Cranial nerve examination Flashcards
What is included in the introduction of a cranial nerve exam?
- Wash hands
- Put on PPE
- Introduce self.
- Confirm name and DOB.
- Explain examination.
- Gain consent.
What comes after the introduction?
- General inspection
What should be noted from general inspection of the patient?
Inspect the patient’s head and neck for:
- Scars.
- Neurofibromas.
- Facial asymmetry.
- Eye/pupil abnormalities.
How is the cranial nerve I examined?
Olfactory nerve (CN I)
Hold olfactory bottles or easily recognised scents under the patient’s nostril. Test each nostril in turn, whilst the other one is blocked.
How is cranial nerve II examined?
- Schnellen chart if available. If not, ask the patient to read a newspaper or tell how many fingers you are holding up may be adequate.
- Test visual fields. Sit opposite patient and ask them to cover up their own eye (on the same side as yours). Then use a pin or finger and gradually bring into the visual field of both you and the patient, and ask them to signal when they see it. Should be roughly the same for both you and the patient.
- Test visual extinction. Hold both fingers on either side of the patient’s visual field and wiggle at the interphalangeal joint. Ask the patient to say which finger is moving. Do this on one side, then the other, and also both. If the patient cannot tell when both are moving, but can tell individually they are exhibiting visual extinction.
- Light reflex. Ask the patient to look straight ahead at a point in the distance. Shine a pen torch into the patients eye from the side, and look for contraction of BOTH pupils. Do this on both sides.
- Accommodation. Ask patient to focus into the distance, then switch focus to an upclose finger. Pupils should visibly constrict.
How are the 3rd, 4th and 6th cranial nerve tested?
Oculomotor nerve (III), trochlear nerve (IV) and abducens nerve (VI).
- Ask the patient to trace a ‘H’ shape that you draw with your own finger.
- Observe for any odd eye movement.
- Ask the patient if they experience any double vision.
How is the 5th cranial nerve tested?
Trigeminal nerve (V).
- Test sensation using cotton wool above the eye, on the cheekbone and on the chin.
- Ask the patient to clench their teeth. Ask the patient to open their mouth wide.
- Jaw jerk reflex. Whilst the patients mouth is open, place finger on the chin and hit with tendon hammer. Observe for a sudden jaw closure (UMN sign).
How is the 7th cranial nerve tested?
Facial nerve (VII).
- Screw up eyes.
- Puff cheeks.
- Raise eyebrows.
- Purse lips.
- Smile (show teeth).
How is the 8th cranial nerve tested?
Vestibulocochlear nerve.
- Cover opposite ear and whisper a number in the patient’s ear. Ask them what the number was. Repeat on both sides.
- If an abnormality is suspected, conduct a Weber’s and a Rinne’s test.
How is Weber’s test conducted?
- Place vibrating tuning fork on forehead in the midline.
- In conductive hearing loss, sound is louder in the abnormal ear.
- In sensorineural hearing loss, sound is louder in the normal ear.
How is Rinne’s test conducted?
- Place vibrating tuning fork on mastoid process (behind ear).
- Then hold fork close to the external auditory meatus. Normally, patient should hear sound louder when held near the ear. In conductive hearing loss, sound will be louder when on the mastoid process.
How are cranial nerves 9 and 10 tested?
Glossopharyngeal (IX) and vagus (X) nerve.
- Ask patient to open mouth wide and check uvula is in midline.
- Ask patient to say “Aaah” and check uvula moves symmetrically. Uvula will deviate towards the normal side if there is a CN IX palsy.
- Ask patient if they have difficulty swallowing.
- Ask patient to cough. Weak cough suggestive of CN X palsy.
- Note any horseness in patient’s voice.
How is CN 11 tested?
Accessory nerve (XI).
- Ask patient to shrug their shoulders against resistance.
- Ask patient to turn their head both ways against resistance.
How is CN 12 tested?
Hypoglossal nerve (XII).
- Ask patient to open mouth. Observe for any fasciculations.
- Ask patient to stick tongue out. If deviation occurs, it will be towards the lesion.
- Ask patient to push their tongue into their cheek. Press against cheek with finger to assess power.
