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Yr 3 - Clinical Examinations > Cranial Nerve Examination > Flashcards

Cranial Nerve Examination Flashcards

1
Q

Which 8 pieces of equipment are required for a cranial nerve exam?

For which cranial nerves is each required for?

A
  1. Pen torch - CN II
  2. Snellen chart - CN II
  3. Ishihara plates - CN II
  4. Opthalmoscope and mydriatic eye drops - CN II
  5. Cotton wool - CN V
  6. Neuro-tip - CN V
  7. Tuning fork (512 Hz) - CN VIII
  8. Glass of water - CN IX/X
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2
Q

How should patient be positioned at start of exam?

A

On chair at 1 arm’s length away

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3
Q

What 6 clinical signs are you assessing for during general inspection of a cranial nerve exam?

A
  • Speech abnormalities
  • Facial asymmetry
  • Eyelid abnormalities
  • Pupillary abnormalities
  • Strabismus
  • Limbs
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4
Q

Which CN pathology would speech abnormalities indicate?

A

Glossopharyngeal or vagus nerve

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5
Q

What CN pathology may facial asymmetry be suggestive of?

A

Facial nerve palsy

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6
Q

Which eyelid abnormality may indicate which CN pathology?

A

Ptosis may indicate oculomotor nerve pathology

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7
Q

Define mydriasis

A

Mydriasis is the dilation of the pupil

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8
Q

Which CN pathology may mydriasis indicate?

A

Oculomotor nerve pathology

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9
Q

What is strabismus?

A

A disorder in which both eyes do not line up in the same direction so do not look at the same object at the same time – most common form is ‘crossed eyes’

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10
Q

Which CN pathologies may strabismus indicate?

A

CN III (oculomotor), CN IV (trochlear) or CN VI (abducens)

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11
Q

How can you assess the limbs during a general inspection of a cranial nerve exam?

A

Pay attention to the patient’s arms and legs as they enter the room and take a seat noting any abnormalities (e.g. spasticity, weakness, wasting, tremor, fasciculation) which may suggest presence of a neurological syndrome

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12
Q

What objects and equipment are you looking for during general inspection of a CN exam?

A
  • Mobility aids
  • Prescription
  • Visual aids
  • Hearing aids
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13
Q

What may walking aids indicate in a CN exam?

A

Gait issues are associated with a wide range of neurological pathologies including Parkinson’s disease, stroke, cerebellar disease and myasthenia gravis

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14
Q

What may hearing aids indicate in a CN exam?

A

Often worn by patients with vestibulocochlear nerve issues (e.g. Meniere’s disease)

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15
Q

What is Meniere’s disease?

A

A disorder of the inner ear

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16
Q

What are the symptoms of Meniere’s disease?

A
  • Often unilateral (can spread to both after time)
  • Dizziness (vertigo – world spinning around you)
  • Hearing loss
  • Tinnitus
  • Pressure felt deep inside the ear
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17
Q

Define vertigo

A

Feeling like room is spinning around you

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18
Q

What may the use of visual aids such as visual prisms or occluders indicate?

A

Underlying strabismus

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19
Q

Where are the receptors of CN I located?

A

Olfactory receptors in the nasal epithelium

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20
Q

Skull foramina of CN I?

A

Cribriform plate in ethmoid bone

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21
Q

Describe pathway of olfactory receptors from nasal epithelium to olfactory cortex

A

1) Olfactory receptors in nasal epithelium
2) Axons pass through cribriform plate to olfactory bulb (synapse) and then to olfactory tract
3) Lateral olfactory striae take olfactory in formation to parahippocampal gyrus and amygdala (olfactory cortex)

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22
Q

Where is the olfactory cortex located?

A

Inferior surface of the temporal lobe

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23
Q

What is the function of CN I?

A

Special sensory - smell

There is no motor component

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24
Q

What is the assessment for CN I?

A

Ask patient if they have had any recent changes to sense of smell.

Olfaction can be tested more formally using different odours (e.g. lemon, peppermint) or most formally using University of Pennsylvania smell identification test (but this is unlikely to be required in an OSCE).

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25
Q

What are 5 causes of anosmia?

A
  1. Mucous blockage of nose
  2. Head trauma
  3. Genetics (congenital anosmia)
  4. Early feature of Parkinson’s disease
  5. COVID-19
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26
Q

How can head trauma lead to anosmia?

A

Can result in shearing of olfactory nerve fibres leading to anosmia

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27
Q

How can mucous blockage of the nose lead to anosmia?

A

Preventing odours from reaching olfactory nerve receptors

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28
Q

Which CNs are outgrowths of the telecephalon?

A

CN I and CN II

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29
Q

What is the CNS location of CN II?

A

Retina

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30
Q

Describe the pathway of CN II from the retina to the visual cortex

A

1) Emerge from back of eyes in retina and travels back until it reaches the optic chiasma (where 2 optic nerves converge)
2) Optic tracts then pass towards back of midbrain and hook upwards to connects with the lateral geniculate body of the thalamus (this includes LGN)
3) From LGB there are optic radiations – fibres that bring visual information from thalamus to primary visual cortex in occipital lobe

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31
Q

Where is the primary visual cortex located?

