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OD3 (S1&2) > NV - Neuromuscular Disorders I: Orbital Causes - Week 1 > Flashcards

NV - Neuromuscular Disorders I: Orbital Causes - Week 1 Flashcards

1
Q

What age group does thyroid eye disease most commonly affect?

A

21-60

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2
Q

List 6 common causes of orbital disease.

A

Thyroid eye disease
Neoplasia
Inflammation/infection
Cystic
Vascular
Trauma

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3
Q

Does inflammation count as a space-occupying lesion? Explain.

A

Yes, as the tissue swells, there is loss of space for EM movement

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4
Q

Forward and backward eyes are known as what?

A

Forward - proptosis
Backward - sunken or enophthalmos

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5
Q

List three ways an abnormal eye position can be identified.

A

Aperture 9-11mm
-smaller - enophthalmos
-larger-proptosis
Lids at the limbus
-regulates scleral visibility at the top/bottom
Birds-eye view

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6
Q

Is superior lid overhang onto the limbus normal? What about inferior? Explain.

A

Yes, 1-1.5mm overhang is normal
Less for the inferior limbus/lid - due to gravity

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7
Q

What is scleral show and what does it suggest?

A

When the superior and/or inferior limbus are not cleared by the lids and suggests proptosis

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8
Q

With a case of scleral show, what should you look for?

A

Symmetry between the eyes

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9
Q

Can scleral show be normal or is it always indicative of some abnormality? Explain (5).

A

Can be normal for the lower lid
-in upgaze
-in high myopes (>8.00DS)
-in people with high basal sympathetic tone
Will be symmetric in primary gaze (within 0.5mm) - look for difference in lid position

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10
Q

Explain the association between high myopes and scleral show.

A

High myopes can have normal scleral show due to high axial length

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11
Q

When should you suspect proptosis with scleral show (2)?

A

If it is present at the superior margin with primary gaze
If there is asymmetry between the eyes (>0.5mm)

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12
Q

What five things should you consider and look for if you suspect proptosis with scleral show?

A

Look for asymmetry in birds-eye position
Consider eyelid position (11-1 o’clock)
Presence of lid lag
Consider the distance of the lid edge to crease
Consider fellow travellers - pupils, EOM, CNs etc

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13
Q

Which gaze has greater eyelid asymmetry if lid lag is present? What sign is presnet?

A

Downgaze
An S shaped lid can be seen

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14
Q

Explain the birds-eye view.

A

Observe the patient’s eye position (not just eyelid position) from above and checking if they are level with each other
Use the plane parallel to the forehead

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15
Q

Explain the side-view.

A

Measure the position of the eye as corneal apex to zygomatic arch

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16
Q

How can proptosis be quantified? Explain how this works.

A

Exophthamometers
Two slidable prisms are placed at the zygomatic arches of the patient
The corneal apex is aligned with a marking on each prism
Measured in mm

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17
Q

If you suspect proptosis, name one differential to consider and a cause for it.

A

Lid retraction caused by dorsal mid-brain syndrome

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18
Q

How does lid retraction tend to appear (2) and which gaze is restricted?

A

Superior scleral show and stare
Upgaze limitation - they cant look up

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19
Q

How would lid retraction appear on birds-eye and side view?

A

Normal and <20mm side view

20
Q

How does eye position appear with lid retraction?

A

Downcaste appearance

21
Q

What dissociation may be present on downgaze with lid retraction?

A

Light-Near pupil dissociation

22
Q

Are EOM and eyelid function normal on downgaze with lid retraction?

A

Yes

23
Q

What should you do if you suspect dorsal mid-brain syndrome (management)?

A

Prompt neurological referral

24
Q

List five causes of dorsal mid-brain syndrome.

A

Tumour
Stroke
Infection
Trauma
MS

25
Q

What infection can cause dorsal mid-brain syndrome?

A

Syphilis

26
Q

What two symptoms should require extra caution if you suspect lid retraction?

A

Blur and mild double vision

27
Q

List 5 things to do when evaluating ocular misalignment.

A

Quantify region of binocular single vision (red lens with prism alignment or M700 BSV test)
Examine saccades/pursuits
Determine if restriction to movement in cases of trauma
Check oculo-cephalic reflex
Check fellow travellers

28
Q

Do eyes tend to have proptosis or enophthalmos following orbital trauma? Explain why.

A

Enophthalmos due to blow-out fracture

29
Q

Why does limited EOM movement tend to occur with orbital trauma (excluding inflammation)?

A

Entrapment (tethered)

30
Q

Describe the ZSBV test. What is it important for?

A

Measures zone of single binocular vision - a spot of light is followed as it moves. Button is pressed once if it is single and twice if double vision or marked blur
Measurement important for litigation and surgery

31
Q

List two workup tests for limited EOM movement due to entrapment.

A

Diplopic H pattern
Tether test
-IOP increases >4mm with gaze if tethered

32
Q

List three common signs of thyroid eye disease (concerning the eyelids).

A

Upper lid retraction with/without lid lag
Proptosis
EOM issues (inflammation/diplopia)

33
Q

What does lid lag expose on down gaze?

A

Lid crease

34
Q

Why does the lid margin appear S shaped on downgaze with lid lag?

A

Due to regional involvement

35
Q

Where would you expect to see inflammation with thyroid eye disease?

A

Marked hyperaemia at the outer canthus over muscle insertion is typical in TED

36
Q

Aside from inflammation, what else can cause EOM restriction in thyroid eye disease?

A

Orbital congestion

37
Q

What IOP readings can be indicative of thyroid eye disease?

A

Increased IOP in the upgaze by >4mmHg

38
Q

What kind of strabismus can thyroid eye disease swelling cause?

A

Incomitant

39
Q

Why is there less scleral show in infants with orbital mass?

A

Smaller aperture - more resistance

40
Q

What does red eye with proptosis indicate?

A

Exposure

41
Q

What should you consider if there is asymmetric proptosis (4)?

A

Orbital mass by retropulsion
-mass is palpable
-consider vision changes
-DFE for retinal folds

42
Q

How does the eyes move on palpation if there is orbital mass?

A

Away from the mass

43
Q

What must you not miss if you suspect proptosis?

A

Dorsal mid-brain syndrome
-upgaze palsy
-lids close

44
Q

What is the management for proptosis?

A

Ocular decompression

45
Q

Describe how ocular decompression is carried out.

A

Intentionally breaking the orbital sinus bones to allow tissue to expand into that space, relieving pressure on nerves

OD3 (S1&2) (114 decks)

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