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The cranial nerve examination is often considered one of the most difficult OSCE stations, but with plenty of practice you’ll be fine. The important thing to remember is that in an OSCE you’ll not be required to complete an entire cranial nerve exam in one station. This guide provides a step by step approach to cranial nerve examination, with an included video demonstration. Check out the cranial nerve examination mark scheme here.

Introduction

Wash hands

Introduce yourself

Confirm 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 arms length away

Ask if the patient currently has any pain.

Gather equipment

  • Pen torch
  • Snellen chart
  • Ishihara plates
  • Ophthalmoscope
  • Cotton wool
  • Neuro-tip
  • Tuning fork (512hz)
  • Glass of water
  • Mydriatic eye drops (if necessary)

General inspection

General appearance – comfortable at rest?

Obvious facial asymmetries?

Position of eyes – normal alignment / strabismus 

Ptosis – is this unilateral or bilateral?

Abnormality of speech or voice? – dysarthria 

Signs around the bed – e.g. hearing aid / glasses 

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  e.g. coffee / vinegar 

II – Optic nerve

Inspect pupils

Size – normally 2 to 4 mm in diameter in bright light and 4 to 8 mm in the dark

Shape – pupils should be round – abnormal shapes can be congenital or due to pathology

Symmetry – note any asymmetry between the pupils (anisocoria)

  • Inspect pupils.

Visual acuity

1. Stand the patient at 6 metres from the Snellen chart.

2. If the patient normally uses distance glasses, ensure these are worn for the assessment.

3. Ask the patient to cover one eye and read to the lowest line they are able to.

4. Visual acuity is recorded as chart distance (numerator) over the number of the 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. If the patient reads the 6/6 line, but gets 2 letters incorrect, you would record as 6/6 (-2).

7. If the patient gets more than 2 letters wrong, then the previous line should be recorded as their acuity.

8. You can have the patient read through a pinhole to see if this improves vision (if vision is improved with pinhole, it suggests there is a refractive element to their poor vision).

9. Repeat above steps with the other eye.

 

If the patient is unable to read top line at 6 metres (even with pinhole) move through the following steps as necessary:

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.

  • Assess visual acuity.

Pupillary reflexes

To best see pupillary reflexes the room should be dimly lit.

Direct pupillary reflex

Shine light into the pupil and observe constriction of that pupil.

Sluggish reaction or lack of constriction may suggest pathology – optic nerve / brain stem / drugs

 

Consensual pupillary reflex

Again shine a light into the pupil, but this time observe the contralateral pupil.

A normal consensual response involves the contralateral pupil constricting.

Lack of a normal consensual response may suggest:

  • Damage to one or both optic nerves
  • Damage to the Edinger-Westphal nucleus

 

Swinging light test

1. Move the pen torch rapidly between the 2 pupils.

This test may detect a relative afferent pupillary defect (RAPD) – caused by damage of the tract between the optic nerve and optic chiasm (e.g. optic neuritis in multiple sclerosis). It’s also known as a “Marcus-Gunn” pupil.

A RAPD can be detected by paradoxical dilatation of the affected pupil when light is shining into it (it should normally constrict).

 

Accommodation reflex

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

2. Place your finger/object approximately 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 and convergence bilaterally.

  • Assess direct & consensual pupillary reflexes.

 

Colour vision

Assess colour vision using Ishihara charts (unlikely to do this in an OSCE setting)

Ishihara_9

 

 

 

 

 

Visual inattention (visual neglect)

Sit directly facing the patient, approximately 1 metre away.

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

2. Hold both arms out, with your fingers in the periphery of both yours and the patient’s field of vision.

3. Remind the patient to keep their head still and their eyes fixed on your face.

4.  Move one of your fingers (on only one hand) and ask the patient to point at the hand on which the finger is moving.

5. Move the finger on the left and right hand individually in whichever order you prefer.

6. Then move the finger of both hands simultaneously.

7. If patient only reports a finger on one of the hands moving (whilst both are moving simultaneously), it suggests the presence of visual neglect.

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Visual fields

Sit directly facing the patient, approximately 1 metre away.

1. Ask the patient to cover their left eye with their left hand.

2. You should cover your right eye and be staring directly at the patient (mirroring the patient).

3. Ask the patient to focus on your face and 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 and 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 o’clock / 4 o’clock / 8 o’clock.

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

10. Map out any visual field defects you detect.

11. Repeat the same assessment process on the other eye.

  • Assess visual inattention.

