Median nerve branches to the pronator teres: cadaveric study with potential use in neurotization procedures to the radial nerve at the elbow

Pronator teres nerve branch transfer to the extensor carpi radialis brevis nerve branch for wrist extension reconstruction in proximal radial nerve injury following humeral shaft fractures

Background

Tendon and nerve transfers are used for functional reconstruction in cases of proximal radial nerve injury complicated by humeral fractures in patients who do not show functional recovery after primary nerve repair. The effectiveness of pronator teres (PT) nerve branch transfer to the extensor carpi radialis brevis (ERCB) nerve branch for wrist extension reconstruction was investigated and compared to the results of tendon transfer.

Methods

This study included 10 patients with proximal radial nerve injury, who did not show functional recovery after primary nerve repair at our hospital between April 2016 and May 2019. The nerve transfer procedure included PT nerve branch transfer to the ECRB nerve branch to restore wrist extension and the flexor carpi radialis (FCR) nerve branch to the posterior interosseous nerve (PIN) to restore thumb and finger extension. Tendon transfer procedures included PT transfer to the ECRB for wrist extension, FCR transfer to the extensor digitorum communis (EDC) for finger extension and palmaris longus (PL) transfer to the extensor pollicis longus (EPL) for thumb extension.

Results

Five patients recovered Medical Research Council grade M4 muscle strength in the ECRB and EPL in both tendon and nerve groups. Two patients recovered grade M3 strength and three patients recovered grade M4 strength in the EDC in the tendon transfer group, and all five patients recovered grade M4 strength in the EDC in the nerve transfer group. Limited wrist flexion was observed only in one patient in the tendon transfer group.

Conclusion

PT nerve branch transfer to the ECRB nerve branch combined with FCR nerve branch transfer to PIN is a useful strategy for wrist and fingers extension reconstruction in patients with proximal radial nerve injuries.

Radial Nerve Palsy: Nerve Transfer Versus Tendon Transfer to Restore Function

BACKGROUND

Radial nerve injuries cause profound disability, and a variety of reconstruction options exist. This study aimed to compare outcomes of tendon transfers versus nerve transfers for the management of isolated radial nerve injuries.

METHODS

A retrospective chart review of 30 patients with isolated radial nerve injuries treated with tendon transfers and 16 patients managed with nerve transfers was performed. Fifteen of the 16 patients treated with nerve transfer had concomitant pronator teres to extensor carpi radialis brevis tendon transfer for wrist extension. Preoperative and postoperative strength data, Disabilities of the Arm, Shoulder, and Hand (DASH) scores, and quality-of-life (QOL) scores were compared before and after surgery and compared between groups.

RESULTS

For the nerve transfer group, patients were significantly younger, time from injury to surgery was significantly shorter, and follow-up time was significantly longer. Both groups demonstrated significant improvements in grip and pinch strength after surgery. Postoperative grip strength was significantly higher in the nerve transfer group. Postoperative pinch strength did not differ between groups. Similarly, both groups showed an improvement in DASH and QOL scores after surgery with no significant differences between the 2 groups.

CONCLUSIONS

The nerve transfer group demonstrated greater grip strength, but both groups had improved pain, function, and satisfaction postoperatively. Patients who present early and can tolerate longer time to functional recovery would be optimal candidates for nerve transfers. Both tendon transfers and nerve transfers are good options for patients with radial nerve palsy.

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.

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.

Pronator teres selective neurectomy in children with cerebral palsy

The objective of this study was to evaluate the results after selective pronator teres (PT) neurectomy in children with spastic hemiplegia. Patients with PT spasticity without contracture and an active supination improvement after PT botulinum toxin injection were included. Hand function and deformities were evaluated with the House score, Gschwind and Tonkin pronation deformity classification and Zancolli's classification. Twenty-two patients (mean age 11.6 years) were included in this study. The average follow-up was 32.6 months. All but one patient improved their supination with a preoperative mean active supination of 5° (range -80-70°) and postoperative of 48° (range 10-90°). Active pronation was always maintained at the last follow-up. PT selective neurectomy appears to improve active and passive forearm supination and should be included in a global strategy of treatments to improve upper limb function in children with cerebral palsy.

