Surgical Management of Neurogenic Palsies Flashcards

1
Q

What are the aims of surgery?

A
  • Relieve symptoms
  • Restore BSV
  • Enlarge field of BSV
  • Reduce / eliminate AHP
  • Improve alignment
  • Restore concomitance
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2
Q

What factors must we consider before making a surgical decision?

A
  • Extent of muscle sequelae
  • Suitability of each muscle for type of surgery
  • Size of deviation in P.P. and down gaze
  • Presence of horizontal/ vertical components
  • Presence and amount of torsion
    Paralysis / paresis
  • Longstanding / recently acquired
    (Fusion amplitude can help)
  • AHP
  • Forced duction test (FDT)
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3
Q

What are some general surgical principles?

A
  • Consider the suitability of each muscle. If no function is present, avoid that muscle or consider a transposition procedure.
  • An elevator is chosen in preference to a depressor when weakening, as diplopia is less troublesome on elevation
  • Surgery may be performed in stages (to assess the outcome of each individual stage), or at one stage (dependant upon the extent of the palsy)
  • Botulinum toxin may be used in conjunction with muscle surgery
  • For single muscle palsies:
    Where some function is present, strengthen the affected muscle
    Weaken the o/a contralateral synergist
    Weaken the o/a ipsilateral antagonist
    Strengthen the u/a contralateral antagonist
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4
Q

When should we consider a transposition procedure?

A
  • Consider the suitability of each muscle. If no function is present, avoid that muscle or consider a transposition procedure.
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5
Q

When weakening a muscle in surgery do we prefer an elevator or depressor?

A
  • An elevator is chosen in preference to a depressor when weakening, as diplopia is less troublesome on elevation
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6
Q

What are transposition procedures?

A

Involves moving the whole or part of a muscle in order to change the primary or secondary action of that muscle. Whole muscle can be done on either horizontal or vertical recti muscles.

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7
Q

What are the names of the whole muscle transpositions?

A
  • Knapp
  • Foster (posterior fixation sutures)
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8
Q

What are the names of the part muscle transpositions?

A
  • Hummelsheim
  • Jensen
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9
Q

What is the Hummelsheim procedure? When is it used?

A

A transposition procedure of part of the muscle.
Used in CNVI palsy to move the temporal halves of the IR and the SR which are inserted to the LR to allow them to become abductors in leu of the LR.
Often needs to be combined with MR recessions.
Can cause an anterior segment ischaemia because of the number of muscles being worked on

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10
Q

What’s a risk of the Hummelsheim procedure?

A

Due to the number of muscles being worked on it can caused anterior segment ischaemia

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11
Q

What is the Jensen procedure?

A

A part muscle transposition procedure. The temporal halves of the IR and SR are joined to the divided halves of the LR.

Utilises transposition without disinserting the tendons of the muscles, thus maintaining anterior segment blood supply

Needs to be combined with MR recession

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12
Q

What is the Knapp procedure?

A

A full muscle transposition procedure.

Used to correct a double elevator palsy

MR & LR are detached and reinserted along medial (MR) & lateral borders (LR) of SR. This makes the LR and MR into elevators.

If an IO palsy on its own then move the LR and MR down to the IO to make them elevators.

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13
Q

What is the Knapp procedure used for?

A

To correct double elevator palsy (congenital condition, typically have a ptosis, SR and IO palsy)

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14
Q

What is the Inverse Knapp procedure?

A

Used to correct IR palsy by detaching the MR & LR and reinserting these along the medial and lateral borders of the IR

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15
Q

What is the Foster Technique?

A

A full muscle transposition surgery of the vertical recti that are then inserted at the LR.

Posterior fixation sutures (non-absorbable) are then placed 8mm behind the LR insertion which increases abducting force

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16
Q

What does the Foster technique improve?

A

Abducting force through use of posterior fixation sutures which reduces the need for surgery on the MR which means avoiding risk of anterior segment ischaemia

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17
Q

What surgery would you do in Duane’s Syndrome?

A

Foster Technique

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18
Q

What is the Foster Technique used for?

A

Duane’s Syndrome

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19
Q

What is the Scott Procedure being used in replacement of?

A

The Scott procedure is becoming increasingly popular superseding the Faden (posterior fixation suture) technique

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20
Q

What is the Scott Procedure?

