CT Head Without Contrast is the Appropriate Initial Imaging
For a 30-year-old female with severe, worsening headache, nausea, and normal renal function unresponsive to multiple medications, a non-contrast CT head should be performed first to rapidly exclude life-threatening hemorrhage, followed by contrast-enhanced imaging or MRI only if specific pathology (infection, tumor, inflammatory process) is suspected based on initial findings.
Primary Imaging Approach
Start with non-contrast CT head as the first-line test because it rapidly and safely identifies acute intracranial hemorrhage, mass effect, and hydrocephalus—the most immediately life-threatening causes of severe headache 1, 2. Non-contrast CT serves as an effective screening tool with 98% sensitivity and 99% specificity for detecting acute subarachnoid hemorrhage 1.
Key Clinical Features Requiring Urgent Imaging
This patient's presentation includes several concerning features that mandate neuroimaging 1:
- Severe headache intensity beyond typical migraine despite treatment
- Progressive worsening rather than improvement
- Nausea suggesting possible increased intracranial pressure
- Treatment failure with multiple appropriate migraine therapies including rimegepant 1, 3
When to Add Contrast
Add IV contrast only if the non-contrast CT suggests specific pathology requiring further characterization 1. Contrast-enhanced CT should be considered when:
- Initial non-contrast CT shows nonspecific edema or mass-like abnormalities 1
- Clinical suspicion for intracranial infection (meningitis, encephalitis, abscess) remains high 1
- Tumor or inflammatory pathology is suspected based on initial findings 1
- Venous sinus thrombosis is a consideration (though CTV or MRV is preferred) 2
Avoid ordering "CT with and without contrast" routinely as this doubles radiation exposure without added benefit in most acute headache scenarios 1.
Critical Pitfalls to Avoid
Do not skip imaging based solely on prior migraine history 4, 5. Even patients with established migraine can develop secondary causes of headache that mimic their typical pattern. One case report documented a 69-year-old woman with known migraine whose triptan-responsive headaches were actually caused by cavernous sinus dural arteriovenous fistula 5.
Do not rely on non-contrast CT alone to exclude all pathology 2. Non-contrast CT has significant limitations:
- Poor sensitivity for acute ischemia in the first 6 hours 2
- Misses 70% of venous sinus thrombosis cases 2
- Limited detection of posterior fossa pathology due to beam hardening artifact 2
- Cannot adequately visualize subtle meningeal enhancement or small infections 1
When MRI Becomes Necessary
Proceed to MRI with and without contrast if the non-contrast CT is unrevealing but clinical suspicion remains high 1, 2. MRI offers superior sensitivity for:
- Acute ischemia and small infarcts 1, 2
- Encephalitis and meningitis (using T2 FLAIR and post-contrast sequences) 1
- Posterior fossa pathology 2
- Subtle subarachnoid hemorrhage 1
- Venous sinus thrombosis 2
Practical Algorithm
- Order non-contrast CT head immediately for this severe, worsening headache unresponsive to treatment 1, 2
- If non-contrast CT shows hemorrhage, mass effect, or hydrocephalus: Manage accordingly; contrast not needed initially 1
- If non-contrast CT shows suspicious but nonspecific findings: Add contrast-enhanced CT or proceed to MRI with contrast 1
- If non-contrast CT is completely normal but symptoms persist: Consider MRI brain with and without contrast to exclude subtle pathology 1, 2
- If all imaging is normal: Reassess for primary headache disorder, but maintain vigilance for evolving secondary causes 3
Special Consideration for This Patient
Given normal renal function, there is no contraindication to contrast if needed 1. However, the initial screening should still be non-contrast CT because adding contrast to the first study provides minimal additional value for detecting acute hemorrhage or mass effect and unnecessarily delays diagnosis 1.