Cranial nerve examination Flashcards
what do u inspect (before u do formal test), aside from asking DOB, consent, washing hands?
Walking aids/gait on entering the room
Body position
Skin changes on the face/neck
Drooping of face/eyelid
Skin changes around the ears/near hair line
Eye changes (esp. if any squints or asymmetry at rest)
a patient tells u they sense changes in odours of common foods or they can’t smell. What cranial nerve do u suspect cld be damaged?
olfactory (CN I) it’s not formally tested u wld just ask questions about their smell
how do we test cranial nerve II + what name is given to this nerve?
CN II = optic
Visual acuity (with glasses on) - hand-held eye chart or a Snellen’s chart (TEST EACH EYE SEPARATELY)
Visual fields (with glasses off) – by confrontation – see video: https://www.youtube.com/watch?v=2-9FVywV2j4
(TEST EACH EYE SEPARATELY)
Fundoscopy (will be covered in clinical years of study)
**REFER FOR VISUAL PERIMETRY AND FORMAL OPTOMETRIC ASSESSMENT IF ANY CONCERNS
how do we test cranial nerve III, IV + VI?
CN III= oculomotor
CN IV= trochlear
CN VI = abducens
The pupils
Pupil size differences at rest (anisocoria; one of your pupils being bigger than the other. Ptosis is eyelid droop)
Light reflex (direct, consensual, RAPD)
Accommodation
Eye movements
Hold an object (30-40cm from patient and move in a ‘H’ pattern) assess for nystagmus and diplopia
n.b. advanced testing looks for 4 types of movements (pursuit, saccadic, convergence & vestibulo-ocular reflex movements)
how do we test cranial nerve V + name the 3 branches this nerve has?
CN V = trigeminal
V1=ophthalmic
V2= maxillary
V3= mandibular
Facial sensation in the three divisions of the nerve, comparing each side with the other
Light touch can be tested with cottonwool -> an area of dull sensation should be mapped by testing sensation progressively: testing should go from the abnormal to the normal area
Ask the patient to clench the teeth, then palpate for contraction of the masseter above the mandible
Ask the patient to hold open the mouth (pterygoid muscles) while you attempt to force it shut.
Reflexes: corneal reflex; jaw jerk or masseter reflex
how do we test cranial nerve VII?
CN VII= facial nerve
Ask the patient to look up to wrinkle the forehead (feel the muscle strength by pushing down against the corrugation on each side with fingers)
Ask the patient to puff out the cheeks (look for asymmetry and strength can be assessed by pressing the cheeks to check for tension with fingers)
Ask the patient to shut the eyes tightly (Compare how deeply the eyelashes are buried on the two sides and strength can be assessed by trying to open each eye gently with fingers)
Examining for taste on the anterior two-thirds of the tongue is not usually required.
how do we test cranial nerve VIII?
CN VIII= Vestibulocochlear
Remove hearing aids, inspect behind the ears and inspect the patient’s external auditory meatus
Wisper a number into the ear being tested whilst covering the opposite auditory meatus with a finger/rustling fingers together as a distraction
This should be standardised using set numbers for different tones -> the number 68 is used to test high tone and 100 is used to test low tone.
Rinne and Weber testing can be carried out if the whisper test is not normal (https://www.youtube.com/watch?v=RVH4K4EcsiA)
** NOTE THAT JUST LIKE VISION, REFER FOR AUDIOMETRY IF ANY CONCERNS)
how do we test cranial nerve IX and X?
CN IX= glossopharyngeal
CN X= vagus
Although still done, in the current climate of the post-COVID-19 pandemic, it is NOT necessary to elicit a cough
You can wear a mask and ask them to open their mouth and when they say ‘aaaah’, look at the pharynx, uvula
Irrespective of post-pandemic setting we are currently in, it is also unnecessary to perform the gag reflex
At the start of the examination, when the patient introduces themselves, consider if their voice is hoarse or not
** it is unfeasible to undertake water swallowing to check for regurgitation – PLEASE DO NOT DO THIS IF YOU ARE SUSPECTING IMPAIRED BULBAR FUNCTION
how do we test for cranial nerve XI + name the cranial nerve?
CN XI (Spinal accessory)
Cell bodies of this nerve reside in spinal cord
Purely somatic motor nerve
Innervates the sternocleidomastoid muscle and the trapezius muscle
TEST:
Ask the patient to shrug their shoulders and attempt to push the shoulders down
Then instruct the patient to turn the head to the side against resistance (your hand)
**the right sternocleidomastoid turns the head to the left and vice versa. Feel the muscle bulk of the sternocleidomastoids
how do we test for cranial nerve XII + name the cranial nerve?
CN XII (hypoglossal)
Request the patient to stick their tongue out
Look for any deviation at rest (as well as wasting or fasciculations=twitching)
Check strength by pushing the inside of the cheek and oppose your finger pressing on the outside of the cheek
