A 35-year-old previously healthy woman suddenly develops a severe headache while lifting weights. A minute later she has transient loss of consciousness. She awakes with vomiting and a continued headache. She describes the headache as “the worst headache of my life.” She appears uncomfortable and vomits during the physical examination. Blood pressure is 140/85, pulse rate is 100/min, respirations are 18/min, and temperature is 36.8degC (98.2degF). There is neck stiffness. Physical examination, including careful cranial nerve and deep tendon reflex testing, is otherwise normal. Which of the following is the best next step in evaluation?

**Core Concept**
The patient's presentation is consistent with a sudden, severe headache, often referred to as a thunderclap headache, which is a classic symptom of subarachnoid hemorrhage (SAH). SAH is a life-threatening condition that requires immediate medical attention.

**Why the Correct Answer is Right**
The best next step in evaluation is to perform a non-contrast computed tomography (CT) scan of the head to rule out SAH. This is because SAH can cause a sudden, severe headache, often accompanied by vomiting, neck stiffness, and altered mental status. The non-contrast CT scan is the imaging modality of choice in the acute setting because it is quick, easily accessible, and sensitive for detecting blood in the subarachnoid space. If the CT scan is negative, further evaluation, including lumbar puncture and potentially more advanced imaging, may be necessary.

**Why Each Wrong Option is Incorrect**

* **Option A:** Lumbar puncture (LP) is not the best next step because it is not a diagnostic test, but rather a confirmatory test for SAH. Additionally, performing LP in the acute setting can be risky, as it can precipitate brain herniation in the presence of increased intracranial pressure.
* **Option B:** Magnetic Resonance Imaging (MRI) is not the best next step in the acute setting because it is not as readily available as CT and is not as sensitive for detecting acute blood in the subarachnoid space.
* **Option D:** Cerebral angiography is not the best next step because it is an invasive procedure that is typically reserved for patients with a high suspicion of aneurysmal SAH, which has not been established in this patient.

**Clinical Pearl / High-Yield Fact**
The "worst headache of my life" is a classic description of a thunderclap headache, which is a red flag for SAH. This presentation should prompt immediate evaluation and imaging to rule out SAH.

**Correct Answer: C. Non-contrast CT scan of the head**

✓ Correct Answer: A. CT scan without contrast