nerve transfers journal article

Nerve Transfers for the UpperExtremity: New Horizons in NerveReconstruction

Abstract

Nerve transfers are key components of the surgeon’sarmamentarium in brachial plexus and complex nervereconstruction. Advantages of nerve transfers are that nerveregeneration distances are shortened, pure motor or sensory nervefascicles can be selected as donors, and nerve grafts are generallynot required. Similar to the principle of tendon transfers,expendable donor nerves are transferred to denervated nerves withthe goal of functional recovery. Transfers may be subdivided intointraplexal, extraplexal, and distal types; each has a unique role inthe reconstructive process. A thorough diagnostic workup andintraoperative assessment help guide the surgeon in their use.Nerve transfers have made a positive impact on the outcomes ofnerve surgery and are essential tools in complex nervereconstruction.

Although not a new concept,nerve transfers have become an

increasingly important technique inthe strategic algorithm for nerve re-construction. Pioneers such asFlouren introduced the roosterplexus model in 1820, Balance de-scribed the spinal accessory nerve(SAN) transfer to the facial nerve in1903, Vulpius described use of themedial pectoral nerve in 1920, andSeddon, the transfer of intercostalnerves (ICNs) in 1963.1

The definition of nerve transfer isthe surgical coaptation of a healthynerve donor to a denervated nerve.The principle is similar to that oftendon transfers in that a necessarydistal function is recovered by sacri-ficing another function that is less es-sential to the patient. Synonyms fornerve transfer are nerve-to-nerveneurotization, heterotopic nerve su-ture, and nerve crossing. The term

neurotization should be reserved todescribe the direct implantation of adivided donor nerve into muscle,which has shown promise in an ani-mal model.1,2

Indications andContraindications

A variety of indications exists fornerve transfer, primarily when theproximal nerve end is nonfunctionalor nerve reconstruction would re-quire an excessively long nerve graft.Nerve transfer may expedite reinner-vation when traditional nerve graft-ing would exceed the expected via-bility of motor end plates and muscle(approximately 12 to 18 months).3

Nerve transfer may also be indicatedin patients in whom the zone of in-jury is very broad, with dense scar-ring. Nerve transfer outside the zoneof injury is more surgically efficient

Steve K. Lee, MD

Scott W. Wolfe, MD

From the Hospital for SpecialSurgery and Weill Cornell MedicalCollege, New York, NY.

Dr. Lee or an immediate familymember has received royalties from,is a member of a speakers’ bureauor has made paid presentations onbehalf of, and serves as a paidconsultant to or is an employee ofArthrex; serves as an unpaidconsultant to Synthes; has receivedresearch or institutional support fromArthrex, DePuy Mitek, IntegraLifeSciences, Medartis, Axogen, andCheckpoint; and serves as a boardmember, owner, officer, orcommittee member of the AmericanSociety for Surgery of the Hand.Dr. Wolfe or an immediate familymember has received royalties fromExtremity Medical; is a member of aspeakers’ bureau or has made paidpresentations on behalf of SmallBone Innovations and TriMed;serves as a paid consultant to or isan employee of Extremity Medicaland Small Bone Orthopedics; andserves as a board member, owner,officer, or committee member of theNew York Society for Surgery of theHand.

J Am Acad Orthop Surg 2012;20:506-517

http://dx.doi.org/10.5435/JAAOS-20-08-506

Copyright 2012 by the AmericanAcademy of Orthopaedic Surgeons.

Review Article

506 Journal of the American Academy of Orthopaedic Surgeons

and outcomes, more predictable.4

In the upper extremity, nerve trans-fer is most commonly used for recon-struction of brachial plexus injury.Other indications include complexinjuries to peripheral nerves, espe-cially when associated with fracturesand dislocations, lacerations, injuriesfrom projectiles, neoplasia, or, oc-casionally, neuralgic amyotrophy(Parsonage-Turner syndrome).

Contraindications for nerve trans-fer include the presence of a superiorreconstructive option, excessive timebetween injury and reinnervation (ie,>18 months), or donor nerve motorstrength of less than Medical Re-search Council grade M4.

Advantages of NerveTransfer

Nerve transfer has the distinct ad-vantage over primary nerve repairand long nerve grafting of shorteningthe length that the nerve must regen-erate by bringing the donor nervecloser to the target organ.3,5 Withnerve transfer, pure motor fascicleswith maximal axonal counts are di-rected to a recipient nerve. Opti-mally, nerves are directly transferredto the recipient nerve without an in-terposed nerve graft. As opposed totendon transfer, when nerve transferis successful, recovered function issimilar to the original muscle func-tion because synchronous physio-logic motion may be achieved. Withquicker nerve recovery, more rapidmotor reeducation is also possible.

