Transfer of a Terminal Motor Branch Nerve to the Flexor Carpi Ulnaris for Triceps Reinnervation: Anatomical Study and Clinical Cases

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.

Adult traumatic brachial plexus injuries: advances and current updates

Nerve grafting, tendon transfer and joint fusion are routinely used to improve the upper limb function in patients with brachial plexus palsies. Newer techniques have been developed that provide additional options for reconstruction. Nerve transfer is a tool for restoring upper limb function in total root avulsions where nerve grafting is not possible. In partial brachial plexus injuries, nerve transfers can greatly improve shoulder, elbow, wrist and hand function. Intraoperative electrical stimulation can be used to diagnose precisely which nerve is injured and to choose which nerve fascicles should be transferred. Finally, measuring the postoperative outcome can improve the evaluation of our techniques. The aim of this article was to present the current techniques used to treat patients with brachial plexus injury.

Anatomy of Profunda Brachial Artery in the Axilla and Its Relationship With the Radial Nerve: Fresh-Cadaver Anatomical Study and Clinical Observations

PURPOSE

Dissection of the radial nerve in the axilla and upper portion of and posterior aspect of arm may be necessary for brachial plexus reconstruction, in axillary nerve paralysis, and in radial nerve injuries. The radial nerve is in intimate contact with the profunda brachial artery (PBA). The authors sought to describe the relationship of the PBA with the radial nerve.

METHODS

We dissected the PBA and the radial nerve bilaterally in 20 upper limbs from 10 fresh cadavers after subclavian artery injection with green latex. We studied the relationship of the PBA with the radial nerve, its branching patterns, and its diameters. In addition, we performed surgery on 5 patients with brachial plexus, radial, or axillary nerve injury in whom we dissected the PBA.

RESULTS

The PBA was present in all dissections, originating from the brachial artery (n = 19 specimens) close to the latissimus dorsi tendon or from the subscapular artery (n = 1 specimen). In 15 dissections, the PBA bifurcated into an anterior (AB) and a posterior (PB) branch. In one dissection, the AB was absent. The AB traveled toward the triceps medial head. The PB flanked the radial nerve posteriorly and traveled around the humerus, with the radial nerve passing between the medial and the lateral head of the triceps. The AB and PB were longer than the PBA and measured on average 53 mm (SD ± 33 mm) and 39 mm (SD ± 26 mm), respectively. Intraoperatively, the radial nerve could be exposed in the upper arm by pulling the triceps medial head anteriorly together with the AB. The PB was lateral to the radial nerve in the posterior arm approach.

CONCLUSIONS

In the upper arm, the radial nerve was not flanked by a single branch as postulated in anatomical textbooks but by 2 branches resulting from the bifurcation of the PBA.

CLINICAL RELEVANCE

Awareness of PBA anatomy is essential during radial nerve dissection from the anterior or posterior arm approach.

Distal Nerve Transfers in Hand and Forearm for Traumatic Brachial Plexus and Peripheral Nerve Injuries: A Narrative Review

Background

Various studies published good outcomes in brachial plexus injuries using nerve transfers for shoulder and elbow functions. However, little is known about the outcome of the distal nerve transfers in the forearm and hand. Targeting the nerve distally produces an early return of function in brachial plexus and peripheral nerve injuries (BPPNI). Therefore, researchers have focused on nerve transfers from the motor branches of the ulnar, median, and radial nerve. Similarly, sensory reinnervation is also obtained by potential donor transfers in the forearm and hand. There have been various attempts by surgeons to target the muscle and promote early reinnervation by different nerve transfers.

Conclusions

The distal nerve transfers in the forearm and hand are promising when performed early. It effectively restores hand and forearm functions and may be considered a better option than tendon transfer, which has a one-tendon-one function. This narrative review article discusses the different distal nerve transfers for various presentations of BPNNI.