A

Posterior pole of occipital lobe

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32
Q

Which skull foramina does CN II pass through?

A

Optic canal in sphenoid bone

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33
Q

What is the function of CN II?

A

Special sensory - vision (brightness, colour, contrast)

There is NO motor component

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34
Q

What 8 aspects are involved in the assessment of CN II?

A

AFRO + Blind spot

Pupil Inspection

Acuity:

  • Snellen chart for visual acuity
  • Ishihara plates for colour vision (offer)

Fields:

  • Visual fields
  • Visual inattention

Reflexes:

  • Direct & consensual
  • Swinging light
  • Accomodation

Ophthalmoscopy

+ blind spot (offer)

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35
Q

What 3 things are you assessing when inspecting the pupils (CN II)?

A
  1. Pupil size
  2. Pupil shape
  3. Pupil symmetry
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36
Q

How does pupil size change from infancy to adolescence?

A

Infancy - smaller

Adolescence - bigger

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37
Q

What is the normal pupil shape?

A

Round

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38
Q

What can abnormal pupil shape be caused by?

A

Congenital or due to pathology

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39
Q

What are synechiae?

A

Adhesions formed between adjacent structures within the eye usually a result of inflammation

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40
Q

Where are posterior synechiae located?

A

Adhesions between the posterior iris and anterior lens surface

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41
Q

How can posterior synechiae affect the pupil shape? Why?

A

Abnormal pupil shape - adhesions prevent dilation

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42
Q

What is posterior synechiae associated with?

A

Uveitis (eye inflammation) caused by e.g. ocular trauma

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43
Q

What are peaked pupils in the context of trauma suggestive of?

A

Globe injury

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44
Q

What is a globe injury?

A
  • In ocular trauma, injuries can be classified as either closed globe or open globe
  • Globe rupture is where the integrity of the outer membranes of the eye are disrupted by blunt or penetrating trauma
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45
Q

What is the effect of a globe injury on the pupil?

A

Peaked pupil

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46
Q

Define anisocoria

A

Anisocoria is unequal pupil size.

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47
Q

What can cause anisocoria?

A

this may be longstanding and non-pathological or relate to actual pathology

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48
Q

In pupil asymmetry - if one pupil is more pronounced in bright light, which pupil is abnormal?

A

The larger pupil

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49
Q

In pupil asymmetry - if one pupil is more pronounced in dark, which pupil is abnormal?

A

The smaller pupil

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50
Q

How does oculomotor nerve palsy affect pupil symmetry?

A

Causes a large pupil in the affected eye

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51
Q

How does Horner’s syndrome affect pupil symmetry?

A

Causes a small and reactive pupil in the affected eye

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52
Q

Define visual acuity

A

the clarity or sharpness of vision.

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53
Q

What piece of equipment is used to assess visual acuity?

A

A Snellen chart

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54
Q

If a patient normally uses distance glasses, should these be worn for the visual acuity assessment?

A

Yes

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55
Q

Describe the steps of assessing visual acuity using a Snellen chart

A
  1. Stand the patient at 6 metres from the Snellen chart.
  2. Ask the patient to cover one eye and read the lowest line they are able to.
  3. Record the lowest line the patient was able to read (e.g. 6/6 (metric) which is equivalent to 20/20 (imperial).
  4. You can have the patient read through a pinhole to see if this improves vision (if vision is improved with a pinhole, it suggests there is a refractive component to the patient’s poor vision).
  5. Repeat the above steps with the other eye.
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56
Q

How many metres should the patient stand away from the Snellen chart?

A

6 metres

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57
Q

If reading through a pinhole during visual acuity assessment improves vision, what does this suggest?

A

it suggests there is a refractive component to the patient’s poor vision

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58
Q

How is visual acuity recorded?

A

Chart distance (numerator) over the number of the lowest line read (denominator).

E.g. if the patient reads the 6/6 line but gets 2 letters incorrect, you would record as 6/6 (-2).

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

When recording the vision, it should state whether this vision was unaided (UA), with glasses or with pinhole (PH).

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59
Q

If the patient is unable to read the top line of the Snellen chart at 6 metres (even with pinhole), what steps can be taken?

A
  1. Reduce the distance to 3 metres from the Snellen chart (the acuity would then be recorded as 3/denominator).
  2. Reduce the distance to 1 metre from the Snellen chart (1/denominator).
  3. Assess if they can count the number of fingers you’re holding up (recorded as “Counting Fingers” or “CF”).
  4. Assess if they can see gross hand movements (recorded as “Hand Movements” or “HM”).
  5. Assess if they can detect light from a pen torch shone into each eye (“Perception of Light”/”PL” or “No Perception of Light”/”NPL”).
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60
Q

What are 5 causes of decreased visual acuity?

A
  • Refractive errors
  • Amblyopia
  • Ocular media opacities e.g. cataract, corneal scarring
  • Optic nerve CN II pathology e.g. optic neuritis
  • Lesions higher in the visual pathway
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61
Q

Define ambylopia

A

Impaired or dim vision without obvious defect or change in the eye.

