Neurology Cranial Nerves Post Pic

Published on September 5th, 2010 | by Lewis Potter

Cranial nerve examination – OSCE Guide

The cranial nerve examination is often considered one of the most difficult, but with a decent amount of practice and some helpful acronyms along the way you’ll be fine. The important thing to remember is that in an OSCE you’ll rarely be required to complete an entire cranial nerve exam in one station.  

Introduction

Introduce yourself

Check patient details - name / DOB

Explain the examination  – “I’m going to be testing the nerves that supply your face”

Gain consent

Position patient on a chair at eye level, approximately 1 arm length away

Ask if the patient has any pain anywhere before you begin!

General Inspection

General appearance – comfortable at rest?

Head position – abnormal?

Obvious facial asymmetries?

Position of eyes - normal alignment / strabismus 

Abnormality of speech or voice? – dysarthria 

Signs around the bed - hearing aid / glasses / etc

I – Olfactory nerve

Any change in sense of smell? - “what was the last thing you remember smelling?”

With eyes closed, ask patient to identify various scents - coffee / vinegar /etc

II – Optic nerve
Pupils

Size - normal size is approximately 2-4mm in diameter  (bright light)

Position – assess pupil alignment – mis-alignment noted in strabismus

Ptosis – observe for evidence of ptosis 

..Pupils

 

 

Visual acuity

1. Stand the patient at 6 metres from the Snellen chart
2If patient normally uses distance glasses, ensure they wear them for the assessment
3. Ask the patient to cover one eye & read to the lowest line they can manage
4. Visual acuity is recorded as chart distance (numerator) over number of lowest line read (denominator)
5. Record the lowest line the patient was able to read (e.g. 6/6 which is equivalent to 20/20)
6. You can have the patient read through a pinhole to see if this improves vision
7. Repeat above steps with the other eye

 

If patient is unable to read top line at 6 metres (even with pinhole):

1. Reduce the distance to 3 metres from the Snellen chart
2. Reduce the distance to 1 metre from the Snellen chart
3. Assess if they can count the number of fingers you’re holding up
4. Assess if they can see gross hand movement
5. Assess if they can detect light from a pen torch shone into each each
If the patient is unable to perceive light, this suggests they are blind

Visual Acuity..

 

 

Pupillary reflexes

Direct reflex- shine torch into eye - look for pupillary constriction in that eye

Consensual reflex - shine torch into eye  - look for pupillary constriction in opposite eye

Swinging light test- move light in from side of each eye rapidly – relative afferent pupillary defect

 

Accommodation reflex:

1. Ask patient to focus on a distant point (clock on a wall / light switch /etc)

2. Place your finger / an object 15cm in front of the eyes

3. Ask the patient to switch from looking at the distant object to the nearby finger / object

4. Observe the pupils, you should see constriction & convergence bilaterally

Direct pupillary reflex Direct & Consensual Relfexes Accomodation

..

 

Colour Vision

Say you would use Ishihara charts (often don’t have to actually carry this out)

Ishihara_9

 

 

 

 

 

 

 

 

 

Visual Fields
Sit directly facing the patient, approximately 1 metre away
 

Visual inattention

1. Ask patient to focus on your face & not move their head or eyes during the assessment
2. Hold both arms out, with your fingers in the periphery of both yours & the patients field of vision
3. Remind the patient to keep their head still & their eyes fixed on your face
4. Ask patient to point at which fingers are moving
5. Move the fingers of left & right hand in whichever order you choose
6. Then move the fingers of both hands simultaneously
7. If patient only notes one side moving, this suggests the presence of visual neglect

Visual Innattention

 
 
 
 
 
 
 
 
 
 
 
..
Detailed visual fields

1. Ask patient to cover one eye with their hand

2. If the patient covers their right eye, you should cover your left eye (mirror the patient)

3. Ask patient to focus on your face & not move their head or eyes during the assessment

4. Ask the patient to tell you when they can see your fingertip wiggling

5. Outstretch your arms, ensuring they are situated at equal distance between yourself & the patient

6. Position your fingertip at the outer border of one of the quadrants of your visual field

7. Slowly bring your fingertip inwards, towards the centre of your visual field until the patient sees it

8. Repeat this process for each quadrant – at 10 o’clock  /2 oclock / 4 o’clock / 8 o’clock

9. If you are able to see your fingertip, but the patient cannot, this would suggest a reduced visual field

10. Repeat this assessment process on the other eye

Visual Fields Visual field - lower
 
 
 
Fundoscopy

Preparation

1. Darken the room

2. The patient should have their pupils dilated with short-acting mydriatic eye drops 

3. Ask the patient to fixate on a distant object

 

Assess for red reflex

1. Position yourself at a distance of around 30cm from the patients eyes
2. Looking through the ophthalmoscope observe for a reddish / orange reflection in the pupil

An absent red reflex may indicate the presence of cataract, or in rare circumstances neuroblastoma

 

Move in closer & examine the eye with the fundoscope

Begin medially & assess the optic disc - colour / contour / cupping
Assess the retinal vesselscotton wool spots / AV nipping / neovascularisation
Finally assess the maculaask to look directly into the light – drusen noted in macular degeneration

III, IV, VI – Occulomotor, Trochlear & Abducens nerves
Eye movements

1. Ask the patient to keep their head still & follow your finger with their eyes
2. Move your finger through the various axis of eye movement (“H” shape)