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 patient’s 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 and examine the eye with the fundoscope

1. Begin medially and assess the optic disc – colour / contour / cupping

2. Assess the retinal vesselscotton wool spots / AV nipping / neovascularization

3. Finally assess the maculaask the patient to look directly into the light – drusen noted in macular degeneration

III, IV, VI – Oculomotor, Trochlear and Abducens nerves

Ptosis

Note any evidence of ptosis – e.g. oculomotor nerve pathology 

Eye movements

1. Ask the patient to keep their head still and follow your finger with their eyes.

2. Move your finger through the various axes of eye movement (“H” shape).

3. Ask the patient to report any double vision.

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

 

Cover test

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

2. Cover one of the patient’s eyes.

 

3. Observe the uncovered eye for movement:

  • No movement = normal response
  • Eye moves temporally = divergent squint (exotropia)
  • Eye moves nasally = convergent squint (esotropia)

4. Repeat the cover test on the other eye.

  • Assess eye movements using "H" test.

V – Trigeminal nerve

Sensory

Assess light touch and pinprick sensation:

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

Compare left to right for each branch.

Demonstrate sensation on patient’s sternum first, to ensure they understand what it should feel like.

 

Motor

1. Ask patient to clench their teeth whilst you feel 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)

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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:

  • Explain procedure and gain consent
  • Depress lower eyelid
  • Ask patient to look upwards
  • Touch edge of cornea using a wisp of cotton wool
  • Normal response = Direct and consensual blinking
  • Not usually required in an OSCE setting
  • Assess light touch sensation - Ophthalmic branch (V1)

VII – Facial nerve

Inspect the patient’s face at rest for asymmetry:

  • Forehead wrinkles 
  • Nasolabial folds
  • Angles of the mouth

 

Ask the patient to perform specific facial movements

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

Closed eyes  “scrunch up your eyes and don’t let me open them” – assess power

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

Smiling – “can you do a big smile for me?”note asymmetry 

Pursed lips – “can you attempt to whistle for me?” – note asymmetry

  • Raise eyebrows.

Other things to check…

Inspect external auditory meatus (EAM) herpes zoster lesions – Ramsay Hunt syndrome

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 

  • Inspect external auditory meatus.

VIII – Vestibulocochlear nerve

Gross hearing testing

Ask the patient if they have noticed a change in their hearing recently.

Assess each ear individually, standing behind the patient.

1. Explain to the patient that you’re going to say a word or number and you’d like them to repeat it back to you.

2. With your mouth approximately 15cm from the ear, whisper a number or word.

3. Mask the ear not being tested by rubbing the tragus.

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

5. If the patient repeats the correct word or number, repeat the test at an arms length from the ear (normal hearing allows whispers to be perceived at 60cm).

6. Assess the other ear in the same way.

  • Assess hearing at approximately 15cm

 

Rinne’s test

1. Tap a 512 Hz tuning fork and place at the external auditory meatus and ask the patient if they are able to hear it (air conduction)

2. Now move the tuning fork (whilst still vibrating), placing its base onto the mastoid process (bone conduction)

3. Ask the patient if the sound is louder in front of the ear (EAM) or behind it (mastoid process)

  • Normal = Air conduction > Bone conduction (Rinne’s positive)
  • Neural deafness = Air conduction > Bone conduction (both air and bone conduction reduced equally)
  • Conductive deafness = Bone conduction > Air conduction (Rinne’s negative)
  • Place tuning fork on the mastoid process.

 

Weber’s test

1. Tap a 512 Hz tuning fork and place in the midline of the forehead

2. Ask the patient where they can hear the sound:

  • 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
  • Place tuning fork in the midline of the forehead.

Vestibular testing – “turning test”

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

  • Normalpatient remains in the same position
  • Vestibular lesionpatient will turn towards the side of the lesion
  • Turning test - assessing for a vestibular lesion.

IX & X – Glossopharyngeal and Vagus nerves

Assess soft palate and 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 and X can result in a bovine cough

Swallowask patient to take a sip of water – note any coughing / delayed swallow

  • Assess soft palate and uvula.

XI – Accessory nerve

Ask patient to shrug shoulders and resist you pushing downtrapezius 

Ask patient to turn head to one side and resist you pushing it to the other sternocleidomastoid

Note any weakness

  • Assess Trapezius strength.

XII – Hypoglossal nerve

1. Inspect tongue for wasting and fasciculation at rest

2. Ask patient to protrude tongue – any deviation?

3. Place your finger on the patient’s cheek and ask to push their tongue against it – assess power

  • Inspect tongue at rest for fasciculations.

To complete the examination

Thank patient

Wash hands

Summarise findings

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Suggest further assessments and investigations

  • Perform further testing of any nerves that had abnormal results
  • Carry out a full neurological examination of the upper and lower limbs 
  • Further imaging – e.g. CT Head / MRI head 

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