Supinator to Anterior Interosseous Nerve Transfer to Restore Digital Flexion in Spinal Cord and Peripheral Nerve Injury

PURPOSE

Restoration of pinch and grasp is a chief concern of patients with cervical spinal cord injury or peripheral nerve injury involving the anterior interosseous nerve (AIN). We hypothesize that supinator nerve-to-AIN (Sup-AIN) nerve transfer is a viable option for AIN neurotization.

METHODS

We performed a retrospective review of patients who received Sup-AIN. Reported outcomes included Medical Research Council strength of the flexor digitorum profundus and flexor pollicis longus and passive range of digit motion. Patients with <12 months of follow-up were excluded.

RESULTS

Eleven patients underwent Sup-AIN, eight with peripheral nerve injury, and three with spinal cord injury. Three patients were excluded because of insufficient follow-up. Average follow-up was 17 months (range: 12-25 months). Six patients had M4 recovery (75%), one patient had M3 recovery (12.5%), and one did not recover function because of severe stiffness (12.5%). We observed no complications or donor site morbidity in our patients.

CONCLUSIONS

The Sup-AIN nerve transfer is an effective option to restore digital flexion in patients with peripheral nerve injury or spinal cord injury involving the AIN motor distribution. In comparison to previously described extensor carpi radialis brevis to AIN and brachialis to AIN nerve transfers, Sup-AIN offers the benefits of a more expendable donor nerve and shorter regenerative distance, respectively. The one failed Sup-AIN in our series highlights the importance of patient selection.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic V.

Distal nerve transfers for peripheral nerve injuries: indications and outcomes

Distal nerve transfer is a refined surgical technique involving the redirection of healthy sacrificable nerves from one part of the body to reinstate function in another area afflicted by paralysis or injury. This approach is particularly valuable when the original nerves are extensively damaged and standard repair methods, such as direct suturing or grafting, may be insufficient. As the nerve coaptation is close to the recipient muscles or skin, distal nerve transfers reduce the time to reinnervation. The harvesting of nerves for transfer should usually result in minimal or no donor morbidity, as any anticipated loss of function is compensated for by adjacent muscles or overlapping cutaneous territory. Recent years have witnessed notable progress in nerve transfer procedures, markedly enhancing the outcomes of upper limb reconstruction for conditions encompassing peripheral nerve, brachial plexus and spinal cord injuries.

Distal nerve transfer (PT-AIN, SUP-PIN) for regaining hand function in C8, T1 root injury following extirpation of the right C8, T1 schwannoma

A 48-year-old female was admitted to the authors' department due to hand weakness as a consequence of C8, T1 root injury. Eight months earlier, the patient had been treated by a pulmonary surgeon due to an expansive lesion near the apex of the right lung, which resulted in right lower brachial plexus palsy. Postoperative pathohistological findings indicated that the lesion was nerve schwannoma. The diagnostic process included physical examination, electromyoneurography, and MRI. A distal nerve transfer (pronator teres-anterior interosseus nerve [PT-AIN], supinator-posterior interosseus nerve [SUP-PIN]) was performed in order to restore hand function. The video can be found here: https://stream.cadmore.media/r10.3171/2022.10.FOCVID22110.

Single-stage double motor nerve transfer for all finger flexion in iatrogenic C8-T1 spinal nerve injury: a case report and review of literature

Restoration of hand function after C8-T1 spinal nerve injury is challenging. We report a case of a young patient who underwent single-stage transfer of extensor carpi radialis brevis (ECRB) branch of radial nerve to flexor digitorum superficialis (FDS) branch of median nerve and transfer of brachialis branch of musculocutaneous nerve to anterior interosseous nerve (AIN), aiming for restoration of all finger flexion in iatrogenic C8-T1 spinal nerve injury after the resection of a dumbbell-shaped C8 neurofibroma. At 18 months after the operation, the fingers and thumb functions were successfully restored. The operation might be useful for restoration of hand function in selected patients with C8, T1 brachial plexus injury. From the literature review, this is the first case that the technique of double motor nerve transfer and the transfer of ECRB branch to FDS branch were used to restore finger flexion in a patient with brachial plexus injury.

