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Gwen - Neurology > Clinical Signs - Eyes > Flashcards

Clinical Signs - Eyes Flashcards

1
Q

What are the features of occulomotor nerve palsy?

A

Following findings in the primary gaze position:

  • Hypotropia (eye deviated down)
  • Exotropia (eye deviated out) - supressed elevation from lS and LO and unopposed abduction from LR
  • Ptosis - CN3 inervates levator palpebrae superioris
  • Mydriasis - loss of PNS function.
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2
Q

What eye movements are impaired in occulomotor nerve palsy?

A
  • Elevation
  • Depression
  • Adduction
  • Extorsion

Supressed elevation from LS and LO and unopposed abduction from LR

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3
Q

What nerve is affected in the following presentation?

A

Occulomotor nerve palsy (CNIII)

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4
Q

What nerve is affected in the following presentation?

A

Occulomotor nerve - Impaired elevation, depression, adduction and extorsion of the affected eye.

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5
Q

Why do those with occulomotor nerve palsy get hypotropia?

A

Unnopposed superior oblique muscle

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6
Q

What are the different severities of occulomotor nerve palsy?

A
  • Complete
  • Pupil Sparing
  • Myadriasis only
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7
Q

Why do those with occulomotor nerve palsy get myadriasis?

A

Pupillary constrictor muscle weakness

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8
Q

What are the most common causes of occulomotor nerve palsy

A
  • Midbrain pathology
  • Diabetic mononeuropathy/microvascular infarction (hypertension)
  • Uncal herniation
  • Posterior communicating (PCOM) artery aneurysm
  • Ophthalmoplegic migraine (transient)
  • Mass lesion – tumour, abscess, AVM
  • Demyelination
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9
Q

Why do those with occulomotor nerve palsy get Ptosis?

A

Levator palpebrae weakness

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10
Q

Why do those with occulomotor nerve palsy get exotropia?

A

Unnopposed Lateral rectus muscle

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11
Q

Why do those with occulomotor nerve palsy get impaired elevation?

A

Superior rectus muscle weakness

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12
Q

Why do those with occulomotor nerve palsy get impaired depression?

A

Inferior rectus muscle weakness

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13
Q

Why do those with occulomotor nerve palsy get impaired adduction?

A

Medial rectus muscle weakness

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14
Q

Why do those with occulomotor nerve palsy get impaired exotorsion?

A

Inferior oblique muscle weakness

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15
Q

What are causes of the following?

A
  • Diabetic neuropathy
  • Increased ICP - false localising sign
  • Trauma to base of skull
  • MS
  • ​Wernicke’s encephalopathy
  • Cavernous sinus syndrome
  • Cavernous carotid artery aneurysm
  • Giant cell arteritis
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16
Q

How do disorders of the subarachnoid space cause abducens nerve palsy?

A

The abducens nerve emerges from the brainstem adjacent to the basilar and vertebral arteries, and the clivus. Aneurysmal dilation of these vessels and/or infectious or inflammatory conditions of the clivus can compress the abducens nerve

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17
Q

What muscle does abducens nerve innervate?

A

Lateral rectus

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18
Q

Presentaion of abducens neve palsy

A

Eye cant abduct beyond midline - deflective abduction and horizontal diplooa

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19
Q

What is the main mechanism behind abducens nerve palsy?

A

Abducens nerve palsy is caused by a peripheral lesion of the abducens nerve. Lesions of the abducens nuclei typically result in horizontal gaze paresis (i.e. ipsilateral abduction paresis and contralateral adduction weakness) due to an impaired coordination of conjugate eye movements with the oculomotor motor nuclei, via the medial longitudinal fasciculus (MLF).

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20
Q

How does increased ICP cause abducens nerve palsy?

A

Due to the relatively fixed nature of the abducens nerve at the pontomedullary sulcus and at the point of entry into Dorello’s canal, it is vulnerable to stretch and/or compression injury secondary to elevated intracranial pressure.

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21
Q

Why is abducens palsy due to increased ICP known as false localising sign?

A

Referred to as a ‘false localising sign’ as the clinical findings are not solely due to an isolated peripheral lesion of the abducens nerve - due to course the nerve follows

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22
Q

How does diabetic neuropathy cause abducens nerve palsy?

A

Diabetic vasculopathy of the vasa nervorum (i.e. disease of the blood supply of the nerve) may result in microvascular infarction of the abducens nerve.

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23
Q

What are argyle robertson pupils?

A

Characterised by:

  • Miosis (small pupils)
  • Absence of the pupillary light response
  • Brisk accommodation reaction
  • Bilateral involvement.
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24
Q

What is the mechanism behind Argyll-Robertson pupils?

