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Duke Elder 2020 > Neuroopthalmology > Flashcards

Neuroopthalmology Flashcards

1
Q

What is CNII made up of?

A

convergence of retinal ganglion cells

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2
Q

which axons of CNII correspond to which visual fields?

A

temporal axons to nasal field

nasal axons to temporal fields

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3
Q

What are the 4 parts of CNII?

A
  1. Intraocular, shortest 1mm: exits posteriorly via lamina criborsa (scleral opening)
  2. intraorbital (longest, 25mm), myelinated covering and ends at optic foramen
  3. Intracanalicular: where the optic nerve exits the orbit through the optic canal to enter middle cranial fossa
  4. Intracranial fossa: ends at optic chiasm
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4
Q

What is the blood supply for CNII?

A

intraocular: short posterior ciliary artery

intraorbital to intracranial: pial vessels of ophthalmic artery

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5
Q

Where is the optic chiasm located?

A

anterior to the hypothalamus and usually directly superior to pit gland

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6
Q

Where do axons representing the temporal retina within the chiasm continue?

A

ipsilateral

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7
Q

Where do axons representing the nasal retina continue within the chiasm?

A

decussate at the chiasm and to the contralteral optic chiasm

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8
Q

Desrcibe the path of inferonasal axons

A

turn anteriorly within the chiasm to join the contralateral CNII (Willebrand’s knee) before continuing back to optic tract

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9
Q

How is the body’s circadian rhythym controlled?

A

a few photosensitive retinal ganglion cells axons connect with the suprachiasmatic nucleus of the hypothalamus

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10
Q

How do optic tracts connect to the optic chiasm?

A

with the lateral genticulate nuclei

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11
Q

Which retinas does the optic tract convey signals from?

A

contralateral nasal retina

ipisilateral temporal retina

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12
Q

What is the function of optic radiations?

A

connects lateral genitculate nuclei to the occipital lobe

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13
Q

What do superior optic radiations represent?

A

inferior visual field quadrants

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14
Q

Describe the path of superior optic radiations

A

pass through parietal lobe - terminate in the primary visual cortex

this is superior to a calacrine sulcus in the cuneus gyrus)

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15
Q

Describe the path of inferior optic radiations (meyer’s loop)

A

represent superior visual field

temporal lobe - primary visual cortex, inferior to the calacrine sulcus (in the lingual gyrus)

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16
Q

Where is the macula represented?

A

posteriorly, lateral to the tip of the calcarine sulcus

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17
Q

Where is the oculomotor nerve nucleus located?

A

dorsal midbrain at the level of the superior colliculus

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18
Q

What are the motor functions of the oculomotor nerve?

A

Ipsilateral innveration to IO, IR and MR

Contralateral innervation to SR

Bilateral innervation to levator muscle

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19
Q

Describe the pathway of the oculomotor nerve

A

exits brainstem through interpeduncular fossa, passing between posterior cerebral artery and superior cerebellar artery

travels close to uncus of temporal lobe, vulnerable to uncal hernations

next, lateral wall of cavernous sinus superior to CNIV and bifurcates into superior and inferior branch at anterior aspect of sinus

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20
Q

Where does the oculomotor nerve enter the orbit?

A

Enters orbit thorugh the SOF within the annulus of Zinn.

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21
Q

What does the superior branch of the oculomotor nerve innervate?

A

superior rectus and levator muscle

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22
Q

What does the inferior branch of the oculomotor nerve innervate?

A

Medial Rectus, Inferior rectus and inferior oblique

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23
Q

What fibres is CNIII accompanied by?

A

parasympathetic, originating from the Edinger-westphal nuclei

located in the midbrain dorsal to oculomotor nuclei,

innervates sphincter papillae and ciliary body muscles

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24
Q

What nerves are included in the pupillary light reflex?

A

CNII afferent limb

interconnecting neurons in the midbrain

CNIII efferent limb

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25
Q

Describe the pathway of the pupillary light reflex

A

originate from retinal ganglion cells

fibres exit the optic tract before reaching the LGN and entering midbrain to synapse on the ipsilateral pretectal nucleus

pretectal nuclei projects bilateral fibres to the contralateral and ipsilateral edinger westphal nuclei

preganglionic parasympathetic fibres from edinger westphal travel along with CNIII and exit the inferior branch of CNIII to synapse on the ciliary ganglion

from ciliary ganglion, postganglionic sympathetic fibres are carried via short ciliary nerves to innervate the ciliary body muscle and sphincter pupillae

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26
Q

What is the accommodation reflex?