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62
Q

How does CN II pathology affect visual acuity?

A

CN II pathology usually causes a decrease in acuity in the affected eye

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63
Q

What is papilloedema?

A

Optic disc swelling from raised intracranial pressure e.g. head injury, malignant hypertension

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64
Q

How does papilloedema affect visual acuity?

A

Does not affect visual acuity until it is at a late stage

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65
Q

What step should first be taken when assessing pupillary reflexes?

A

With the patient seated, dim the lights to allow you to assess pupillary reflexes effectively.

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66
Q

What 4 tests are involved in assessment of pupillary reflexes?

A
  1. Direct pupillary reflex
  2. Consensual pupillary reflex
  3. Swinging light test
  4. Accommodation reflex
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67
Q

How is a direct pupillary light reflex performed?

A

Shine the light from your pen torch into the patient’s pupil and observe for pupillary restriction in the ipsilateral eye.

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68
Q

What is a normal direct pupillary reflex?

A

Constriction of the pupil that the light is being shone into

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69
Q

How is a consensual pupillary light reflex performed?

A

Once again shine the light from your pen torch into the same pupil, but this time observe for pupillary restriction in the contralateral eye.

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70
Q

What is a normal consensual pupillary reflex?

A

A normal consensual pupillary reflex involves the contralateral pupil constricting as a response to light entering the eye being tested (due to dual efferent pathways)

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71
Q

How is a swinging light test performed?

A

Move the pen torch rapidly between the two pupils

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72
Q

What equipment is required for the pupillary reflex tests?

A

Pen torch

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73
Q

What defect is the swinging light test assessing for?

A

Relative afferent pupillary defect

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74
Q

What is a normal result of the swinging light test?

A

Pupils of both eyes constrict equally regardless of which eye is stimulated by the light

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75
Q

What is relative afferent pupillary defect (RAPD)?

A

A condition in which pupils respond differently to light stimuli shone in one eye

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76
Q

What is the cause of RAPD?

A

Unilateral or asymmetrical disease of the retina or optic nerve

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77
Q

What test is used to assess for RAPD?

A

Swinging light test

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78
Q

What is the result of the swinging light test in RAPD?

A

Pupils dilate when a bright light is swung from unaffected eye to affected eye i.e. less pupil constriction in the eye with retinal/optic nerve disease

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79
Q

What is the purpose of the accommodation reflex?

A

To coordinate visual attention to near objects.

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80
Q

How is the accommodation reflex test performed?

A
  1. Ask the patient to focus on a distant object (clock on the wall/light switch).
  2. Place your finger approximately 20-30cm in front of their eyes (alternatively, use the patient’s own thumb).
  3. Ask the patient to switch from looking at the distant object to the nearby finger/thumb.
  4. Observe the pupils, you should see constriction and convergence bilaterally.
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81
Q

What is the normal result of the accommodation reflex test?

A

you should see constriction and convergence bilaterally

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82
Q

Each afferent limb of the pupillary light reflex has how many efferent limbs?

A

2 - one ipsilateral and one contralateral

83
Q

Which CN is involved in the afferent limb of the pupillary light reflex?

A

CN II

84
Q

Describe the afferent limb of the pupillary light reflex

A

Sensory input (e.g. light being shone into eye) is transmitted from the retina, along the optic nerve to the ipsilateral pretectal nucleus in the midbrain

85
Q

Which CN is involved in the efferent limb of the pupillary light reflex?

A

CN III

86
Q

Describe the two efferent limbs of the pupillary light reflex

A
  • Motor output is transmitted from the pretectal nucleus to the Edinger-Westphal nuclei on both sides of the brain (ipsilateral and contralateral)
  • Each Edinger-Westphal nucleus gives rise to efferent nerve fibres which travel in the oculomotor nerve to innervate the ciliary sphincter and enable pupillary constriction
87
Q

Which limb of the pupillary light reflex is the direct pupillary light reflex testing?

A

Assesses the ipsilateral afferent limb and ipsilateral efferent limb of the pathway

88
Q

Which limb of the pupillary light reflex is the consensual pupillary light reflex testing?

A

the contralateral efferent limb of the pathway

89
Q

Which limb of the swinging light test is the direct pupillary light reflex testing?

A

used to detect relative afferent limb defects

90
Q

What is RAPD also known as?

A

Marcus-Gunn pupil

91
Q

What is limb of the pupillary light reflex is damaged in RAPD/Marcus-Gunn pupil?

A

The afferent limb in one of the optic nerves

92
Q

How does this defect present in RAPD present during a swinging torch test?

A

When the afferent limb in one of the optic nerves is damaged, partially or completely, both pupils will constrict less when light is shone into the affected eye compared to the healthy eye

The pupils, therefore, appear to relatively dilate when swinging the torch from the healthy to the affected eye (RAPD).

93
Q

What is the cause of RAPD?

A
  • Significant retinal damage in the affected eye 2ary to central retinal artery or vein occlusion and large retinal detachment
  • Significant optic neuropathy e.g. optic neuritis, unilateral advanced glaucoma and compression 2ary to tumour or abscess
94
Q

How would a unilateral efferent defect present?

