Which pupillary change would indicate depressed brain function?

Which pupillary change would indicate depressed brain function?

• A. Both pupils are sluggish with introduction of a bright light
• B. Both pupils rapidly constrict
• C. Pupils remain equally and actively reactive
• D. One pupil dilates and remains fixed

Answer: (A)

Pupillary light response reflects brainstem integrity, and when brain function is depressed, the reflex tends to be slow. Shining a bright light causes the pupils to constrict, but in a brain that's functionally down, this constriction is sluggish rather than brisk. So a description where both pupils are slow to constrict after a bright light points to depressed brain function. By contrast, rapid constriction indicates a normal reflex; equally reactive pupils also suggest preserved brainstem function; and a pupil that dilates and remains fixed suggests a local lesion or raised pressure affecting a cranial nerve, which is a different pattern than global depression.

Pupillary light response reflects brainstem integrity, and when brain function is depressed, the reflex tends to be slow. Shining a bright light causes the pupils to constrict, but in a brain that's functionally down, this constriction is sluggish rather than brisk. So a description where both pupils are slow to constrict after a bright light points to depressed brain function.

By contrast, rapid constriction indicates a normal reflex; equally reactive pupils also suggest preserved brainstem function; and a pupil that dilates and remains fixed suggests a local lesion or raised pressure affecting a cranial nerve, which is a different pattern than global depression.