A

Caused by a pretectal lesion in the dorsal midbrain affecting the fibres of light reflex, which spare the fibres of the accommodation pathway that innervate the Edinger–Westphal nuclei

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25
Q

What conditions are argyll robertson pupils associated with?

A
  • Multiple sclerosis
  • Neurosarcoidosis
  • Tertiary syphilis
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26
Q

What is an afferent cornreal reflex defect?

A

Absence of bilateral blinking, due to ophthalmic division of the trigeminal nerve (CNV V1) dysfunction

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27
Q

What nerve is implicated in an afferent corneal reflex deficit?

A

Opthalmic division of trigeminal nerve

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28
Q

What is an efferent defect of the corneal reflex?

A

Absence of unilateral blinking, due to facial nerve (CNVII) palsy.

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29
Q

What nerve is implicated in an efferent defect of the corneal reflex?

A

Facial nerve

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30
Q

What are causes of absent corneal reflex?

A
  • Bell’s palsy (idiopathic facial nerve palsy)
  • Facial nerve palsy
  • Brain death
  • Cerebellopontine angle tumour – acoustic schwannoma, glomus tumour
  • Cavernous sinus syndrome
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31
Q

What is horners synrome?

A

Interrupted sympathetic innervation to the eye. Can occur at any level - central lesion to post gangliotic fibres.

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32
Q

What are features of horner’s syndrome?

A
  • Miosis (fixed constricuted pupil due to loss of sympathetic function)
  • Ptosis with apparent enopthalmos (eye lid lag with sunken eye)
  • Anhydrosis (unilateral reduction in sweating)
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33
Q

Differentials of horners

A

Central lesions: anhidrosis of face, arm and trunk

  • Stroke
  • Syringomyelia
  • Multiple sclerosis
  • Tumour
  • Encephalitis

Pre-ganglionic lesion: anhydrosis of face

  • Pancoats tumour
  • Thyroidectomy
  • Trauma

Post gangliotic lesions: no anhidrosis

  • Carotid artery dissection
  • Carotid aneurysm
  • Cavernous sinus thrombosis
  • Cluster headache
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34
Q

What is Hutchison’s pupil?

A

Hutchinson’s pupil is a non-reactive dilated pupil caused by oculomotor nerve compression secondary to uncal herniation. Other signs of oculomotor nerve palsy (e.g. extraocular muscle weakness, ptosis) may also be present

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35
Q

What is the cause of a hutchison’s pupil (fixed dilated pupil)?

A

Uncal herniation - results from an expanding extra-axial intracranial haematoma or mass. Increasing intracranial volume pressure result in cerebral herniation when the expanding intracranial contents (e.g. a mass) exceed the capacity of the cerebral tissue and intracranial contents to accommodate such a change.

Cerebral tissue moves in the direction of the pressure gradient (i.e. caudally towards the foramen magnum). Herniation of the medial temporal lobe and uncus may result in compression of the midbrain and oculomotor nerve, resulting in a non-reactive dilated pupil

36
Q

If someone had a hutchison’s pupil, what would this indicate in terms of prognosis?

A

Catastrophic sign of oculomotor nerve compression due to uncal herniation. When present, mortality approaches 100% without emergent medical intervention and surgical decompression

37
Q

What is internuclear opthalmoplegia?

A

Characterised by

  1. Impaired adduction of the eye on the abnormal side
  2. Horizontal jerk nystagmus in the opposite eye upon lateral gaze away from the side of the lesion
38
Q

What does internuclear opthalmoplegia occur in?

A
  • Multiple sclerosis
  • Dorsal pontine infarction
39
Q

What is the mechanism behind internuclear opthalmoplegia?

A

INO is caused by a lesion in the medial longitudinal fasciculus (MLF). The MLF connects the abducens nerve (CNVI) nuclei to the oculomotor nerve (CNIII) nuclei and facilitates conjugate eye movements during lateral gaze by coordinating adduction with abduction. Typically, on horizontal gaze, the abducting eye moves normally but the adducting eye fails to follow. Adduction is preserved on convergence

40
Q

What are the afferent and efferent nerves involved in the jaw jerk reflex?

A

Mandibular branch of trigeminal nerve

41
Q

What can cause occulomotor nerve palsy with pupillary sparing?

A

Lesion limited to the central fibres of the oculomotor nerve may result in oculomotor nerve palsy with pupillary sparing

42
Q

What can cause occulomotor nerve palsy with isolated pupil involvement?

A

Compressive peripheral lesions of the oculomotor nerve may initially manifest with isolated pupil involvement - fibres of the oculomotor nerve innervating the pupillary constrictor muscle are located superomedially near the nerve surface and are particularly prone to compressive lesions

43
Q

Why do posterior communicating artery aneurysms cause occulomotor nerve palsy?