A
  • Loss of efferent limb of ipsilateral pupillary reflexes
  • Ipsilateral pupil is dilated** and **non-responsive to light entering either eye; due to loss of ciliary sphincter function
  • Consensual light reflex in unaffected eye would still be present as the afferent pathway (i.e. optic nerve) of affected eye and efferent pathway (i.e. oculomotor nerve) of unaffected eye remain intact
95
Q

Cause of unilateral efferent defect?

A

Extrinsic compression of the oculomotor nerve

96
Q

What equipment is required for colour vision assessment?

A

Ishihara plates

97
Q

Ishihara plates are difficult/impossible to see for those with which defect?

A

For those with a red-green colour vision defect.

98
Q

Describe the steps of the colour vision assessment

A

If the patient normally wears glasses for reading, ensure these are worn for the assessment.

1. Ask the patient to cover one of their eyes.

2. Then ask the patient to read the numbers on the Ishihara plates. The first page is usually the ‘test plate’ which does not test colour vision and instead assesses contrast sensitivity. If the patient is unable to read the test plate, you should document this.

3. If the patient is able to read the test plate, you should move through all of the Ishihara plates, asking the patient to identify the number on each. Once the test is complete, you should document the number of plates the patient identified correctly, including the test plate (e.g. 13/13).

4. Repeat the assessment on the other eye.

99
Q

What is usually the first page of the Ishihara plates? What does it assess?

A

The first page is usually the ‘test plate’ which does not test colour vision and instead assesses contrast sensitivity.

100
Q

What are some causes of acquired colour vision deficiencies?

A
  • Optic neuritis: results in a reduction of colour vision (typically red)
  • Vitamin A deficiency
  • Chronic solvent exposure
101
Q

What vitamin deficiency is often implicated in acquired colour vision deficiencies?

A

A

102
Q

What is visual neglect/inattention?

A

a condition in which an individual develops a deficit in their awareness of one side of their visual field

103
Q

What injury is typically implicated in visual neglect?

A

Parietal lobe injury after a stroke - results in an inability to perceive or process stimuli on one side of the body

N.B. The side of the visual field that is affected is contralateral to the location of the parietal lesion.

104
Q

Why is the visual neglect test not often included in a CN OSCE?

A

As visual neglect is not caused by optic nerve pathology

105
Q

Describe the steps off the visual neglect test

A

1. Position yourself sitting opposite the patient approximately 1 metre away.

2. Ask the patient to remain focused on a fixed point on your face (e.g. nose) and to state if they see your left, right or both hands moving.

3. Hold your hands out laterally with each occupying one side of the patient’s visual field (i.e. left and right).

4. Take turns wiggling a finger on each hand to see if the patient is able to correctly identify which hand has moved.

5. Finally wiggle both fingers simultaneously to see if the patient is able to correctly identify this (often patients with visual neglect will only report the hand moving in the unaffected visual field – i.e. ipsilateral to the primary brain lesion).

106
Q

The visual fields assessment relies on comparing the patient’s visual fields with your own. Therefore, what 2 aspects is needed for it to work?

A
  • You need to position yourself, the patient and the target correctly
  • You need to have normal visual fields and a normal-sized blind spot
107
Q

Describe the steps of the visual fields assessment

A

This method of assessment relies on comparing the patient’s visual field with your own and therefore for it to work:

  • You need to position yourself, the patient and the target correctly (see details below)
  • You need to have normal visual fields and a normal-sized blind spot

1. Sit directly opposite the patient, at a distance of around 1 metre.

2. Ask the patient to cover one eye with their hand.

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

4. Ask the patient to focus on part of your face (e.g. nose) and not move their head or eyes during the assessment. You should do the same and focus your gaze on the patient’s face.

5. As a screen for central visual field loss or distortion, ask the patient if any part of your face is missing or distorted. A formal assessment can be completed with an Amsler chart.

6. Position the hatpin (or another visual target such as your finger) at an equal distance between you and the patient (this is essential for the assessment to work).

7. Assess the patient’s peripheral visual field by comparing to your own and using the target. Start from the periphery and slowly move the target towards the centre, asking the patient to report when they first see it. If you are able to see the target but the patient cannot, this would suggest the patient has a reduced visual field.

8. Repeat this process for each visual field quadrant, then repeat the entire process for the other eye.

9. Document your findings.

108
Q

During the visual field assessment, how do you screen for central visual field loss or distortion?

A

Ask the patient if any part of your face is missing or distorted.

A formal assessment can be completed with an Amsler chart.

109
Q

Describe bitemporal hemianopia.

What is it caused by?

A

Loss of temporal visual field in both eyes resulting in central tunnel vision

Cause - typically result of optic chiasm compression by a tumour (e.g. pituitary adenoma, craniopharyngioma)

110
Q

What is a homonymous field defect? What are they commonly attributed to?

A

Affects the same side of the visual field in each eye

Commonly attributed to stroke, tumour, abscess (pathology affecting visual fields posterior to the optic chiasm)

111
Q

Heminanopia vs quadrantopia?

