Week 2 - H - Ophthamology 7 - CN III,IV,VI palsies, INO &visual field defects Flashcards

1
Q

What muscles of the eye are supplied by the oculomotor nerve? (try name 7)

A

Superior rectus Inferior rectus Medial rectus Inferior oblique Levator palpebrae superioris

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the features of an oculomotor nerve palsy?

A

The eye points down and out There is a ptosis (due to the LPS not being supplied - drooping eyelid) There is also a dilated pupil

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the causes of oculomotor nerve palsy?

A

Microvascular eg diabetes Tumour If painful - anuerysm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Which muscle of the eye has the main function to abduct, depress and internally rotate the eye? What is the end eye position?

A

This is the superior oblique muscle Moves the eye down and out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What nerve supplies the superior oblique muscle? WHat does it look like if there is a palsy of this nerve?

A

Supplied by trochlear nerve. If CN IV palsy Then head is tilted, the eye points up and in and also a vertical diplopia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Which way does the head tilt in a fourth nerve palsy?

A

To compensate for the double-vision resulting from the weakness of the superior oblique, patients characteristically tilt their head down and to the side opposite the affected muscle ie if Right SO palsy, patients head will tilt left

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the most common cause of fourth nerve palsies?

A

Congenital trauma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Blunt nerve trauma can cause a bilateral trochlear nerve palsy What happens here as presentation?

A

Will cause depressed chin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What muscle causes abduction of the eye? What nerve supplies it? What does palsy if this nerve present like?

A

Lateral rectus supplied by the abducent nerve Palsy presents like eye is unable to look laterally and eyes will be medially deviated, horizontal diplopia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What type of squint is the one seen in abudcent nerve palsies?

A

This would be an esotropic squint (convergent squint)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is the main cause of sixth nerve palsies? and therefore what is ususally also seen on fundoscopy?

A

Raised intracranial pressure Therefore may seen papilloedema on fundsocopy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Which cranial nerve palsy is common in diabetic retinopathy - a microvascular complication of diabetes? (all three can have palsies due to it remember)

A

This would be cranial nerve VI palsy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Why is cranial nerve VI palsy more likely to be affected by an increase intracranial pressure?

A

This is because it has to curve around the petrous part of temporal bone therefore raised ICP may cause it to push down on this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Why are the pupils involved in oculomotor nerve palsies?

A

The parasympathetics run on the outside of the nerve and therefore if there is something pressing on the nerve it will also affect this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Eyes need to be able to work at the same time Eg look left involves the left eye using the abducent nerve and the right eye using the oculomotor nerve The nerves are therefore connected by pathways What are these pathways known as?

A

Known as inter-nuclear pathways

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Ophthalmoplegia is paralysis of the muscles within or surrounding the eye. Where is the lesion in the eye that would cause inter-nuclear opthalmopegia?

A

The lesion lies within the medial longtiudional fasciculus - this is a heavy myelinated tract connect nerve nuclei

17
Q

What is the main cause of inter-nuclear ophthalmplegia? (in bilateral and unilateral)

A

In young patients with bilateral INO, multiple sclerosis is often the cause. In older patients with one-sided lesions a stroke is a distinct possibility.

18
Q

In internuclear opthalmoplegia, a the medial longtiduinal fasciculus connects the abducent and the oculomtor nerves Which oculomotor nerve side does the medial longitudinal fasciculus connect the abducent nerve to?

A

Connects the abuducent nerve to the contralateral oculomotor nerve

19
Q

If a patient has a right medial longitudinal fasciculus injury, how would you be able to tell this on examination? Asking the patient to look right

A

The patient would be able to abduct the ipsilateral and adduct the contralateral eye The patient would not be able to adduct the eye on the ipsalteral side and would have a horizontal diplopia Also the contralateral eye would be able to abduct but would have a nystagmus

20
Q

Describe the type of gaze seen in the internuclear ophthalmoplegia? This is the gaze palsy when the eyes are meant to move the same way

A

Would have a conjugate gaze palsy - inability to move both eyes in a single horizontal gaze motion

21
Q

Which eye in INO shows affected adduction?

A

It is the affected eye which shows affection adduction with the contralteral eye showing nystagmus on abduction

22
Q

Describe the visual field defect at each number Dont include number 2 or 7

A
  1. Right monocular blindness 2. - 3. Bitemporal hemianopia 4. Left homonymous hemianopia 5. Left homonymous superior quadrantanopia 6. Left homonymous inferior quadrantanopia 7. - 8. Left homonymous hemianopia with central (macular) sparing
23
Q

* 1. Left monocular blindness * 2. Bitemporal hemianopia * 3. Right homonymous hemianopia * 4. Right homonymous superior quadrantanopia * 5. Right homonymous inferior quadrantanopia * 6. Right homonymous hemianopia with central (macular) sparing Where are the lesions?

A
  1. Right optic nerve
  2. Optic chiasm
  3. Left optic tract
  4. Left temporal lower optic radiation
  5. Left parietal upper optic radiation
  6. Left occipital cortex
24
Q

What are some causes of optic nerve pathology causing a visual field defect?

A

Optic neuritis - due to MS usually Ischaemic optic neuropathy (occluded posterior ciliary arteries supply the optic nerve head)

25
Q

What are some optic chiasm causing pathologies?

A

Pituitary adenoma - most commonly is a prolactinoma so will have the associated effect, can also be a growth hormone adenoma Craniopharyngioma - usually in patients under 20 and can press on pituitary gland also

26
Q

What type of tissue are craniopharnygiomas derived from?

A

Dervied from the pituitary gland embryonic tissue known as rathke’s pouch

27
Q

Both craniopharyngiomas and pituitary adenomas can cause bitemporal hemianopias however tend to infect the visual fields differently at the start How is this?

A

Craniopharyngiomas, which tend to be suprasellar - the visual field defect will first appear as bitemporal inferior quadrantanopia if originating inferior to the optic chiasm, the visual field defect will first appear as bitemporal superior quadrantanopia. like in pituitary adenomas

28
Q

• Optic Tracts & Optic Radiations – Tumours (primary or secondary, Demyelination, Vascular anomalies) What is the loop which the temporal lobe optic radiation goes around the lateral ventricle known as?

A

Known as Meyer’s loop

29
Q

What is the most common cerbrovascular incident causing the occipital cortex disruption?

A

Stroke