Would you obtain a CT (Computed Tomography) angiogram of the head and neck if a patient experiences a sudden sensation like a 'pop' at the base of the skull followed by a persistent headache?

CT Angiography for Patient with Skull Base "Pop" and Persistent Headache

Yes, a CT angiogram of the head and neck should be obtained for a patient who felt a "pop" at the base of the skull followed by a 4-day persistent headache, as this presentation raises concern for a potential vascular event such as arterial dissection or aneurysm. 1

Clinical Reasoning for CTA

• The sensation of a "pop" at the skull base followed by persistent headache is concerning for a potential vascular event, particularly arterial dissection or aneurysm rupture with subarachnoid hemorrhage (SAH) 1, 2
• Sudden onset headache (thunderclap headache) has been associated with subarachnoid hemorrhage in 11.3% of cases, making this a potentially life-threatening condition requiring prompt evaluation 3
• The American College of Radiology recommends CTA head for evaluation of patients with suspected acute subarachnoid hemorrhage, with sensitivity >90% for detecting aneurysms 1

Diagnostic Algorithm

1. Initial Evaluation:

   • CT head without contrast should be performed first to assess for subarachnoid hemorrhage or other intracranial pathology 1
   • If CT head is negative but clinical suspicion remains high, proceed to CTA 1

2. CTA Benefits:

   • CTA head is a fast, noninvasive study with >90% sensitivity and specificity for aneurysm detection 1
   • CTA can detect arterial dissection, which may present with the described "pop" sensation and subsequent headache 1, 2
   • CTA neck may be included if cervical arterial dissection is suspected, though this is typically based on individual clinical assessment 1

3. Follow-up Testing:

   • If CTA is negative but clinical suspicion remains high, catheter cerebral angiography may be considered as it can identify vascular abnormalities in up to 13% of patients with SAH and negative CTA 1
   • Lumbar puncture may be necessary if imaging is negative but clinical suspicion for SAH remains high 4

Red Flags in This Case

• The "pop" sensation at the skull base suggests a potential vascular event 2
• Persistent headache for 4 days following this event is concerning for ongoing pathology 5, 4
• The combination of these symptoms warrants vascular imaging to exclude potentially life-threatening conditions 1

Potential Pitfalls

• Relying solely on non-contrast CT head may miss vascular abnormalities, especially small aneurysms <3mm or those adjacent to bone 1
• Delaying imaging in patients with warning signs like sudden onset headache with unusual features (such as the "pop" sensation) can lead to missed diagnoses of serious conditions 5, 4
• Assuming a benign cause without appropriate vascular imaging could result in failure to diagnose conditions with high morbidity and mortality 1, 3

Special Considerations

• While radiation exposure is a concern with CT imaging, the benefit-risk ratio favors CTA in cases with concerning clinical features suggesting potential vascular pathology 6
• MRA could be considered as an alternative if available promptly, but CTA is typically faster and more readily available in urgent scenarios 1

1