A rugby player hit his head on the post whilst involved in a tackle. He was unconscious for 5 min but regained full consciousness and sat on the sideline until the end of the game. He was then noted to be drowsy and over the past 30 min became confused and no longer obeyed commands. Most likely diagnosis is:

**Core Concept**
The question tests the student's understanding of the pathophysiology of traumatic brain injury, specifically the concept of second impact syndrome. This phenomenon occurs when a second head injury occurs before the symptoms of the first injury have resolved, leading to severe and potentially life-threatening consequences.

**Why the Correct Answer is Right**
The correct answer is likely related to the concept of second impact syndrome. This condition occurs when a second head injury occurs before the symptoms of the first injury have resolved, leading to a worsening of the initial injury. In this scenario, the player was initially unconscious but regained consciousness and continued to play, only to deteriorate over the next 30 minutes. This sequence of events is consistent with second impact syndrome, which can be caused by a second head injury, even if the first injury was minor.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the scenario described, which involves a second head injury rather than a primary injury.
**Option B:** This option is incorrect because it does not address the concept of second impact syndrome, which is the most likely diagnosis based on the scenario.
**Option C:** This option is incorrect because it does not accurately describe the pathophysiology of traumatic brain injury or the concept of second impact syndrome.

**Clinical Pearl / High-Yield Fact**
Second impact syndrome is a potentially life-threatening condition that can occur when a second head injury occurs before the symptoms of the first injury have resolved. It is essential for healthcare providers to recognize this condition and take prompt action to prevent further injury.

**Correct Answer:** C. Second impact syndrome.

✓ Correct Answer: A. Extradural hematoma