surgical management of neurological palsies

Question 1

what are the aims of surgery

Answer 1

Relieve symptoms
Restore BSV
Enlarge field of BSV
Reduce / eliminate AHP
Improve alignment
Restore concomitance

Question 2

what factors influence surgery choice

Answer 2

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
AHP
Forced duction test (FDT)

Question 3

what are general surgical procedures

Answer 3

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
(ie. Confine surgery to muscles affected by muscle sequelae)

Question 4

what are transposition procedures

Answer 4

Involves moving whole or partial of muscle to change 1° or 2° actions

Whole muscle transposition
Knapp
Foster (posterior fixation sutures)
Part muscle transposition
Hummelsheim
Jensen

Question 5

what is hummelsheim procedure

Answer 5

Hummelsheim first introduced a transposition procedure in 1907
It involved transposing temporal halves of the IR & SR muscles to the insertion of the LR muscle

Question 6

what is the Jensen procsure

Answer 6

temporal halves of inferior redctus and superior rectus joined to divide halves of the lateral rectus

so the anterior segment blood supply is maintained

Question 7

what is the knapp procedure

Answer 7

Full muscle transposition

Knapp: correct double elevator palsy
MR & LR are detached and reinserted along medial & lateral borders of SR

Inverse Knapp: correct IR palsy
MR & LR are detached and reinserted along medial & lateral borders of IR

Question 8

what is the foster technique

Answer 8

Foster technique was introduced in 1997 by Foster
He fully transposed the SR and IR muscles to the LR insertion
In addition he placed non-absorbable posterior fixation sutures in the SR and IR muscle and attached them to the superior and inferior border of the LR muscle respectively, 8mm behind the insertion

Question 9

what are advantages of the foster technique

Answer 9

posterior fixation sutures increase tonic abucting force

Fixtion sutures increase the abducting force and reduce the need for surgery on the MR and thus avoid risk of ant. Segment ischaemia

Question 10

is surgery indicated in a third nerve palsy

Answer 10

Paresis (partial loss of function):
Prognosis for useful area of BSV better than with a total paralysis of III nerve
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.
Paralysis (total loss of function):
Aim of surgery: Realignment of the affected eye in primary position
Compromise: Limited ocular motility
Very small field of BSV achievable at best
Due to number of muscles involved, surgery is usually performed in stages
If ptosis surgery is required, this is usually performed after all strabismus surgery
Surgery is concentrated around the affected eye

Question 11

what are the surgical procedures involved in a third nerve palsies

Answer 11

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, LR recession up to 17mm using looped sutures.
SO tenotomy / tenectomy to prevent mechanically induced hypotropia, associated with a ‘supermaximal’ (up to 9mm) MR resection.

Question 12

what transposition procedure can be done in a third nerve palsy

Answer 12

Transposition of the vertical recti to the upper and lower borders of the MR, with LR recession and an extensive conjunctival recession.
Reverse Jensen procedure applied to the MR, with a LR and conjunctival recession.
Transposition of the SO (+/- a trochleotomy, and +/- SO tenectomy) to the MR insertion. This will result in a long-term adducting force to ensure ocular stability. Due to the formation of extensive scar tissue, this procedure is no longer favoured.
Transposition of the SO as above, but with the SO muscle being moved medial to the SR insertion. Whilst this reduces the exotropia, progressive hypertropia has been reported. This procedure is now infrequently used.
Recession of the overacting contralateral synergists.
Anchor sutures - used to anchor the eye in the adducted position for around 4 - 6 weeks postoperatively to prevent contracture of the recessed LR.

Question 13

if someone has third nerve plasie and has a 30d hypotropia in pp what surgery would you do

Answer 13

Knapp: full superior transposition of LMR and LLR
RSR recession and LIR recession

Question 14

if someone had a complete third nerve palsy and a large exotropia what surgery would be done

Answer 14

Large LR recession/ MR resection, combined with muscle traction sutures leftin situfor 6 weeks.
Vertical muscle surgery will follow to correct vertical deviation if needed

Question 15

what does the surgical treatment of a third nerve paresis depend on

Answer 15

Due to the presence of some degree of muscle function, there is an increased chance of achieving a useful field of BSV.
Treatment is dependent upon the characteristics of the palsy, ie, whether there are single muscles of the III nerve affected, or whether there is a divisional III nerve palsy.

Question 16

for a single muscle palsie in a third nerve palsie what is done for the medial rectus and the inferior rectus

Answer 16

To optimise the position and range of movement of the affected eye

MR:
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.
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.

Question 17

what surgical procedure is done if a single muscle palsy is affected on a third nerve palsy , specifically the superior rectus and inferior oblique

Answer 17

SR:
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
IO:
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.