Triceps and cutaneous radial nerve branches investigated via an axillary anterior arm approach: new findings in a fresh-cadaver anatomical study

OBJECTIVE

The authors sought to describe the anatomy of the radial nerve and its branches when exposed through an axillary anterior arm approach.

METHODS

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

RESULTS

Via the anterior arm approach, all triceps muscle heads could be dissected and individualized. The radial nerve overlaid the latissimus dorsi tendon, bounded by the axillar artery on its superior surface, then passed around the humerus, together with the lower lateral arm and posterior antebrachial cutaneous nerve, between the lateral and medial heads of the triceps. No triceps motor branch accompanied the radial nerve's trajectory. Over the latissimus dorsi tendon, an antero-inferior bundle, containing all radial nerve branches to the triceps, was consistently observed. In the majority of the dissections, a single branch to the long head and dual innervations for the lateral and medial heads were observed. The triceps long and proximal lateral head branches entered the triceps muscle close to the latissimus dorsi tendon. The second branch to the lateral head stemmed from the triceps lower head motor branch. The triceps medial head was innervated by the upper medial head motor branch, which followed the ulnar nerve to enter the medial head on its anterior surface. The distal branch to the triceps medial head also originated near the distal border of the latissimus dorsi tendon. After a short trajectory, a branch went out that penetrated the medial head on its posterior surface. The triceps lower medial head motor branch ended in the anconeus muscle, after traveling inside the triceps medial head. The lower lateral arm and posterior antebrachial cutaneous nerve followed the radial nerve within the torsion canal. The lower lateral brachial cutaneous nerve innervated the skin over the biceps, while the posterior antebrachial cutaneous nerve innervated the skin over the lateral epicondyle and posterior surface of the forearm. The average numbers of myelinated fibers were 926 in the long and 439 in the upper lateral head and 658 in the upper and 1137 in the lower medial head motor branches.

CONCLUSIONS

The new understanding of radial nerve anatomy delineated in this study should aid surgeons during reconstructive surgery to treat upper-limb paralysis.

Reconstruction of C5-C8 (T1 Hand) Brachial Plexus Paralysis in a Series of 52 Patients

PURPOSE

A C5-C8 brachial plexus root injury, also known as a T1 hand, is associated with paralysis of shoulder abduction or external rotation and elbow flexion, accompanied by variable elbow, wrist, thumb, or finger extension deficits. We report the results of reconstruction for C5-C8 brachial plexus paralysis in 52 patients operated upon within 12 months of injury and having at least 24 months of follow-up.

METHODS

We considered surgery to be indicated if, by the fifth month after trauma, shoulder abduction and external rotation and elbow flexion remained paralyzed. Root grafting was possible in 35% of the patients and was performed concomitantly with nerve transfers. Shoulder motion was reconstructed by transferring the spinal accessory to the suprascapular nerve. Elbow flexion was restored by transferring fascicles from either the median or ulnar nerve to the biceps motor branch. When needed, elbow extension was reconstructed by transferring 1 motor branch of the flexor carpi ulnaris to the triceps lower medial head motor branch. Wrist extension was restored by transferring the distal anterior interosseous nerve to the extensor carpi radialis brevis motor branch.

RESULTS

Within 12 months of injury, we observed preserved or spontaneous recovery of elbow, wrist, finger, and thumb extension in 25%, 12%, 50%, and 68% of patients, respectively. After surgical reconstruction, improved range of motion for shoulder, elbow flexion, and wrist extension scoring at least M3 was present in 90% of our patients. All 10 patients in whom a motor branch of the flexor carpi ulnaris was used for triceps reconstruction recovered elbow extension, while flexor carpi ulnaris function was preserved.

CONCLUSIONS

In approximatively 90% of our patients, distal nerve transfers resulted in functional recovery of shoulder abduction, elbow flexion or extension, and wrist extension.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

The muscular branching patterns of the ulnar nerve in fetal forearms

OBJECTIVE

We aimed to present our findings systematically by examining the muscular branching patterns of the ulnar nerve (UN) in the forearms of fetuses.