A

adaption of the eye when focusing on a near object

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27
Q

How does the accommodation reflex work?

A

Increasing lens curvature: ciliary body muscles contract via parasympathetic from edinger Westphal, leading to relaxation of lens zonules

Pupil constriction: activation of the sphincter pupillary via parasympathetic from Edinger-Westphal

Eye convergence: contraction of media recti via CNIII

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28
Q

Where are the trochlear nerve nuclei located?

A

in the midbrain, at the level of the inferior colliculus

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29
Q

Which muscles to the trochlear nuclei innervate?

A

contralateral SO

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30
Q

Describe the pathway of the trochlear nerve

A

passes through the lateral wall of the cavernous sinus inferior to CNIII and enters the SOF above the common tendinous ring

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31
Q

Describe the CNIV characteristics

A

only cranial nerve that exits dorsally from the brainstem

fewest number of axons of all nerves

longest unprotected intracranial course

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32
Q

Where is the abducens nucleus located?

A

In the pontine tegmentum ventral to the fourth ventricle

nucleus is located near the paramedian pontine reticular formation and surrounded by looping fibres of CNVII

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33
Q

Where does the abducens nerve (CNVI) exit the brainstem? Describe the pathway

A

pontomedullary junction and crosses over the petrous apex of the temporal bone through an osteofibrous channel (dorello’s canal)

then travels through the cavernous sinus, lateral to the internal carotid

then enters the orbit via the SOF, through the tendinous ring to innervate the LR muscle

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34
Q

Where is CNVI most susceptible to stretching

A

at Dorello’s canal

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35
Q

Which system is responsible for pupillary dilatation and contraction of the Muller muscle?

A

Sympathetic

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36
Q

Describe the pathway for pupilry dilation

A

First order neurons: start at the posterolateral hypothalamus and synapse at the intermediolateral cell column between C8 to T2 (cilispinal centre of Budge)

Second order preganglionic neurons: leave centre of budge, travel over the lung apex and synapse at the superior cervical ganglion at the carotid bifurcation.

  • this is where the sudomotor fibres exit to course with the external carotid and supply the sweat glands of the face

3rd order post ganglionic neurons: travel around the internal carotid artery to finally innervate the dilator pupillae via the long ciliary nerves (branches of the nasociliary nerve)

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37
Q

How are supranuclear eye movements controlled?

A

voluntary / reflex control

Voluntayr movements are initiated in the frontal eye field, brodmann area 8 in the frontal lobe

reflex movements coordinated via occipital cortex and superior colliculus in response to a visual stimulus

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38
Q

What are the 3 types of supranuclear motor movements?

A

saccadic eye movements

smooth pursuit movements

vestibulo-ocular movements

39
Q

Describe saccadic movements

A

fast eye movements which involve the rapid fixation of a desired object onto the fovea

abrupt change of point fixation when switching from one object to the next

40
Q

Describe the angular speed and duration of saccadic movements

A

600 degrees / s

lasting around 30-100 milliseconds after a latency of approx 200 milliseconds

41
Q

What are voluntary saccadic movements initiated by?

A

frontal eye field

42
Q

Describe how activation of FEF leads to saccadic movements

A

Right FEF = looking left

43
Q

Describe the pathway of the projections from the frontal eye field

A

go directly or via the superior colliculus to the contralateral PPRF (which lies ventral to the abducens nucleus in the brainstem)

44
Q

How does PPRF activation lead to saccadic movements?

A

activates the ipsilateral abducens nucleus and sends impulses through the medial longitudinal fasciculus to activate the contralateral oculomotor nucleus

45
Q

How are vertical saccades controlled?

A

rostral interstitial nucleus of the MLF

46
Q

What is smooth pursuit?

A

slow movements of the eye designed to keep a moving stimulus fixed at the fovea

47
Q

describe the latency of smooth pursuit

A

100 milliseconds

48
Q

Where are smooth movements initiated from?