Nomenclature

Intraplexal versus extraplexal: Intra-plexal refers to nerve transfers inwhich the donor nerve originates inthe brachial plexus, including the ter-minal peripheral nerve branchesabove the elbow. Examples includethe medial pectoral or thoracodorsal

nerve to the axillary nerve, a fascicleof the ulnar nerve to the biceps mo-tor branch, a fascicle of the mediannerve to the brachialis motor branch,and triceps branches of the radialnerve to the axillary nerve and itsbranches. Extraplexal refers to do-nor nerves that originate outside theplexus. Examples include the SAN tothe suprascapular nerve (SSN) andthe ICN or phrenic nerve to the mus-culocutaneous nerve (MCN).

Distal transfer: Nerve transfer thatis at or distal to the elbow.

Single versus dual transfer: Singletransfer refers to the use of one nervetransfer to achieve one action. Anexample of a single transfer is an ul-nar nerve fascicle to the biceps motorbranch to achieve elbow flexion.Dual transfer refers to the use of twonerve transfers to achieve one action.An example is an ulnar nerve fascicleto the biceps motor branch and amedian nerve fascicle to the brachia-lis motor branch to achieve elbowflexion.

Direct nerve transfer: A direct nervetransfer connects the donor nerve tothe recipient nerve without an inter-posed graft. If a tensionless nerve co-aptation is not possible, an interposi-tion nerve graft must be used.

Motor versus sensory transfer:Transfers with the goal of recoveringmotor or sensory function. Transfersperformed to restore sensory func-tion have the added benefit of de-creasing neuropathic pain.6

End-to-end, end-to-side, reverse end-to-side: End-to-end nerve transfer refersto direct coaptation of the end of thedonor nerve to the proximal end of therecipient nerve (Figure 1). End-to-sidenerve transfer describes coaptation ofthe proximal end of the recipient nerveto an epineural window in the side ofan intact and functioning donor nerve.Reverse end-to-side is when the end ofa freshly divided donor nerve iscoapted to an epineural window in theside of an intact but functionally com-

promised recipient nerve.7 End-to-end transfer is preferable for alltransfers; reverse end-to-side trans-fers have not been demonstrated toimprove motor outcomes in humansbut do show experimental promise.7,8

End-to-side transfers have demon-strated efficacy in sensory nerves.3,6

The most common upper extremitydeficits that benefit from nerve trans-fer are elbow flexion and shoulder sta-bilization, abduction, and external ro-tation. Other indications includescapular stabilization for winging, el-bow extension, wrist extension, fingerand thumb extension, finger flexion,and intrinsic hand function. Tables 1 to3 describe intraplexal, extraplexal, anddistal motor transfers. Sensory deficitsof the thumb, index, ring and small fin-ger and ulnar border of the hand aretreated by nerve transfers listed in Ta-ble 4.

Intraplexal donors include the fol-lowing: ulnar nerve fascicle, mediannerve fascicle, medial pectoral nerve,thoracodorsal nerve, triceps branchesof the radial nerve, brachialis branch ofthe MCN, and pectoral fascicle fromthe middle trunk of C7.

Extraplexal donors include the fol-lowing: SAN, ICNs, phrenic nerve,and contralateral C7 nerve root.

Distal transfer donors include thefollowing: distal anterior interosse-ous nerve (AIN), radial nerve branchto the extensor carpi radialis brevis,supinator branches of the posteriorinterosseous nerve (PIN), and radialnerve branch to the brachioradialis.

Common Transfers andOutcomes

Intraplexal Transfers

Ulnar Nerve Fascicle to BicepsMotor BranchTransfer of the ulnar nerve fascicle tothe biceps motor branch, describedby Oberlin et al9 in 1994, criticallyaltered the approach to modern

Steve K. Lee, MD, and Scott W. Wolfe, MD

August 2012, Vol 20, No 8 507

nerve transfers. In this transfer, oneor two fascicles of the ulnar nerveare transferred directly to the motorbranch of the biceps. In our practice,fascicles are identified intraopera-tively by electrically stimulating an

individual fascicle (Checkpoint Sur-gical Stimulator; Checkpoint Surgi-cal, Cleveland, OH) and observingthe distal muscular contraction. Afascicle to the flexor carpi ulnaris ischosen, which is usually in the lateral

or central part of the nerve;10 anyfascicles that give no response arepresumed to be sensory, and thosethat cause flexor digitorum profun-dus stimulation are avoided. Evi-dence suggests that any of the fasci-

Illustrations of the types of nerve transfer. A, End-to-end. B, End-to-side. C, Reverse end-to-side.

