What is the recommended imaging study, with or without contrast (Magnetic Resonance Imaging, MRI), for a patient presenting with migraine headaches and unilateral arm tremors?

MRI Brain WITH Contrast for Migraine with Unilateral Arm Tremor

For a patient presenting with migraine headaches and unilateral arm tremor, MRI brain WITH contrast is recommended because the focal neurological finding (unilateral tremor) represents an abnormal neurological examination that significantly elevates concern for secondary causes requiring contrast enhancement to detect tumors, vascular malformations, or other structural lesions. 1

Clinical Reasoning

Why This is NOT Primary Migraine

• Unilateral arm tremor constitutes an abnormal neurological finding that transforms this from a straightforward primary headache into a secondary headache concern requiring investigation 2, 3
• The American Academy of Family Physicians explicitly recommends neuroimaging in patients with headache and unexplained abnormal neurological examination findings (Grade B recommendation) 2, 3
• Focal neurological symptoms or signs associated with headache are a primary indication for neuroimaging 3

Why Contrast is Essential

• MRI with contrast is specifically indicated when there are signs suggesting possible tumor or structural lesions that could explain focal neurological deficits 1
• The ACR Appropriateness Criteria state that when there is concern for possible tumor or increased intracranial pressure, MRI is the imaging modality of choice 1
• Contrast enhancement is critical for detecting:
  • Meningeal infiltration 1
  • Isodense tumors that may be missed without contrast 1
  • Vascular malformations 4
  • Enhancing lesions that could cause focal motor symptoms 1

MRI Superiority Over CT

• MRI provides superior soft tissue resolution and detailed evaluation of intracranial structures compared to CT 1
• MRI reveals more details without radiation exposure and is better able to evaluate for structural lesions that could cause focal neurological deficits 1
• While CT may be appropriate for initial screening in emergency settings, MRI is the definitive study when focal neurological findings are present 1

Key Red Flags Present in This Case

The unilateral arm tremor represents a focal neurological abnormality that must be investigated because:

• Abnormal neurological examination findings increase the likelihood of intracranial pathology such as brain tumors, arteriovenous malformations, and hydrocephalus 3
• Studies show that 94% of children with brain tumors had abnormal neurological findings at diagnosis, emphasizing the importance of investigating any focal deficit 1
• The prevalence of significant intracranial abnormalities jumps dramatically from 0.2% in migraine patients with normal exams to much higher rates when neurological abnormalities are present 2, 3

Common Pitfalls to Avoid

• Do not treat this as uncomplicated migraine simply because the patient has a history of headaches—the focal tremor changes everything 3
• Do not order MRI without contrast when focal neurological findings are present, as this may miss enhancing lesions 1
• Do not delay imaging based on the assumption that migraine can cause any neurological symptom—unilateral tremor is not a typical migraine manifestation 3
• Avoid the error of "overlooking the need for neuroimaging when red flags are present" 3

What to Evaluate on MRI

The contrast-enhanced MRI should specifically assess for:

• Brain parenchymal lesions (tumors, metastases) 1
• Vascular malformations (arteriovenous malformations, cavernomas) 4
• Demyelinating lesions 4
• Structural abnormalities in the motor pathways that could explain unilateral tremor 1
• Signs of increased intracranial pressure 1

The presence of a focal neurological finding (unilateral arm tremor) fundamentally changes the clinical scenario from primary to secondary headache evaluation, mandating contrast-enhanced MRI to exclude serious structural pathology. 1, 3