Nerve transfers in the forearm: potential use in spastic conditions

PURPOSE

Deformities of the spastic upper limb result frequently from the association of spasticity, muscle contracture and muscle imbalance between strong spastic muscles and weak non-spastic muscles. This study was designed to evaluate the feasibility of combining selective neurectomy of the usual spastic and strong muscles together with transfer of their motor nerves to the usual weak muscles, to improve wrist and fingers motion while decreasing spasticity.

METHODS

Twenty upper limbs from fresh frozen human cadavers were dissected. All motor branches of the radial and median nerve for the forearm muscles were identified. We attempted all possible end-to-end nerve transfers between the usually strong "donor" motor branches, namely FCR and PT, and the usually weak "recipient" motor branches (ERCL, ECRB, PIN, AIN).

RESULTS

 The PT had two nerve branches in 80%, thus allowing selective neurectomy. The proximal PT branch could be anastomosed end-to-end in 45% (AIN) to 85% (ECRL) of cases with the potential recipient branches. The distal PT branch could be anastomosed end to end to all potential recipient nerves. The FCR had a single branch in all cases. End-to-end anastomosis was possible in 90% for the ECRL and in 100% for all other recipient branches, but sacrificed all FCR innervation, ruling out hyperselective neurectomy.

CONCLUSION

 Selective neurectomies can be associated with distal nerve transfers at the forearm level in selected cases. The motor nerve to the PT is the best donor for nerve transfer combined with selective neurectomy, transferred to the ECRL, ECRB, PIN or AIN.

Combined Nerve and Tendon Transfers for C7-T1 Brachial Plexus Avulsion Injury

BACKGROUND

In patients with C7-T1 brachial plexus avulsions, complete loss of hand function is commonly seen. However, the reconstruction of hand function is difficult.

OBJECTIVE

To report the outcomes of hand function recovery after combined nerve and tendon transfers in C7-T1 brachial plexus injury.

METHODS

From 2012 to 2019, 8 patients with C7-T1 brachial plexus injury underwent combined nerve and tendon transfers for hand function restoration, which included the following: (1) the pronator teres motor branch to the anterior interosseous nerve and brachialis motor branch to the flexor digitorum superficialis branch for finger flexion, (2) the supinator motor branch to the posterior interosseous nerve for finger extension, (3) the brachioradialis tendon transfer for thumb opposition, and (4) the radial branch of the superficial radial nerve to the sensory branch of the ulnar nerve for sensory reconstruction. Patients were evaluated for functional improvement of finger flexion, finger extension, thumb opposition, and sensory recovery.

RESULTS

No clinical donor deficits were observed. Seven of eight patients recovered finger and thumb flexion (4 patients scored British Medical Research Council grade M4 and 3 scored M3). The average grip strength was 3.4 kg. All patients regained finger extension (4 scored M4 and 4 scored M3), thumb opposition, and protective sensation on the ulnar hand. Patients were able to use their reconstructed hands in daily lives.

CONCLUSION

Combined nerve and tendon transfers are reliable and effective. This strategy could be an option for hand function reconstruction after C7-T1 brachial plexus injury.

Patterns of median nerve branching in the cubital fossa: implications for nerve transfers to restore motor function in a paralyzed upper limb

OBJECTIVE

The purpose of this study was to describe the anatomy of donor and recipient median nerve motor branches for nerve transfer surgery within the cubital fossa.

METHODS

Bilateral upper limbs of 10 fresh cadavers were dissected after dyed latex was injected into the axillary artery.

