Principles of nerve repair

1. PRINCIPLES OF NERVE
TRANSFER & APPLICATIONS
DR MAHEEN FATIMA
PLASTIC SURGERY RESIDENT

3. TYPES OF NERVE INJURIES

5. INTRODUCTION
• Ballance published a description of side-to-end nerve transfer of the spinal
accessory nerve to the injured facial nerve in 1903
• First world war accelerated the concept of nerve transfer
• Otfrid Foerster first to introduced 3 types of nerve transfers; End to End, End to side
& Partial Nerve transfer with 30% donor nerve in 1929
• Nerve transfer involves bringing an innervated donor nerve to a denervated target
nerve to provide reinnervation to the target muscle or sensory end organ.
• When the donor nerve is closer to the target end organ, the nerve transfer will
provide faster reinnervation and the opportunity for superior results with better
sensorimotor function.

6. BRIDGING THE NERVE GAP

7. NERVE GRAFTS VS TRANSFER

8. NERVE GRAFT TYPES

9. NERVE TRANSFER VS TENDON
TRANSFER
• Nerve transfer can restore sensibility in addition to motor function
• A nerve that innervates multiple muscle groups can be restored with a single
nerve transfer
• The insertion and attachment of muscles are not distrubed

10. BASICS
• Two critical reasons for considering nerve transfer : pain control and sensory
reconstruction
• Muscles will atrophy if not reinnervated within 12 to 18 months, but the time frame
for sensory regeneration is longer, but not well known
• Nerve transfers enable rapid and successful reinnervation, even when patients
present late. T
• Enable reconstruction when no proximal stump of the injured nerve is available,
when a large zone of injury exists, or when the exact location of injury is unknown
• It requires supple joints and careful donor planning

11. INDICATIONS
• Injury distant from target
• Proximal nerve stump not available
(e.g., intracranial VII, avulsed brachial
plexus root)
• Large zone of injury
• Segmental or multiple nerve injuries
• Unknown location of nerve injury
• Partial nerve injuries
• Zone of injury adjacent to critical
structures
• Prolonged time from injury

12. DONOR & RECIPIENT NERVE SELECTION
• Functioning or recovering donor
• Redundant function (expendable)
• Synergistic movement
• Similar power
• Proximity to target muscle
• Reconstruct motor with motor and sensory with sensory

13. TECHNIQUES FOR COAPTATIONS
• The coaptation should be tension-free
• The donor nerve should be dissected as far distally as possible to maximize length, and the
recipient nerve must be divided as proximally as reasonable
END-TO-END REPAIR:
• Both the recipient and donor nerves are divided and coapted, such that neither the recipient
nor donor nerve is left in continuity
END-TO-SIDE REPAIR:
• When the donor nerve is left in continuity and the recipient end is coapted into the side of
the donor nerve, these are classically considered ETS or terminolateral coaptations
• The most significant advantage of ETS is that donor morbidity is minimized and useful when
donor nerves are scarce
• An epineurial window is cut in the donor nerve to facilitate regeneration into the recipient
nerve

14. REVERSE END-TO-SIDE REPAIR:
• Also known as Supercharge ETS
• In this type, recipient nerve remains intact
& proximal end of the donor nerve is
coapted to the side of the recipient nerve
• This technique is particularly useful when a
large mixed nerve is injured proximally and
repaired
• As preserving continuity of the nerve may
allow for sensory regeneration whereas the
transfer allows motor reinnervation prior to
loss of motor endplates.
• Also used in partial nerve injuries

16. BABYSITTER PROCEDURE:
• Babysitter nerve transfers are used to temporarily maintain
recipient muscles
• It is used in scenarios requiring regeneration over very long
distances such as cross-facial nerve grafts or extensive brachial
plexus grafting, or in cases of delayed treatment for preserving
recipient muscle motor endplates.
• The first stage involves coapting cross-face nerve grafts to the
functional, contralateral facial nerve branches (the distal graft
ends were left free). On the injured side of the face, 40% of the
hypoglossal nerve is transferred to the critical branches of the
nonfunctional facial nerve.
• In the second stage, 8 to 12 months later, the free ends of the
cross-face grafts are connected to the distal stumps of the injured
facial nerve and the mini hypoglossal nerve transfer is left intact.
• The intervening hypoglossal transfer preserved the facial mimetic
muscle motor endplates, while regeneration proceeded through
the cross- facial grafts

17. APPLICATIONS
FACIAL MOTOR RECONSTRUCTION:
• Facial muscles have longer reinnervation window (12 to 24 months)
• Reconstruction may be performed for a specific movement, globally for tone or multiple movements.
• Most integral movements for facial function are eye closure and smile
• The masseteric nerve is likely the most commonly used donor nerve
• Advantages: Robust axonal supply, Ability to be transferred without a graft ,Reliable location & Low donor site morbidity.
• Postoperatively, there is the challenge of motor reeducation & results in less spontaneous and emotional movement
• Use of the hypoglossal nerve has yielded greater results with respect to resting tone.
• Other donor nerves for transfers to reestablish facial expression include
• Deep temporal nerve
• Platysma motor nerve (for lower lip depression)
• C7
• Phrenic nerve
• Spinal accessory nerve
• Mylohyoid, suprascapular, and long thoracic nerves

