9.2 Eye movement disorders Flashcards Preview

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Flashcards in 9.2 Eye movement disorders Deck (24)
1

What is primary position, duction, version and strabismus of the eye?

Primary position: looking forward
Duction: rotation of the eye while it is moving alone
Version: movement of both eyes together
Strabismus: a misalignment or deviation of the visual axis

2

What is tropia and phoria?

Tropia: relative deviation of the visual axis with both eyes viewing (manifest misalignment)
Phoria: relative deviation of the visual axis with one eye covered (latent misalignment)

3

What is congenital strabismus and what are the causes?

Squint due to misalignment
Due to: defective central vision, other cause of impaired vision in one eye, anatomical disturbance, accomodative discrepancy

4

What are the types of congenital strabismus?

Concomitant: same in all positions
Intermittent: fine most of the time but may happen when tired
Latent: bought on by covering one eye

5

What are the nerves involved with the eye muscles?

III (superior, medial and inferior rectus and inferior oblique), IV (superior oblique), VI (lateral rectus)

6

What is the function of the 6 extraocular muscles

Superior rectus - elevates from abducted
Inferior rectus - depresses from abducted
Lateral rectus - abducts eye
Medial rectus - adducts eye
Inferior oblique - elevates from adducted
Superior oblique - depresses from adducted

7

What is the presentation of a III nerve palsy?

Complete ptosis, dilation of pupil, eye will be down and out

- Failure of elevation and adduction

8

What are the two divisions of III and what do they supply?

Superior: Superior rectus and levator palpibrae
Inferior: Inferior and medial rectus, inferior oblique and pupil/ciliary

9

What will you see in IV palsy?

Failure of abduction and inability to depress when adducted
Tend to get a head tilt away from the side of the lesion

10

How do you test for IV palsy?

Bielschowsky head tilt test - When you tilt the head the affected eye will be elevated as the superior oblique is unable to resist the movement

11

What will you see in VI palsy?

Failure of abduction

12

What happens in mysathenia gravis and how do you reverse it?

Eye muscle weakenss, ptosis and dipolopia reversed with IV tensilon

13

What are the 3 nuclear/internuclear lesions?

Gaze palsy, internuclear opthalmoplegia and one and a half syndrome

14

What do you see in a horizontal gaze palsy and what causes it ?

Cause by an abducens nucleus lesion - prevents the patient being able to look in the direction of the lesion

15

Where is the lesion in internuclea opthalmoplegia and what does it prevent?

In the medial longitudinal fasiculus - This prevents information from the VI nucleus going to the III nucleus leading to an inability of the C/L adduction when looking to the side of the lesion

e.g. if there is a lesion on the L side, when looking to the L the R eye will be unable to adduct in that direction

16

Where is the lesion in one and a half syndrome and what does it cause?

Lesion in the VI nucleus and the medial longitudinal fasiclus
Inability of everything except abduction of the good eye

17

What will you see in a supranuclear lesion and what does it mean?

Inability to look up and down when looking straight ahead - if you help you can cause the vestibuloocular reflex to drive the eyes down
This indicates that the connection is working fine but the brain cant access the information

18

What are the 5 types of eye movements?

Vestibular

Optokinetic - train phenomenon

Saccadic - rapid movement used when scanning (corrective phase in nystagmus)

Smooth pursuit - allows you to track movements

Convergence

19

What are the 5 types of saccades and what do they indicate?

Square wave jerks: involuntary to L/R before correcting, tend to occur when excited/stressed, 1 degree movement, non pathological

Macro square wave jerks: >7degree movement, indicates cerebellar issue

Flutter: back t back saccade - cerebellar

Opsoclonus

Voluntary nystagmus

20

What are the pathological nystagmus?

Vestibular: linear slow phase
Cerebellar/brainstem: exponentially decreasing slow phase
Congenital: exponentially increasing slow phase

21

In which direction of the nystagmus is the problem?

The direction of the slow phase
- The jerk is usually corrective

22

How can you tell central vs. peripheral vestibular nystagmus?

Pure vertical nystagmus = central
Peripheral can usually be overcome by vision (usually unidirectional)

23

What are the characteristics of cerebellar nystagmus?

Gaze evoked, fast phase in direction of gaze, slow phase exponentially decreasing

24

WHat is rebound nystagmus?

Wen you look out to one side you will get nystagmus and when you come back to the middle you will have it to that side