## **Core Concept**
The patient's presentation of the "most severe headache of his life" is a classic symptom that raises suspicion for a subarachnoid hemorrhage (SAH), a type of stroke caused by bleeding into the space surrounding the brain. This condition requires immediate medical attention. The initial approach involves stabilizing the patient and promptly diagnosing the cause of the headache.

## **Why the Correct Answer is Right**
The correct approach involves immediate imaging to confirm the diagnosis, typically a non-contrast computed tomography (CT) scan of the head, which is highly sensitive for acute blood. This is because SAH can lead to significant morbidity and mortality if not promptly treated. The CT scan can quickly differentiate between SAH and other causes of severe headache, such as meningitis or cerebral infarction.

## **Why Each Wrong Option is Incorrect**
- **Option A:** Administering analgesics without imaging would be inappropriate as it may mask symptoms and delay diagnosis of a potentially life-threatening condition like SAH.
- **Option B:** Although a lumbar puncture (LP) can help diagnose SAH by detecting blood in the cerebrospinal fluid (CSF), it should not be performed before imaging, especially if there's suspicion of increased intracranial pressure, as it can precipitate brain herniation.
- **Option C:** While obtaining a detailed history and performing a physical examination are crucial, they do not replace the need for immediate imaging in this scenario.

## **Clinical Pearl / High-Yield Fact**
A key clinical pearl is the "thunderclap headache," which is a severe headache that reaches maximum intensity within one minute, often described as "the worst headache of my life." This presentation is highly suggestive of SAH. Immediate non-contrast CT of the head is the diagnostic test of choice.

## **Correct Answer:** D. **Immediate non-contrast CT scan of the head**.