Workup for Left Arm Tremor in Adults
Begin by determining whether the tremor occurs at rest or with action/posture, as this single distinction directs the entire diagnostic pathway and treatment strategy. 1
Initial Clinical Characterization
Observe the tremor activation pattern:
- Resting tremor (improves with voluntary movement) indicates Parkinsonian syndrome and requires evaluation for Parkinson's disease or atypical parkinsonism 1
- Action/postural tremor (worsens with goal-directed activity) suggests essential tremor 1
- Functional tremor demonstrates distractibility—the tremor stops completely when attention is redirected to another task 1
- Cerebellar tremor becomes more pronounced during goal-directed movements and associates with dysarthria and ataxic gait 1
Essential History Elements
Document these specific features:
- Functional impact: Assess interference with daily activities (writing, eating, drinking) to determine treatment necessity 1
- Medication review: Identify tremor-inducing agents including antiparkinsonians, lithium, sympathomimetics, antipsychotics, valproic acid, and bronchodilators 1, 2
- Exacerbating factors: Anxiety, caffeine, strenuous exercise, or fatigue suggest enhanced physiologic tremor 1
- Family history: Essential tremor demonstrates autosomal dominant inheritance in 50% of cases 2, 3
- Alcohol response: Improvement with alcohol strongly suggests essential tremor 1
Red Flags Requiring Urgent Evaluation
If resting tremor is present, assess for atypical parkinsonism features:
- Early prominent falls and gait dysfunction suggest progressive supranuclear palsy (PSP) or multiple system atrophy (MSA) rather than classic Parkinson's disease 1
- Early autonomic dysfunction (orthostatic hypotension, urinary incontinence) suggests PSP or MSA 1
- Vertical gaze palsy suggests PSP 1
- Poor or absent levodopa response suggests PSP or MSA 1
- Unilateral tremor with other focal neurologic deficits may indicate structural brain lesion requiring urgent imaging 2
Imaging Strategy
For suspected Parkinsonian syndrome:
- MRI brain without contrast is the optimal first-line imaging modality due to superior soft-tissue characterization and sensitivity to iron deposition, and can exclude focal atrophy, structural lesions, or vascular disease 1
- Ioflupane SPECT/CT (DaTscan) differentiates Parkinsonian syndromes from essential tremor and drug-induced tremor—a normal scan essentially excludes Parkinsonian syndromes 1
- FDG-PET/CT discriminates PSP from idiopathic Parkinson's disease based on characteristic hypometabolism patterns in medial frontal and anterior cingulate cortices, striatum, and midbrain 1
For action/postural tremor without Parkinsonian features:
- Neuroimaging is generally not required if the clinical presentation is consistent with essential tremor and there are no red flags 3
Laboratory Evaluation
Order targeted laboratory tests based on clinical suspicion:
- Thyroid function tests (TSH, free T4) to exclude thyrotoxicosis 4
- Metabolic panel including calcium and parathyroid hormone if hyperparathyroidism suspected 4
- Hepatic function panel if flapping tremor (asterixis) present, suggesting hepatic encephalopathy 4
- Lyme and syphilis serology if meningeal signs or bilateral sixth nerve palsy present 5
Common Diagnostic Pitfalls
Avoid these errors:
- Do not assume all resting tremors are Parkinson's disease—combination of resting tremor with prominent early gait difficulties and falls is atypical for classic Parkinson's and should raise suspicion for PSP or MSA 1
- Do not overlook secondary causes such as medications, caffeine, or metabolic disturbances before attributing tremor to a primary tremor disorder 1
- Do not confuse akathisia (severe restlessness from antipsychotics manifesting as pacing) with tremor—lowering the antipsychotic dose is the primary intervention 1
- Do not ignore functional impact—treatment decisions should be based on interference with quality of life or function, not tremor presence alone 1