A

parieto-occipital areas

49
Q

What are vestibulo-ocular movements?

A

Stabilise the eye relative to head movements

50
Q

Describe how vestibulo-ocular movements work

A

when head is moving and eyes are fixed

sensory information of the SEMICIRCULAR CANALS results in the movements of the eyes in the opposite direction to the head movement

51
Q

how do vestibulo-ocular movements occur?

A

occurs via projections from the vestibular nuclei to creanial nerves and PRF

52
Q

What is optic neuropathy?

A

damage of the optic nerve

53
Q

What are the common signs of optic nerve dysfunction?

A

dVA
Dyschromatopsia

Visual field Defects: centrla scotomas, arcuate /

altitudinal defects

diminished contrast sensitivity

absolute / relative afferent pupillary defect

54
Q

What are the cuases of optic neuritis?

A

Retrobulbar neuritis

Papillitis

Neuroretinitis

55
Q

Describe retrobulbar neuritis?

A

optic nerve behind the globe is affected

optic nerve head is not involved, giving rise to a normal looking optic disc on fundoscopy

more common in aduls

56
Q

Describe papillitis

A

Hyperaemia and oedematous optic disc with associated peripapillary flame shaped haemorrhage

optic nerve head is affected

more common in children especially post viral

57
Q

Describe neuroretinitis

A

Papillitis with involvement of the retina

occurs in cat scratch disease and lyme disease

58
Q

What is multiple sclerosis?

A

AI condition characterised by demyelination of the CNS

female predominance presenting in 3rd/4th decades of life

more common in countries further from equator

59
Q

Describe the systemic features of MS

A

parasthesia

muscle cramping and wakness

bladder, bowel and sexual dysfunction

cerebellar dysfunction: tremor, dysarthria, ataxia (charcot’s triad)

Lhermitte sign: electrical shock on neck flexion

Uhthoff phenomenon: worse symptoms in warm temperature

60
Q

Describe the ophthalmic features of MS

A

retrobulbar optic neuritis: acute unset of unilateral retrobulbar pain exacerbated by eye movements, dVA, central scotoma, dyschromatopsia and RAPD

-followed by spontaneous resolution after a few months

Internuclear opthalmoplegia

nystagmus

61
Q

What investigations are used for MS

A

MRI - demyelinating plaques disseminated in space and time

Lumbar Puncture: oligoclonal bands in CSF

62
Q

Describe how MS is managed

A

IV methylprednisolone for 3 days

oral prednisolone for 11 days

63
Q

What is neuromyelitis optica?

A

A demyelinating disorder characterised by severe retrobulbar optic neuritis and transverse myelitis in three of more vertebral columns causing:

muscle weakness

increased tone

spasms

64
Q

What key feature is found in neuromyelitis optica?

A

IgG antibodies against astrocytic aquaporin-4

65
Q

What is neuroretinitis?

A

Inflammation of the optic nerve with oedema spreading from the optic nerve head along the papillomacular bundle to reach the macula

formation of exudates around macula gives a ‘macular star’ appearance

mainly caused by cat-scratch disease

66
Q

What is cat scratch disease?

A

caused by: bartonella henslae (gram negative rod)

via cat scratch / bite

features:
- fever lymphadenopathy
- neuroretinitis: unilateral, painless dVA, papilitis, mild optic nerve dysfunction and star pattern of macular exudates
- uveitis
- granulomatous conjunctivitis

67
Q

What is anterior ischaemic optic neuropathy?

A

occurs due to damage to the optic nerve as a result of ischaemia

can cause optic neuropathy in the elderly due to occlusion of short posterior ciliary artery

split into arteritic and non-arteritic

68
Q

What is Leber hereditary optic neuropathy?

A

MITOCHONDRIAL inherited disease caused by ganglion cell degeneration

mitochondrial DNA mutation occurs at the 11,778 (most common and worst prognosis)

69
Q

Describe the aetiology of non-arteriotic AION

A

HTN, diabetes,

sleep apnoea

physiologically small or absent cup (structural crowding of the optic nerve head)

70
Q

Describe the vision loss of non-arteriotic AION

A

sudden

painless
unilateral

VA usually >6/60

often inferior / superior visual field defect

71
Q

Describe the disc findings in non-arteriotic AION

A

usually segmental hyperaemic disc swelling with peripapillary splinter hemorrhages

72
Q

What are the investigations used in non-arteriotic AION?

