Surgical management of neurogenic palsies Flashcards
What are the aims of surgery
▪ Relieve symptoms
▪ Restore BSV
▪ Enlarge field of BSV
▪ Reduce / eliminate AHP
▪ Improve ocular alignment
▪ Restore concomitance
Factors affecting surgical choice
▪ 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)
Torsion
Torsion is associated with 4th nerve palsy typically
Longstanding so palsy extended SO palsy
Forced Duction Test (FDT)
FDT tells us about mechanical movement and if there is a mechanical limiataion or of there is still some movement of the muscle
General surgical principles
▪ Consider each muscle individually
* No function – avoid or transposition procedure
▪ Weakening procedure
* Elevator in preference to a depressor
▪ Surgery in stages / at once
▪ Botulinum toxin may be used in conjunction
▪ Single muscle palsy
* Surgery confined to muscles of muscle sequelae
▪ Adjustable sutures used in incomitant and concomitant strabismus- done in adults
▪ Consider the suitability of each muscle. If no function is present, avoid that muscle or consider a transposition procedure
More surgical principles
▪ An elevator is chosen in preference to a depressor when weakening, as diplopia is less troublesome on elevation
▪ Weakening procedure are preferred on SR and IO
▪ Inject BT into SR muscle
▪ Single muscle surgery on muscle sequelae
▪ 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)
Strengthening procedures
Resect and Tuck
Weakening procedures
Recess, tenotomy, myectomy, tendon spacer
Transposition procedure
Anterolateral, anteromedial, foster, hummelsheim, jensen, knapp
What do transposition procedures do
move whole or partial of muscle to change 1° or 2° actions
Whole muscle transposition
▪ Knapp and Foster (posterior fixation sutures)
Part muscle transposition
Hummelsheim and Jensen
You can do whole muscle transposition of either horizontal or vertical recti. If muscle was an elevator it can be transposed to be an abductor
Hummelsheim
Hummelsheim first introduced a transposition procedure in 1907. It is partial. It involved transposing temporal halves of the IR & SR muscles to the insertion of the LR muscle 6th – eso and no adduction. This surgery makes the SR and IR become adductors. Risk for anterior segment ischameia. Temporal halves of IR and SR transposed to insertion of LR
Used in VI N Palsy
Jensen
- No muscle disinserted and temporal halves of IR and SR joined to divided halves of LR. Utilises transposition without disinserting the tendons of the muscles, thus maintaining ant segment blood supply. More of an abducting function after this surgery
Typically, a MR recession as well but there is a risk for anterior segment ischameia
USE-heavy eye syndrome and large et
Knapp procedure
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
Double elevator palsy
IO and SR not working pt cant elevate the eye
Move MR and LR up to the insertion of the SR muscle make MR and LR become elevator muscles but still abbuct and adduct
Foster technique
Transpose vertical recti to LR insertion, Posterior fixation sutures- increasing abducting force, Non-absorbable sutures attached 8mm behind LR insertion. LLR doesn’t abduct and posterior fixation sutures increase the abducting force of the SR and IR. Less risk for anterior segment ischameia and you can operate again. Advantages- Advantages of Foster technique are that the posterior fixation sutures increase the abducting force and reduce the need for surgery on the MR and thus avoid risk of anterior segment ischaemia
Strabismus in 3rd nerve palsy
Large XT and HoT
Aim of 3rd nerve surgery
Correct XT surgically
Prognosis of paresis
Transpose vertical recti to LR insertion, Posterior fixation sutures- increasing abducting force, Non-absorbable sutures attached 8mm behind LR insertion. LLR doesn’t abduct and posterior fixation sutures increase the abducting force of the SR and IR. Less risk for anterior segment ischameia and you can operate again. Advantages- Advantages of Foster technique are that the posterior fixation sutures increase the abducting force and reduce the need for surgery on the MR and thus avoid risk of anterior segment ischaemia
Paralysis
Aim- realignment of affected eye in primary position
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
Operating doesn’t always give perfect outcome
Also, ptosis in some cases and surgery for this after the strabismus surgery
Pseudo- makes ptosis appear bigger
LR and SO contract if
Act in opposes and may contract weakening is indicated
What type of sutures are combined for LR recession
A, C and L
This is done on adjustable sutures combined with conjunctival recession or maximised recession with loop sutures
SO tenotomy/ tenectomy can prevent
medically induced HoT and combined with super maximal MR resection
What can LR and SO do in 3rd NP
Can overact and contract becoming tighter
The principle is to weaken these muscles
What is tenotomy
splitting within the tendon
Third nerve paralysis surgical option
Transposition
▪ 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
Complete third nerve palsy surgery
The upper half of the LR muscle was transposed to the superior border and the lower half to the inferior border of
the medial rectus insertion.
3rd nerve paresis features
▪ Presence of some degree of muscle function
* chance of achieving field of BSV
▪ Treatment depend upon
* Single muscle palsy
Divisional palsy
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.