A

Hemianopia → when half the vision is affected

Quadrantopia → when a quarter of the vision is affected

112
Q

What is a scotoma?

A

An area of absent or reduced vision surrounded by areas of normal vision

113
Q

What can cause a scotoma?

A

A range of possible aetiologies including demyelinating disease (e.g. multiple sclerosis) and diabetic maculopathy.

114
Q

What is monocular vision loss? What is it caused by?

A

Total loss of vision in one eye

Caused by optic nerve pathology (e.g. anterior ischaemic optic neuropathy) or ocular diseases (e.g. central retinal artery occlusion, total retinal detachment)

115
Q

What does everyone have a physiological blind spot?

A

A physiological blind spot exists in all healthy individuals as a result of the lack of photoreceptor cells in the area where the optic nerve passes through the optic disc.

116
Q

How does the brain reduce our awareness of our blind spot?

A

by using information from other areas of the retina and the other eye to mask the defect

117
Q

Describe the steps in assessment of the patient’s blind spot

A

1. Sit directly opposite the patient, at a distance of around 1 metre.

2. Ask the patient to cover one eye with their hand.

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

4. Ask the patient to focus on part of your face (e.g. nose) and not move their head or eyes during the assessment. You should do the same and focus your gaze on the patient’s face.

5. Using a red hatpin (or alternatively, a cotton bud stained with fluorescein/pen with a red base) start by identifying and assessing the patient’s blind spot in comparison to the size of your own. The red hatpin needs to be positioned at an equal distance between you and the patient for this to work.

6. Ask the patient to say when the red part of the hatpin disappears, whilst continuing to focus on the same point on your face.

7. With the red hatpin positioned equidistant between you and the patient, slowly move it laterally until the patient reports the disappearance of the top of the hatpin. The blind spot is normally found just temporal to central vision at eye level. The disappearance of the hatpin should occur at a similar point for you and the patient.

8. After the hatpin has disappeared for the patient, continue to move it laterally and ask the patient to let you know when they can see it again. The point at which the patient reports the hatpin re-appearing should be similar to the point at which it re-appears for you (presuming the patient and you have a normal blind spot).

9. You can further assess the superior and inferior borders of the blind spot using the same process.

118
Q

Where is the blind spot normally found?

A

The blind spot is normally found just temporal to central vision at eye level.

119
Q

In the context of a cranial nerve examination, why is fundoscopy performed?

A

To assess the optic disc for signs of pathology (e.g. papilloedema).

You should offer to perform fundoscopy in your OSCE, however, it may not be required.

120
Q

What is the function of CN III?

A
  • Somatic motor - majority of the extraocular muscles (levator palpebrae superioris, SR, IR, MR, IO)
  • Parasympathetic (visceral motor) - sphincter pupillae and ciliary muscle
  • Sympathetic - no direct function, but sympathetic fibres run with the oculomotor nerve to innervate the superior tarsal muscle (helps to raise the eyelid).
121
Q

Function of CN IV?

A

Somatic motor - superior oblique (extraocular muscle)

122
Q

Function of CN VI

A

Somatic motor - lateral rectus (extraocular)

123
Q

What is the CNS location of CN III?

A

Pontomesencephalic junction (between midbrain and pons)

124
Q

What is the CNS location of CN IV?

Of CN VI?

A

IV - dorsal midbrain

VI - pontomedullary junction

125
Q

Which skull foramina does CN III, IV and VI pass through?

A

Superior orbital fissure

126
Q

What 3 aspects are involved in the assessment of CN III, IV and VI?

A
  1. Eyelid inspection
  2. Eye movements
  3. Strabismus assessment
127
Q

Why are CN III, IV and VI assessed together?

A

Similar function

128
Q

What are you assessing the eyelids for in assessment of CN III, IV and VI?

A

Ptosis

129
Q

What 3 conditions can ptosis be associated with?

A
  1. Horner’s syndrome
  2. Oculomotor nerve pathology
  3. Neuromuscular pathology (e.g. myasthenia gravis)
130
Q

Which CN pathology can ptosis be associated with?

A

CN III

131
Q

Which CN palsy can abnormalities of eye movements be caused by?

A

oculomotor, trochlear, abducens, vestibular nerve pathology

132
Q

Describe the steps of assessing eye movements in assessment of CN III, IV and VI

A

1. Hold your finger (or a pin) approximately 30cm in front of the patient’s eyes and ask them to focus on it. Look at the eyes in the primary position for any deviation or abnormal movements.

2. Ask the patient to keep their head still whilst following your finger with their eyes. Ask them to let you know if they experience any double vision or pain.

3. Move your finger through the various axes of eye movement in a ‘H’ pattern.

4. Observe for any restriction of eye movement and note any nystagmus (which may suggest vestibular nerve pathology or stroke).

133
Q

What should you observe for during assessment of eye movements (III, IV, VI)?