A

BP, blood sugar, examination of optic disc and exclude GCA

FA: delayed optic disc filling

73
Q

What is the tratments for non-arteriotic AION?

A

treat underlying cause

74
Q

What is the aetiology of arteriotic AION?

A

GCA most commonly

75
Q

Describe the vision loss in arteriotic AION

A

sudden

painful

unilateral with high risk to fellow eye if untreated

severe visual loss <6/60

76
Q

Describe the disc findings of arteriotic AION

A

chalky white diffuse swollen disc

77
Q

Describe the associated symptoms of arteriotic AION

A

scalp tenderness, headache and jaw claudication

78
Q

What investigations are used for arteritic AION?

A

ESR

CRP

temporal artery biopsy (high specificty but low sensitivity)

FA: delayed choroidal and optic disc filling

79
Q

how is arteritic AION treated?

A

High dose IV methylprednisolone and oral prednisolone

80
Q

What are the features of Leber Hereditary optic neuropathy

A

Unilateral initially with bilateral ocular involvement over weeks to months

painless visual loss

central / centrocaecal scotomas

Triad of: pseudo-oedema, peripapillary telangiectasia and tortuosity of medium-sized retinal arterioles

optic atrophy in late disease

81
Q

What investigations are used for leber’s optic neuropathy?

A

Family history and genetic testing

OCT which can show optic nerve oedema (early) or atrophy (late)

82
Q

What is nutritional optic neuropathy?

A

aka tobacco-alcohol ambylopia

caused by vit B, copper and folic acid deficiencies

medications (ethambutol, amiodarone or sildenafil) and other toxic causes

83
Q

what are the features of nutritional optic neuropathy?

A

gradual, progressive, painless bilateral dVA and centrocaecal scotomas

Dyschromatopsia

84
Q

What is papilloedema?

A

bilateral disc swelling secondary to raised ICP

85
Q

what are some causes of raised ICP?

A

tumours,

haemorrhages

hydrocephalus

idiopathic intracranial HTN (typically in young obese females)

86
Q

What are the features of an increased ICP?

A

headache worse in the morning

nausea and vomiting

pulsatile tinnitus

unilateral or bilateral transient visual loss with a duration of seconds

enlarged blind spot

diplopia due to CNVI palsy

HTN, bradycardia and bradypnea (Cushing reflex)

87
Q

What signs are seen on teh optic disc in papillodema?

A

Hyperaemia and blurred margins of the optic disc (early)

swelling and elevation of the whole optic disc with peripapillary hemorrhages (late)

88
Q

What are tilted discs?

A

bilateral, small optic discs tilted inferonasally

associated with high myopia

superotemporal field defect are common

89
Q

What is morning glory anomaly?

A

unilateral and causes severe dVA

Characterised by FUNNEL-SHAPED EXCAVATION of the optic disc and surrounding retinal tissue

characteristically, the retinal vessels emerge from the periphery of the optic nerve head rather than from the centre

associated with retinal detachment

90
Q

What is an optic disc pit?

A

characterised by a greyish oval depression in the optic nerve head, usually located temporally

complications: exudative retinal detachment

91
Q

What is an optic disc coloboma?

A

occurs due to defect in embryonic fissure closing

cane be sporadic or associated with Golden har syndrome, micropthalmos and CHARGE syndrome

glistening white bowl shaped excavation of the disc (inferior part predominantly affected) causing superior field defect and dVA

92
Q

What are optic dis cdrusen?

A

Collection of mucoproteins and mucopolysaccharides that progressively calcify in the optic disc, present as yellow or white bodies on the optic disc

commonly bilateral

varying degrees of blurring and visual loss

associations: retinitis pigmentosa and angiod streaks

93
Q

What is optic nerve hypoplasia?

A

caused due to underdevelopment of the optic nerve

patients often present with visual loss and a double ring sign

risk factors include genetic diseases and maternal use of recreational drugs, smoking and alcohol

Duke Elder 2020 (9 decks)

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