Which finding indicates increased intracranial pressure or brain herniation?

• A. Pupils equal, round, reactive to light
• B. Central support structure of vertebrae
• C. Clear drainage from nose/ears
• D. Unequal Pupils

Answer: (D)

Raising intracranial pressure can compress the oculomotor nerve, which carries parasympathetic signals that constrict the pupil. When this nerve is compressed on one side, the pupil on that side dilates and may become non-reactive to light, producing unequal pupils. This anisocoria is a red flag for impending brain herniation and requires urgent evaluation and intervention. In contrast, pupils that are equal and reactive suggest intact cranial nerve function, while a clear nasal/ear drainage or an anatomical feature of the spine doesn’t reflect acute brain herniation risk.