LEVEL OF EVIDENCE

IV.

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.

Nerve Transfers to Restore Upper Extremity Function in Cervical Spinal Cord Injury: Update and Preliminary Outcomes

BACKGROUND

Cervical spinal cord injury can result in profound loss of upper extremity function. Recent interest in the use of nerve transfers to restore volitional control is an exciting development in the care of these complex patients. In this article, the authors review preliminary results of nerve transfers in spinal cord injury.

METHODS

Review of the literature and the authors' cases series of 13 operations in nine spinal cord injury nerve transfer recipients was performed. Representative cases were reviewed to explore critical concepts and preliminary outcomes.

RESULTS

The nerve transfers used expendable donors (e.g., teres minor, deltoid, supinator, and brachialis) innervated above the level of the spinal cord injury to restore volitional control of missing function such as elbow extension, wrist extension, and/or hand function (posterior interosseous nerve or anterior interosseous nerve/finger flexors reinnervated). Results from the literature and the authors' patients (after a mean postsurgical follow-up of 12 months) indicate gains in function as assessed by both manual muscle testing and patients' self-reported outcomes measures.

CONCLUSIONS

Nerve transfers can provide an alternative and consistent means of reestablishing volitional control of upper extremity function in people with cervical level spinal cord injury. Early outcomes provide evidence of substantial improvements in self-reported function despite relatively subtle objective gains in isolated muscle strength. Further work to investigate the optimal timing and combination of nerve transfer operations, the combination of these with traditional treatments (tendon transfer and functional electrical stimulation), and measurement of outcomes is imperative for determining the precise role of these operations.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Pronator Teres Branch Transfer to the Anterior Interosseous Nerve for Treating C8T1 Brachial Plexus Avulsion

BACKGROUND:

The treatment of C8T1 avulsion is challenging for neurosurgeons. Various methods for the restoration of finger flexion are used. However, most of these methods have different disadvantages and cannot restore the full active range of motion of the fingers.

OBJECTIVE:

To determine the feasibility of the pronator teres branch transfer to the anterior interosseous nerve with anatomic study and to use this method in 1 case.

METHODS:

The upper limbs of 15 fresh cadavers were dissected to identify the main trunk of the median nerve, the pronator teres branch, and the anterior interosseous nerve. The mean number and length of the pronator teres branches were recorded. The anterior interosseous nerve was dissected atraumatically to the most proximal level where the fibers of the anterior interosseous nerve did not mingle with the fibers of the main trunk of the median, which was defined as the atraumatic level of the anterior interosseous nerve. A line joining the most protruding point of the medial condyle and lateral condyle of the humerus was used as a measurement landmark. Pronator teres branch transfer to the anterior interosseous nerve was performed in 1 patient with C8T1 avulsion.

RESULTS:

The mean number of the pronator teres branches was 2.37 ± 0.49. The mean length of the pronator teres branches was 9.64 ± 0.71 mm. The mean distance between the point where the pronator teres branches originated and the landmark line was 3.87 ± 0.34 mm. The mean distance between the atraumatic level of the anterior interosseous nerve and the landmark line was −5.46 ± 0.73 mm. Transfer of the pronator teres was used to innervate the anterior interosseous nerve in 1 patient with C8T1 avulsion. When assessed 14 months after the operation, a full active range of motion of the fingers had been restored, and the patient's finger flexor muscles had regained grade 4 power.

CONCLUSION:

The pronator teres can be transferred to the anterior interosseous nerve directly at the elbow level. This operation was performed successfully in 1 patient, who exhibited finger flexion recovery.

Nerve transfers from branches to the flexor carpi radialis and pronator teres to reconstruct the radial nerve

PURPOSE

To present our method and results for transferring branches of the median nerve for radial nerve palsy or posterior cord lesions.

METHODS

We transferred 1 branch to the pronator teres to the branch to the extensor carpi radialis longus muscle and transferred the branch to the flexor carpi radialis to the posterior interosseous nerve. We carried out these transfers in 6 patients with radial nerve palsy or posterior cord lesions. We reviewed functional outcomes, Disabilities of the Arm, Shoulder and Hand scores, and Patient Evaluation Measure scores.