Figure 1

Nerve Transfers for the Upper Extremity: New Horizons in Nerve Reconstruction


cles of the ulnar nerve at the level ofthe proximal arm can be used fortransfer without the loss of ulnarnerve function.11

After 10 years of experience,Teboul et al12 reported their out-comes in 32 patients with uppernerve root brachial plexus injuries

(C5-6, C5-7). There were no deficitsin the donor ulnar nerve; 24 of 32patients achieved strength grade M3or higher. A Steindler flexorplasty

Table 1

Common Intraplexal Motor Transfers

Motor Deficit Recipient Nerve or Nerves Donor Nerve or Nerves Comment

Elbow flexion Musculocutaneous nerve: bi-ceps and brachialis branchesdual transfer

Ulnar nerve fascicle and me-dian nerve fascicle

Primary choice, if possible, inupper nerve root brachialplexus injury (C5-6, C5-7)

Musculocutaneous nerve Medial pectoral nerve Secondary choiceMusculocutaneous nerve Thoracodorsal nerve Secondary choice

Shoulder stabilization/abduction/external rotation

Suprascapular nerve and axil-lary nerve dual transfer

Spinal accessory nerve andtriceps branches

Primary choice, if possible, com-bination intraplexal and extra-plexal

Shoulder stabilization/abduction Axillary nerve Medial pectoral nerve Secondary choiceAxillary nerve Thoracodorsal nerve Secondary choice

Scapular stabilization/anti-winging

Long thoracic nerve Thoracodorsal nerve Primary choice if possible

Long thoracic nerve Pectoral fascicle from middletrunk from C7

Secondary choice

Thumb and index finger flexion Posterior fascicle of the mediannerve in the arm which corre-sponds to the anterior in-terosseous nerve

Brachialis branch of musculo-cutaneous nerve or extensorcarpi radialis brevis supinatorbranches of radial nerve

For lower trunk plexus injury orhigh median nerve injury. Cou-pled with tenodesis of the fourflexor digitorum profundus ten-dons in the forearm

Elbow extension Triceps branch of radial nerve Ulnar nerve fascicle to flexorcarpi ulnaris or median nervefascicle to flexor digitorumsuperficialis

—

Table 2

Common Extraplexal Motor Transfers

Motor Deficit Recipient Nerve or Nerves Donor Nerve or Nerves Comment

Elbow flexion Musculocutaneous nerve Intercostal nerves Primary choice if intraplexalnerve transfers not possible

Musculocutaneous nerve Spinal accessory nerve Secondary choiceMusculocutaneous nerve Phrenic nerve Infrequently performed given

decreased exercise toleranceShoulder stabilization/abduction/

external rotationSuprascapular nerve Spinal accessory nerve Primary choice as part of dual

nerve transfer with tricepsbranches to axillary nerve

Suprascapular nerve Intercostal nerves Secondary choiceShoulder stabilization/abduction Axillary nerve Intercostal nerves Secondary choice if triceps

branch is not availableScapular stabilization/anti-

wingingLong thoracic nerve Intercostal nerves Secondary choice if thoracodor-

sal nerve is not availableElbow extension Triceps branch of radial nerve Intercostal nerves —Elbow flexion, hand function Musculocutaneous nerve, me-

dian nerveContralateral C7 For five-root avulsion in a young

patient, less commonly per-formed


August 2012, Vol 20, No 8 509

was performed as a secondary proce-dure in 10 patients with strengthgrade M3 or lower. Overall, includ-ing all patients with and without

Steindler flexorplasty, 30 of 32 pa-tients achieved a good (M4) or a fair(M3) result. Leechavengvongs andcolleagues reported 30 of 32 patients

with M4 strength13 and, in a differ-ent series, 13 of 15 patients with M4strength, without using the comple-mentary Steindler flexorplasty.13,14

Table 3

Common Distal Motor Transfers

Motor Deficit Recipient Nerve or Nerves Donor Nerve or Nerves Comments

Intrinsic hand Ulnar nerve motor branch Distal anterior interosseousnerve

For high ulnar nerve lesions

Thumb, finger extension Posterior interosseous nervebranches of radial nerve

Nerve to supinator For C7-T1 plexus injuries

Wrist, finger extension Radial nerve branch to exten-sor carpi radialis brevis andposterior interosseous nerve

Median nerve fascicles to flexordigitorum superficialis andmedian nerve fascicles toflexor carpi radialis

Dual transfer

Thumb, finger flexion Anterior interosseous nerve Radial nerve branch to thebrachioradialis