A

The oculomotor nerve exits the midbrain adjacent to the posterior communicating (PCOM) artery, posterior cerebral artery (PCA) and superior cerebellar arteries (SCAs). Aneurysms of any of these arteries can cause oculomotor nerve palsy.

44
Q

What is optic atrophy?

A

The optic disc appears asymmetrical, smaller in size, and pale white in colour

45
Q

What are causes of optic atrophy?

A
  • Anterior ischaemic optic neuropathy (AION)
  • Multiple sclerosis
  • Chronic optic neuritis
  • Glaucoma
  • Tumour
  • Thyroid eye disease
  • Leber’s hereditary optic neuropathy
46
Q

What is the following?

A

Optic atrophy

47
Q

Why does optic atrophy occur?

A

Optic atrophy is caused by a long-standing lesion of the optic nerve or by increased intracranial pressure. The patient may have associated bedside clinical evidence of optic nerve dysfunction (e.g. decreased visual acuity, central scotoma)

Often due to a lesion of the optic nerve of at least 4–6 weeks duration

48
Q

What is orbital apex syndrome?

A

A cranial nerve syndrome associated with proptosis, involving the contents of the orbital apex:

  • Optic nerve (CNII)
  • Oculomotor nerve (CNIII)
  • Trochlear nerve (CNIV)
  • Ophthalmic division of the trigeminal nerve (CNV V1)
  • Abducens nerve (CNVI)
  • Sympathetic fibres.
49
Q

What can cause orbital apex syndrome?

A

Typically, an enlarging infectious/inflammatory mass at the orbital apex leads to proptosis and pain

  • Tolosa–Hunt syndrome
  • Orbital granuloma
  • Mucormycosis
  • Retrobulbar haemorrhage
  • Graves’ ophthalmopathy
50
Q

What is the following?

A

Papilloedema

51
Q

What are causes of the following?

A
  • Optic neuritis
  • Elevated intracranial pressure, any cause
  • Drugs – ethambutol, chloramphenicol
  • Idiopathic intracranial hypertension (IIH)
  • Optic nerve lesion – tumour, AVM
  • Hydrocephalus
52
Q

What is optic neuritis?

A

Demyleinaatio within optic nerve - unilateral loss of activity, worse on exercise/heat, pain on eye movment, reduced colour vision.
RAPD defect
Managmeent with methypredisolone

53
Q

What is the mechanism behind the development of papilloedema?

A

Papilloedema is caused by increased intracranial pressure or a compression lesion of the optic nerve. Disc swelling papilloedema results from blockage of axoplasmic flow in neurons of the optic nerve, resulting in swelling of the axoplasm of the optic disc

54
Q

What other clinical signs is papilloedema often associated with?

A

General

  • Decreased visual acuity
  • Relative afferent pupillary defect [RAPD]
  • Monocular vision loss).

Acute

  • Enlargement of the physiological blind spot
  • Inferior nasal field loss
55
Q

What is photophobia?

A

Photophobia is light-induced ocular and/or cephalic discomfort. The patient exhibits discomfort and aversion to light stimuli, resulting in involuntary eye closure and/or gaze deviation.

56
Q

What conditions does photophobia occur in?

A
  • Migraine headache
  • Corneal abrasion
  • Keratitis – UV, contact lens
  • Glaucoma
  • Subarachnoid haemorrhage, aneurysmal
  • Meningitis – bacterial, viral, fungal, aseptic
  • Anterior uveitis
  • HSV keratitis
57
Q

What field defect would someone have if they had a lesion at 1 (in the following image)/

A

Blindness - Right uniocular VF defect

58
Q

What visual field defect would someone have if they had a lesion at 3 (in the attached image)?

A

Bitemporal hemianopia

59
Q

What visual field defect would you get in someone with a lesion at 4 (on the attached diagram)?

A

Left homonimous hemianopia

60
Q

What visual field defect would be present if there was a lesion at 8 (in the attached diagram)?

A

Left homonimous hemianopia

61
Q

What visual field defects would be present in someone with a lesion in the superior optic radiation (F or I in the diagram attached)?

A

Left inferior homonimous quadrantanopia

62
Q

What visual field defects would be present in someone with a lesion in the inferior optic radiation (E or J in the diagram attached)?

A

Left superior homonimous quadrantanopia

63
Q

What are causes of bilateral miosis (pinpoint pupils)?

A
  • Opioid – morphine, heroin
  • Senile miosis
  • Pontine haemorrhage
  • Cholinergic toxicity – organophosphate poisoning
  • Upward transtentorial herniation
  • Central α-2 agonist – clonidine, dexmedetomidine
  • Beta-adrenergic antagonist – carvedilol, timolol
64
Q

How do opiods cause bilateral miosis?

A

Bind to central kappa-1 receptors

65
Q

How does pontine haemorrhage cause bilateral miosis?

