What could be causing hand shaking in an adult with no known medical history?

Hand Shaking in Adults with No Known Medical History

In an adult presenting with hand shaking (tremor) without known medical history, the most critical initial step is to distinguish between benign essential tremor and tremor indicating serious neurological disease through detailed characterization of the tremor's timing, triggers, associated symptoms, and a focused neurological examination to identify red flags requiring urgent imaging or specialist referral.

Initial Clinical Assessment

The diagnostic approach must focus on specific tremor characteristics rather than generic history-taking:

Tremor Characterization

• Timing and position: Determine if tremor occurs at rest (suggesting parkinsonism), with action/posture (suggesting essential tremor or physiologic tremor), or with intention (suggesting cerebellar pathology) 1
• Onset and progression: Sudden onset with associated neurological symptoms suggests stroke or structural lesion requiring urgent evaluation 2, 3
• Unilateral vs bilateral: Asymmetric tremor, especially if associated with rigidity or bradykinesia, raises concern for Parkinson's disease 2

Critical Red Flags Requiring Urgent Evaluation

• Associated neurological deficits: Weakness, sensory changes, ataxia, altered consciousness, or cranial nerve abnormalities suggest central nervous system pathology (stroke, tumor, demyelination) requiring immediate brain imaging 2, 4
• Acute onset with vertigo/dizziness: Tremor with brainstem or cerebellar involvement can present with movement disorders and requires MRI to exclude stroke 2, 3
• Autonomic dysfunction or myoclonus: Suggests brainstem encephalitis from infections (listeriosis, viral) or other serious pathology 2
• Movement disorders with altered consciousness: Consider flavivirus infections (West Nile, Japanese encephalitis) or alphavirus infections that cause tremors with thalamic/basal ganglia involvement 2

Systematic Evaluation Algorithm

Step 1: Rule Out Life-Threatening Causes

• Perform focused neurological examination looking for focal deficits, gait abnormalities, eye movement disorders, or signs of increased intracranial pressure 2, 4
• Obtain 12-lead ECG to evaluate for arrhythmias that could cause cerebral hypoperfusion mimicking neurological symptoms 1
• Assess cardiovascular risk factors (hypertension, diabetes, hyperlipidemia, atrial fibrillation) that increase stroke risk 1, 3

Step 2: Characterize Associated Symptoms

• Headache with photophobia/phonophobia: Consider vestibular migraine which can present with tremor and dizziness 1
• Hearing loss, tinnitus, aural fullness: Suggests Meniere's disease, though tremor is not typical 2, 1
• Fever, altered consciousness, seizures: Requires immediate consideration of encephalitis with lumbar puncture and brain imaging 2
• Medication review: Many drugs cause tremor (antihypertensives, antidepressants, antiarrhythmics) 2

Step 3: Determine Need for Urgent Imaging

MRI brain with and without contrast is indicated when: 4

• Acute onset tremor with any focal neurological signs
• Tremor with severe headache or altered consciousness
• High cardiovascular risk factors with acute presentation
• Atypical features not consistent with benign essential tremor
• Failure to respond to standard treatments

CT imaging alone is inadequate as it frequently misses posterior circulation strokes and brainstem pathology 3

Age-Specific Considerations

At any adult age, but particularly in middle-aged and older adults:

• Increased risk for stroke and tumors requiring lower threshold for imaging 1
• Higher likelihood of medication-induced tremor due to polypharmacy 2
• Greater fall risk if tremor affects balance, requiring falls risk screening 3

Common Pitfalls to Avoid

• Do not assume absence of focal deficits rules out stroke: Up to 80% of patients with stroke-related acute vestibular syndrome may have no focal neurologic deficits 3
• Do not rely on patient's description of "dizziness" alone: Many patients use vague terms; specifically ask about true spinning vertigo, lightheadedness, or imbalance 2
• Do not delay imaging in high-risk patients: Posterior circulation strokes are frequently missed on initial evaluation 3
• Do not attribute tremor to anxiety without thorough evaluation: Serious pathology can present with tremor and anxiety-like symptoms 2

Laboratory Testing

Laboratory tests should be targeted based on clinical suspicion, not routine 1:

• Complete blood count, glucose, electrolytes, renal function, thyroid function if metabolic causes suspected
• Consider inflammatory markers if infection or vasculitis suspected

When to Refer Urgently

Immediate neurosurgical or neurological consultation required for: 4

• Tremor with mass lesion on imaging
• Tremor with signs of increased intracranial pressure
• Acute stroke with tremor
• Suspected encephalitis or CNS infection 2