RESULTS

In the cubital fossa, the first branch was always the proximal branch of the pronator teres (PPT), whereas the last one was the anterior interosseous nerve (AIN) and the distal motor branch of the flexor digitorum superficialis (DFDS) on a consistent basis. The PT muscle was also innervated by a distal branch (DPT), which emerged from the anterior side of the median nerve and provided innervation to its deep head. The palmaris longus (PL) motor branch was always the second branch after the PPT, emerging as a single branch together with the flexor carpi radialis (FCR) or the proximal branch of the flexor digitorum superficialis. The FCR motor branch was prone to variations. It originated proximally with the PL branch (35%) or distally with the AIN (35%), and less frequently from the DPT. In 40% of dissections, the FDS was innervated by a single branch (i.e., the DFDS) originating close to the AIN. In 60% of cases, a proximal branch originated together with the PL or FCR. The AIN emerged from the posterior side of the median nerve and had a diameter of 2.3 mm, twice that of other branches. When dissections were performed between the PT and FCR muscles at the FDS arcade, we observed the AIN lying lateral and the DFDS medial to the median nerve. After crossing the FDS arcade, the AIN divided into: 1) a lateral branch to the flexor pollicis longus (FPL), which bifurcated to reach the anterior and posterior surfaces of the FPL; 2) a medial branch, which bifurcated to reach the flexor digitorum profundus (FDP); and 3) a long middle branch to the pronator quadratus. The average numbers of myelinated fibers within each median nerve branch were as follows (values expressed as the mean ± SD): PPT 646 ± 249; DPT 599 ± 150; PL 259 ± 105; FCR 541 ± 199; proximal FDS 435 ± 158; DFDS 376 ± 150; FPL 480 ± 309; first branch to the FDP 397 ± 12; and second branch to the FDP 369 ± 33.

CONCLUSIONS

The median nerve's branching pattern in the cubital fossa is predictable. The most important variation involves the FCR motor branch. These anatomical findings aid during nerve transfer surgery to restore function when paralysis results from injury to the radial or median nerves, brachial plexus, or spinal cord.

Optimizing nerve transfer surgery in tetraplegia: clinical decision making based on innervation patterns in spinal cord injury

OBJECTIVE

Nerve transfers are increasingly being utilized in the treatment of chronic tetraplegia, with increasing literature describing significant improvements in sensorimotor function up to years after injury. However, despite technical advances, clinical outcomes remain heterogenous. Preoperative electrodiagnostic testing is the most direct measure of nerve health and may provide prognostic information that can optimize preoperative patient selection. The objective of this study in patients with spinal cord injury (SCI) was to determine various zones of injury (ZOIs) via electrodiagnostic assessment (EDX) to predict motor outcomes after nerve transfers in tetraplegia.

METHODS

This retrospective review of prospectively collected data included all patients with tetraplegia from cervical SCI who underwent nerve transfer at the authors' institution between 2013 and 2020. Preoperative demographic data, results of EDX, operative details, and postoperative motor outcomes were extracted. EDX was standardized into grades that describe donor and recipient nerves. Five zones of SCI were defined. Motor outcomes were then compared based on various zones of innervation.

RESULTS

Nineteen tetraplegic patients were identified who underwent 52 nerve transfers targeting hand function, and 75% of these nerve transfers were performed more than 1 year postinjury, with a median interval to surgery following SCI of 24 (range 8-142) months. Normal recipient compound muscle action potential and isolated upper motor neuron injury on electromyography (EMG) were associated with greater motor recovery. When nerve transfers were stratified based on donor EMG, greater motor gains were associated with normal than with abnormal donor EMG motor unit recruitment patterns. When nerve transfers were separated based on donor and recipient nerves, normal flexor donors were more crucial than normal extensor donors in powering their respective flexor recipients.

CONCLUSIONS

This study elucidates the relationship of the preoperative innervation zones in SCI patients to final motor outcomes. EDX studies can be used to tailor surgical therapies for nerve transfers in patients with tetraplegia. The authors propose an algorithm for optimizing nerve transfer strategies in tetraplegia, whereby understanding the ZOI and grade of the donor/recipient nerve is critical to predicting motor outcomes.

