What is the differential diagnosis for an adult patient presenting with shaky hands?

Differential Diagnosis for Shaky Hands

The most common causes of shaky hands in adults include essential tremor, enhanced physiologic tremor (often drug-induced or metabolic), Parkinsonian tremor, cerebellar tremor, and psychogenic tremor, with essential tremor being the most prevalent pathologic cause affecting approximately 50% of cases on a hereditary basis. 1

Primary Tremor Categories

Essential Tremor

• Presents as postural and kinetic tremors affecting hands, head, and voice, with approximately 50% of cases being hereditary 1
• Characterized by tremor that occurs during voluntary movement and maintaining posture against gravity 1
• Can cause significant functional disability requiring treatment 1
• Approximately 8% of healthy adults exhibit an EMG-acceleration pattern indistinguishable from mild essential tremor, making diagnosis challenging 2

Enhanced Physiologic Tremor

• Present in all individuals but becomes symptomatic when enhanced by drugs or metabolic disturbances 1
• Common drug culprits include caffeine, nicotine, sympathomimetics (decongestants, anorectics), cocaine, amphetamines, sodium-containing antacids, NSAIDs, oral contraceptives, cyclosporine, tacrolimus, and neuropsychiatric agents 3
• Associated clinical features include fine tremor, tachycardia, and sweating with stimulant use 3
• Diagnosis confirmed by response to withdrawal of suspected agent 3

Parkinsonian Tremor

• Occurs in both resting and postural positions, distinguishing it from essential tremor 1
• Typically responds to levodopa treatment, though anticholinergics may cause problematic mental side effects in elderly patients 1
• Part of broader Parkinson's disease syndrome with additional motor features 1

Cerebellar Tremor

• Manifests as kinetic tremor of extremities or trunk shakiness 1
• Results from cerebellar pathway disturbances 1
• MRI of the head without IV contrast is the preferred imaging modality to evaluate cerebellar atrophy and signal alterations 3

Metabolic and Endocrine Causes

Hyperthyroidism

• Presents with warm, moist skin; heat intolerance; nervousness; tremulousness; insomnia; weight loss; and diarrhea 3
• Physical examination reveals lid lag and fine tremor of outstretched hands 3
• Screen with thyroid-stimulating hormone and free thyroxine 3
• Confirm with radioactive iodine uptake and scan 3

Hypothyroidism

• Associated with delayed ankle reflex, periorbital puffiness, coarse skin, cold skin, and slow movement 3
• Screen with thyroid-stimulating hormone and free thyroxine 3

Pheochromocytoma

• Presents with paroxysmal hypertension, "spells," blood pressure lability, headache, sweating, palpitations, and pallor 3
• Screen with 24-hour urinary fractionated metanephrines or plasma metanephrines 3
• Confirm with CT or MRI scan of abdomen/pelvis 3

Vascular and Neurologic Causes

Cerebrovascular Disease

• Internal carotid artery occlusion can present with continuous rhythmic hand shaking (limb-shaking syndrome), a special manifestation of transient ischemic attack 4
• Particularly important to consider in patients with poorly controlled rheumatoid arthritis or other inflammatory conditions that accelerate atherosclerosis 4
• Requires urgent vascular imaging and antiplatelet therapy 4

Multiple Sclerosis

• Tremor can occur as part of MS presentation, though typically accompanied by other neurologic symptoms 5
• Common associated features include optic neuritis, sensory disturbances, motor symptoms, diplopia, and balance dysfunction 5
• MRI shows characteristic periventricular lesions, corpus callosum involvement, and ovoid lesions perpendicular to ventricles 5

Peripheral Neuropathy with Sensory Ataxia

• Presents as disequilibrium with worsening when eyes are closed (positive Romberg test) 3
• Can occur in spinocerebellar ataxias affecting dorsal columns and dorsal root ganglia 3
• MRI cervical and thoracic spine may show spinal cord atrophy 3

Age-Related Considerations

Elderly Patients

• Age has no significant effect on the frequency and amplitude of mechanical-resonant component of hand tremor, but elderly patients may have different EMG peak frequencies (5-7 Hz) compared to young adults (9-12 Hz) during mass loading 2
• Anticholinergic medications for tremor often cause problematic mental side effects in elderly patients 1
• Consider vascular causes more prominently in elderly with risk factors 4

Critical Diagnostic Pitfalls

Distinguishing Physiologic from Pathologic Tremor

• Approximately 8% of both young and elderly healthy adults have tremor patterns indistinguishable from mild essential tremor on electrophysiologic studies 2
• Requires careful medication history, as many common substances enhance physiologic tremor 3
• Urinary drug screen indicated for suspected illicit drug use 3

Overlooking Vascular Causes

• Continuous hand shaking can be the initial presentation of internal carotid artery occlusion, particularly in patients with inflammatory conditions like rheumatoid arthritis 4
• Requires high index of suspicion and vascular imaging when tremor is continuous and rhythmic 4

Missing Metabolic Causes

• Thyroid dysfunction, pheochromocytoma, and other endocrine disorders must be systematically excluded through appropriate screening tests 3
• These conditions are treatable and may present primarily with tremor before other symptoms become apparent 3

Diagnostic Algorithm

1. Characterize tremor type: resting versus postural versus kinetic 1
2. Obtain comprehensive medication and substance use history, including over-the-counter medications, caffeine, nicotine, and alcohol 3
3. Screen for metabolic causes: thyroid function tests, consider 24-hour urinary metanephrines if hypertension or paroxysmal symptoms present 3
4. Assess for neurologic disease: if additional neurologic symptoms present, obtain MRI brain without contrast 3, 5
5. Consider vascular causes: if tremor is continuous and rhythmic, particularly with vascular risk factors, obtain carotid imaging 4
6. Trial of medication withdrawal: if drug-induced tremor suspected, observe response to discontinuation 3