Cranial Nerve Exam Flashcards
What is CN I (1)?
Olfactory Nerve
What is CN II (2)?
Optic nerve
What is CN III (3)?
Occulomotor nerve
What is CN IV (4)?
Trochlear nerve
What is CN V (5)?
Trigeminal nerve
What is CN VI (6)?
Abducens nerve
What is CN VII (7)?
Facial nerve
What is CN VIII (8)?
Vestibulocochlear nerve
What is CN IX (9)?
Glossopharyngeal Nerve
What is CN X (10)?
Vagus nerve
What is CN XI (11)?
Spinal accessory nerve
What is CN XII (12)?
Hypoglossal nerve
How should you first assess a patient’s cranial nerves?
General inspection
What is the pathology?
Bell’s Palsy (unilateral facial nerve weakness)
What is the pathology?
Stroke (UMN lesion affecting the facial muscles)
How can Bell’s be differentiated from a facial stroke?
Forehead sparing in stroke
Why is there forehead sparing in stroke?
Bilateral UMN supply to the superior part of the facial nerve nucleus
What should be looked for in eyes on general inspection?
- Strabismus
- Ptosis
- Asymmetrical pupil
What is this sign?
Ptosis
What is this sign?
(Not the ptosis)
Miosis (pupil constricted)
What is this sign?
Mydriasis (pupil dilation)
How can you distinguish unilateral miosis from unilateral mydriasis?
The normal pupil should be more constricted in brighter light
What abnormality of speech is relevant to a cranial nerve exam?
Dysarthria (problems with articulation)
What signs of cranial nerve problems can be seen around the bedside?
- Glasses
- Hearing aids
How can the function of the olfactory nerve be assessed?
Ask if they have had any changes to their sense of smell
What are the aspects of a full optic nerve assessment?
(Doing all of these in an exam is excessive unless specifically asked to)
- Pupil inspection
- Visual acuity
- Pupillary reflexes
- Colour vision
- Visual fields
- Fundoscopy
What are the essential aspects of an optic nerve assessment?
- Pupil inspection
- Visual acuity (brief tests of ability to read/see)
- Visual fields
- Fundoscopy (may not be needed)
- Pupillary reflexes (also CN III)
What aspects of optic nerve assessment can be modified or excluded for OSCE purposes?
- Visual acuity - not always necessary to do full Snellen chart
- Colour vision - exclude in most exams
What is the pathology*?
Anisocoria (unequal pupil size) - in this case, mydriasis
*Up to 20% of people are born with very mild anisocoria
(Fun Fact: David Bowie developed anisocria when a friend damaged his iris in a fight)
What is the type of anisocoria and what is the likely cause?
Mydriasis - CN III lesion
What is the type of anisocoria and what is the likely cause?
Miosis - Horner’s syndrome
How can visual acuity be tested in an OSCE?
Ask the patient to cover one eye at a time and read a part of a book or magazine
Should patients be given their glasses when testing visual acuity?
Yes
What can be used to more formally test visual acuity?
Snellen chart
If performing fundoscopy as part of a cranial nerve exam, what aspects should be included?
- Red reflex
- Retinal visualisation
Which eye should be used to look in the patients left eye?
Left (and vice versa)
How can visual fields be assessed?
- Sit/stand level with the patient
- Ask them to cover one eye and cover/close your corresponding eye
- Hold finger at the edge of your visual fields (2/4/8/10 o’clock positions) midway between you and the patient and ask the patient if they can see your finger moving
- Repeat with the other eye
What shows a visual field defects in a cranial nerve exam?
Needing to move your finger in from where you can see it so that the patient can see it
What is the name of and what can cause this sort of visual field defect?
- Monocular blindness
- Optic nerve or retinal lesion
What is the name of and what can cause this sort of visual field defect?
- Bitemporal hemianopia
- Lesion at the optic chiasm