Innervation Patterns of the Pronator Teres Muscle and Their Possible Role in Neurotization: A Systematic Review of Cadaveric Studies

BACKGROUND

Contrary to the classic anatomical description, many recent studies have reported wide variations in branching patterns and location of motor branches that are supplying the pronator teres muscle. To understand these variations and their implications in surgical procedures of the nerve transfers, a systematic review was performed on the innervation of pronator teres muscle from cadaveric studies.

METHODS

A systematic literature search was performed in databases such as Medline, PubMed, Google Scholar, SciELO, ScienceDirect, Cochrane reviews and orthopedics textbooks using the search terms "pronator teres nerve branches"; AND "number" OR "location" OR "length" OR "diameter" yielded 545 article links. Articles were evaluated according to PRISMA guidelines.

RESULTS

A total of twenty cadaveric studies including 648 branches have registered 52.9% of two branch innervation pattern followed by 31.3%-single branch pattern; 13.5%-three branch pattern; 1.7%-four branch pattern, and 0.4%-five branch patterns, respectively. Of the 403 branches studied for their location in relation with the humeral intercondylar line, most branches were located distal to the line (50.3%), followed by 32.7% (proximal to it) and 16.8% at the line, respectively. The distance of branches located proximal and distal to humeral intercondylar line was in the range of 1.25-10 cm, and 1.1-7.5 cm, respectively. The mean length and diameter of nerves reported were 4.37 ± 2.43 cm, and 1.5 mm, respectively.

CONCLUSIONS

Our data defined the morphometrics of nerve branches and they often met the required diameter for neurotization procedures. Our findings also demonstrated that the morphometrics, branching pattern and their location vary between populations and this information is very vital for surgeons during the nerve transfers.

Distal pronator teres motor branch transfer for wrist extension restoration in radial nerve paralysis

OBJECTIVE

The authors describe the anatomy of the motor branches of the pronator teres (PT) as it relates to transferring the nerve of the extensor carpi radialis brevis (ECRB) to restore wrist extension in patients with radial nerve paralysis. They describe their anatomical cadaveric findings and report the results of their nerve transfer technique in several patients followed for at least 24 months postoperatively.

METHODS

The authors dissected both upper limbs of 16 fresh cadavers. In 6 patients undergoing nerve surgery on the elbow, they dissected the branches of the median nerve and confirmed their identity by electrical stimulation. Of these 6 patients, 5 had had a radial nerve injury lasting 7-12 months, underwent transfer of the distal PT motor branch to the ECRB, and were followed for at least 24 months.

RESULTS

The PT was innervated by two branches: a proximal branch, arising at a distance between 0 and 40 mm distal to the medial epicondyle, responsible for PT superficial head innervation, and a distal motor branch, emerging from the anterior side of the median nerve at a distance between 25 and 60 mm distal to the medial epicondyle. The distal motor branch of the PT traveled approximately 30 mm along the anterior side of the median nerve; just before the median nerve passed between the PT heads, it bifurcated to innervate the deep head and distal part of the superficial head of the PT. In 30% of the cadaver limbs, the proximal and distal PT branches converged into a single trunk distal to the medial epicondyle, while they converged into a single branch proximal to it in 70% of the limbs. The proximal and distal motor branches of the PT and the nerve to the ECRB had an average of 646, 599, and 457 myelinated fibers, respectively.All patients recovered full range of wrist flexion-extension, grade M4 strength on the British Medical Research Council scale. Grasp strength recovery achieved almost 50% of the strength of the contralateral side. All patients could maintain their wrist in extension while performing grasp measurements.

CONCLUSIONS

The distal PT motor branch is suitable for reinnervation of the ECRB in radial nerve paralysis, for as long as 7-12 months postinjury.

Nerves transfers for functional hand recovery in traumatic lower brachial plexopathy

Background:

Distal nerve transfers are an innovative modality for the treatment of C8-T1 brachial plexus lesions. The purpose of this case series is to report the authors’ results with hand restoration function by nerve transfer in patients with lower brachial plexus injury.