METHODS

This study was conducted on the 52 forearms of 26 formalin-fixed fetal cadavers with gestational ages varying between 19 and 37 weeks. The anatomical dissection was performed by using stereomicroscope with × 8 magnification. The numbers of muscular branches leaving UN and their order of leaving main nerve were noted down. The findings were classified according to the muscles they reached, and branching typing was done.

RESULTS

It was found that a total of 2-6 muscular branches left UN to reach flexor carpi ulnaris (FCU) and flexor digitorum profundus (FDP). UN was classified by separating into five main types according to the number of muscular branches, and these types were classified into 16 different branching patterns according to the order of branches leaving from the main trunk and going to FCU and FDP. The pattern where two branches left UN was classified as Type I (n = 6), three branches left was classified as Type II (n = 18), four branches left was classified as Type III (n = 24), five branches left was classified as Type IV (n = 3), and six branches left was classified as Type V (n = 1). Martin-Gruber connection occurred in 17 (32.7%) fetal forearms.

CONCLUSION

We believe that the information that UN can demonstrate different branching patterns on the forearm can help the surgeons to prevent complications that may develop in potential nerve injury during the selection and transfer of relevant branch.

Functional reconstructions using only ulnar nerve and ulnar nerve-innervated muscles for traumatic musculocutaneous, median and radial nerve palsies

A 20-year-old right-handed fisherman experienced a severe injury in a high-energy traffic accident. These injuries included a shaft fracture of the right humerus, open comminuted fracture of the right forearm and multiple peripheral nerve palsies involving the musculocutaneous, median and radial nerves. Six months after the initial treatment, the patient was referred to our hand surgeons for further treatment. Several operations for functional reconstruction using only the ulnar nerve and ulnar nerve-innervated muscles were performed: the main procedures included a partial ulnar nerve transfer for elbow flexion, flexor carpi ulnaris transfer for reconstruction of wrist and finger extension and opponensplasty using the abductor digiti minimi. Three years after the initial injury, the patient had relatively good function including elbow flexion and stable side pinch and grasp. Functional reconstruction using a combination of the ulnar nerve and ulnar nerve-innervated muscles may be useful in specific cases involving multiple peripheral nerve injuries.

Nerve transfers in the upper extremity: A review

Injury of the brachial plexus and peripheral nerve often result in significant upper extremity dysfunction and disability. Nerve transfers are replacing other techniques as the gold standard for brachial plexus and other proximal peripheral nerve injuries. These transfers require an intimate knowledge of nerve topography, a technically demanding Intraneural dissection and require extensive physical therapy for retraining. In this review, we present a summary of the most widely accepted nerve transfers in the upper extremity described in the current literature.

Reanimation of triceps muscle using ulnar nerve fascicle transfer to the nerve to long head of the triceps muscle

BACKGROUND

Triceps muscle serves an important role in extension of the elbow. Its action is required for reaching out objects without using the trunk. Elbow extension is an important function for natural stabilization of the elbow. The aim of this study was to evaluate restoration of elbow extension in adults suffering triceps muscle palsy with various causes, by using transfer of a fascicle of ulnar nerve to the long head of triceps branch of the radial nerve.

MATERIALS AND METHODS

In the present case series, 7 patients with partial brachial plexus injury or posterior cord injury, where triceps muscle was involved, were subjected to motor fascicle of ulnar nerve transfer to the nerve to long head of triceps for restoration of elbow extension. Follow-ups, including EMG-NCV (electromyography-nerve conduction velocity) 6 and 12 months after surgery and elbow extension muscle strength using MRC grading, were carried out.

RESULTS

Six patients (85.71%) achieved a functional muscle strength of M4 for their elbow extension. In all of the patients, re-innervation was discovered using EMG-NCV.