Indicated for lower trunk plexusinjury or high median nerveinjury. Coupled with tenodesisof the four flexor digitorumprofundus tendons in the fore-arm

Table 4

Common Sensory Transfers

Sensibility Deficit Recipient Nerve or Nerves Donor Nerve or Nerves Comments

Radial hand Lateral cord contribution to themedian nerve

Intercostal sensory nervebranches

Proximal transfer

Thumb and index finger Common digital nerve to firstweb space, radial digitalnerve to thumb

Superficial radial nerve —

Digital nerves of the ulnar as-pect of the thumb and radialaspect of the index finger

Digital branches of superficialradial nerve

Very distal transfer

Common digital nerve to firstweb space, radial digitalnerve to thumb

Common digital nerve to thirdweb space

—


Common digital nerve to fourthweb space

—


Dorsal branch of the ulnarnerve

—

Ring and small fingers Ulnar nerve Lateral antebrachial cutaneousnerve

C7-T1 injuries

Common digital nerve to fourthweb space, ulnar digital nerveto small finger

Common digital nerve to thirdweb space

—

Ulnar border of hand Dorsal branch of the ulnarnerve

Lateral antebrachial cutaneousnerve

—

Dorsal branch of the ulnarnerve

Median nerve at distal forearm(end to side)

—



Medial Pectoral orThoracodorsal Nerve toMusculocutaneous NerveBrandt and Mackinnon15 reported onfive cases in which biceps/brachialisreinnervation was performed by us-ing one or more medial pectoralnerve branches, which lie in closeproximity to the MCN. Novaket al16 examined the feasibility andsuccess of the thoracodorsal transferto the MCN; in five of six cases, thepatients recovered M4 or M5strength of elbow flexion.

Dual Transfer: Ulnar NerveFascicle to Biceps Transfer andMedian Nerve Fascicle toBrachialisGiven the initial 80% success ratewith the single nerve transfer for el-bow flexion, Ray et al,10 Mackinnonet al,17 and Liverneaux et al18 pro-posed a dual transfer to regain elbowflexion. The first part of the dualtransfer is transfer of an ulnar nerve

fascicle to the biceps motor branch,as described above. This is followedby transfer of a median nerve fascicle(generally, the branch to the flexorcarpi radialis or flexor digitorum su-perficialis) to the brachialis motorbranch (Figure 2). In practice, eitherulnar or median nerve fascicles maybe transferred to either the biceps orbrachialis branches, depending onthe patient’s anatomy. Liverneauxet al18 reported on 10 patients, allwith grade M4 elbow flexionstrength. Ray et al10 reported on 29patients: 23 had strength of grade 4or better, and 4 had grade 3. Therewere no donor deficits.

Mackinnon et al17 and Liverneauxet al18 make a strong argument fordual transfer for elbow flexion, espe-cially compared with previous pub-lished results of single transfer.Carlsen et al19 reported that, with thenumbers tested, there was no differ-ence between single and dual trans-

fers. However, these authors still usethe dual nerve transfer in practice.Garg et al4 performed a systematicreview comparing the outcomes ofnerve transfers for elbow functionwith autogenous nerve grafting fromC5 or C6; they found that 83% ofnerve transfers achieved elbow flex-ion strength of grade M4 or higher,and that 96% achieved grade M3 orhigher. By comparison, for nervegraft outcomes, 56% achieved gradeM4 or higher and 82% achievedgrade M3 or higher. The authorsconcluded that, compared with tra-ditional nerve grafting for restora-tion of elbow function, nerve trans-fers led to improved outcomes.4

Triceps Branch to Axillary NerveRegarding shoulder function, a keytransfer is the triceps branch of theradial nerve to the axillary nerve.20,21

The nerve branches to the long, me-dial, or lateral head of the triceps aretransferred to branches of the axil-lary nerve. Because of the critical im-portance of external rotation, Ber-telli and Ghizoni21 recommendtransfer to both the anterior branchand the teres minor branch. Transferof the triceps branch to the axillarynerve may be combined with SSN re-innervation,21,22 thereby making theprocedure a dual nerve transfer forboth shoulder abduction and exter-nal rotation (Figure 3). In seven pa-tients who had dual transfers of SANto SSN and of the triceps branch tothe axillary nerve, Leechavengvongset al20 reported all patients as havinggrade M4 deltoid function with 124°of abduction. In 10 patients withC5-6 brachial plexus injury, Bertelliand Ghizoni21 reported that, with dualshoulder nerve transfers, 3 patients hadgrade M4 abduction, 7 had grade M3shoulder abduction (average, 92°), 2had grade M4 external rotation, and 5had grade M3 external rotation; aver-age external rotation was 93° from fullinternal rotation. In their systematic re-

Illustration of dual transfer to regain elbow flexion. Transfer of an ulnar nervefascicle to the biceps motor branch, plus transfer of a median nerve fascicleto the brachialis motor branch.