Methods:

Three consecutive nerve transfers were performed in a series of 11 patients to restore hand function after injury to the lower brachial plexus: brachialis motor branch to anterior interosseous nerve (AIN) and supinator branch to the posterior interosseous nerve (PIN) in a first surgical procedure, and AIN to pronator quadratus branch of ulnar nerve between 4 and 6 months later.

Results:

In all, 11 male patients underwent 33 surgical procedures. Time between brachial plexus injury and surgery was a mean of 11 months (range 4–13 months). Postoperative follow-up ranged from 12 to 24 months. We observed recovery of M3 or better finger flexion strength (AIN) and wrist extension (PIN) in 8 of the 11 surgically treated upper limbs. These patients recovered full thumb and finger extension between 6 and 12 months of surgery, without significant loss of donor function.

Conclusion:

Nerve transfers represent a way of restoring volitional control of upper extremity function in patients with C8-T1 brachial plexus injury.

Delayed Transfer of the Extensor Carpi Radialis Brevis Branch of the Radial Nerve to the Anterior Interosseous Nerve for Restoration of Thumb and Index Finger Flexion: Case Report

High median nerve injuries (HMNIs) are rare lesions involving the upper extremities and affect the median nerve from its origin to the emergence of the anterior interosseous nerve (AIN). Proximal reconstruction has long been considered the gold standard in treating HMNI, but thumb and index flexion and pinch and grip weakness are consistently not recovered. We report the surgical results of a patient affected by an HMNI with partial spontaneous recovery after a gunshot wound. AIN function was successfully restored in a delayed fashion by transferring the radial nerve branch to the extensor carpi radialis brevis to the AIN.

Reconstruction of a C7-T1 brachial plexus lower root injury by transferring multiple nerves and a free gracilis muscle: Case report

Lower-type brachial plexus injuries (BPI) are uncommon, and traditional reconstruction with tendon transfer procedures generally produce mediocre results. However, the advent of nerve transfers has rejuvenated the reconstructive options for peripheral nerve and spinal cord injuries. In this paper, we report the case 32 year-old patient with a C7-T1 avulsion BPI in whom multiple motor and sensory nerve transfers, combined with a free gracilis muscle flap transfer, were used to restore upper-limb functional defects. Five months after injury, several nerves were transferred (posterior division of the axillary nerve to motor nerve branches of the triceps, extensor carpi radialis brevis to flexor pollicis longus, supinator to the posterior interosseous nerve, brachialis to the ulnar nerve, and a cutaneous branch to the palm of the median nerve to the ulnar proper palmar digital nerve of the little finger). No complications occurred. M4 strength elbow extension, complete active finger extension and ulnar protective sensation were obtained. However, unsuccessful finger flexion reconstruction required a free gracilis muscle flap transfer motorized by the distal branch of the pronator teres, performed 43 months after the first surgery and resulting in complete finger flexion. Multiple nerve transfers might be a valid strategy for reconstructing lower BPIs, either in their early or late stage, which might be combined with a free gracilis muscle flap transfer.

Comparative study of pronator teres branch transfer and brachialis motor branch transfer to the anterior interosseous nerve to treat lower brachial plexus injury in rats

Distal nerve transfer is used to treat lower brachial plexus palsy, but outcome series on these transfer procedures following lower plexus injuries are sparse. The objective of this study is to compare treatment outcomes after nerve transfer using the brachialis motor branch (BMB) versus that using the pronator teres motor branch (PTMB). One hundred twenty adult rats with C8T1 nerve root avulsion were randomly divided into three groups (40 each): A: BMB transfer to the anterior interosseous nerve (AIN), B: PTMB transfer to the AIN, and C: no repair. Electrophysiological examination result, muscle tension test result, muscle weight and muscle fiber cross-sectional area of the flexor digitorum profundus and flexor pollicis longus, and number of myelinated nerve fibers in the AIN were compared among the groups to evaluate the treatment outcome. Nerve regeneration and muscle recovery in group B was better than those in group A at 4 and 8 weeks postoperatively (P < 0.05). There was no significant difference in the myelinated nerve fibers in groups A and B at 12 and 16 weeks postoperatively. The rats in group B showed greater and more significant improvement in other measured values than those in group A (P < 0.05). In conclusion, the PTMB seems a better donor nerve than the BMB for distal nerve transfer to treat lower brachial plexus injury according to the electrophysiological and histological examination in this rat study.

