Cranial Nerve exam Flashcards
Introduction:
Go through the introduction of Cranial nerve examination
WIPE
- Wash hands
- Introduce self
- Ask Patient’s name, DOB and what they like to be called
- Explain examination and obtain consent
- General Inspection
Go through General inspection of cranial erve exam
Look at the patient in general from the end of the bed
* Posture
* Habitus
* Other signs of neurological conditions
And look around the bed for signs such as:
* Mobility aids
* NBM signs
* Fluid thickener
* Glasses
* Hearing aids
- How is CN I tested?
CN I: Optic nerve
* Changes in smell? Unilateral/bilateral
* Test each nostril with smelling salts/strong smelling substance
- How is CN II tested?
- Visual acuity
- Pupillary responses
- Visual fields
- Visual inattention
- Accommodation
- Fundoscopy
How is visual acuity tested?
- Crude: asking is pateint can see equally well from both eyes
- Snellen’s chart:
- Distant visionone eye at a time. Read down the line until pt gets > 2 letters wrong, previous line recorded as acuity
- Near vision: read a line of magazine/letter
- Colour vision: Ishihara plates
How is pupillary response tested?
- Inspect size/shape of pupil/ symmetry?
- Pt fixes gaze on distant point in dark room, light shone on each pupil
- Ipsilateral: direct response
- Contralateral: indirect repsonse
What is the afferent and efferent barnch of the pupuillary response?
- Afferent: CN II
- Efferent: CN III
How are visual fields tested?
Confrontation (compares the patient’s visual fields to your own)
* Sit at same level as patient (1m apart) Ask patient to cover
one eye and to look at your nose. You cover your opposite eye
(i.e. your left and patient’s right)
* Bring your finger from the furthest periphery towards the central vision and ask the patient to say ‘yes’ when they can see your finger moving. Test each quadrant in turn
* Positioning your hand equi-distant between you and the patient will allow you to compare your visual field with
that of the patient. Repeat for the other eye.
What are visual field defects a sign of?
- Cranial nerve problem: bitemporal hemianopia
- Hemisphere problem: homonomous hemianopia
What are visual field defects a sign of?
- Cranial nerve problem
- Hemisphere problem
What is monocular vsiual loss a sign of?
How is accomodation tested?
Ask the patient to focus on a distant object, then hold your finger close to their face and ask them to focus on it. Pupils should constrict and eyes should converge
How are CN III, CN IV and CN VI tested?
Eye movements
* Inspect eyes: pupilabnormality/ptosis/abnormal gaze
* Ask pateint to follow finger in slow H pattern. Ask if theres any double vision. Nyastagmus?
What does CN III innervate (motor)?
- Superior, medial and inferior rectus muscles
- Inferior oblique
- Levator palpebrae superioris
What does CN III innervate (parasympathetic)?
Constrictor pupillae
Cillairy msucles (accommodation)
What does CN IV innervate?
Superior oblique muscles of eye
What does CN VI innervate?
Lateral rectus muscle
How is trigeminal nerve tested?
What does CN VII innervate?
- Motor: msucles of facial expression
- Sensory: ant. 2/3rd tongue
- Secretomotor: submandibular and sublingual glands
How is CN VII tested?
Inspection: asymmetry?
Motor: Facial movements
* Wrinkle forehead, screw up eyes, smile/show teeth, puff cheeks
Sensation: Taste (rarely tested)
What does the vestibular nerve innervate?
Equillibrium and balance apparatus in ear
What does cochlear nerve innervate?
Hearing
How is CN VIII tested?
- Vestibular: nyastagmus/ balance (done when testing gait)
- Hearing:
- Whisper test
- Tuning fork: Rinne’s and Webber’s
What does CN IX innervate (somatic)?
Motor: salphyngopharyngeus
Sensory: pharynx, tonsils
Special sensory: Taste posterior 1/3rd tongue
What does CN X innervate?
Vagus nerve
Sensory: Palatine, pharyngeal and laryngeal muscles
How are CN IX and CN X tested for?
- Inspection: Open mouth and say “ Ah” (symmetrical palate movement, uvula central)?
- Cough: ask to cough, listen if normal
- Gag reflex: elicit gag reflex on each side at a time (done with clinical indication) looking for pharyngeal muscle contraction
What are the afferent and efferent barnches of teh gag reflex?
Afferent: CN IX
Efferent CN X
What does CN XI inneravte?
- Motor: Trapezius, sternocleidomastoid
How is CN XI tested?
Trapezius: ask pt to shrug whilst placing hands on shoulders (look/feel for contraction)
SCM: as pt to turn head to one side (contralateral muscle contraction) pt should push face against your fist
What does CN XII innervate?
Motor: muscles of tongue
How is CN XII teste?
Inspection: open mouth, look at tongue for fasiculations/ wasting/deviation
Motor: stick tongue into each cheek, move from side to side
Speech: say days of the week
How is the whisper test done?
To estimate degree of hearing loss (mild/mod/severe/profound)
* Stand behind the patient and start with conversational voice at 60 cm from the ear being tested while masking the other ear by gently rubbing the tragus.
* Say a series of sounds (letters + numbers) and ask the patient to repeat what they have heard - conversational voice.
* If heard then repeat using a whispered voice at 60 cm and record if these are also heard
* If not heard repeat at a distance of 15 cm using a
conversational voice, and if this is not heard then escalate to
a loud voice at same distance.
Which tuning fork is used for tuning fork tests?
512 Hz (short)
Why is Rinne’s test performed first?
To compare Air Conduction (AC) to Bone Conduction (BC) in each ear
How is Rinne’s test done?
Using a 512 Hz tuning fork make it vibrate by activating vs
elbow
• Hold it about 5cm from the external auditory meatus – ask
the patient if they can hear the sound
• Immediately place the base of the tuning fork on the base of
the mastoid process and check that the patient can hear the
sound
• Ask the patient which was louder - AC or BC – you may have
to repeat the test to confirm the result – (normality AC>BC)
• Repeat for the other ear
• The test is positive if AC>BC
• The test is negative if BC>AC = a Conductive Deafness
• In unilateral neural deafness a false negative may occur
(sound being transmitted through the bone to the good ear)
but the whispering test should have demonstrated a unilateral
deafness
How is Weber’s test performed?
Advise pt you’ll place a tuning fork on the middle of the forehead/head and ask them to determine
1. Can they hear it ‘in their head’
2. if yes, is it more on one side of the head or the other,
or equally throughout the head
• Make the tuning fork vibrate by activating vs elbow
• Place the base of the tuning fork in the midline – either on
the vertex or the middle of the forehead
• Ask the patient if the sound is louder in one ear or the other
• If they can’t hear it at all repeat once and record result
• In normality or if the hearing loss is symmetrical the sound is
heard equally
• If there is a conductive deafness on one side the sound will be heard loudest in that ear
• If there is a sensori-neural hearing loss the sound will be
referred to the good (unaffected) ear