A
  • Restriction of eye movement
  • Nystagmus (vestibular nerve pathology, stroke)
134
Q

What is the action of:

  1. Superior rectus
  2. Inferior rectus
  3. Medial rectus
  4. Lateral rectus
  5. Superior oblique
  6. Inferior oblique
A
  1. Elevation of eyeball (2ary actions: adduction and medial rotation)
  2. Depression of eyeball (2ary: adduction and lateral rotation)
  3. Adduction of eyeball
  4. Abduction of eyeball
  5. Depresses, abducts and medially rotates
  6. Elevates, abducts and laterally rotates
135
Q

Which 2 extraocular muscles does CN III not supply?

A

Superior oblique (IV) and lateral rectus (VI)

136
Q

What does oculomotor nerve palsy result in?

A

Unopposed action of lateral rectus and superior oblique muscles (which pull the eye inferolaterally) → ‘down and out’ pupil

137
Q

What does oculomotor nerve palsy result in?

What is the presentation of the patient?

A

Unopposed action of lateral rectus and superior oblique muscles (which pull the eye inferolaterally)

Presentation:

  • ‘Down and out’ appearance of the affected eye
  • Ptosis (due to loss of innervation to levator palpebrae superioris)
  • Mydriasis (due to loss of parasympathetic fibres to sphincter pupillae)
138
Q

What is action of levator palpebrae superioris?

A

The function of the levator palpebrae superioris muscle is to raise the upper eyelid and to maintain the upper eyelid position.

139
Q

Define ptosis

A

drooping of the upper eyelid

140
Q

Define mydriasis

A

dilation of the pupil of the eye.

141
Q

What is the action of sphincter pupillae?

A

constrict the pupil in bright light via the pupillary light reflex or during accommodation

142
Q

What does trochlear nerve (IV) palsy result in? What is the presentation of the patient?

A

Loss of superior oblique’s action of pulling the eye downwards as well as its assistance with intorsion of the eye as the head tilts.

Presentation:

  • Vertical diplopia when looking inferiorly - patient’s try to compensate by tilting their head forwards and tucking their chin in which minimises vertical diplopia
  • Torsional diplopia - patient’s try to compensate by tilting their head to the opposite side in order to fuse the two images together
143
Q

Define vertical diplopia

A

Patients with vertical diplopia complain of seeing two images, one atop or diagonally displaced from the other.

144
Q

What CN palsy causes vertical diplopia?

A

CN IV (trochlear) → causing superior oblique palsy

145
Q

How do patients with vertical diplopia compensate?

A

by tilting their head forwards and tucking their chin in

146
Q

What CN palsy causes torisonal diplopia?

A

CN IV (trochlear) → due to superior oblique palsy

147
Q

What does CN VI (abducens) palsy result in? What is the presentation?

A

Paralysis of the lateral rectus muscle results in unopposed adduction of the eye (by medial rectus).

Presentation: horizontal diplopia which is worsened when they attempt to look towards the affected side

148
Q

Horizontal vs vertical diplopia?

A

Vertical diplopia indicates vertical alignment of the images, which usually suggests pathology in the vertical muscles, including superior oblique, inferior oblique, superior rectus, and inferior rectus.

Horizontal diplopia suggests pathology of the medial or lateral rectus.

149
Q

What is strabismus?

A

Strabismus is a condition in which the eyes do not properly align with each other when looking at an object.

Pathology affecting the oculomotor, trochlear or abducens nerves can cause strabismus.

150
Q

What 2 tests are used to assess strabismus in CN III, IV and VI examination?

A
  1. Light reflex test (corneal reflex test/Hirschberg test)
  2. Cover test
151
Q

Describe the steps of the light reflex test

A

1. Ask the patient to focus on a target approximately half a metre away whilst you shine a pen torch towards both eyes.

2. Inspect the corneal reflex on each eye

152
Q

What is a normal result of the light/corneal reflex test?

A

The corneal/blink/light reflex, is an involuntary blinking of the eyelids elicited by stimulation of the cornea, though could result from any peripheral stimulus (e.g. light). Stimulation should elicit both a direct and consensual response.

If the ocular alignment is normal, the light reflex will be positioned centrally and symmetrically in each pupil.

153
Q

What would suggest misalignment in the light/corneal reflex test?

A

Deflection of the corneal light reflex

154
Q

What is the purpose of the ‘cover test’?

A

The cover test is used to determine if a heterotropia (i.e. manifest strabismus) is present.

155
Q

What is a heterotropia?

A

Heterotropia is an upward deviation of the non-fixing eye.

156
Q

What steps are involved in the cover test?

A

1. Ask the patient to fixate on a target (e.g. light switch).

2. Occlude one of the patient’s eyes and observe the contralateral eye for a shift in fixation

3. Repeat the cover test on the other eye.

157
Q

In the cover test, if there is no shift in fixation in the contralateral eye while covering either eye, the patient is orthotropic. What does this mean?

A

Normal eye alignment

158
Q

In the cover test, if there is a shift in fixation in the contralateral eye, while covering the other eye, what does this indicate?

