American Board of Internal Medicine (ABIM) Certification Practice Exam

What is the initial workup order for a patient presenting with a thunderclap headache?

1. Lumbar puncture followed by CT

2. CT scan followed by neurovascular imaging

3. Neurovascular imaging followed by MRI

4. Telemedicine consultation

The correct answer is: CT scan followed by neurovascular imaging

When a patient presents with a thunderclap headache, which is characterized as a sudden and severe headache that reaches maximal intensity within minutes, the primary concern is to rule out life-threatening conditions, particularly subarachnoid hemorrhage (SAH). The initial workup typically begins with a CT scan of the head, as it is the most widely available and effective tool for quickly detecting hemorrhagic strokes, including SAH. If the CT scan indicates no abnormalities but clinical suspicion for SAH remains high (often aided by the patient's history and physical examination findings), further imaging with neurovascular studies, such as CT angiography or traditional angiography, may be necessary to evaluate for vascular abnormalities like an aneurysm or vascular malformation. This approach aligns with established clinical protocols and guidelines for managing acute headache presentations. Performing a lumbar puncture first could delay the diagnosis and may not provide immediate information on intracranial bleeding. While neurovascular imaging and MRI are important follow-up steps, initiating the evaluation with a CT scan maximizes the chance of rapidly identifying a critical condition that necessitates immediate intervention.