Medically Fit For Exams
Medically Fit For Exams

Cranial nerve examination

  • Wash your hands and introduce yourself
  • Explain the examination and gain consent

 

CRANIAL NERVE I – Olfactory nerve, sensory

  • Ask the patient if they’ve had any change in smell recently
  • Ask if they can remember the last thing they smelled

 

CRANIAL NERVE II – Optic nerve, sensory

  • Ask the patient if they wear glasses or contacts, and ask them to put them on
  • Acuity:
    • Position your patient in front of a SNELLEN CHART (3m if half size, 6m if full size)
    • Ask them to cover one eye, and read down the chart
    • Ask them to swap eyes and repeat
  • Visual fields:
    • Sit in front of the patient, ask them to cover one eye, and cover your eye on the same side
    • Ask them to keep their head still and look straight at your face
    • Ask them to tell you when your finger comes into their line of vision
    • Position your arm halfway between yourself and the patient and bring your finger out from the periphery of the four quadrants. To test the same side as your covered eye, swap the hand that you are using to cover your eye
    • Ask the patient to swap eyes and repeat for the other eye
    • Test for visual neglect by asking which of your fingers you are wiggling in the peripheries
    • Wiggle both sides independently and together
    • Compare the patient’s visual fields with your own, and compare between eyes
  • State that you would like to carry out fundoscopy to visualise the optic nerve

 

CRANIAL NERVE III – Oculomotor, motor

CRANIAL NERVE IV – Trochlear, motor

CRANIAL NERVE VI – Abducens, motor

  • Combine examination of the three nerves for eye movements
  • Observe the eyes for:
    • Ptosis (CNIII)
    • Eye position (CNIII, IV + VI)
    • Pupil symmetry (CNII + III)
  • Eye movements ‘H test’:
    • Sit in front of the patient, ask them to keep their head positioned facing towards you and only to move their eyes (you may have to steady their head if they can’t keep still)
    • Ask them to follow your finger with (both) eyes
    • Draw a large ‘H’ shape, holding at the peripheries to assess for nystagmus (flickering of eyes back to midline)
    • Ask if the patient has experienced any double vision
  • Accommodation reflex:
    • Ask the patient to focus on something far away, eg curtain pole and then hold your finger close to their face and ask them to switch focus to your finger
    • Look for eye convergence
    • Look for pupil constriction
  • Pupillary light reflexes – CNII for sensory, CNIII for motor response
    • Shine the torch into one eye
    • The pupil should constrict in a direct response, the other pupil should also constrict in consensual response
    • Do the same for the other eye
    • Swing the light quickly back over to the first eye and back again to assess for a RAPD
    • The affected pupil will appear to dilate in response to light, as the consensual response from the opposite eye is intact, whereas the direct response is diminished

 

CRANIAL NERVE V – Trigeminal nerve, sensory and motor

  • Assess sensation of the three branches
    • Ask the patient to close their eyes
    • Use a cotton wool tip to touch the areas supplied by the ophthalmic, maxillary and mandibular branches
    • Test one side of the face followed by the other side for each branch
    • State that you would also assess pain and temperature
  • Assess muscles of mastication (mandibular branch)
    • Place your hands on the jaw and ask the patient to open and close their mouth
    • Feel the contraction of the masseter and temporalis muscles, it should be even on both sides
    • Ask the patient to open their mouth against resistance, with your hand under their chin
  • State that you would also like to assess corneal reflex and jaw jerk

CRANIAL NERVE VII – Facial, sensory and motor

  • CNVII is responsible for taste sensation of the anterior 2/3 of the tongue (chorda tympani branch), although this is rarely tested
  • CNVII is also responsible for parasympathetic saliva production from submandibular and sublingual salivary glands, and for lacrimal gland function
  • Ask about changes in taste
  • Ask about changes in saliva production
  • Inform the patient that you are going to ask them to do some facial movements, and in each case do the movement yourself
  • Ask the patient to raise their eyebrows (temporal)
  • Repeat, but with resistance
  • Ask the patient to screw they eyes up (zygomatic)
  • Repeat, but with you holding the eyelids open
  • Ask the patient to puff out their cheeks (buccal)
  • Repeat, but push on their cheeks
  • Ask the patient to give a big grin (mandibular)
  • Ask the patient to whistle (mandibular)
  • Ask the patient to stick their chin forward (cervical)

 

CRANIAL NERVE VIII – Vestibulocochlear, sensory

  • Check/ask about hearing aids
  • Whisper test:
    • Stand to the side of the patient, tell them that you are about to whisper a number and that you’d like them to repeat it back
    • Rub the tragus of the opposite ear, and whisper a number at a full arms width
    • If the patient can’t hear, repeat, but getting louder until they can hear
    • Repeat for the opposite ear
  • Rinnie’s test (air vs bone conduction)
    • Tap a 512Hz tuning fork on your elbow, and check it is vibrating
    • Place it on the mastoid process behind the ear
    • Move it forwards to in front of the ear
    • Ask the patient which was louder
    • A normal result is for air conduction (in front of the ear) to be louder, however sensorineural deficits will also present this way
    • A conduction deafness is suggested if bone conduction is greater – possibly a result of ear wax, or ear drum abnormality
  • Weber’s test (localisation, sensorineural vs conduction)
    • Tap a 512 Hz tuning fork on your elbow and place in the centre of the patient’s forehead
    • Ask the patient whether they hear the sound loudest in the left, right or middle
    • Normal result would be to hear in the middle
    • Sensorineural deafness would be indicated if heard louder in the non-affected ear (as identified by whisper test)
    • Conductive deafness would be indicated if heard louder in the affected ear

 

CRANIAL NERVE IX – Glossopharyngeal, sensory and motor

CRANIAL NERVE X – Vagus, sensory and motor

  • CNIX is responsible for taste and sensation of posterior 1/3 of tongue
  • CNX is responsible for sensation of pharynx/larynx, motor innervation of swallowing and vocalisation muscles, parasympathetic autonomic bodily functions
  • Ask the patient to cough
  • Ask the patient to swallow (water if available)
  • Ask the patient to open their mouth and say ‘ahh’
  • Visualise the palate and uvular, should have symmetrical rise on both sides when saying ‘ahh’
  • Uvula will move away from the affected side, arch won’t rise on affected side

UvulA

Away

Tongue

Towards

  • Statue that you would test for the gag reflex

 

CRANIAL NERVE XI – Spinal accessory nerve, motor

  • Place your hands on the patient’s shoulders and ask them to shrug them against resistance
  • Ask the patient to look over each shoulder in turn, against resistance, with your hand placed on the side of their hear or on their chin

 

CRANIAL NERVE XII – Hypoglossal nerve, motor

  • This can normally be carried out at the same time as CNIX and CNX
  • Ask the patient to open their mouth and assess for tongue fasciculation
  • Ask the patient to stick out their tongue, assess for muscle wasting or deviation
    • Tongue will deviate towards the affected side
  • Ask the patient to move their tongue from side to side
  • Ask the patient to stick their tongue into their cheek
  • Push against their tongue/cheek, assess for reduced power

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