Figure 2


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view, Garg et al4 found that 74% ofpatients with dual nerve transfershad shoulder abduction strength ofgrade M4 or higher, compared with35% of patients with single nervetransfer and 46% of patients withnerve grafts. They concluded thatdual nerve transfers are associatedwith improved outcomes for shoul-der abduction.

Thoracodorsal Nerve to LongThoracic NerveRaksakulkiat et al23 have shown thefeasibility and value of reinnervatingthe serratus anterior muscle using thethoracodorsal nerve in five patientswith C5-6 root avulsion. Postopera-

tively, two patients had no scapularwinging, and three had decreasedscapular winging. These patients alsohad transfers of the SAN to SSN andof the triceps branch to the axillarynerve. Average shoulder external ro-tation from the fully internally ro-tated resting position improved to124°. The authors concluded that re-innervating the serratus anteriormuscle is beneficial for shoulderfunction.24 This finding may be par-ticularly important in managing pa-tients with C5-7 injuries and conse-quent complete denervation of theserratus anterior; reinnervationshould be considered critical to res-toration of shoulder function.

Extraplexal Transfers

Spinal Accessory Nerve toSuprascapular NerveThe SAN (ie, cranial nerve XI) inner-vates the sternocleidomastoid andtrapezius muscles. Transferring thedistal fascicles of the SAN to the SSNis part of a key nerve transfer set forregaining shoulder function. In thistransfer, the inferior branch of theSAN is divided distally and directlytransferred to the SSN. Superiorbranches to the trapezius are left in-tact, which preserves strong trape-zius function. It is best to transferwithout a nerve graft; interposednerve grafting worsens results.22,25

Illustrations of dual nerve transfer for shoulder stabilization, abduction, and external rotation. Transfer of the spinalaccessory nerve to the suprascapular nerve (A), plus transfer of triceps branches to the anterior division of the axillarynerve and teres minor branch (B). CN XI = cranial nerve XI

Figure 3



Segmental injury of the SSN canoccur; patients with upper trunk orC5 root injuries can also have a dis-tal injury to the SSN at the supra-scapular notch, especially those whohave sustained scapular fractures,scapulothoracic dissociation, andclavicle dislocations. In these situa-tions, Bertelli and Ghizoni26 pro-posed to dissect both the SAN andSSN via a distal oblique supraclavic-ular incision, prolonged up to thescapular notch, so that the SSN canbe decompressed and the nerve in-spected for continuity. As discussed,dual transfers for shoulder functionlead to improved results over iso-lated transfers to the axillarynerve.4,22,25,26 However, poor recoveryof external rotation continues to af-fect outcomes, especially with moreextensive injury patterns. Bertelli andGhizoni26 showed that no patientwith a five-level plexus palsy recov-ered external rotation. Suzuki et al27

reported results in 12 patients with amix of injuries at the C5-6, C5-7,

and C5-8 levels, with mean out-comes of 77° abduction and 17° ex-ternal rotation. With less severe, iso-lated C5-6 injury, patients havebetter results.21

Intercostal NerveICNs are among the most useful anddependable extraplexal donors. Usedmost frequently in cases of five-level(C5-T1) plexus palsy, up to sevenICNs can be transferred to regainsome control of the upper extremity.ICNs are most frequently used forrestoration of elbow flexion, butother recipients include the axillarynerve, long thoracic nerve, and SSN(Figure 4). A systematic review byMerrell et al22 showed that 72% ofpatients achieved elbow flexion re-covery of grade M3 or better whendirect transfer of ICNs to MCNs wasperformed; only 47% achieved gradeM3 or better when interposed nervegrafts were used. Given the originalfunction of the ICNs, it is not con-sidered a synergistic transfer; retrain-

ing takes dedicated patient effort andconsiderable time (12 to 24 months).The sensory branches of the ICNsmay also be used for recovery of lim-ited hand sensation and relief of neu-ropathic pain.28 Kovachevich et al29

reported a 15% complication ratewith ICN transfers, the most com-mon being pleural tears. They statedthat the current literature showsminimal effect of ICN harvest onpulmonary function. Giddins et al30

reported no pulmonary dysfunctionafter intercostal harvest, even withconcomitant phrenic nerve palsy.ICNs may also be used as the motornerve for free-functioning muscletransfers.31