3. Ask the patient to report any double vision

4. Observe for restriction of eye movement & note any nystagmus

 

H - Test

Eye movement - H test
Cover Test

1. Ask patient to focus on a target (e.g. your pen top)

2. Cover one of the patients eyes

 

3. Observe the uncovered eye for movement:

  • No movement = normal response
  • Eye moves temporally = convergent squint
  • Eye moves nasally = divergent squint

4. Repeat the cover test on the other eye

V – Trigeminal Nerve
Sensory

Assess light touch & pin-prick sensation:

  • Forehead - opthalmic branch (V1)
  • Cheek - maxillary branch (V2)
  • Jaw – mandibular branch (V3)

Compare left to right for each branch

Demonstrate sensation of patients sternum first, to ensure they understand what it should feel like

Sensory Trigeminal Opthalmic Trigeminal Maxillary Trigeminal - Mandibular Trigeminal - Sharp Touch

 

Motor

1. Ask patient to clench teeth & feel for the bulk of masseter and temporalis bilaterally

2. Ask patient to open their mouth whilst you apply resistance under the jaw – note any deviation (jaw will deviate to side of lesion)

Temporarlis Bulk - Trigem Trigeminal Motor - Masseter..
Reflexes

 

Jaw jerk:

  • Ask patient to open mouth loosely
  • Place your finger horizontally across the chin
  • Tap your finger with a tendon hammer
  • Normal = slight closure of the jaw
  • Abnormal = brisk, complete closure of the jaw – UMN lesion

 

Corneal reflex - touch cornea using a wisp of cotton wool – observe for direct/consensual blinking

VII – Facial nerve
Inspect the patients face at rest for asymmetry, paying attention too…

Forehead wrinkles
Nasolabial folds
Angles of the mouth

 

Ask the patient to perform the following facial movements…

Raised eyebrows – “raise your eyebrows as if you’re surprised” – observe for asymmetry

Scrunched up eyes - “scrunch up your eyes & don’t let me open them” – assess power

Blown out cheeks“blow out your cheeks & don’t let me deflate them” – assess power

Baring teeth“can you do a big smile for me?” – note any asymmetry 

Purse lips - “can you attempt to whistle for me?” – note any asymmetry

 

Other things to check…

Inspect external auditory meatus - herpes zoster lesions – Bell’s Palsy

Any hearing changes? - facial nerve supplies stapedius – paralysis results in hyperacusis

Any taste changes? - supplies taste sensation to the anterior 2/3 of the tongue 

VIII – Vestibulocochear  Nerve

 

Raise eyebrows Facial - Eyes screwed up Blow Out Cheeks Purse Lips Bare Teeth Smile

 

 

VIII – Vestibulocochear  nerve
Gross hearing testing

1. Assess each ear individually

2. Whisper a number into the patients ear – 66 and 99 are often used

3. Mask the ear not being tested by rubbing two fingers together beside it to create white noise

4. Ask the patient to repeat the number back to you

5. Assess the other ear in the same way

..
Gross hearing
Gross hearing left side
Rinne’s test

1. Tap a 512HZ tuning fork & place onto mastoid process- bone conduction

2. When patient can no longer hear the tuning fork, hold it next to the ear – air conduction

3. Ask the patient if they can now hear the tuning fork:

  • Normal = Air conduction > Bone conduction (Rinne’s positive)
  • Neural deafness = Air conduction > Bone conduction
  • Conductive deafness = Bone conduction > Air conduction (Rinne’s negative)

Air conduction RinneBoneConduction 

Weber’s test

1. Tap a  512HZ tuning fork & place in the midline of the forehead

2. Ask the patient if the sound is louder on a particular side:

  • Normal = sound is heard equally in both ears
  • Neural deafness = sound is heard louder on the side of the intact ear
  • Conductive deafness = sound is heard louder on the side of the affected ear

Webers Test

 

Vestibular testing – turning test

Ask patient to march on spot with arms outstretched & eyes closed:

  • Normal – patient remains in the same position
  • Vestibular lesion – patient will turn toward the side of the lesion
IX & X – Glossopharyngeal & Vagus nerves

Assess soft palate & uvula:

  • Symmetry – note any obvious deviation of the uvula
  • Ask patient to say “ahhhh” – observe uvula moving upwards – any deviation?

Gag reflexyou won’t do this in the OSCE, but just make sure you mention it!
Ask patient to cough- damage to nerves IX & X can result in a “bovine” cough
Swallowask patient to take a sip of water – note any coughing / delayed swallow

Glossopharyngeal - Soft palate

 

 

 

 

 

 

 

 

XI – Accessory nerve

Ask patient to shrug shoulders & resist you pushing downtrapezius 

Ask patient to turn head to 1 side & resist you pushing it to the other - sternocleidomastoid

Note any unilateral / bilateral weakness present

Trapezius Muscle Strength Sternocleidomastoid Stregth

 

XII – Hypoglossal nerve

1. Inspect tongue for wasting & fasciculation at rest
2. Ask patient to protrude tongue –
any deviation?
3. Place your finger on the patients cheek & ask to push their tongue against it – 
weakness?

Hypoglossal - Tongue in mouth Tongue sticking out Tongue in cheek

 

 

 

 

 

 

 

 

 

To complete the examination

Thank patient

Wash hands

Summarise findings

.

Say you would…

Perform further testing of any nerves that had abnormal results

Carry out a full neurological examination of the upper / lower limbs 

Perform further imaging if indicated – MRI / CT head

 

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