19. APPLICATIONS
FACIAL SENSORY RECONSTRUCTION:
• Facial paralysis with corneal exposure is devastating
• Corneal anesthesia can be reconstructed with functional regional sensory nerves.
• The contralateral supraorbital and supratrochlear nerves are frequently used donors.
• After interfascicular dissection of the distal nerve end, fascicles are tunneled in the subtenon plane and
grouped three or four locations around the limbus.
• The fascicles are secured and regeneration occurs into the stromal and subbasal layers of the cornea.
• Preliminary results from patients undergoing a modified technique for corneal neurotization have been
promising
• Most patients regained normal sensation, with all patients achieving protective sensation

21. UPPER EXTREMITY NERVE TRANSFERS

22. SUPRASCAPULAR NERVE:
• The suprascapular nerve innervates the supraspinatus & infraspinatus
muscles, thus providing shoulder stability and external rotation.
• Transfer of the spinal accessory to the suprascapular can be done either
through an anterior or posterior approach.
• The anterior approach combines well with a cervical approach to the brachial
plexus.
• A posterior approach is used to release the suprascapular notch, but does
require lateral or prone positioning. In larger patients, this dissection can be
quite deep and lighted retractors are necessary
• Most robust branch of SA should be used for transfer with care to preserve
branches for trapezius function.
• Transfer of the rhomboid nerve to suprascapular has also been described.

24. AXILLARY NERVE :
• Deltoid function is the most important deficit with axillary nerve injury.
• A branch of the radial nerve to the triceps is used for transfer
• This procedure is commonly referred to as the Leechavengvong or Somsak
procedure
• Originally, the branch to the long head of the triceps was favored, but others
have argued in favor of the medial branch because it has a longer
extramuscular course.
• This transfer is best done in prone position and can be combined with a
spinal accessory to suprascapular nerve transfer.
• The medial pectoral nerve is another donor.

26. MUSCULOCUTANEOUS NERVE :
• Restoration of elbow flexion is a priority in upper trunk injuries
• Transfer of an FCU branch of the ulnar nerve to the motor nerve to biceps, referred to as an
Oberlin transfer, provides both elbow flexion and supination
• An FDS or flexor carpi radialis (FCR) branch of the median nerve can also be transferred to the
biceps.
• The double fascicular transfer, reinnervates two elbow flexors: it combines the Oberlin transfer
with transfer of the median FDS/FCR branch to brachialis.
• This transfer carries a theoretical risk of eliminating both major wrist flexors
• Only significant difference is improvement of hand grip
• Other donor options include the thoracodorsal and medial pectoral nerve.
• In the scenario of complete plexus avulsion injuries, the distal spinal accessory or intercostal
nerves can be used with an interpositional nerve graft.

27. OBERLIN PROCEDURE DOUBLE FASICULAR PROCEDURE

28. RADIAL NERVE :
• Elbow extension can be restored via transfer of the nerve branch to FCU to the medial triceps.
• In the hand, radial nerve function can be restored via median donors (branches to FCR and FDS)
and motor branch to pronator quadratus transferred to posterior interosseous nerve (PIN) and
extensor carpi radialis brevis (ECRB) branches
• Nerve transfer to the PIN is the only method of achieving individual finger extension
• The musculocutaneous branch to brachialis is another possible donor.
• To restore radial hand sensation, lateral antebrachial cutaneous nerve (LABC) to radial sensory
can be used.
• Because of nerve territory overlap in the hand, the transfer should only be used when necessary

30. ULNAR NERVE :
• High ulnar injuries are challenging due to the long distance to the target, the ulnar intrinsic
muscles.
• Transfer of the median AIN branch of pronator quadratus to the motor branch of the ulnar nerve
addresses this issue and is likely one of the most commonly used transfers
• Transfer can be done in ETS manner
• For sensory reconstruction, the median branch to the third webspace can be transferred.
• The median palmar cutaneous is another possible donor, as is the LABC but requires a very lengthy
incision. It is of high utility when the median nerve is also damaged.
• Comparison of grafting versus motor and sensory transfers in proximal ulnar nerve injuries showed
showed significantly improved functional outcomes: 80% were at least M3 in the nerve transfer,
versus 22% with grafting.
• Interestingly, sensory outcomes were not significantly different.