Outcome of Finger Extension After Nerve Transfer to Repair C7-T1 Brachial Plexus Palsy in Rats: Comparative Study of the Supinator Motor Branch Transfer to the Posterior Interosseous Nerve and the Contralateral C7 Transfer to the Lower Trunk

BACKGROUND

Functional recovery following supinator motor branch transfer requires further investigation.

OBJECTIVE

To compare the outcome of finger extension after supinator motor branch transfer or contralateral C7 (cC7) transfer in C7-T1 brachial plexus palsies in rats.

METHODS

In this study, 120 adult rats underwent C7-T1 nerve root avulsion and received different nerve transfer repairs: group A, cC7 nerve transfer to the lower trunk; group B, supinator motor branch nerve transfer to the posterior interosseous nerve (PIN); and group C, no repair. The ethology of the rats, latency and amplitude of the compound muscle action potential from the PIN, muscle mass and muscle fiber cross-sectional area of the extensor digitorum communis and extensor carpi ulnaris, and number of myelinated nerve fibers in the PIN were examined postoperatively.

RESULTS

There was no finger extension in group C. We observed finger extension in groups A and B 50.2 ± 5.66 and 13.1 ± 2.08 days postoperatively, respectively. Finger extension restoration in group B was greater than that in group A at 4, 8, and 12 weeks postoperatively ( P < .05). Sixteen weeks after surgery, the recovery rate of the myelinated nerve fibers in group A was marginally higher than that in group B, but the difference was not significant. Of the other measured values, group B showed a greater and significant improvement compared to group A ( P < .05).

CONCLUSION

Supinator motor branch transfer allows for faster recovery and is a more effective procedure for restoring finger extension in C7-T1 brachial plexus palsies.

Upper Extremity Innervation Patterns and Clinical Implications for Nerve and Tendon Transfer

BACKGROUND

The authors previously studied the intramuscular innervation of 150 upper limb muscles and demonstrated that certain patterns of intramuscular innervation allowed muscles to be split into compartments with independent function. This study aims to determine the location, extramuscular course, and number of motor nerve branches of upper limb peripheral nerves. The authors want to combine this information with their previous work to create a blueprint of upper limb neuromuscular anatomy that would be useful in reconstructive surgery.

METHODS

Ten fresh frozen cadaveric upper limbs were dissected. The origin of branches from the peripheral nerve trunk, their course, and the number of motor nerves per muscle were determined. The authors reviewed all the images of the Sihler-stained muscles from their earlier study.

RESULTS

Motor nerve branches arise at the intersection of nerve trunk and muscle belly and are clustered near the origin of muscle groups. Two patterns of extramuscular innervation were noted, with one group having a single motor nerve and another group with consistently more than one motor nerve. A modified classification of muscles was proposed based on the orientation of muscle fibers to the long axis of the limb, the number of muscle compartments, and the number of heads of origin or the tendons of insertion.

CONCLUSIONS

Motor nerve clusters can be located based on fixed anatomical landmarks. Muscles with multiple motor nerves have morphology that allows them to be split into individual compartments. The authors created a muscle and nerve blueprint that helps in planning nerve and split muscle transfers.