CONCLUSION

This surgical technique (ulnar nerve fascicle transfer to long head of the triceps) for improving elbow extension is promising in patients with brachial plexus injury.

Distal Nerve Transfers to the Triceps Brachii Muscle: Surgical Technique and Clinical Outcomes

PURPOSE

To report the clinical outcomes and describe the surgical technique of triceps muscle reinnervation using 2 different distal nerve transfers: the flexor carpi ulnaris (FCU) fascicle of the ulnar nerve and the posterior branch of the axillary nerve (PBAN) to the triceps nerve branch.

METHODS

A retrospective review of patients undergoing FCU fascicle of ulnar nerve or PBAN to triceps nerve branch transfer was performed. Outcome measures included preoperative and postoperative modified British Medical Research Council (MRC) score, EMG results, and complications.

RESULTS

Between September 2003 and April 2017, 6 patients were identified. Four patients with a traumatic upper trunk and posterior cord palsy underwent ulnar nerve fascicle to triceps nerve transfer. Two patients with a recovering upper trunk following a pan-brachial plexus palsy underwent PBAN to triceps nerve branch transfer. The median age was 30.0 years (range, 18-68 years). Surgery was performed at a median of 6.9 months (range, 5.0-8.9 months) postinjury, with a median follow-up of 18.4 months (range, 7.6-176.3) months. Before surgery, 4 patients exhibited grade M0 and 2 patients exhibited grade M1 triceps strength. Four patients had M5 donor muscle strength and 2 had grade M4. Postoperatively, 4 patients regained MRC grade M4 triceps muscle strength, 1 regained M3, and 1 regained M2. There was no noticeable donor muscle weakness.

CONCLUSIONS

Nerve fascicles to the FCU and PBAN are viable options for obtaining meaningful triceps muscle recovery in a select group of patients.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic V.

Partial ulnar nerve transfer to the branch of the long head of the triceps to recover elbow extension in C5, C6 and C7 brachial plexus palsy

Elbow flexion is the first goal in upper partial brachial plexus palsy treatment. However, elbow extension is essential for daily living activities. To recover this function, one fascicle of ulnar nerve can be transferred to the branch of the long head of the triceps, but this procedure has been previously published in only two patients. The goal of our study is to assess a larger series of transfers of one fascicle of ulnar nerve to the branch of the long head of the triceps to help patients recover elbow extension. Ten male patients with C5, C6 and C7 brachial plexus injuries underwent operation. For shoulder recovery, we transferred the spinal accessory nerve and rhomboid nerve. For elbow flexion, one fascicle of median nerve was transferred to the nerve of the biceps. For elbow extension, we transferred one fascicle of ulnar nerve to the branch of the long head of the triceps. Tendon transfers were performed for wrist and finger extension. Nine patients recovered M4 elbow flexion and extension. One patient had M3 elbow extension and flexion. Average active shoulder elevation was 85° and average active shoulder external rotation was 65° All patients recovered finger and wrist extension. The classical techniques of grafts or phrenic or intercostal nerve transfers to recover elbow extension are not always reliable, according to the literature. Because the harvested ulnar nerve motor fascicle is close to the branch of the long head of the triceps, the recovery time for this procedure is shorter than that of other described nerve transfers. The isolated recovery of the reinnervated long head of the triceps muscle excludes spontaneous recovery occasionally noted in upper root plexus injuries. The transfer of one fascicle of ulnar nerve to the branch of the long head of the triceps is reliable for active elbow extension recovery in C5, C6 and C7 brachial plexus palsies.

Upper Extremity Axon Counts and Clinical Implications for Motor Nerve Transfer

BACKGROUND

Nerve transfers are planned based on the following parameters: location, number of branches, and axon count matching of the donor and recipient nerves. The authors have previously defined the former two in upper limb muscles. In the literature, axon counts are obtained from various sources, using different methods of histomorphometry. This study describes the axon counts of the same primary motor nerve branches from the authors' previous study using a uniform method of manual histomorphometry and completes the authors' blueprint of upper limb neuromuscular anatomy for reconstructive surgery.

