What labs or diagnostics should be ordered for a patient with bilateral upper extremity tremors and daily headaches?

Diagnostic Workup for Bilateral Upper Extremity Tremors and Daily Headaches

For a patient with bilateral upper extremity tremors and daily headaches, a comprehensive laboratory and imaging workup should include thyroid function tests, brain MRI, basic metabolic panel, and medication review to identify the underlying cause.

Initial Laboratory Evaluation

• Thyroid function tests (TSH, free T4) should be ordered as both hypothyroidism and hyperthyroidism can cause tremors and headaches 1
• Complete blood count (CBC) to evaluate for anemia or other hematologic abnormalities that could contribute to symptoms 1
• Basic metabolic panel to assess for electrolyte disturbances, kidney function, and glucose levels 1
• Liver function tests to rule out hepatic causes of tremor 1
• Serum calcium to evaluate for hyperparathyroidism which can rarely present with tremor 1

Medication and Toxicology Screening

• Comprehensive medication review to identify potential drug-induced tremors from medications such as SSRIs/SNRIs, lithium, valproate, β-adrenergic agonists, or amiodarone 2
• Urinary drug screen to rule out illicit substances that can cause tremor (cocaine, amphetamines) 1
• Serum caffeine levels if high consumption is suspected 1
• Consider alcohol withdrawal as a potential cause of both tremor and headache 1

Neuroimaging

• Brain MRI with and without contrast is the preferred neuroimaging study to evaluate for structural causes of both tremor and headaches 1, 3
• MRI can detect lesions that may cause both symptoms, including tumors, vascular malformations, or inflammatory processes 1
• Neuroimaging is particularly indicated with the presence of red flags such as:
  • New-onset headache in a patient over 50 years of age 3, 4
  • Progressively worsening headache pattern 3
  • Headaches that wake the patient from sleep 3
  • Headaches worsened by Valsalva maneuver 3
  • Abnormal neurological examination findings 3

Specialized Testing for Tremor

• Consider electromyography (EMG) to characterize the tremor if the diagnosis remains unclear after initial evaluation 5
• For suspected essential tremor, document tremor characteristics including frequency, amplitude, and activating conditions 5
• If parkinsonian features are present, consider DaTscan to evaluate dopaminergic function 5

Headache-Specific Evaluation

• Headache diary to document frequency, duration, intensity, and associated symptoms of headaches 1
• If chronic migraine is suspected (≥15 headache days per month for >3 months, with ≥8 days having migraine features), document response to migraine-specific medications 1
• Consider lumbar puncture if there are concerns for increased intracranial pressure, especially if papilledema is present on fundoscopic examination 1

Additional Considerations

• Evaluate for cervical dystonia which can present with both tremor and headache 1, 6
• Screen for sleep disorders, particularly if headaches occur upon awakening 1
• Consider autoimmune panels if inflammatory or autoimmune processes are suspected 1
• In patients on immune checkpoint inhibitors, evaluate for immune-related adverse events that can present with both neurological symptoms 1

Interpretation of Results

• Abnormal thyroid function tests may indicate hyper/hypothyroidism as the cause of both tremor and headache 1
• Structural abnormalities on MRI may require neurosurgical consultation 1
• Normal neuroimaging in the context of chronic daily headaches and tremor may suggest primary headache disorder with comorbid essential tremor 6, 7
• Consider the possibility of medication overuse headache if the patient is taking analgesics frequently 1

By systematically evaluating these diagnostic parameters, clinicians can identify the underlying cause of bilateral upper extremity tremors and daily headaches, leading to appropriate treatment strategies that address both symptoms effectively.