A

A resection-recession procedure on a single palsy

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21
Q

When is the Scott Procedure used?

A

Used in incomitant strabismus with small deviation in P.P. and incomitance in eccentric gaze in the field of action of the paresed muscle

Used in CNIII, CNIV & CNVI palsy

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22
Q

What is the aim of the Scott Procedure?

A

Combine a large resection with recession of a single muscle (so the resection and recession is just on one muscle) will reduce the action of the over-acting yoke muscle and thus reduce incomitance

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23
Q

What muscle(s) do you work on using the Scott procedure in CNIII palsy?

A

3rd Nerve palsy - the resection-recession is on the LR

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24
Q

What muscle(s) do you work on using the Scott procedure in CNIV palsy?

A

4th Nerve palsy - the resection-recession is on the IR

25
Q

What muscle(s) do you work on using the Scott procedure in CNVI palsy?

A

6th Nerve palsy – the resection-recession is on the MR

26
Q

What surgery would we do in a CNIII paresis (incomplete CNIII palsy)?

A

Correct horizontal 1st with ipsilateral LR recession / MR resection, then strengthen IR or SR if needed

Preferable to correct the horizontal angle first with a LR recession and a MR resection of the affected eye (as some residual muscle function).
Prismatic or further surgical correction may be required postoperatively to correct any residual vertical deviation.

If further surgery is required, the affected SR or IR strengthening procedures are suggested.

27
Q

What do we need to consider for surgery in a complete CNIII palsy?

A
  • Aim for realignment in P.P.
  • Compromise post-op = limited ocular motility, small field of BSV
  • Sx performed in stages & concentrated on affected eye
  • Ptosis Sx performed after Strabismus Sx
28
Q

Why is ptosis surgery performed after strabismus surgery in CNIII palsy?

A

Pseudo-ptosis can occur so we want to deal with ptosis surgery AFTER strabismus surgery so we can see how much true ptosis we actually have as the strabismus may be making the ptosis (if vertical) look worse than it is.

29
Q

What surgery in a complete CNIII palsy would we perform?

A

As the LR and SO of the affected eye can now act unopposed, contracture of these muscles occurs. Therefore weakening procedures on these muscles are indicated.

LR recession (10mm) on an adjustable suture, with conjunctival recession OR maximise LR recession up to 17mm using looped sutures.

SO tenotomy (splitting and lengthening) / tenectomy (tendon removal) to prevent mechanically induced hypotropia, associated with a ‘supermaximal’ (up to 9mm) MR resection.

30
Q

In complete CNIII palsy can we do transposition procedures? If yes, which?

A

Yes:
- Vertical recti transposition to MR (Knapp) with LR recession

  • Foster transposition to MR without LR recession
  • Reverse Jensen to MR with LR & conjunctival recession
  • Recession of o/a synergists
  • Anchor sutures
    To prevent contracture of recessed LR
31
Q

What is the difference between a paresis and a paralysis in a CNIII palsy?

A
  • Presence of some degree of muscle function
    chance of achieving field of BSV
  • Treatment depend upon whether it’s a single muscle palsy or a divisional palsy
32
Q

What surgery do we do in a total MR palsy?

A

Rare
If total MR palsy = transposition of the vertical recti to the insertion of the MR, with LR recession
MR resection, with ipsilateral or contralateral LR recession (improves persistent incomitance evident on contralateral gaze that is caused by limitation of adduction of the affected eye.

33
Q

What surgery do we do in a total IR palsy?

A

IR:
If mild = IR resection or contralateral IR weakening
If moderate / severe = IR resection or SR recession
If marked = Inverse Knapp procedure - transposition of the MR and LR to the medial and lateral borders of the IR.
A contralateral SO weakening procedure is NOT favoured due to the induction of a possible torsional effect.

34
Q

What surgery do we do in a total SR palsy?

A
  • The type of surgery is dependant upon the degree of residual SR function
  • Ipsilateral SR resection with / without IR recession
  • Contralateral IO recession
  • If marked palsy (-ve FDT) = Knapp procedure
35
Q

What surgery do we do in a total IO palsy?

A

Intrasheath tenotomy of the SO, or recession of the contralateral SR dependant upon whether the hypotropia is more marked on downgaze or upgaze respectively, and on the extent of torsion present.
Surgery may be performed on the unaffected eye to balance the defect, or on the ipsilateral antagonist (SO).
A -ve FDT will exclude a mechanical problem and therefore exclude the possibility of Brown syndrome.