Multiple nerve and tendon transfers: a new strategy for restoring hand function in a patient with C7-T1 brachial plexus avulsions

C7-T1 brachial plexus palsies result in a loss of finger motion and hand function. The authors have observed that finger flexion motion can be recovered after a brachialis motor branch transfer. However, finger flexion strength after this procedure merely corresponds to Medical Research Council Grades M2-M3, lowering the grip strength and practical value of the reconstructed hand. Therefore, they used 2 donor nerves and accomplished double nerve transfers for stronger finger flexion. In a patient with a C7-T1 brachial plexus injury, they transferred the pronator teres branch to the anterior interosseous nerve and the brachialis motor branch to the flexor digitorum superficialis branch for reinnervation of full finger flexors. Additionally, the supinator motor branch was transferred for finger extension, and the brachioradialis muscle was used for thumb opposition recovery. Through this new strategy, the patient could successfully accomplish grasping and pinching motions. Moreover, compared with previous cases, the patient in the present case achieved stronger finger flexion and grip strength, suggesting practical improvements to the reconstructed hand.

Neurotization of free gracilis transfer with the brachialis branch of the musculocutaneous nerve to restore finger and thumb flexion in lower trunk brachial plexus injury: an anatomical study and case report

OBJECTIVE

To investigate the feasibility of using free gracilis muscle transfer along with the brachialis muscle branch of the musculocutaneous nerve to restore finger and thumb flexion in lower trunk brachial plexus injury according to an anatomical study and a case report.

METHODS

Thirty formalin-fixed upper extremities from 15 adult cadavers were used in this study. The distance from the point at which the brachialis muscle branch of the musculocutaneous nerve originates to the midpoint of the humeral condylar was measured, as well as the length, diameter, course and branch type of the brachialis muscle branch of the musculocutaneous nerve. An 18-year-old male who sustained an injury to the left brachial plexus underwent free gracilis transfer using the brachialis muscle branch of the musculocutaneous nerve as the donor nerve to restore finger and thumb flexion. Elbow flexion power and hand grip strength were recorded according to British Medical Research Council standards. Postoperative measures of the total active motion of the fingers were obtained monthly.

RESULTS

The mean length and diameter of the brachialis muscle branch of the musculocutaneous nerve were 52.66±6.45 and 1.39±0.09 mm, respectively, and three branching types were observed. For the patient, the first gracilis contraction occurred during the 4th month. A noticeable improvement was observed in digit flexion one year later; the muscle power was M4, and the total active motion of the fingers was 209°.

CONCLUSIONS

Repairing injury to the lower trunk of the brachial plexus by transferring the brachialis muscle branch of the musculocutaneous nerve to the anterior branch of the obturator nerve using a tension-free direct suture is technically feasible, and the clinical outcome was satisfactory in a single surgical patient.

Double Distal Intraneural Fascicular Nerve Transfers for Lower Brachial Plexus Injuries

PURPOSE

To evaluate outcomes following transfer of the supinator motor branch of the radial nerve (SMB) to the posterior interosseous nerve (PIN) and the pronator teres motor branch of median (PTMB) to the anterior interosseous nerve (AIN) in patients with lower brachial plexus injuries.

METHODS

Since December 2010, 4 patients have undergone combined transfer of the SMB to PIN and PTMB to AIN for lower brachial plexus palsies. The study was prospectively designed, and the patients were followed for 4 years to monitor their functional improvement.

RESULTS

One patient failed to return after his 4-month postoperative visit. The other 3 patients all regained M4 thumb and finger extension, and 2 recovered M4 thumb and finger flexion at the final evaluation, a mean 30 months after the nerve transfer surgeries.