32. MEDIAN NERVE :
• The most significant motor deficits in high median nerve injury are flexor pollicis longus (FPL) and
flexor digitorum profundus.
• An ulnar FDS branch, radial branch to ECRB, or musculocutaneous branch to brachialis can be
transferred to the AIN branch.
• Before reinnervation, FPL may lengthen due to unopposed EPL pull and become less effective, thus
interphalangeal extension blocking can be a helpful adjunct during reinnervation.
• The median recurrent motor branch can be restored through an ulnar motor branch to the third
lumbrical, nerve to abductor digiti quinti, or a radial PIN branch to extensor digiti minimi and
extensor carpi ulnaris
• Transfer of the sensory digital nerve of the 4th webspace end-to-end to the sensory component of
the median nerve can be used to restore sensation.
• In turn, sensation to the 4th webspace can be returned by coapting the distal end of the 4th
webspace sensory branch to the side of the ulnar digital nerve of the small finger.

34. FLAIL ARM:
• In the scenario of a flail arm, there may be no available branches of the brachial plexus for transfer
• Intercostal (IC) nerve or nerve to rectus transferred to the musculocutaneous nerve, either directly
or with an interposition nerve graft, can be used to restore elbow flexion or elbow extension.
• Given the long distance, this transfer must be done relatively soon after injury.
• The number of complications increased significantly when four or more ICs were used
• It is critical to assess whether the patient has had ipsilateral rib fractures or any respiratory
impairment preoperatively, such as phrenic palsy
• The presence of phrenic palsy has been associated with increased risk of respiratory compromise
• The risk of iatrogenic pneumothorax in the dissection is 9% if prior trauma caused scarring

36. BIRTH-RELATED BRACHIAL PLEXUS PALSIES:
• The standard in birth-related brachial plexus palsies (BRBPP) is excision of the neuroma and
grafting the intact roots.
• Distal nerve transfers have several advantages: Avoid morbidity of neuroma dissection Avoid graft
donor site morbidity & reduce distance to target muscle (especially advantageous in late
presentations)
• Transfers are possible in the scenario of multiple root avulsions when there are minimal donors for
grafting.
• The spinal accessory to suprascapular nerve transfer was accepted early, because the spinal
accessory nerve is in the field of the standard cervical approach to the plexus
• However there is no significant difference in grafting C5 to suprascapular versus the spinal
accessory transfer.
• More distal transfers such as the Oberlin transfer and radial to axillary transfers for shoulder
abduction have also been utilized in BRBPP
• The triple transfer of spinal accessory to suprascapular, Oberlin transfer, and radial to axillary shows
shows improved supination and shoulder external rotation , no donor morbidity, decrease
operative time & length of hospital stay

37. LOWER EXTREMITY NERVE TRANSFERS
FEMORAL NERVE :
• The femoral nerve most critically supplies the quadriceps and is responsible for knee extension.
• Unfortunately, this nerve can be injured in common procedures such as total hip arthroplasty.
• The anterior branch of the obturator, supplying the gracilis, adductor longus, and adductor
brevis, can serve as a donor to the femoral branches to rectus femoris and vastus medialis.
• The rectus femoris provides a straight pull for knee extension whereas the medial pull of the
vastus medialis balances the lateral pull of the tensor fascia latae, innervated by the superior
gluteal nerve

38. TIBIAL NERVE :
• Tibial nerve function is a critical decision point for lower extremity amputation. Loss of protective
protective sensation to the plantar foot is linked to failure of limb salvage.
• The predominant motor role of the tibial nerve is plantar flexion.
• In proximal tibial nerve injuries, there are multiple redundant femoral branches to the quadriceps
quadriceps muscles that can be used as donors.
• Branches to the vastus medialis and vastus lateralis can be transferred to the tibial branches of
the gastrocnemius to return plantar flexion.
• Its challenging as the donor and recipient are a significant distance apart. With sufficient
neurolysis of the medial gastrocnemius branch, an ETE coaptation can be made with the donor;
however, a nerve graft is necessary to connect the vastus lateralis to the lateral gastrocnemius
• Sensation can be restored with a saphenous to tibial nerve transfer, but the distance
between these nerves requires an interposition graft.
• Transfer of the deep peroneal for plantar sensation has also been successful

39. PERONEAL NERVE :
• Unusually superficial and may be involved in knee dislocations and tibial fractures.
• Peroneal nerve deficits result in foot drop.
• The tibial nerve branches to flexor digitorum longus or flexor hallucis longus can be
used as donors to the anterior tibialis to restore extension
• Patient age, time from injury, and length of follow-up likely contribute to the
discrepancy in outcomes

40. POSTOPERATIVE CARE
• The surgical dressing frequently includes a splint or bulky soft dressing that is
removed at postoperative day 2 or 3.
• Patients begin working with a therapist who is knowledgeable about motor
retraining ideally preoperatively and then beginning at 3 to 4 weeks postoperatively
to begin contractions of donor nerve muscles.
• For sensory transfers, sensory input to the newly reinnervated region is critical for
cortical relearning.

41. THANK YOU