36
Q

What type of surgery do we do in a superior division CNIII palsy?

A

The type of surgery is dependent upon the amount of residual SR function present, and the extent of the muscle sequelae that has developed. It is also very dependent upon the extent of any diplopia. Diplopia on upgaze is less troublesome and may lead to problems on downgaze postoperatively (more of a problem).

  • If mild = recession of the contralateral SR, with / without recession of the ipsilateral IR
  • If marked = Ipsilateral Knapp procedure

Procedure will involve ptosis surgery

37
Q

What type of surgery do we do in a inferior division CNIII palsy?

A

Rare

  • LR recession
  • Tenectomy of the ipsilateral SO to reduce intorsion
  • Transposition of the LR to the IR insertion, and the SR to the MR insertion
38
Q

What surgery do we do in a double elevator palsy?

A
  • Limitation of upgaze in both adduction and abduction (SR and IO).
  • If -ve FDT (forced duction test) = Knapp’s procedure transposing the MR and LR to the medial and lateral borders of the SR respectively.
  • If +ve FDT (+ve restriction to passive upgaze suggesting secondary IR contracture) = ipsilateral IR recession combined with a Knapp procedure.

Alternatively Foster transposition may be considered

39
Q

What surgery do we do in a double elevator palsy with a -ve forced fuction test?

A

If -ve FDT = Knapp’s procedure transposing the MR and LR to the medial and lateral borders of the SR respectively.

40
Q

What surgery do we do in a double elevator palsy with a +ve forced fuction test?

A

If +ve FDT (+ve restriction to passive upgaze suggesting secondary IR contracture) = ipsilateral IR recession combined with a Knapp procedure.

41
Q

What surgery do we do in a CNIII nerve palsy when aberrant regeneration is present?

A
  • Left untreated - difficult!
  • Disinsertion of levator, followed by sling procedure
  • Often caused my muscle trauma
  • Less likely to be treated via surgery if a patient has this as it is unclear what the outcome would be
42
Q

What must we consider when it comes to ptosis surgery after CNIII palsy?

A

A hypotropic eye will result in pseudoptosis, therefore masking the true extent of ptosis due to the III nerve palsy.
Assessment of the true ptosis should be made with the affected eye fixing in primary position.

Ptosis surgery should be undertaken after strabismus surgery with the following considerations:
- A sufficient field of BSV should be available without the need to adopt a marked AHP

  • Conservative lid surgery should be undertaken to prevent the possibility of corneal exposure, as the patient will have lost Bell’s phenomenon.
  • Any aberrant movement of the lid is accounted for
  • Any frontalis sling operation is reversible in the event of overcorrection.
43
Q

In a CNIV palsy, what factors influence choice of surgery?

A
  • Unilateral / bilateral
  • Extent of muscle sequelae
  • Degree of residual SO function
  • Extorsion
  • Extent of muscle sequelae
44
Q

What surgery do we do in the case of a unilateral CNIV palsy?

A

O/a of the ipsilateral antagonist:
Ipsilateral IO weakening (myectomy or recession) due to its ease of procedure and effectivity in overcoming the vertical and in part, the torsional deviation.

O/a of the contralateral IR:
Surgical decision depends upon the extent and superability of the extorsion.

If superable torsion (fusable torsion) following temporary fresnel prism correction of the vertical deviation for 2 - 3 weeks = IR recession with an adjustable suture.

If insuperable torsion (torsion that cannot be fused) = Harada-Ito procedure on affected SO, following which, IR recession may be performed to overcome any residual vertical deviation
A SO tuck may be performed to strengthen any residual function in the SO, to correct any hypertropia in primary position and any cyclotorsion. However, this procedure is technically difficult and may induce an iatrogenic Brown Syndrome (caused by surgery, when the tuck stops the SO being able to move through the trochlear).

o/a ipsilateral antagonist & contralateral synergist:
Recession ipsilateral IO
Recession contralateral IR if persistent vertical

45
Q

What surgery do we do in the case of a unilateral CNIV palsy with an o/a of ipsilateral antagonist?

A

Ipsilateral IO weakening (myectomy or recession) due to its ease of procedure and effectivity in overcoming the vertical and in part, the torsional deviation.