RESULTS

After 20 months of follow-up evaluation, all patients had recovered extensor carpi radialis longus activity of M4. Activity of the extensor carpi ulnaris was M3 in 2 patients and M4 in 4 patients. Extensor pollicis longus activity was M4 in all 6 cases. Metacarpophalangeal extension was M4 in 4 cases and M3 in 2 cases. The mean Disabilities of the Arm, Shoulder, and Hand score was 26 (range, 7-43), and the mean Patient Evaluation Measure score was 34 (range, 24-53).

CONCLUSIONS

Selective independent synergistic transfer of median nerve fascicles to the radial nerve branches has shown excellent results in the treatment of severe lesions of the radial nerve.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Diagnostic biopsy of the pronator teres and a motor branch of the median nerve: indications and technique

PURPOSE

Biopsy of muscle tissue and motor nerve is helpful in the neurological evaluation of patients who present with upper limb and/or diffuse motor weakness. The procedure is indicated to supplement clinical, serological, and imaging diagnostic work-up of myopathic and neuropathic disorders. We describe a surgical technique and clinical series of biopsy of the pronator teres muscle and a motor branch of the median nerve.

METHODS

We performed a retrospective review of 20 patients who underwent biopsy of the pronator teres and a motor branch of the median nerve as part of a clinical, serological, and radiographic evaluation for weakness of the upper extremity. All of the biopsies were performed by a single surgeon. The surgical technique is described. Follow-up visits with both the surgeon and the neurologist were reviewed to evaluate preoperative and postoperative neurological function to identify any changes in nerve or muscle function and any postoperative complications.

RESULTS

Biopsied tissue was sufficient for pathological diagnosis in all 20 patients. Diagnoses included multifocal motor neuropathy in 14 patients, amyotrophic lateral sclerosis in 3 patients (2 sporadic; 1 familial), inclusion body myositis (1 patient), inflammatory myopathy (1 patient), and chronic inflammatory demyelinating polyneuropathy (1 patient). At a mean follow-up of 11 weeks (range, 5-31 wk), there were 6 minor surgical complications, all of which were superficial hematomas that resolved with use of a compressive wrap.

CONCLUSIONS

Biopsy of the pronator teres and a motor branch of the median nerve was safe and effective. The technique is particularly useful when considering the diagnosis of multifocal motor neuropathy affecting the upper extremity.

Combined proximal nerve graft and distal nerve transfer for a posterior cord brachial plexus injury

The treatment of patients with prolonged denervation from a posterior cord brachial plexus injury is challenging and no management guidelines exist to follow. The authors describe the case of a 26-year-old man who presented to our clinic for treatment 11 months after suffering a high-energy injury to the posterior cord of the brachial plexus. A combined 9-cm proximal cable nerve graft procedure and a pronator branch to the posterior interosseous nerve transfer were performed. Satisfactory deltoid, triceps, wrist, and finger extensor recovery was noted 3 years after surgery. Patients with prolonged denervation from posterior cord injuries can be successfully treated with a combination of a proximal nerve graft and a distal nerve transfer.

Transfer of median and ulnar nerve fascicles for lesions of the posterior cord in infraclavicular brachial plexus injury: report of 2 cases

In infraclavicular lesions of brachial plexus, severe lesions of the posterior cord often occur when medial and lateral cord function is preserved to a greater or lesser extent. In these cases, shoulder function may be preserved by activity of the muscles innervated by the suprascapular nerve, but complete paralysis exists in the deltoid, triceps, and brachioradialis, and all wrist and finger extensors. Classical reconstruction procedures consist of nerve grafts, but their results in adults are disappointing. We report an approach transferring: (1) an ulnar nerve fascicle to the motor branch of the long portion of the triceps brachii muscle, (2) a median nerve branch from the pronator teres to the motor branch of the extensor carpi radialis longus, and (3) a median nerve branch from the flexor carpi radialis to the posterior interosseous nerve. We describe the procedure and report 2 clinical cases showing the effectiveness of this technique for restoring extension of the elbow, wrist, and fingers in the common infraclavicular lesions of the brachial plexus affecting the posterior cord.