Phrenic Nerve toMusculocutaneous NerveThe phrenic nerve is most commonlyused as a donor to regain elbow flex-ion when other donor nerves are notavailable. Exposure of the phrenicnerve is rapid, but it must be length-ened by a nerve graft to reach theMCN or the median nerve. Endo-scopic harvest has been described tolengthen the donor phrenic nerve toallow for direct transfer to the MCNor median nerve.32 Gu and Ma33 re-ported on results of this technique in65 patients; 85% achieved a strengthgrade of M3 or higher, and 50%achieved a grade of M4 or M5. Pul-monary function tests showed de-creased pulmonary capacities within1 year of surgery, improving toward2 years. Disadvantages of this trans-fer are that, in young, active patients,the donor defect may permanentlyaffect aerobic performance. Also,considerable retraining is required.Because of this, the phrenic nervetransfer has diminished in popularityin the last several years.

Contralateral C7The contralateral C7 nerve root orits posterior division may be pro-longed with a nerve graft and

Illustration of transfer of intercostal nerves to the musculocutaneous nerve.

Figure 4


August 2012, Vol 20, No 8 513

crossed over the chest to the injuredside, to be used as a donor nervewhen there is a paucity of othernerve donors. The best results havebeen reported in young patients withcomplete five-level (C5-T1) rootavulsions. In this transfer, the ipsilat-eral full-length vascularized ulnarnerve graft is raised on a pediclebased on the superior ulnar collateralartery and is reversed to cross thechest to the contralateral brachialplexus. Usually several fascicles ofC7 are isolated, identified as fasciclesto the shoulder, then divided andcoapted to the ulnar nerve. Usual tar-gets include the median nerve and/orthe MCN. Hierner and Berger34 re-ported on 10 cases—6 to the MCN,4 to the median nerve. All 10 pa-tients had temporary donor sensorydeficits but no donor motor deficits.All six of the MCN transfer patientshad M3 or M4 elbow flexion return,but two required a “start” com-mand—that is, contracting the con-

tralateral latissimus dorsi muscle toflex the elbow. These authors re-ported no functional median nerverecovery in the four median nervepatients.

Liu et al35 reported on two caseswith severe donor C7 motor and sen-sory deficits. Full functional recoverywas documented at 6 months. How-ever, objective qualitative and quan-titative differences in the motor andsensory deficits in the donor limbswere still present at 1.5 to 2 years.Songcharoen et al36 reported on 21patients with transfer of the contra-lateral C7 to the median nerve; 6 pa-tients (29%) obtained grade M3 re-covery of the wrist and fingerflexors, and 4 (19%) achieved gradeM2. Ten of the 21 patients (48%)achieved British Medical ResearchCouncil grade S3, and 7 (33%) hadgrade S2 recovery in the mediannerve distribution. Average time torecovery was 34 months. Three of 6patients aged <18 years had gradeM3 finger flexion; 3% of the original111 patient cohort had motor defi-cits in the donor extremity, with per-manent wrist extension weakness inone patient. Sammer at al37 recom-mended against the use of this proce-dure, given its poor outcomes andrisk of permanent donor site morbid-ity. Enthusiasm for this transfer haswaned in recent years.

Distal Transfers

Brachialis Motor Branch to theAnterior Interosseous Nerve,Coupled With Tenodesis ofthe Flexor Digitorum ProfundusFor patients with the rare C8-T1 orlower trunk plexus injury, and po-tentially for patients with a high me-dian nerve injury, the brachialis mo-tor branch of the MCN can betransferred to the posterior third ofthe median nerve in the arm to re-store median motor function.3,38 Theposterior third of the median nervewas identified by Zheng et al38 to

represent the AIN fascicles. Thistransfer must be coupled with side-to-side flexor digitorum profundustenodesis to transmit forces from themedian-innervated index and middlefingers to the ulnar-innervated ringand small fingers. Zheng et al38 re-ported that five of six patients hadrecovery of digital flexion at 18-month follow-up. Grip strength aver-aged 66 lb.

Distal Anterior InterosseousNerve to Ulnar Nerve MotorBranchFor patients with high ulnar nerve le-sions, the AIN branch to the prona-tor quadratus can be transferred tothe motor branch of the ulnarnerve39,40 (Figure 5). In a series ofeight patients, all had reinnervationof their intrinsic muscles at 18months. Pinch increased from 2.2 lbpreoperatively to 13.8 lb postopera-tively. Grip strength increased from8.8 lb to 61.2 lb.39

Supinator Branches to PosteriorInterosseous NerveIn the uncommon C7-T1 palsies ofthe brachial plexus, shoulder and el-bow function is preserved, but digitalfunction is absent. Supinator musclefunction is preserved because inner-vation arises from the C6 nerve root.Sacrifice of the supinator motorbranches does not eliminate supina-tion because biceps muscle functionis preserved in C7-T1 palsies. Bertelliet al41 performed a cadaver feasibilitystudy and showed that one or twobranches of the PIN to the supinatorcan be transferred to the PINbranches that innervate the extensorpollicis longus and the extensor digi-torum communis muscles (Figure 6).These authors later reported thatfour of four patients had full meta-carpophalangeal joint extension afterthis transfer.42 Dong et al43 also re-ported good results with this trans-fer.

