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Strabismus > Double elevator palsy; Marcus Gunn, Aberrant regeneration > Flashcards

Double elevator palsy; Marcus Gunn, Aberrant regeneration Flashcards

1
Q

Features of double elevator palsies

A

Unilateral (bilateral)
Limitation elevation
- ABDuction & ADDuction
No manifest deviation in PP or Hypotropia
- pseudo ptosis
Ptosis
- true/pseudo ptosis
Intact Bells phenomenon (in most cases)
AHP - chin elevation and +ve FDT (if mechanical restriction)
Associated Marcus Gunn jaw winking ptosis
DVD

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2
Q

Aetiology of double elevator palsies

A
  • Congenital
  • Supranuclear defect (+ve Bells, full passive movement, -ve FDT & full elevation under GA)
  • Contracture of IR (mechanical, primary/secondary and abnormality of IR (thickened)
  • Also familial cases are linked to the TUB3 gene (Thomas et al 2019)
  • SR paresis- Approx 50% and reduced SR volume shown on MRI
  • Absent Bells- sup div 3rd N palsy c spread of concomitance
  • Acquired upgaze palsy- suspect dorsal midbrain lesion
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3
Q

Orthoptic investigation

A

VA, AHP, CT, BSV, OM can tell if true V pseudo ptosis, jaw wink, bells phenomenon,
lower lid crease, PCT, Hess, Field of BSV, Field of Uniocular Fixation, Upward saccadic velocity if reduced - indicates SR weakness

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4
Q

Management options

A

Conservative management is preferred where possible but reftaction and amblyopia treatment are offered. Treating strabismic, stimulus deprivation, meridional, anisometropic
amblyopia.

Surgery is considered if the patient has a marked AHP, hypotropia and pseudo ptosis or ptosis. Strabismus surgery is offered before ptosis surgery and the choice of surgery depends on FDT.

Marked AHP- poor cosmesis and is comfortable
Hypotropia and pseudo ptosis- significant in PP
Ptosis- significantly obscuring visual axis, cosmetically poor and Marcus gunn can be present

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5
Q

If -FDT

A
  • Knapp procedure
  • transpose LR & MR up to the borders of SR
  • may have an increased effect over time
  • can be graded
  • minimal restriction of elevation
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6
Q

If +FDT

A
  • indicates contracture of IR
  • IR weakening
  • +/- Knapp procedure
  • usually perform both
  • marked restriction of elevation
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7
Q

Double depressor palsy

A

They are very rare and congenital. Ensure to differentiate: IR palsy / absent IR and the spread of concomitance. It induves llimited depression, FDT - if +ve determines contracture of SR. It can be treated using surgery, inverse Knapp, SR recession andif FDT +ve for SR contracture.

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8
Q

Marcus Gunn phenomenon

A

It induces a jaw winking ptosis and a trygemino- oculomotor synkinesis. Its part of the CCDD spectrum

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9
Q

Features of Marcus gunn

A

Its congenital & unilateral and is caused by a misdirection of nerve supply branch of mandibular divison of Vth CN which supplies pterygoid muscles and its misdirected into superior division 3rd CN which is supplying the levator and is supported by MRI evidence (Conte et al, 2012).Structural abnormality in brainstem (midbrain tegmentum). neural misdirection happens in brainstem. Can cause supranuclear synkinesis which can be familial.

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10
Q

More features of Marcus gunn

A
  • partial ptosis
    variable in different patients
    2-13% congenital ptosis
  • upper lid position changes with jaw movement, increase ptosis (lid lowers)
    move jaw to the affected side
    close mouth, decrease ptosis (lid lifts)
    move jaw to the unaffected side
    open mouth
    project mandible forwards
  • lid may change position on:
    chewing
    sucking
    jaw protrusion
    smiling
  • commonly noticed in infancy
    feeding / sucking / eating
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11
Q

Associated features of Marcus gunn

A

strabismus, amblyopia, anisometropia OM defect- DEP, SR palsy, HoT, HT, AHP- to maintain BSV and avoid ptosis, other developmental abnormalities, rarely other synkinsesis which is unwanted contractions of the muscles of the face during attempted movement.
- important to observe these patients due to this

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12
Q

Investigation of Marcus gunn

A

VA, AHP, CT BSV, Conv and PCT. Also consider HESS, field of BSV and field of uniocular fixation

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13
Q

OMs of Marcus gunn

A

Lid position
- lid crease & brow position
- ? pupil covered - at worst & at best
- ? normal situation

Lid movement
- anomalous movement
- observe during OM
- lid closure

Ptosis
- true VERSUS pseudo
- measurement
- levator function

there is variability

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14
Q

Differential diagnosis of Marcus gunn

A

Aberrant regeneration. SR palsy- sup division 3rd nerve, double elevator palsy, HoT and pseudoptosis, congenital ptosis and myasthenia gravis