46
Q

What surgery do we do in the case of a unilateral CNIV palsy with an o/a of contralateral IR?

A

O/a of the contralateral IR:
Surgical decision depends upon the extent and superability of the extorsion.

If superable torsion (fusable torsion) following temporary fresnel prism correction of the vertical deviation for 2 - 3 weeks = IR recession with an adjustable suture.

If insuperable torsion (torsion that cannot be fused) = Harada-Ito procedure on affected SO, following which, IR recession may be performed to overcome any residual vertical deviation
A SO tuck may be performed to strengthen any residual function in the SO, to correct any hypertropia in primary position and any cyclotorsion. However, this procedure is technically difficult and may induce an iatrogenic Brown Syndrome (caused by surgery, when the tuck stops the SO being able to move through the trochlear).

47
Q

What surgery do we do in the case of a unilateral CNIV palsy with an o/a of ipsilateral antagonist & contralateral IR?

A

Recession ipsilateral IO
Recession contralateral IR if persistent vertical

48
Q

What is the aim of a myectomy?

A

Aim is to produce a predictable weakening of a muscle without altering its line of action. And allow residual muscle action remains intact.

49
Q

What is a SO (superior oblique) tuck?

A

SO tuck: is a strengthening procedure. The SO tendon is folded and tucked and the fold is sutured together with non-absorbable sutures. Risk of iatrogenic brown’s syndrom

50
Q

What is the aim of Bilateral CNIV palsy?

A
  • To o/c insuperable bilateral torsion
  • To achieve BSV in primary position and downgaze.

Need to strengthen both SO muscles

51
Q

What surgery would we do in asymmetrical bilateral CNIV nerve palsy?

A

Bilateral Harada-Ito, the greater amount being performed on the more affected eye. Harada-Ito corrects any excyclotorsion without influencing any vertical or horizontal deviation.

52
Q

What surgery would we do in bilateral CNIV palsy where there’s a large vertical component?

A

Bilateral SO tucks (~8mm). The tuck is the procedure of choice in the presence of a large vertical component.

Both eyes must be corrected. A ‘masked bilateral SO palsy’ may be revealed following surgery for a unilateral case.

53
Q

What surgery would we do in bilateral CNIV palsy where there’s a marked IO contracture?

A

IO weakening required. In the event of marked bilateral IO contracture (‘V’ exo), or superable torsion, bilateral IO weakening is the initial procedure of choice. Further surgery will be influenced by any residual torsional deviation.

54
Q

What surgery would we do in bilateral CNIV palsy where there’s a V ET deviation?

A

Downward displacement of MR insertions

55
Q

What is the Harado-Ito Bilateral Procedure?

A

The anterior half of the SO tendon is mainly concerned with intorsion

The posterior half is concerned with abduction and depression.

It is possible to affect the torsional action without affecting the secondary actions by operating on the anterior half of the tendon only.

The torsional action of the SO can be increased by moving the anterior half of its tendon antero-laterally.

The anterior half of the SO tendon is divided from the posterior half along its length for 10mm. The half tendon is then re-attached to the globe 8mm behind the LR insertion and above its upper border, the anterior half of the tendon being pulled laterally and anteriorly.

56
Q

What factors influence the management of CNVI palsy?

A

Unilateral / bilateral

Paralysis / paresis

Presence / absence of BSV

Concomitant / incomitant deviation

57
Q

In a partial CNVI palsy (paresis) which eye should we do?

A

Recession of MR of affected eye
Resection of LR of affected eye
Recession of MR of unaffected eye (with posterior fixation suture)
Resection of the LR of the unaffected eye

These procedures may be performed alone, or in combination depending upon the extent of the palsy.

In children who have recovered from a VI nerve palsy, a residual esotropia may remain and can be treated in the conventional way.

58
Q

What specific test can we use to diagnose CNVI palsy?

A

May need to eliminate MR contracture to diagnose – Botulinum toxin injection

  • Improvement in abduction after BT: (paresis)
    Supermaximal MR recession of affected eye with adjustable
    LR resection of affected eye
    MR recession of unaffected eye with adjustable
  • No improvement after BT: (paralysis)
    Hummelsheim, Jensen or Foster:
    SR & IR transposition to LR of affected eye
  • Force generation test:
    Can help quantify the amount of residual function