Illustration of transfer of the distalanterior interosseous nerve (AIN)to the ulnar motor nerve.

Figure 5



Median Nerve Branches toRadial Nerve BranchesThis procedure is a dual transfer setin which median nerve branches tothe flexor digitorum superficialis aretransferred to the radial nervebranch to the extensor carpi radialisbrevis, and median nerve branches tothe flexor carpi radialis are trans-ferred to the PIN.44,45 Ray and Mac-kinnon46 reported that 18 of 19 pa-tients had good to excellent wristextension; 9 patients also had prona-tor teres to extensor carpi radialisbrevis tendon transfer. Twelve of 19patients had good to excellent fingerand thumb extension (grade M4 orM4+), 2 of 19 had fair recovery(M3), and 5 of 19 had poor recovery(M0 to M2) (Figure 7). A compara-tive functional study of nerve trans-fers versus tendon transfers for resto-ration of PIN function has not beenperformed.

Sensory TransfersSensory transfers are employed to re-gain essential zones of sensibility andto decrease neuropathic pain.6 Ber-telli and Ghizoni47 reported on very

distal superficial radial nerve trans-fers to the digital nerves of the ulnaraspect of the thumb and radial as-pect of the index finger in eight pa-tients with high median nerve le-sions. Protective or better sensationwas recovered in all patients. Ducicet al48 presented two successful casesof radial sensory nerve transfers tothe thumb and index finger. InC7-T1 injuries, the lateral antebra-chial cutaneous nerve can be trans-ferred to the ulnar nerve in the armto regain distal sensory function.

Authors’ Preferred NerveTransfers andReconstructive Strategies

Nerve transfers are part of our arma-mentarium for nerve reconstruction,along with nerve grafting and sec-ondary procedures. When we evalu-ate a patient with brachial plexus in-jury, the physical examination,imaging studies, and electrodiagnos-tic studies help us define whether vi-able roots are present to use for rein-nervation. We routinely employ

intraoperative electrodiagnostic stud-ies and histopathologic frozen-tissueexamination to further evaluate po-tential donor root viability. Each re-constructive strategy is individual-ized.

Our main goals for reinnervationare (1) elbow flexion, (2) shoulderabduction and external rotation, (3)scapular stabilization, (4) elbow ex-tension, (5) sensory reinnervation forcontrol of neuropathic pain, and (6)restoration of distal (below-elbow)function. For elbow flexion, we pre-fer the double fascicular transfer ofulnar and median fascicles to bicepsand brachialis. We perform doublenerve transfers whenever possible forshoulder recovery—generally, trans-fer of the SAN to the SSN and of thetriceps, medial pectoral, thoracodor-sal, or ICN to the axillary nerve.Whenever possible, reinnervation of

Illustration of transfer of supinator branches to the posterior interosseousnerve (PIN). (Adapted with permission from Bertelli JA, Ghizoni MF: Transferof supinator motor branches to the posterior interosseous nerve in C7-T1brachial plexus palsy. J Neurosurg 2010;113[1]:129-132.)

Figure 6

Illustration of transfer of mediannerve branches to the posteriorinterosseous nerve (PIN) andextensor carpi radialis brevis(ECRB) branches. FCR = flexorcarpi radialis, FDS = flexordigitorum superficialis, MN = me-dian nerve, PL = palmarislongus, RN = radial nerve.(Adapted with permission from RayWZ, Mackinnon SE: Clinicaloutcomes following median toradial nerve transfers. J Hand SurgAm 2011;36[2]:201-208.)

Figure 7


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the teres minor branch of the axillarynerve is performed to improve exter-nal rotation. If there is an intact C5nerve root, the target will often bethe axillary nerve or the posteriorcord, lengthened by sural nervegrafts.