METHODS

The distal ends of the primary nerve branches of 23 upper limb muscles were harvested from 10 fresh frozen cadaveric upper limbs. Manual quantitative histomorphometry was performed by two independent investigators, and the average was reported.

RESULTS

The primary nerve branches of the arm muscles had higher average axon counts (range, 882 to 1835) compared with those of the forearm muscles (range, 267 to 883). In the forearm, wrist flexor (range, 659 to 746) and extensor (range, 543 to 745) nerve branches had axons counts that were similar to those of potential donors (e.g., supinator, n = 602; pronator teres, n = 625; flexor digitorum superficialis, n = 883; and flexor digitorum profundus, n = 832).

CONCLUSIONS

Apart from describing the axon counts of the upper limb, the authors have found that the forearm axon counts are very comparable. This insight, when combined with information on the location and number of primary nerve branches, will empower surgeons to tailor bespoke nerve transfers for every clinical situation.

Combined flexor carpi ulnaris and flexor carpi radialis transfer for restoring elbow function after brachial plexus injury

The result of combined agonist and antagonist muscle innervation in traumatic brachial plexus injury through the intraplexal fascicle nerve transfers with the same donor function has not yet been reported. We describe a patient with a C5-C7 traumatic brachial plexus injury who had a combined transfer of the flexor carpi radialis (FCR) fascicle to the musculocutaneous nerve and the flexor carpi ulnaris (FCU) fascicle to the radial nerve of the triceps. The patient returned for his follow-up visit 2 years after his surgery. The muscle strengths of his triceps and biceps were Medical Research Council grade 2 and 0, respectively. Compared with his uninjured side, his grip strength was 9.8%, and his pinch strength was 14.2%. Our case report provides insights on result of combined agonist and antagonist muscle innervation through combining the motor fascicle of the FCR and FCU to restore the elbow flexor and extensor. The result may not be promising.

Elbow flexion reconstruction with nerve transfer or grafting in patients with brachial plexus injuries: A systematic review and comparison study

INTRODUCTION

Posttraumatic brachial plexus (BP) palsy was used to be treated by reconstruction with nerve grafts. For the last two decades, nerve transfers have gained popularity and believed to be more effective than nerve grafting. The aim of this systematic review was to compare elbow flexion restoration with nerve transfers or nerve grafting after traumatic BP injury.

METHODS

PRISMA-IPD structure was used for 52 studies included. Patients were allocated as C5-C6 (n = 285), C5-C6-C7 (n = 150), and total BP injury (n = 245) groups. In each group, two treatment modalities were compared, and effects of age and preoperative interval were analyzed.

RESULTS

In C5-C6 injuries, 93.1% of nerve transfer patients achieved elbow flexion force ≥M3, which was significantly better when compared to 69.2% of nerve graft patients (p < 0.001). For improved outcomes of nerve transfer patients, shorter preoperative interval was a significant factor in all injury patterns (p < 0.001 for C5-C6 injuries and total BP injuries, p = 0.018 for C5-C6-C7 injuries), and young age was a significant factor in total BP injury pattern (p = 0.022).

CONCLUSIONS

Our analyses showed that nerve transfers appear superior to nerve graftings especially in patients with a C5-C6 injury. Unnecessary delays in surgery must be prevented, and younger patients may have more chance for better recovery.

LEVEL OF EVIDENCE

Level II.

Recovery of respiratory function and autonomic diaphragm movement following unilateral recurrent laryngeal nerve to phrenic nerve anastomosis in rabbits

The authors studied restoration of respiratory function in rabbits, using the recurrent laryngeal nerve to restore function after the phrenic nerve had been severed. The results of this animal study are encouraging and suggest that a similar technique could possibly be used to help patients with severe cervical spinal cord injuries.