American Board of Surgery Qualifying Exam (ABS QE) Practice Test

What term describes a period of lucidity after a blow to the head, particularly in cases of an epidural hematoma?

1. Concussion

2. Lucid interval

3. Post-concussive syndrome

4. Coma

The correct answer is: Lucid interval

The term "lucid interval" refers specifically to a clear period of consciousness that can occur after a head injury, especially in cases involving epidural hematomas. This phenomenon is significant in the clinical context because it can be misleading; patients may appear to recover and regain full consciousness only to later deteriorate as the hematoma expands and compresses brain structures. This interval can vary in duration but highlights the critical nature of monitoring head injury patients, as the initial apparent improvement can precede a rapid decline in neurological status. In the context of head trauma, lucid intervals are particularly observed with epidural hematomas typically due to tears in the middle meningeal artery. This is distinct from other head injuries, such as concussions, which involve a loss of consciousness but do not typically feature a lucid period afterward. Additionally, post-concussive syndrome describes a range of symptoms following a concussion that can last for weeks to months, and coma implies a prolonged state of unconsciousness that would not include periods of lucidity. Therefore, the specificity of "lucid interval" as it pertains to the timeline and progression of symptoms following a head injury makes it the correct answer in this context.