ICNs are our extraplexal source ofchoice, especially in five-level plexusinjuries. Common intercostal targetsare the MCN, axillary nerve, andlong thoracic nerve. Intercostal sen-sory nerves are often transferred tothe lateral cord contribution of themedian nerve for pain relief and pro-tective sensibility. “Crossing the el-bow” for hand and wrist reanima-tion with nerve reconstruction isrelatively ineffective in adult totalplexus palsies; if there is insufficientnerve regeneration 2 years afternerve reconstruction, we generallyemploy a combination of tendontransfers, joint fusions, and free-functioning muscle transfers to im-prove the position and function ofthe wrist and hand. The phrenicnerve and contralateral C7 are notcommon donor sources in our prac-tice.

Summary

Nerve transfers are a vital part of theglobal strategy for the surgical treat-ment of brachial plexus and complexnerve injuries. All of the varioustypes of transfers may be used for avariety of indications, including in-traplexal, extraplexal, and distal,and for recovery of motor and sen-sory function. Knowledge of and theability to perform these transfers isparamount to the success of thesecomplex reconstructions.

References

Evidence-based Medicine: Levels ofevidence are described in the table of

contents. In this article, references 2,4, 7, 8, 19, and 22 are level III studies.References 6, 9-18, 20, 21, and 23-48are level IV studies. References 1, 3,and 5 are level V expert opinion.

References printed in bold type arethose published in the past 5 years.

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19. Carlsen BT, Kircher MF, Spinner RJ,Bishop AT, Shin AY: Comparison ofsingle versus double nerve transfers forelbow flexion after brachial plexusinjury. Plast Reconstr Surg 2011;127(1):269-276.

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21. Bertelli JA, Ghizoni MF: Reconstructionof C5 and C6 brachial plexus avulsioninjury by multiple nerve transfers: Spinalaccessory to suprascapular, ulnarfascicles to biceps branch, and tricepslong or lateral head branch to axillarynerve. J Hand Surg Am 2004;29(1):131-139.

22. Merrell GA, Barrie KA, Katz DL, WolfeSW: Results of nerve transfer techniques



for restoration of shoulder and elbowfunction in the context of a meta-analysis of the English literature. J HandSurg Am 2001;26(2):303-314.

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27. Suzuki K, Doi K, Hattori Y, PagsaliganJM: Long-term results of spinalaccessory nerve transfer to thesuprascapular nerve in upper-typeparalysis of brachial plexus injury.J Reconstr Microsurg 2007;23(6):295-299.

28. Hattori Y, Doi K, Sakamoto S, YukataK: Sensory recovery of the hand withintercostal nerve transfer followingcomplete avulsion of the brachial plexus.Plast Reconstr Surg 2009;123(1):276-283.

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30. Giddins GE, Kakkar N, Alltree J, BirchR: The effect of unilateral intercostalnerve transfer upon lung function.J Hand Surg Br 1995;20(5):675-676.

31. Doi K, Muramatsu K, Hattori Y, et al:Restoration of prehension with thedouble free muscle technique followingcomplete avulsion of the brachial plexus:Indications and long-term results. J BoneJoint Surg Am 2000;82(5):652-666.

32. Xu WD, Lu JZ, Qiu YQ, et al: Handprehension recovery after brachial plexusavulsion injury by performing a full-length phrenic nerve transfer viaendoscopic thoracic surgery. J Neurosurg2008;108(6):1215-1219.

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36. Songcharoen P, Wongtrakul S,Mahaisavariya B, Spinner RJ: Hemi-contralateral C7 transfer to mediannerve in the treatment of root avulsionbrachial plexus injury. J Hand Surg Am2001;26(6):1058-1064.

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38. Zheng XY, Hou CL, Gu YD, Shi QL,Guan SB: Repair of brachial plexuslower trunk injury by transferringbrachialis muscle branch ofmusculocutaneous nerve: Anatomicfeasibility and clinical trials. Chin Med J(Engl) 2008;121(2):99-104.

39. Novak CB, Mackinnon SE: Distalanterior interosseous nerve transfer tothe deep motor branch of the ulnar nervefor reconstruction of high ulnar nerve

injuries. J Reconstr Microsurg 2002;18(6):459-464.

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44. Brown JM, Tung TH, Mackinnon SE:Median to radial nerve transfer torestore wrist and finger extension:Technical nuances. Neurosurgery 2010;66(3 suppl operative):75-83.

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46. Ray WZ, Mackinnon SE: Clinicaloutcomes following median to radialnerve transfers. J Hand Surg Am 2011;36(2):201-208.

47. Bertelli JA, Ghizoni MF: Very distalsensory nerve transfers in high mediannerve lesions. J Hand Surg Am 2011;36(3):387-393.

48. Ducic I, Dellon AL, Bogue DP: Radialsensory neurotization of the thumb andindex finger for prehension afterproximal median and ulnar nerveinjuries. J Reconstr Microsurg 2006;22(2):73-78.


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