CONCLUSIONS

Combined transfer of the SMB to PIN and PTMB to AIN may lead to successful recovery of digital extrinsic flexion and extension in lower brachial plexus injuries.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Sleeve bridging of the rhesus monkey ulnar nerve with muscular branches of the pronator teres: multiple amplification of axonal regeneration

Multiple-bud regeneration, i.e., multiple amplification, has been shown to exist in peripheral nerve regeneration. Multiple buds grow towards the distal nerve stump during proximal nerve fiber regeneration. Our previous studies have verified the limit and validity of multiple amplification of peripheral nerve regeneration using small gap sleeve bridging of small donor nerves to repair large receptor nerves in rodents. The present study sought to observe multiple amplification of myelinated nerve fiber regeneration in the primate peripheral nerve. Rhesus monkey models of distal ulnar nerve defects were established and repaired using muscular branches of the right forearm pronator teres. Proximal muscular branches of the pronator teres were sutured into the distal ulnar nerve using the small gap sleeve bridging method. At 6 months after suture, two-finger flexion and mild wrist flexion were restored in the ulnar-sided injured limbs of rhesus monkey. Neurophysiological examination showed that motor nerve conduction velocity reached 22.63 ± 6.34 m/s on the affected side of rhesus monkey. Osmium tetroxide staining demonstrated that the number of myelinated nerve fibers was 1,657 ± 652 in the branches of pronator teres of donor, and 2,661 ± 843 in the repaired ulnar nerve. The rate of multiple amplification of regenerating myelinated nerve fibers was 1.61. These data showed that when muscular branches of the pronator teres were used to repair ulnar nerve in primates, effective regeneration was observed in regenerating nerve fibers, and functions of the injured ulnar nerve were restored to a certain extent. Moreover, multiple amplification was subsequently detected in ulnar nerve axons.

Transfer of the radial nerve branch to the extensor carpi radialis brevis to the anterior interosseous nerve to reconstruct thumb and finger flexion

PURPOSE

To report our experiences reconstructing thumb and finger flexion in patients with extensive palsy of the upper limb by transferring the radial nerve branch to the extensor carpi radialis brevis (ECRB) to the anterior interosseous nerve (AIN).

METHODS

Within 8 months after injury, 4 patients with either a combined high median/ulnar nerve palsy or C7-T1 brachial plexus root avulsion underwent surgical reconstruction for thumb and finger flexion. As part of the reconstructive procedure, the branch of the radial nerve to the ECRB was transferred to the AIN.

RESULTS

At final evaluation, which averaged 13 months postoperatively, all patients had recovered full finger and thumb flexion, scoring M4 per Medical Research Council guidelines. Average grasp strength was 5 kg, and pinch strength was 2 kg. Even in anesthetic fingers and with their eyes closed, patients could correctly identify passive extension of their distal interphalangeal joints. Wrist extension was preserved in all patients.

CONCLUSIONS

In 4 patients, transfer of the branch of the radial nerve to the ECRB to the AIN predictably reconstructed thumb and finger flexion. Finger flexion also recovered in those fingers in which the flexor digitorum profundus was primarily innervated by the ulnar nerve. Despite extended sensory deficits, patients ultimately were able to use their hands regularly in daily life.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

The median nerve consistently drives flexion of the distal phalanx of the ring and little fingers: Interest in finger flexion reconstruction by nerve transfers

Surgeons believe that in high ulnar nerve lesion distal interphalangeal joint (DIP) flexion of the ring and little finger is abolished. In this article, we present the results of a study on innervation of the flexor digitorum profundus of the ring and little fingers in five patients with high ulnar nerve injury and in 19 patients with a brachial plexus, posterior cord, or radial nerve injury. Patients with ulnar nerve lesion were assessed clinically and during surgery for ulnar nerve repair we confirmed complete lesion of the ulnar nerve in all cases. In the remaining 19 patients, during surgery, either the median nerve (MN) or the anterior interosseous nerve (AIN) was stimulated electrically and DIP flexion of the ring and little fingers evaluated. All patients with high ulnar nerve lesions had active DIP flexion of the ring and little fingers. Strength scored M4 in the ring and M3-M4 in the little finger. Electrical stimulation of either the MN or AIN produced DIP flexion of the ring and little fingers. Contrary to common knowledge, we identified preserved flexion of the distal phalanx of the ring and little fingers in high ulnar nerve lesions. On the basis of these observations, nerve transfers to the AIN may provide flexion of all fingers.