A

Disrupts the descending sympathetic fibres in the pons, resulting in unopposed parasympathetic input and bilateral miosis.

66
Q

How does cholinergic toxicity cause bilateral miosis?

A

Cholinergic toxicity causes bilateral miosis due to potentiation of muscarinic receptors at the neuromuscular junction.

67
Q

How does central herniation with pontine compression cause bilateral miosis?

A

Central transtentorial herniation, cerebellotonsillar herniation and upward transtentorial herniation cause bilateral miosis due to compression of the pons

  • Central - Caused by an expanding vertex, frontal lobe or occipital lobe lesion
  • Cerebellotonsillar - Cerebellar mass or rapid brainstem displacement
  • Upward - Expanding posterior fossa lesion
68
Q

What mnemonic is used to remember the areas of the brain affected in superior or inferior quandrantopias?

A

PITS

Parietal Inferior, Temporal Superior

69
Q

What is ptosis?

A

An abnormally droopy eyelid. It can be unilateral or bilateral. Normally, the upper eyelid covers the upper 1–2 mm of the iris, and the lower eyelid just touches the lower border of the iris

70
Q

What are causes of unilateral ptosis?

A
  • Levator aponeurosis dehiscence
  • Dermatochalasis
  • Horner’s syndrome - tarsal muscle weakness - positive constricted pupil
  • Myasthenia gravis - fatiguable
  • Oculomotor nerve (CNIII) palsy - LP muscle weakness, positive dilated pupil
71
Q

What are causes of bilateral ptosis?

A
  • Myasthenia gravis (bilateral)
  • Myotonic dystrophy (bilateral)
72
Q

What is a relative afferent pupillary defect?

A

Marcus Gunn pupil

Relative dilation of both pupils occurs when a torch is moved from the normal side to the abnormal side (i.e. the side with the afferent pupillary defect) during the swinging torch test. An afferent pupillary defect is a disorder of the afferent limb of the pupillary light response pathway (e.g. optic nerve, retinal neuroepithelium).

On beaming light to NORMAL eye both pupils constrict (direct and indirect reaction)

If swinging the light to the affected eye the pupil dilates (has a RAPD).

73
Q

What is the mechanism behind a relative afferent pupillary defect?

A

Caused by asymmetrical input to the EWN from the optic nerve (CNII) or retinal neuroepithelium. Symmetrical disorders (i.e. symmetric disease in both optic nerves) will not produce a relative afferent pupillary defect. The swinging torch test is only able to detect relative differences between the two afferent pathways.

74
Q

What does an RAPD indicate?

A
  • Optic nerve disorders
  • Retinal neuroepithelium disorders (uncommon).
75
Q

What are causes of RAPD?

A
  • Optic neuritis
  • Anterior ischaemic optic neuropathy (AION)
  • Vitreal haemorrhage
  • Retinal detachment
  • Retinoblastoma
  • Mass lesion – tumour, abscess, AVM
76
Q

What muscle does the trochlear nerve innervate?

A

Superior oblique

77
Q

What eye movements are impaired in trochlear nerve palsy?

A
  • Depression
  • Intorsion

So downward gaze and vertical diplopia

78
Q

Why do patients with trochlear nerve palsy have a tilted head?

A

To accomodate for extorted eye

79
Q

What are the characteristic findings in trochlear nerve palsy?

A
  • Hypertropia (upward deviation)
  • Extorsion (external rotation)
  • Head tilt, in the direction opposite to the side of the affected eye.

Eye can’t look down - may present with fall!

80
Q

What nerve palsy is occuring in the following?

A

Trochlear nerve

  • A - left hypertropia and extorsion
  • B - relatively normal left gaze away
  • C - right gaze
  • D - no vertical deviation of the left eye during contralateral head tilt
  • E - pronounced left hypertropia on ipsilateral head tilt
81
Q

Why does C (in attached image) occur in the nerve palsy which causes it?

A

Lack of depression of the eyeball by superior oblique in adduction

82
Q

What type of diplopia is present in trochlear nerve palsy?

A

Vertical and torsional diplopia

83
Q

What are the most common causes of trochlear nerve palsy?

A
  • Blunt head trauma
  • Diabetic mononeuropathy/microvascular infarction
  • Midbrain lesion – tumour, multiple sclerosis, AVM
  • Hydrocephalus
  • Pinealoma
  • Cavernous sinus syndrome
84
Q

What does the trochlear nerve supply?

A

The contralateral superior oblique muscle and crosses the midline immediately after exiting the dorsal midbrain. Lesions of the trochlear nerve result in contralateral findings

85
Q

Presentation of lesion of CrN5

A

Loss of facial sensation

Deviation of jaw towards side of lesin

Loss of corneal reflex

Paralysis of mastication muscles

86
Q
A

Gwen - Neurology (38 decks)

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