physical Examination Maneuvers

• Entrainment testing: Have patient perform voluntary rhythmic movements with the unaffected limb while observing the tremor—if tremor changes frequency or temporarily stops, this is pathognomonic for functional tremor 1, 4
• Finger-to-nose testing: Intention tremor worsening near target suggests cerebellar pathology 4
• Postural holding: Observe tremor with arms outstretched to assess postural tremor characteristics 2

Diagnostic Algorithm Based on Tremor Type

For Unilateral Resting Tremor

• Primary diagnosis to evaluate: Parkinson's disease 1
• No routine imaging required unless atypical features present (rapid progression, early falls, poor levodopa response) 1
• Trial of levodopa/carbidopa 25/100 mg three times daily serves as both diagnostic and therapeutic—significant improvement confirms parkinsonian tremor 1

For Unilateral Action/Postural Tremor

• Consider essential tremor if bilateral family history and gradual progression 1, 6
• Enhanced physiologic tremor if associated with caffeine, stress, or thyroid dysfunction 4, 5
• Dystonic tremor if isolated to specific tasks (e.g., writing) or associated with abnormal posturing 5, 7

For Variable/Entrainable Tremor

• Functional tremor diagnosis requires positive demonstration of entrainment, distractibility, or variability—not a diagnosis of exclusion 1, 5
• Avoid extensive neuroimaging in clear functional cases, as symptoms are involuntary and require specific therapeutic approaches 1

Laboratory and Imaging Workup

Essential Laboratory Tests

• Thyroid function tests (TSH, free T4) to exclude hyperthyroidism causing enhanced physiologic tremor 5
• Serum ceruloplasmin and 24-hour urine copper if patient under age 40 to exclude Wilson's disease 2
• Basic metabolic panel to assess for metabolic derangements 5

Neuroimaging Indications

• Brain MRI is NOT routinely indicated for typical unilateral resting tremor consistent with Parkinson's disease 1
• Brain MRI should be obtained if: atypical features (rapid progression, early cognitive decline, poor levodopa response), age under 40, or concern for structural lesion (stroke, tumor, multiple sclerosis) 2, 7
• The provided evidence about temporal bone CT relates to tinnitus workup and is not applicable to hand tremor evaluation 8

Common Pitfalls to Avoid

• Do not diagnose essential tremor based solely on unilateral resting tremor—essential tremor is primarily postural/action tremor and typically bilateral 1
• Do not start tremor medications before discontinuing potentially causative drugs like stimulants or antipsychotics 1
• Do not use propranolol for parkinsonian resting tremor—beta-blockers are only effective for essential tremor and enhanced physiologic tremor 1, 3
• Do not dismiss functional tremor as "psychogenic"—symptoms are involuntary and require specific therapeutic approaches including rhythm modification techniques 1, 3
• Do not order extensive imaging for typical presentations—clinical diagnosis based on tremor characteristics is usually sufficient 1, 2