What is the initial workup for worsening tremors in a patient with a history of Parkinson's disease?

Workup for Worsening Tremor in Parkinson's Disease

The initial workup for worsening tremor in a patient with established Parkinson's disease should prioritize checking serum calcium levels and assessing for medication-related issues before attributing symptoms to disease progression. 1

Immediate Laboratory Assessment

Check serum calcium levels first, as hypocalcemia can induce or worsen tremors and other movement disorders in patients with Parkinson's disease. 2, 1 This is a critical and often overlooked reversible cause that should be corrected before assuming disease progression. 1

Additional metabolic screening should include:

• Parathyroid hormone (PTH) to evaluate for hypoparathyroidism 2
• Magnesium levels, as hypomagnesemia can contribute to or worsen tremor 2
• Thyroid-stimulating hormone (TSH) to exclude thyroid dysfunction 2
• Vitamin B12, folate, and vitamin D levels as deficiencies can impact neurological symptoms 1

Medication Review

Evaluate current dopaminergic therapy and assess for "off" periods where tremor worsens when medication effects wear off. 3, 4 This is particularly important as tremor can fluctuate with medication timing. 5

Review for:

• Adequacy of levodopa dosing, as levodopa remains the most efficacious treatment for PD tremor 5
• Timing of tremor worsening relative to medication doses to identify motor fluctuations 3, 4
• Drug-induced causes including medications that may worsen tremor 2

Clinical Assessment

Determine tremor characteristics to distinguish progression from other causes:

• Assess if tremor is present during "on" versus "off" medication states 5
• Evaluate for new postural or action tremor components in addition to resting tremor 2, 6
• Screen for autonomic dysfunction, constipation, and other non-motor symptoms that may indicate disease progression 1, 4
• Document any new rigidity, bradykinesia, or gait changes to assess overall disease status 4

Neuroimaging Considerations

Neuroimaging is NOT routinely indicated if the patient meets diagnostic criteria for known Parkinson's disease and the clinical picture is consistent with disease progression or medication fluctuations. 2

However, MRI brain should be obtained if:

• New focal neurological signs develop 2
• Atypical features suggest alternative diagnoses (multiple system atrophy, progressive supranuclear palsy, corticobasal degeneration) 2
• Rapid progression or asymmetric findings raise concern for structural lesions 2

Advanced Diagnostic Testing

DaTscan (ioflupane SPECT) is NOT indicated in patients with established Parkinson's disease, as it is used to differentiate parkinsonian syndromes from essential tremor at initial diagnosis, not to evaluate progression. 2

Consider referral to movement disorders neurology if:

• Tremor remains refractory after optimizing levodopa therapy 5
• Diagnostic uncertainty exists about whether symptoms represent PD progression versus another condition 2
• Advanced therapies (deep brain stimulation, focused ultrasound) may be appropriate 7, 5

Common Pitfalls to Avoid

Do not assume worsening tremor equals disease progression without first:

• Correcting metabolic abnormalities, especially hypocalcemia 2, 1
• Optimizing dopaminergic medication timing and dosing 5
• Ruling out medication-induced worsening 2

Do not order unnecessary vestibular testing unless vertigo or balance symptoms suggest a vestibular disorder rather than parkinsonian postural instability. 2

Do not obtain routine brain imaging in the absence of red flags, as this adds cost without changing management in typical PD progression. 2