Suspect herniation due to an intracranial mass lesion as a cause of fixed dilated pupil in an unconscious patient. A fixed dilated pupil in an awake patient is NOT due to herniation.
Holmes-Adie syndrome (aka Adie syndrome) affects the autonomic nervous system. Patients present with the pupil of one eye being larger and only slowly constricts in bright light (tonic pupil). There is also absence of deep tendon reflexes, usually the Achilles tendon.
A medical student on your team asks you to review an 81 year-old female who speaks little English. She was BIBA to the ED following a fall. Her nursing home transfer sheet says that the fall was witnessed: she tripped and there was no loss of consciousness. The student is concerned that the patient’s right pupil is fixed and slightly dilated in the presence of facial abrasions. Facial views have been ordered.