A

Heterotropia

159
Q

The direction of the shift in fixation during the cover test determines the type of tropia:

A
160
Q

Describe the direction of the:

a) eye at rest
b) shift in fixation of unoccluded eye when opposite eye is occluded

in exotropia

A

Exotropia → eye turned outward

a) temporally (laterally/outwardly)
b) nasally (medially/inwards)

161
Q

Describe the direction of the:

a) eye at rest
b) shift in fixation of unoccluded eye when opposite eye is occluded

in esotropia

A

Esotropia → eye turned inward

a) medially
b) laterally

162
Q

Describe the direction of the:

a) eye at rest
b) shift in fixation of unoccluded eye when opposite eye is occluded

in hypertropia?

A

Hypertropia → eye turned upwards

a) superiorly
b) inferiorly

163
Q

Describe the direction of the:

a) eye at rest
b) shift in fixation of unoccluded eye when opposite eye is occluded

in hypotropia?

A

Hypotropia → eye turned downward

a) downwards
b) upwards

164
Q

What is the CNS location of CN V?

A

Dorsal midbrain

165
Q

There are 3 parts to CN V.

Which skull foramina does each pass through?

A

V1 - superior orbital fissure

V2 - foramen rotundum

V3 - foramen ovale

166
Q

What is the function of each part of CN V?

A

Somatic sensation from:

  • V1 – upper face (scalp and forehead, nose, upper eyelid, conjunctiva and cornea of eye)
  • V2 – middle face (lower eyelid, cheek, nares, upper lip, upper teeth and gums)
  • V3:
    • Lower face (chin, jaw, lower lip, mouth, lower teeth and gums)
    • Somatic motor to muscles of mastication (masseter, temporal muscle and the medial/lateral pterygoids)
    • Tensor tympani (anterior 2/3 tongue), tensor veli palatini, mylohyoid and digastric muscles
167
Q

Which 3 aspects are involved in the assessment of CN V?

A
  1. Sensory assessment
  2. Motor assessment
  3. Reflexes
168
Q

Describe the steps of the sensory assessment of CN V exam

A

Ask the patient to close their eyes and say ‘yes’ each time they feel you touch their face.

Assess the sensory component of V1, V2 and V3 by testing light touch and pinprick sensation across regions of the face supplied by each branch:

  • Forehead (lateral aspect) → ophthalmic branch V1
  • Cheek → maxillary branch V2
  • Lower jaw (avoid angle of mandible as is supplied by C2/C3) → mandibular branch V3

You should compare each region on both sides of the face to allow the patient to identify subtle differences in sensation.

169
Q

Why should you avoid the angle of the mandible in sensory assessment of V3?

A

as it is supplied by C2/C3

170
Q

Before the light touch and pinprick sensation assessment of CN V on the face, what should you do first? Why?

A

First, explain the modalities of sensation you are going to assess (e.g. light touch/pinprick) to the patient by demonstrating on their sternum. This provides them with a reference of what the sensation should feel like (assuming they have no sensory deficits in the region overlying the sternum).

171
Q

What component of CN V are you assessing in the motor assessment part?

A

V3 - muscles of mastication

172
Q

Describe the steps of the motor assessment of CN V exam

A

1. Inspect the temporalis (located in the temple region) and masseter muscles (located at the posterior jaw) for evidence of wasting.

2. Palpate the masseter muscle (located at the posterior jaw) bilaterally whilst asking the patient to clench their teeth to allow you to assess and compare muscle bulk.

3. Ask the patient to open their mouth whilst you apply resistance underneath the jaw to assess the lateral pterygoid muscles.

173
Q

During the inspection of temporalis and masseter muscles for wasting, where is evidence of wasting most noticeable?

A

In the temporalis muscles, where a hollowing effect in the temple region is observed.

174
Q

What can an ability to open the jaw against resistance or deviation of the jaw (typically to the side of the lesion) indicate?

A

CN V palsy

175
Q

What 2 reflexes are assessed in the CN V exam?

A
  1. Jaw jerk reflex
  2. Corneal reflex
176
Q

What is the jaw jerk reflex?

A

The jaw jerk reflex is a stretch reflex that involves the slight jerking of the jaw upwards in response to a downward tap

177
Q

What CN is involved in the jaw jerk reflex?

A

Both afferent and efferent pathways of the jaw jerk reflex involve the trigeminal nerve.

178
Q

Who is the jaw jerk reflex exaggerated in?

A

patients with an upper motor neuron lesion

179
Q

Describe the steps of assessing the jaw jerk reflex

A

1. Clearly explain what the procedure will involve to the patient and gain consent to proceed.

2. Ask the patient to open their mouth.

3. Place your finger horizontally across the patient’s chin.

4. Tap your finger gently with the tendon hammer.

5. In healthy individuals, this should trigger a slight closure of the mouth. In patients with upper motor neuron lesions, the jaw may briskly move upwards causing the mouth to close completely

180
Q

What is the corneal reflex?

A

The corneal reflex involves involuntary blinking of both eyelids in response to unilateral corneal stimulation (direct and consensual blinking).

181
Q

What is the afferent and efferent branch of the corneal reflex pathway?

