A 48-year-old man on ICU develops a unilateral dilated pupil (right, 7 mm) that is unreactive to light. He has a known traumatic brain injury with rig...

Question

A 48-year-old man on ICU develops a unilateral dilated pupil (right, 7 mm) that is unreactive to light. He has a known traumatic brain injury with right-sided subdural haematoma. GCS has dropped from 12 to 7. What does the unilateral fixed dilated pupil indicate?

Accepted Answer

Uncal herniation causing compression of the ipsilateral (right) CN III, indicating imminent transtentorial herniation - an emergency requiring urgent CT and neurosurgical intervention

Answer

Optic nerve damage

Answer

Horner's syndrome

Answer

Pharmacological mydriasis from atropine

Answer

Normal pupillary asymmetry

uk-fficm MCQ (SBA): Uncal Herniation

A 48-year-old man on ICU develops a unilateral dilated pupil (right, 7 mm) that is unreactive to light. He has a known traumatic brain injury with right-sided subdural haematoma. GCS has dropped from 12 to 7. What does the unilateral fixed dilated pupil indicate?