Question 18

if a third nerve palsy of the superior or inferior division occurred what surgical procedure would be done

Answer 18

Superior division:
Mild = recession of contralateral IO, with / without recession ipsilateral IR
Marked = Ipsilateral Knapp
Ptosis Sx after Strabismus Sx

Inferior division:
LR recession
Tenectomy ipsilateral SO
Transposition of LR to IR insertion, and SR to MR insertion

Question 19

if someone had double elevator palsy or abberent regeneration occurred what surgical procedures would be done

Answer 19

Double elevator palsy:
Limitation of upgaze in both adduction and abduction (SR and IO).
If -ve FDT = 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
Aberrant regeneration:
Usually left untreated as difficult to correct satisfactorily
? disinsertion of the levator muscle if upper eyelid retraction is a problem, followed by a sling procedure.

Question 20

how would you surgically correct associated ptosis of a third nerve palsy

Answer 20

Correction of associated ptosis:
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.

Question 21

what factors influence the choice of surgery for a 6th nerve palsy

Answer 21

Factors influencing choice of Surgery:
Unilateral / bilateral
Extent of muscle sequelae
Degree of residual SO function
Extorsion

Surgery governed by
Extent of muscle sequelae

Question 22

what surgery is donee for a unilateral 6th nerve palsy

Answer 22

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

Question 23

what surgery is done for a unilateral 6th nerve palsy

Answer 23

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

Question 24

what alternative surgical procedures can be done for a unilateral 6th nerve palsie

Answer 24

Alternative surgical procedures
Weakening of IO muscle
Anterior transposition of IO: effective in correcting IO o/a and hypertropia in P.P. (Keskinbora 2010)
Ipsilateral SR recession to correct residual head tilt following ipsilateral IO weakening – 75% success rate (Ahn et al 2012)
IO recession, SO tucking or advancement or a combination of both are most popular treatments for acquiredtrochlearnervepalsy (Gräf et al 2010

Weakening of IO muscle for congenital SO palsy
IO myectomy – 92% success rate (≤4 PD Hypertropia post-op) – Lee et al (2016)
7-mm nasal transposition of IR muscle combined with contralateral IR recession if hypertropia in P.P. is ≤10 PD (Kushner 2010)

Question 25

what is a myectomy

Answer 25

Myectomy: aim is to produce a predictable weakening of a muscle without altering its line of action. And allow residual muscle action remains intact.
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 syndrome

Question 26

what surgery is done for bilateral 6th nerve palsy

Answer 26

Bilateral palsies are frequently asymmetrical, in which case surgery is also asymmetrical.
Aim: To o/c insuperable bilateral torsion
To achieve BSV in primary position and downgaze.
A strengthening procedure on both SO muscles is required to correct excyclotorsion.
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.
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.
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.
Surgery of the medial recti for any eso deviation may be performed with possible downward displacement of insertions for ‘V’ pattern correction

Question 27

what is a hard- ito surgery

Answer 27

Principle:
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.
Method:
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.
According to Parks (1971):
In bilateral procedures:
Re-insertion of the tendon at the upper border of the LR results in 15-20° of correction.
Re-insertion of the tendon 4mm above the upper border of the LR results in 6-8° of correction.

Question 28

what factors influence management in a 6th nerve palsy

Answer 28

Factors influencing management:

Unilateral / bilateral

Paralysis / paresis

Presence / absence of BSV

Concomitant / incomitant deviation

Question 29

if there is a partial 6th nerve palsy what surgical procedures are done

Answer 29

Partial VI nerve palsy:
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.

Question 30

what surgery is done for a 6th nerve paralysis

Answer 30

Diagnosis may only be possible after BT to the MR, or after EMG to LR, due to MR contracture.
Recession of MR of affected eye - up to 15mm (loops), combined with muscle transposition of the IR of the affected eye.
If abduction improves following BT =
Recess affected eye MR supermaximally with adjustable suture
Resect the LR of the affected eye
Recess the MR of the unaffected eye with adjustable suture
If no improvement in abduction following BT to MR =
Transposition of the LR of the affected eye
The forced duction test reveals information about mechanical limitations to full ocular rotation. When voluntary ocular rotation is limited, and the forced duction test is completely free, paresis of an extraocular muscle is suggested. The active force generation test and saccadic velocity measurements both provide information about the active forces available to move the globe.

Question 31

what are important considerations for surgical procedures on nerve palsies

Answer 31

Consider deviation in P.P.
Ascertain position of greatest symptoms
Note degree of palsy
Note spread of concomitance
Explain aim of surgery to patient
Diplopia may still occur in certain positions of gaze
May require more than one procedure
May still require small prism