Tremor

Background

• Involuntary, rhythmic, oscillatory movement of a body part
• Clinical classification commonly distinguished by whether tremor occurs at rest or with action
• The primary EM role is to identify emergent and treatable causes (toxicologic, metabolic, infectious) and differentiate from seizure or other movement disorders
• Most new-onset tremor in the ED is caused by a reversible etiology (medication, metabolic, toxin)

Clinical Features

Classification

• Rest tremor: present when body part is relaxed and supported; classic for Parkinson's disease ("pill-rolling")
• Action tremor: occurs during voluntary movement
  • Postural tremor: present when maintaining posture against gravity (essential tremor, enhanced physiologic tremor)
  • Kinetic/intention tremor: occurs during movement, worsens approaching target (cerebellar dysfunction)

History

• Acute vs. chronic onset (acute suggests toxic/metabolic; chronic suggests essential tremor or Parkinson's)
• Unilateral vs. bilateral
• Rest vs. action
• Medication and substance use (caffeine, stimulants, lithium, valproic acid, antipsychotics)
• Alcohol use (enhanced physiologic tremor in withdrawal)
• Associated symptoms: weight loss (hyperthyroidism), confusion (hepatic encephalopathy), fever (infection)
• Family history of tremor (essential tremor)

Physical Exam

• Observe at rest, with arms outstretched, and during finger-to-nose testing
• Assess for cogwheel rigidity, bradykinesia (Parkinson's)
• Mental status exam
• Thyroid exam
• Look for asterixis (hepatic encephalopathy, uremia) — distinguish from tremor (asterixis is negative myoclonus, not a true tremor)

Red Flags

• Acute onset new tremor (toxic/metabolic cause until proven otherwise)
• Fever + tremor (infection, serotonin syndrome, neuroleptic malignant syndrome, thyroid storm)
• Altered mental status + tremor (toxic exposure, metabolic derangement, hepatic encephalopathy)
• Signs of alcohol withdrawal (tachycardia, hypertension, diaphoresis, agitation)
• Associated rigidity + hyperthermia (neuroleptic malignant syndrome, serotonin syndrome)
• New tremor with focal neurologic deficits (stroke, intracranial mass)

Differential Diagnosis

Enhanced Physiologic Tremor (Most Common Acute)

• Anxiety, stress
• Caffeine, theophylline
• Sympathomimetics
• ETOH withdrawal
• Hypoglycemia
• Hyperthyroidism / thyroid storm

Neurologic

• Essential tremor (familial, bilateral postural, improves with alcohol)
• Parkinson's disease (unilateral rest tremor, cogwheel rigidity, bradykinesia)
• Cerebellar dysfunction (intention tremor, ataxia)
• Wilson's disease (young patient, liver disease)
• Stroke (acute onset with focal deficits)
• Multiple sclerosis

Toxic

• Lithium toxicity
• Serotonin syndrome
• Neuroleptic malignant syndrome
• Antipsychotics (tardive dyskinesia, drug-induced parkinsonism)
• Metoclopramide, prochlorperazine
• Valproic acid, levothyroxine
• Tricyclic antidepressants, bupropion
• Heavy metal toxicity (mercury, lead, manganese)
• Salicylate toxicity
• Hydrogen Sulfide

Metabolic/Infectious

• Hepatic encephalopathy
• Hypoglycemia
• Hyponatremia, hypocalcemia, hypomagnesemia
• West Nile virus
• Sepsis

Evaluation

Immediate

• Bedside glucose (rule out hypoglycemia)
• Vital signs: tachycardia + hypertension + tremor = think withdrawal, thyroid storm, sympathomimetic

Laboratory

• BMP: glucose, electrolytes (Na, Ca, Mg), renal function
• Liver function tests, ammonia (hepatic encephalopathy)
• TSH (hyperthyroidism)
• Drug levels if applicable: lithium, valproic acid, theophylline
• Toxicology screen if ingestion suspected
• CBC, blood cultures if febrile

Imaging

• CT head if focal neurologic deficits, sudden onset, or concern for intracranial pathology
• MRI brain if Wilson's disease, MS, or cerebellar pathology suspected (outpatient)

Management

Treat Underlying Cause

• Hypoglycemia: dextrose
• ETOH withdrawal: benzodiazepines (see Alcohol withdrawal)
• Thyroid storm: beta-blockers, PTU/methimazole, steroids, cooling (see Thyroid storm)
• Serotonin syndrome: discontinue offending agents, cyproheptadine, benzodiazepines, cooling
• NMS: discontinue offending agent, cooling, dantrolene, benzodiazepines
• Hepatic encephalopathy: lactulose, rifaximin
• Lithium toxicity: IV fluids, consider dialysis for severe toxicity
• Drug-induced tremor: discontinue or reduce offending medication when possible

Symptomatic

• Essential tremor: propranolol or primidone (outpatient management)
• Parkinson's disease: neurology referral (do not typically start dopaminergic agents in ED)

Disposition

Admit

• Alcohol withdrawal requiring inpatient management
• Serotonin syndrome or NMS
• Thyroid storm
• Hepatic encephalopathy
• Significant metabolic derangement
• Acute intracranial pathology

Discharge

• Enhanced physiologic tremor with identifiable and correctable trigger
• Known essential tremor or Parkinson's disease at baseline
• Drug-induced tremor with plan for medication adjustment
• Arrange neurology follow-up for new-onset tremor without emergent etiology
• Return precautions: worsening tremor, fever, confusion, difficulty swallowing, falls

See Also

• Alcohol withdrawal
• Serotonin syndrome
• Neuroleptic malignant syndrome
• Thyroid storm
• Parkinson's disease