A

Afferent - V1 trigeminal

Efferent - temporal & zygomatic branches of CN VII

182
Q

Describe the steps of the corneal reflex in assessment of CN V

A

1. Clearly explain what the procedure will involve to the patient and gain consent to proceed.

2. Gently touch the edge of the cornea using a wisp of cotton wool.

3. In healthy individuals, you should observe both direct and consensual blinking. The absence of a blinking response suggests pathology involving either the trigeminal or facial nerve.

The corneal reflex is not usually assessed in an OSCE scenario, however, you should offer to test it and understand the purpose behind the test.

183
Q

What is the CNS location of CN VII (facial)?

A

Pontine-medulla junction

184
Q

What skull foramina does CN VII enter/exit via?

A

Enter - internal acoustic meatus

Exit - stylomastoid foramen

185
Q

What is the function of CN VII?

A

Motor - muscles of facial expression and the stapedius muscle

Sensory - conveyance of taste from anterior 2/3 of tongue

186
Q

What 2 aspects are involved in the assessment of CN VII?

A
  1. Sensory
  2. Motor
187
Q

What does the sensory assessment of CN VII involve?

A

Ask the patient is they have noticed any recent changes in their sense of taste.

188
Q

What 3 aspects does the motor assessment of CN VII involve?

A
  1. Hearing changes
  2. Inspection of the face
  3. Facial movement
189
Q

Why are you asking about hearing changes in the motor assessment of CN VII?

A

Ask the patient if they’ve noticed any changes to the hearing.

Paralysis of the stapedius muscle can result in hyperacusis (noise sensitivity)

190
Q

What are you inspecting the face for in CN VII assessment?

A

Inspect the patient’s face at rest for asymmetry, paying particular attention to:

  • Forehead wrinkles
  • Nasolabial folds
  • Angles of the mouth

CN VII controls muscles of facial expression

191
Q

During the ‘facial movement’ aspect of CN VII examination, ask the patient to carry out a sequence of facial expressions while observing for asymmetry.

What are these 5 facial expressions? What muscle does each assess?

A
  • Raised eyebrows: assesses frontalis – “Raise your eyebrows as if you’re surprised.”
  • Closed eyes: assesses orbicular oculi – “Scrunch up your eyes and don’t let me open them.”
  • Blown out cheeks: assesses orbicularis oris – “Blow out your cheeks and don’t let me deflate them.”
  • Smiling: assesses levator anguli oris and zygomaticus major – “Can you do a big smile for me?”
  • Pursed lips: assesses orbicularis oris and buccinator – “Can you try to whistle?”
192
Q

how does facial nerve palsy present?

A

with unilateral weakness of the muscles of facial expression

193
Q

Is facial nerve palsy caused by upper or lower motor neuron lesions?

A

Can be caused by both

194
Q

What is the most common cause of LMN facial palsy?

A

Bell’s palsy

195
Q

How does facial palsy caused by LMN lesion (i.e. Bell’s palsy) present?

A

Weakness of all ipsilateral muscles of facial expression:

  • Orbicularis oculi muscle and facial muscles involved
    • Unable to close eyes
    • Weakness of angle of mouth
    • Cannot elevate eyebrows
196
Q

What is the most common cause of UMN facial palsy?

A

Stroke

197
Q

How does an UMN facial palsy present (i.e. stroke)?

A

Unilateral facial muscle weakness, however, the upper facial muscles are partially spared because of bilateral cortical representation (resulting in forehead/frontalis function being somewhat maintained).

  • Can elevate eyebrows
  • Contralateral lower quadrant weakness (corner of mouth drops)
198
Q

CNS location of CN VIII (vestibulocochlear)?

A

Cerebellopontine angle

199
Q

Which skull foramina does CN VIII pass through?

A

Internal acoustic meatus

200
Q

What is the function of CN VIII?

A

Hearing and balance from inner ear to brain (special sensory)

201
Q

What 5 aspects are involved in the examination of CN VIII?

A
  1. Gross hearing assessment
  2. Rinne’s test
  3. Weber’s test
  4. Vestibular testing - Unterberger/Turning test
  5. Vestibular testing - Head thrust test/Vestibular-ocular reflex
202
Q

What is involved in the ‘gross hearing assessment’ of the CN VIII exam?

A
  1. Ask the patient if they’ve noticed any change in the hearing recently.
  2. Explain that you are going to say three words or three numbers and you’d like the patient to repeat them back to you (choose two-syllable words or bi-digit numbers).
203
Q

Describe the steps of the gross hearing assessment

A
  1. Position yourself approximately 60cm from the ear and then whisper a number or word.
  2. Mask the ear not being tested by rubbing the tragus. Do not place your arm across the face of the patient when rubbing the tragus, it is far nicer to occlude the ear from behind the head. If possible shield the patient’s eyes to prevent any visual stimulus.
  3. Ask the patient to repeat the number or word back to you. If they get two-thirds or more correct then their hearing level is 12db or better. If there is no response use a conversational voice (48db or worse) or loud voice (76db or worse).
  4. If there is no response you can move closer and repeat the test at 15cm. Here the thresholds are 34db for a whisper and 56db for a conversational voice.
  5. Assess the other ear in the same way.

Yr 3 - Clinical Examinations (11 decks)

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