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15
Q

Management of Marcus gunn

A

Refraction, occlusion, AHP, may learn to minimise or disguise jaw wink, Sx- strabismus may come before ptosis and it may leave ptosis if possible
Surgery cosmesis is poor and the patient and parents must be made aware of limited prognosis for improvement

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16
Q

Surgical options of Marcus gunn

A
  • Unilateral levator excision & frontalis suspension
  • can perform this Sx bilaterally to try & gain a more symmetrical result
  • Levator resection
  • Fasenella-Servat procedure
  • Levator myectomy
  • Removal of levator aponeurosis & muscle
17
Q

Post op complications of Marcus gunn

A
  • Lagopthamlos on downgaze
  • Eyelash malpositon
  • Loss of eyelid crease
  • Eyelid contour abnormality
  • Entropian
  • Residual ptosis
  • Recurrence of ptosis (10%)
  • Residual jaw winking- cosmetically unacceptable
18
Q

Abberant regeneration can occur following a

A

3rd nerve palsy

19
Q

Abberant regeneration causes

A

It can cause lid elevation on adduction on downgaze, adduction on attempted upgaze, glove retraction on upgaze and or down gaze, pupil constriction on adduction. There aren’t signs in every case and lid elevation is most common. Abnormal movements due to co-contraction of muscles supplied by 3rd CN- 8-12 weeks after onset of 3rd N palsy, 6 weeks and cosmetically upsetting.

20
Q

Examples of aberrant regeneration

A

R 3rd nerve palsy
◦ R lid elevates on ADDuction
◦ R lid elevates on depression

21
Q

Investigating 3rd nerve palsy

A

pay attention to OM, aberrant features and document as accurately as possible- descriptions, drawing OM, video, photographs

22
Q

In patient with 3rd nerve palsy what aberrant regeneration features are seen

A

lid elevates on ADDuction or downgaze
ADDuction on attempted upgaze
globe retraction on upgaze &/or downgaze
pupil constriction on ADDuction

23
Q

Aetiology if aberrant regeneration

A

usually significant head injury
? loss of consciousness
? other neurological deficits
Compressive lesion – aneurysm
Damage to the structure of the nerve

24
Q

Other aetiologies of aberrant regeneration

A

Congenital 3rd nerve palsy, migraine, following neuroSx- carnivorous sinus, inflammatory conditions- Guillain barre syndrome, miller fisher and primary aberrant regeneration syndrome- without acute 3rd nerve palsy and without any 3rd nerve palsy

25
Q

Aberrant regeneration and diabetes

A

Aberrant regeneration almost never (?) occurs in diabetic or microvascular 3rd N palsy
The structure of the nerve remains intact. If you see aberrant regeneration features in a 3rd nerve palsy previously assumed to be ‘microvascular’ aetiology → imaging and further investigation

26
Q

Theories of aberrant regeneration

A

Misdirection theory
Central synaptic reorganisation Ephaptic transmission

27
Q

Misdirection theory

A
  • Causes traumatic damage to 3rd CN as fibres regrow but innervate different muscles which ‘misrouting of axons. It has been confirmed by some EMG evidence and doesn’t explain mechanism in every case. There is experimental evidence in rats and fibres regenerate along the length of the nerve and its not just at the site of the lesion
28
Q

Central synaptic reorganisation

A
  • It causes a disruption of synapses of 3rd CN nuclei
    central mechanism. It induces axonal injury > changes then affect & disrupt:
    organisation of cell bodies, synapses. It is supported by cases of primary regeneration without 3rd N palsy.
29
Q

Ephaptic transmission

A
  • It causes neuronal transmission between nerve axons instead of at the synapse and it causes slow growing lesion. These will cause a destruction & regeneration of 3rd CN fibres. It allows electrical cross-talk between individual 3rd CN fibres
    especially if myelin sheaths have been damaged by slow compression
30
Q

Management of 3rd nerve palsies

A

Observe and allow for recovery (6 months). Conservative options are prisms, occlusion,
total, sector and AHP & head movements
Management dependent on symptoms & BSV

31
Q

Patient symtoms

A

diplopia and abberant features e.g. lids, abnormal eye movements and pupils

32
Q

How to assess potential for BSV

A

This can be done using prisms in free space and the synoptophore
If potential BSV then surgery is done to achieve this
If no potential for BSV then query traumatic loss of fusion, improve eye alignment and occlusion if necessary

33
Q

What is the aim of surgery if there is BSV

A

Expanding it and move it to a more useful area, important in primary position and downgaze. But the patient needs to have realistic aims

34
Q

Surgery

A

-contralateral eye may worsen aberrant signs if operate on affected eye
-weakening o/a muscles
-faden
-adjustable sutures
-strabismus sx before ptosis sx- because ptosis sx is more unpredictable
-can involve >1 sx procedure
-occlusion

Strabismus (46 decks)

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