What is the appropriate imaging workup for a patient with a new-onset severe headache associated with nausea and vomiting?

Imaging for Headaches with Nausea and Vomiting

For new-onset severe headache with nausea and vomiting, obtain a non-contrast head CT immediately as first-line imaging to rule out life-threatening intracranial pathology.

Initial Imaging Approach

Non-contrast head CT is the first-line neuroimaging test of choice in this clinical scenario 1. This presentation represents a higher-risk profile, as nausea and vomiting are recognized risk factors associated with intracranial findings requiring urgent evaluation 2, 1.

Why CT First?

• Speed and accessibility: Can be performed rapidly without safety screening delays
• Detects emergent pathology: Accurately identifies intracranial hemorrhage, stroke, mass effect, hydrocephalus, and tumors requiring immediate intervention 3
• Critical for subarachnoid hemorrhage (SAH): This presentation is classic for SAH, where CT must be done immediately on arrival 4, 5

Timing Considerations for SAH

If SAH is suspected based on severe headache with nausea/vomiting:

• <6 hours from onset: High-quality CT interpreted by a board-certified neuroradiologist may be sufficient to exclude SAH 5
• >6 hours from onset OR new neurological deficit: Non-contrast CT followed by lumbar puncture if CT is negative 5
• High clinical suspicion with negative CT: Lumbar puncture is mandatory, with xanthochromia evaluation ideally after 12 hours from headache onset 4

When to Add MRI

MRI should be obtained as a second-line test in the following scenarios 1:

• Initial CT is unrevealing but clinical suspicion remains high
• Suspected intracranial infection (meningitis, encephalitis)
• Suspected tumor or inflammatory pathology
• Need to characterize abnormalities found on CT

MRI with and without IV contrast is preferred when infection, tumor, or vascular pathology is suspected 1.

Common Pitfalls to Avoid

1. Don't skip imaging based on normal neurological examination alone: Studies show that 1.6% of patients with normal neurological exams have clinically significant findings requiring immediate management changes 6. Even neurologist-performed normal exams don't rule out secondary causes 6.

2. Don't use contrast-enhanced CT as first-line: Contrast adds minimal value over non-contrast CT in the acute setting 2, 1. Perform non-contrast screening first, then add contrast or proceed to MRI if specific pathology is suspected.

3. Don't delay imaging for "observation": Severe headache with nausea/vomiting warrants immediate evaluation, not watchful waiting.

Risk Stratification Context

Your patient's presentation includes two key risk factors from validated criteria 2, 1:

• Headache (the primary complaint)
• Nausea or vomiting (associated symptoms)

Additional high-risk features that would further elevate concern include:

• Anticoagulant use or coagulopathy
• Hypertension
• Older age
• Impaired consciousness
• History of malignancy
• Sudden onset ("thunderclap")

The yield of acute contributory findings on CT in patients with altered mental status and these risk factors ranges from 2-45%, with 7.4% showing acute changes even without focal neurological deficits 1.

Algorithmic Summary

1. Immediate non-contrast head CT for all patients with severe headache + nausea/vomiting
2. If CT shows acute pathology: Manage accordingly (neurosurgical consultation, stroke protocol, etc.)
3. If CT negative but high SAH suspicion: Lumbar puncture (especially if >6 hours from onset)
4. If CT negative and occult pathology suspected: MRI brain with and without contrast
5. If vascular imaging needed: CT angiography or catheter angiography based on initial findings 5