PBL 4 - Cranial nerve tests Flashcards Preview

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Flashcards in PBL 4 - Cranial nerve tests Deck (18)
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Olfactory Nevre

What other sensations would be affected?


  • Ask for changes in smell - test with noteable smell if required.
  • taste


Optic nerve - what 3 things should you check?

  • Size
  • Shape
  • Symmetry


Describe how you would assess visual acuity. Also describe how visual acuity is recorded


  • Stand patient from chart (with glaases is they normally wear
  • Ask patient to cover one eye and read the lowest line they are able to
  • Visual acuity is recorded as chart distance in metres (as the numerator) over the number of the lowest line read (denominator)
  • For example, 6m from the chart, being able to read the 6th line, would give them 6/6
  • If they did 6/6 but got 2 letters wrong, you would write 6/6 (-2)
  • If they got more than 2 wrong, the previous line would be recorded as their acuity i.e.  6/5
  • Can also use pinhole (if vision improves, suggest there is a refractive component to their poor vision)
  • Record whether glasses, or pinhole is used
  • Repeat with other eye and compare


If a patient was unable to read any letters from 6m, what would you do? (even with pinhole)

  • Do in the following order
  1. Read from 3m (3/denominator)
  2. Read from 1m (1/denominator)
  3. Access if they can count number of fingers (record as CF)
  4. Asess if they can see gross hand movements (record as HM)
  5. Assess if they can detect light from a pen torch shone into each eye (record as perception of light)



After having inspected the eyes and looked at visual acuity, what would you do next? Explain how this is done 

  • Perform pupil reflex test
  • Shine light in first eye and observe constriction of the pupil (direct pupillary reflex)
  • Shine light in same eye but this time observe the pupil response of the opposite pupul (indirect/consensual pupillary reflex)
  • Repeat for opposite eye


You have done a general inspection, looked at the visual acuity, and assessed the pupillary reflexes. What would you do next?

  • Check the visual fields
  1. Sit directly facing patient, approximately 1m away
  2. Ask patient not to move their head or eyes during assessment
  3. Ask patient to cover their left eye with their left hand (you should then do the same with your right eye, so that you are mirroring the patient
  4. Ask patient to tell you when they can see when your fingertips are wiggling (using your opposite hand), testing each of the 4 quadrants. You swap hands when assessing the other sides, but the patient does not
  5. You then ask the patient to do the same again, but covering their other eye.


So far, we have done a general inspection, assessed visual acuity, tested the reflexes and assessed the visual fields. What next?

  • Fundoscopy - examine optic disc and retina using opthalmoscope


Oculuomotor, trochlear and abducens are tested together. How is this done?

  • Hold finger about 18 inches from patients eye
  • As patient to follow your finger as you draw the letter H
  • Their eyes should move together as they watch you
  • Make sure they do not move their head
  • Ask if they experience double vision


Trigeminal test - sensory function



  • Patient closes eyes
  • Touch head with cotton ball, ensuring to get cover for the 3 trigeminal branches (forehead, cheek, and jaw)
  • Get patient to say when they can feel touch
  • Pain can also be tested using a neurotip, which is single use


Trigeminal motor function (masseter and temporalis muscles) via the mandibular nerve



  • Temporalis
    • Placefingertips on temples and ask to clench teeth
  • Masseter
    • Place fingertips on jaw and ask to clench teeth
  • Compare both sides for weakness


There are also reflex tests for the trigeminal nerve. Outline them

  • Jaw Jerk reflex
    • Ask patient to let their mouth hang loosley open
    • place infex finger on chin and strike with tendon hammer
    • note for any reflex closing of the jaw
    • Positive tests suggests UMNL
  • Corneal Reflex (typically you would not perform this in the osce)
    • THe sensory nerve for the cornea is the trigeminal nerve
    • lightly touch croner of cornea with wool, askingthem to look away so they dont see the cotton wool
    • A normal response is shutting of the eyelids


What nerves are involved in ellicting the corneal reflex (afferent and efferent)

afferent: Trigeminal

efferent: Facial


Test for facial nerve


  • Ask patient to raise eyebrownss, frown, smile and puff out cheeks
  • Also ask to close eyes and resist attempts to open them


Vestibulocochlear nerve

  • Stand a few ste[s behind partners right side, whisper severa numbers as them to repeat
  • Hold ticking watch and move it to them and ask them when they can repeat
  • Perform RInne's and Weber's test
  • Vestibular portion is not usually carried out in CN examination


Glossopharyngeal test


  • Toungue is pressed down with toungie depressor, touch back of throat with cotton swab to elicit gag reflex


Vagus test


  • Get patient to say ahh and look for uvula deviation
  • Uvula points the opposite side from the lesion (so right point uvula is left vagus lesion)


Accessory nerve test (stenocleidomastoid and trapezius)


  • Test strentght of strenocleidomastoid by placing your hand against patients check, asking them to turn head as the apply resistance
  • Problem turning left is a problem with right SCM
  • Problem turning right is a problem with left SCM
  • Trapezius
    • Place hands on shoulders and get the, to shrug shlulders as you apply resistance


Hypoglossal taste


  • Get patient to stick out tongue
  • Deviation suggests weakness