Cranial Nerve Exam Flashcards

1
Q

What are you looking for in general inspection?

A
  1. Speech abnormalities
  2. Facial Asymmetry
  3. Eyelid abnormalities
  4. Pupillary abnormalities
  5. Strabismus
  6. Limbs
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2
Q

What could speech abnormalities indicate?

A

glossopharyngeal or vagus nerve pathology

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3
Q

What would facial asymmetry indicate?

A

facial nerve palsy

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4
Q

What would eyelid abnormalities indicate?

A

ptosis may indicate oculomotor nerve pathology

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5
Q

What would pupillary abnormalities indicate?

A

mydriasis occurs in oculomotor nerve palsy

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6
Q

What would strabismus indicate?

A

oculomotor, trochlear or abducens nerve palsy

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7
Q

Why do you look at limbs?

A

any abnormalities (e.g. spasticity, weakness, wasting, tremor, fasciculation) which may suggest the presence of a neurological syndrome

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8
Q

What objects or equipment are you looking for around the bed?

A
  1. Walking aids
  2. Hearing aids
  3. Visual aids
  4. Prescriptions
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9
Q

What could walking aids indicate?

A

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

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10
Q

What would hearing aids indicate?

A

patients with vestibulocochlear nerve issues (e.g. Ménière’s disease).

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11
Q

What would visual aids indicate?

A

use of visual prisms or occluders may indicate underlying strabismus

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12
Q

What are causes on anosmia (CN1)?

A
  1. Mucous blockage of the nose: preventing odours from reaching the olfactory nerve receptors.
  2. Head trauma: can result in shearing of the olfactory nerve fibres leading to anosmia.
    3 Genetics: some individuals have congenital anosmia.
  3. Parkinson’s disease: anosmia is an early feature of Parkinson’s disease
  4. COVID-19
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13
Q

What is asymmetry in pupil size between pupils called?

A

aniscocoria

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14
Q

What are examples of asymmetry of pupil size?

A
  1. large pupil in oculomotor nerve palsy and

2. small and reactive pupil in Horner’s syndrome

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15
Q

What could peaked pupils suggested?

A

in the context of trauma are suggestive of globe injury

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16
Q

What are possible causes of decreased visual acuity?

A
  1. Refractive errors
  2. Amblyopia
  3. Ocular media opacities such as cataract or corneal scarring
  4. Retinal diseases such as age-related macular degeneration
  5. Optic nerve (CN II) pathology such as optic neuritis
  6. Lesions higher in the visual pathways
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17
Q

How does papilloedema and optic nerve pathology different for visual acuity?

A
  1. Optic nerve (CN II) pathology usually causes a decrease in acuity in the affected eye
  2. Papilloedema (optic disc swelling from raised intracranial pressure), does not usually affect visual acuity until it is at a late stage
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18
Q

What does afferent limb of pupillary reflex?

A

each afferent limb has two efferent limbs, one ipsilateral and one contralateral

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19
Q

What is the function of the afferent limb?

A

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

20
Q

How do the two efferent limbs function?

A

motor output is transmitted from the pretectal nucleus to the Edinger-Westphal nuclei on both sides of the brain (ipsilateral and contralateral)

21
Q

What does each Edinger-Westphal nucelus give rise to?

A

efferent nerve fibres which travel in the oculomotor nerve to innervate the ciliary sphincter and enable pupillary constriction

22
Q

What does the direct pupillary reflex test?

A

ipsilateral afferent limb and ipsilateral efferent limb

23
Q

What does consensual pupillary reflex test?

A

contralateral efferent limb

24
Q

What does the swinging light test detect?

A

relative afferent limb defects

25
Q

What is ptosis associated with?

A
  1. occulomotor nerve path
  2. horner;s
  3. neuromusc patho (e.g myasthenia gravis)
26
Q

What is function of superior rectus muscle?

A
  • elevation
  • adduction
  • medial rotation
27
Q

What is function of inferior rectus?

A
  • depression
  • adduction
  • lateral rotation
28
Q

What is function of medial rectus?

A

adduction of eyeball

29
Q

What is function of lateral rectus?

A

abduction of the eyeball

30
Q

What is function of suprior oblique?

A
  1. depresses
  2. abducts
  3. medially rotates
31
Q

What does inferior oblique test?

A
  1. elevates
  2. abducts
  3. laterally rotates
32
Q

What is occulomotor palsy known as?

A

3rd nerve palsy

33
Q

What does 3rd nerve palsy look like?

A

down and out appearance of affected eye

34
Q

What muscles are still going in 3rd nerve palsy?

A

superior oblique and lateral rectus is unopposed

35
Q

What else can occulomtor nerve palsy cause and why?

A
  1. ptosis as loss of innervation of levator palpebrae

2. mydriasis as loss of parasympathetic fibres that innervate sphincter pupillae muscle

36
Q

Which muscle does the trochlear nerve innervate?

A

superior oblique

37
Q

What does 4th nerve palsy result in?

A

vertical diplopia

38
Q

What can 4th nerve palsy also result in?

A

torsional diplopia (as the superior oblique muscle assists with intorsion of the eye as the head tilts)

39
Q

How do people with 4th nerve palsy compensate?

A

tilt their head to the opposite side, in order to fuse the two images together

40
Q

What does the abducens nerve innervate?

A

lateral rectus muscle

41
Q

What does abducens nerve palsy result in?

A

convergent squint

42
Q

Why does abducens nerve palsy result in this?

A

unopposed adduction of the eye (by the medial rectus muscle)

43
Q

How do patients with abducens nerve palsy usually present?

A

horizontal diplopia worsened when attempt to look towards affected side

44
Q

What is strabismus?

A

eyes do not properly align with each other when looking at an object

45
Q

What can cause strabismus?

A

pathology affecting oculomotor, abducens or trochlear nerve

46
Q

What is exotropia?

A
  1. Direction of eye at rest: temporally (laterally or outwards)
    2.