What is the recommended evaluation and treatment approach for new onset tremors?

Evaluation and Management of New-Onset Tremor

Initial Clinical Characterization

The first critical step is to classify the tremor based on when it occurs: determine if the tremor is present at rest (suggesting Parkinson's disease), with posture/action (suggesting essential tremor or enhanced physiologic tremor), or with goal-directed movement (suggesting cerebellar pathology). 1

Key Historical Features to Obtain

• Activation condition: Does the tremor occur at rest, with sustained posture, during movement toward a target, or with isometric muscle contraction 1
• Onset characteristics: Abrupt onset with spontaneous remissions and changing characteristics suggest psychogenic tremor 1
• Medication history: Many drugs can induce tremor, including beta-agonists, valproate, lithium, and stimulants 2
• Caffeine, fatigue, and anxiety: These enhance physiologic tremor 1
• Family history: Essential tremor is autosomal dominant in 50% of cases 1
• Associated symptoms: Bradykinesia, rigidity, or postural instability suggest Parkinson's disease 1

Physical Examination Findings

• Resting tremor (4-6 Hz, unilateral, pill-rolling): Most commonly parkinsonian tremor, affecting >70% of Parkinson's disease patients as the presenting feature 1
• Postural/action tremor (8-12 Hz, bilateral, affects hands): Most commonly essential tremor, which affects 0.4-6% of the population 1
• Isolated head tremor: More likely dystonic rather than essential tremor 3
• Tremor extinction with distraction: Suggests psychogenic tremor 1

Diagnostic Workup

Laboratory Testing

Check thyroid function tests, basic metabolic panel (including calcium and magnesium), and liver function tests to exclude metabolic causes of enhanced physiologic tremor. 2, 1

• Hyperthyroidism, hypocalcemia, and hepatic encephalopathy can all cause tremor 2
• Review medication list for tremor-inducing drugs 2

Neuroimaging

Brain MRI is indicated if there are atypical features, rapid progression, associated neurological signs (ataxia, weakness, cognitive changes), or age of onset under 40 years with no family history. 1

• MRI helps identify structural lesions, Wilson's disease (basal ganglia signal changes), or multiple sclerosis 1
• Routine neuroimaging is not necessary for typical essential tremor or enhanced physiologic tremor 1

Advanced Diagnostic Studies (When Uncertain)

• Single-photon emission computed tomography (SPECT): Visualizes dopaminergic pathway integrity to distinguish Parkinson's disease from essential tremor when diagnostic uncertainty exists 1
• Transcranial ultrasonography: May help diagnose Parkinson's disease 1

Treatment Approach by Tremor Type

Essential Tremor (Most Common Pathologic Tremor)

First-line pharmacological treatment is propranolol (starting 20-40 mg twice daily, titrating up to 120-320 mg/day) or primidone (starting 12.5-25 mg at bedtime, titrating to 250 mg/day). 4, 2

• Propranolol is effective in approximately 50% of essential hand tremor cases 3
• Topiramate is an alternative first-line option 4
• Botulinum toxin injections are effective for midline tremors (head, voice) and are the treatment of choice for these presentations 3
• Deep brain stimulation (DBS) of the thalamic/subthalamic region should be considered for severe, refractory tremor that significantly impairs quality of life 4
• Focused ultrasound thalamotomy is an emerging alternative to DBS 4

Parkinsonian Tremor

Treat the underlying Parkinson's disease with levodopa/carbidopa combination therapy, which often relieves the rest tremor. 5

• Parkinsonian tremor is typically unilateral, occurs at rest (4-6 Hz), and becomes less prominent with voluntary movement 1
• If tremor persists despite adequate dopaminergic therapy, consider DBS 4

Enhanced Physiologic Tremor

Treat with low-dose propranolol (10-40 mg as needed before situations requiring steady hands) and address underlying causes (anxiety, caffeine, medications, hyperthyroidism). 2, 5

• This tremor is high-frequency (8-12 Hz) and low-amplitude 1
• Beta-blockers are highly effective at much lower doses than required for essential tremor 5

Cerebellar Tremor

Cerebellar tremor is notoriously difficult to treat pharmacologically; consider occupational therapy adaptations and weighted utensils. 4, 3

• Propranolol may provide modest benefit 2
• Address underlying cause (multiple sclerosis, stroke, alcohol-related degeneration) 3

Dystonic Tremor

Botulinum toxin injections are the treatment of choice for dystonic tremor. 3

• This tremor occurs in a body part affected by dystonia 3
• Isolated head tremor should be considered dystonic until proven otherwise 3

Critical Pitfalls to Avoid

• Do not assume all tremors are benign essential tremor: Parkinson's disease presents with tremor in >70% of cases, and missing this diagnosis delays neuroprotective treatment 1
• Do not overlook drug-induced tremor: Carefully review all medications, including over-the-counter stimulants and supplements 2
• Do not dismiss psychogenic tremor as a diagnosis of exclusion: Look for positive signs including abrupt onset, extinction with distraction, and changing characteristics 1
• Do not use propranolol in patients with asthma, heart block, or uncontrolled heart failure: These are absolute contraindications 2

When to Refer to Neurology

• Diagnostic uncertainty after initial evaluation 1
• Tremor refractory to first-line medications 4
• Consideration of botulinum toxin or surgical interventions 4, 3
• Atypical features or rapid progression 1
• Age under 40 with no family history of tremor 1