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Cranial Nerve Examination

From Mediwikis

There are 12 pairs of Cranial Nerves arising from the brain, including both efferent and afferent nerve tracts. This is a guide to a systematic cranial nerve examination, including assessment of all 12 cranial nerves. Note that in an examination setting such as an OSCE, not all the cranial nerves may be assessed, either due to time constraints, or for the comfort of the patient.

Introduction

Wash Hands

Introduce self  

  • I've been asked to examine some of the nerves in your face and head today to find out how well things are working. Would that be okay?
  • Confirm Age, Date of birth
  • Do you have any questions?

Questions for the patient

  • Are you in any pain?
  • Comment: I would begin with a full patient history, and then proceed with the physical examination.

I - Olfactory

Ask the patient "have you experienced any change in your sense of smell?"

  • Assess formally using bottled scents

II - Visual

Snellen chart

A complete assessment of CN II should include:

  • Visual Acuity
  • Visual Fields
  • Visual Inattention
  • Fundoscopy

For a detailed guide on performing opthalmoscopy and eye examination, see the guide Eye Examination & Opthalmoscopy.

V - Trigeminal

Inspection

  • Scars
  • Rashes
  • Wasting
  • Asymmetry

Sensory

  • Fine touch - cotton wool to touch each of the 3 sensory regions of the patient's face -V1,2,3. Repeat for both sides, asking the patient to say when they feel the touch.

Motor

  • Temporalis & masster muscle bulk - patient's jaw clenched
  • Patient moves jaw from side to side, and opens mouth, against resistance from your hand
  • Jaw jerk reflex - tapping just above the chin with a tendon hammer, with patient's mouth clenched & slightly open
  • Corneal reflex - dabbing cotton wool tip on the corneal surface - not routinely tested

III, IV, VI - Oculomotor, Trochlear, Abducens

Neuro-ophthalmologic examination in a patient with Tolosa-Hunt syndrome, prior to treatment, shows left palpebral ptosis, strabismus of the primary look of the left eye, paresis of the third, fourth and sixth left cranial nerves.
  • Eye movements - move finger in 1 metre squared "H"
    • Ask if any double vision
    • Nystagmus
    • Asymmetry.

VII - Facial

Examination of CN VII, courtesy of All Access Medicine.

Inspection

  • Asymmetry
  • Involuntary movements
  • Drooping eyes.

Sensory

  • Any change in taste

Motor

  • Independently, then against resistance
    • Raise eyebrows
    • Close eyes
    • Purse lips
    • Blow out cheeks
    • Bear teeth
    • Grimace

VIII - Vestibulocochlear

A full assessment of hearing should include:

  • Crude hearing
  • Rinne's & Weber's test
  • Rhomberg's test
  • Otoscopy

For the full guide on performing assessment of hearing and otoscopy, see Ear Examination & Otoscopy

IX, X - Glossopharyngeal, Vagus

  • Phonation - ask patient to repeat "tuhtuhtuh" and "kuhhuhkuh"
    • Speech problems - dysarthria or dysphonia
  • Patient says "aaah"
    • Uvula deviation - away from the lesion affected side
  • Gag reflex - not routinely tested.

XI - Accessory

  • Observe and palpate muscle bulk of Sternocleidomastoid and Trapezium
  • Ask patient to shrug shoulders, and turn their head to each side. Repeat against resistance

XII-Hypoglossal

Hypoglossal paralysis

Supplies efferent fibres to the muscles of the tongue

Inspection

  • Wasting
  • Fasciculations

Motor

  • Stick tongue out
    • Tongue deviation towards the affected side
  • Move tongue side to side while stuck out
  • Push tongue against inside of the cheeks against resistance of your hand

Wash Hands