Which finding would most strongly prompt pre-LP imaging?

• A. Focal neurologic deficits
• B. Fever only
• C. Mild nausea
• D. Normal exam

Answer: (A)

The main idea is that before a lumbar puncture you only image when there’s a risk of increased intracranial pressure or a mass lesion that could cause herniation. A focal neurologic deficit points to a localized brain process that could be raising ICP or creating a mass effect, making LP dangerous unless imaging rules out these issues. A noncontrast head CT is typically done first to look for mass effect, midline shift, or other signs of elevated ICP before proceeding with LP. Fever alone, mild nausea, or a normal neurologic exam do not suggest a mass or raised ICP and don’t by themselves justify delaying LP with imaging. So, the finding that most strongly prompts pre-LP imaging is the presence of focal neurologic deficits.