Median to radial nerve transfer to restore wrist and finger extension: technical nuances

Initial findings in traumatic peripheral nerve injury and repair with diffusion tensor imaging

OBJECTIVE

Management of peripheral nerve injuries requires physicians to rely on qualitative measures from patient history, electromyography, and physical exam. Determining a successful nerve repair can take months to years for proximal injuries, and the resulting delays in clinical decision-making can lead to a negative impact on patient outcomes. Early identification of a failed nerve repair could prevent permanent muscle atrophy and loss of function. This study aims to test the feasibility of performing diffusion tensor imaging (DTI) to evaluate injury and recovery following repair of wrist trauma. We hypothesize that DTI provides a noninvasive and reliable assessment of regeneration, which may improve clinical decision-making and alter the clinical course of surgical interventions.

METHODS

Clinical and MRI measurements from subjects with traumatic peripheral nerve injury, carpal tunnel syndrome, and healthy control subjects were compared to evaluate the relationship between DTI metrics and injury severity.

RESULTS

Fractional anisotropy from DTI was sensitive to differences between damaged and healthy nerves, damaged and compressed nerves, and injured and healthy contralateral nerves. Longitudinal measurements in two injury subjects also related to clinical outcomes. Implications of other diffusion measures are also discussed.

INTERPRETATION

DTI is a sensitive tool for wrist nerve injuries and can be utilized for monitoring nerve recovery. Across three subjects with nerve injuries, this study has shown how DTI can detect abnormalities between injured and healthy nerves, measure recovery, and determine if re-operation was successful. Additional comparisons to carpal tunnel syndrome and healthy nerves show that DTI is sensitive to the degree of impairment.

A Porcine Model of Peripheral Nerve Injury Enabling Ultra-Long Regenerative Distances: Surgical Approach, Recovery Kinetics, and Clinical Relevance

BACKGROUND

Millions of Americans experience residual deficits from traumatic peripheral nerve injury (PNI). Despite advancements in surgical technique, repair typically results in poor functional outcomes due to prolonged periods of denervation resulting from long regenerative distances coupled with slow rates of axonal regeneration. Novel surgical solutions require valid preclinical models that adequately replicate the key challenges of clinical PNI.

OBJECTIVE

To develop a preclinical model of PNI in swine that addresses 2 challenging, clinically relevant PNI scenarios: long segmental defects (≥5 cm) and ultra-long regenerative distances (20-27 cm). Thus, we aim to demonstrate that a porcine model of major PNI is suitable as a potential framework to evaluate novel regenerative strategies prior to clinical deployment.

METHODS

A 5-cm-long common peroneal nerve or deep peroneal nerve injury was repaired using a saphenous nerve or sural nerve autograft, respectively. Histological and electrophysiological assessments were performed at 9 to 12 mo post repair to evaluate nerve regeneration and functional recovery. Relevant anatomy, surgical approach, and functional/histological outcomes were characterized for both repair techniques.

RESULTS

Axons regenerated across the repair zone and were identified in the distal stump. Electrophysiological recordings confirmed these findings and suggested regenerating axons reinnervated target muscles.

CONCLUSION

The models presented herein provide opportunities to investigate peripheral nerve regeneration using different nerves tailored for specific mechanisms of interest, such as nerve modality (motor, sensory, and mixed fiber composition), injury length (short/long gap), and total regenerative distance (proximal/distal injury).

Trends in Nerve Transfer Procedures Among Board-Eligible Orthopedic Hand Surgeons

Purpose

Enthusiasm for peripheral nerve transfers increased over the past several years, but further studies are still needed to establish the role of these procedures in peripheral nerve reconstruction. The primary goal of this study was to describe the frequency of nerve transfer surgery among newly trained orthopedic surgeons.

Methods

We queried the American Board of Orthopaedic Surgery Part II case log database for all nerve reconstruction Current Procedural Terminology codes for examination years 2004 to 2018 for surgeries performed between 2003 and 2017. Information collected for each patient included examination year, year of surgery, surgeon fellowship training subspecialty, geographic region (as defined by the American Board of Orthopaedic Surgery Part II case log database), patient age, and patient sex.

Results

A total of 3,359 nerve reconstruction cases were logged by 1,542 individual candidates from examination years 2004 to 2018. Of the nerve reconstruction codes, 2.1% were nerve transfer codes. There was a statistically significant increase in the proportion of nerve transfer codes over the study period, from 0% of nerve reconstruction codes in examination years 2004 to 2006 to 4.1% of nerve reconstruction codes in examination years 2016 to 2018 (Z = –6.82; P < .001).

Conclusions

There has been an increase in the number of nerve transfer procedures relative to all nerve reconstruction codes for peripheral nerve conditions.

Clinical relevance

There is a modest but significant increase in nerve transfer procedures over time among newly trained orthopedic surgeons, which suggests the need for long-term outcomes studies for nerve transfers procedures performed in the setting of peripheral nerve conditions.

Peripheral nerve injuries in the pediatric population: a review of the literature. Part I: traumatic nerve injuries

OBJECTIVE

This article reviews the clinical results that can be obtained after repair of a traumatic peripheral nerve injury in the pediatric population.

METHODS

A systematic review of the published literature has been made.

RESULTS

Functional outcome after major nerve injuries is sometimes disappointing in adults. However, children have been reported to experience much better functional results after nerve repair than adults. Moreover, recovery generally is faster in children. The superior capacity of children's central nervous system to adapt to external or internal environmental changes (neural plasticity) and the shorter recovery distance from the axon repair site to the target muscle are claimed to be crucial determinants of their favorable outcomes. Moreover, even in the pediatric population, it has been demonstrated that functional results are better the younger the patient is, including better clinical results in those injured in early childhood (< 6 years old) than in those injured in adolescence. Other favorable prognostic factors include the type of nerve injury (with complete transections doing less well than crush injuries) and the timing of surgery (with better outcomes after early repairs).

CONCLUSIONS

All efforts should be done to repair in a timely and adequate fashion traumatic peripheral nerve injuries in children, as the results are good.

TRANSFER OF NERVE BRANCHES OF THE FLEXOR CARPI RADIALIS TO THE POSTERIOR INTEROSSEOUS NERVE

Objective:

The objective of this paper was to study the anatomical variations of the flexor carpi radialis muscle (FCR) and determine in cadaver limbs whether the FCR nervous branch can be connected to the posterior interosseous nerve (PIN) without tension and how close to the target muscles the transfer can be performed.

Method:

Thirty cadaveric upper limbs were dissected.

Results:

The FCR received exclusive innervation of the median nerve, distally to the intercondylar line of the humerus. In 5 limbs, an isolated branch was found and in 25, a common trunk with other nervous branches occurred. We investigated whether the branch for the FCR was long enough to be transferred to the PIN. The diameter of the nerve branch for the FCR corresponded on average to 50% of the PIN.

Conclusion:

In 12 limbs, the branch destined to the FCR could be connected to the PIN, distally to the nerve branches to the supinator muscle even during the movements of the forearm and the elbow. In 18 specimens, it was necessary to mobilize the PIN for this innervation. Level of Evidence IV, Case Series.

An evidence-based algorithm for the management of common peroneal nerve injury associated with traumatic knee dislocation

Traumatic knee dislocation is a complex ligamentous injury that may be associated with simultaneous vascular and neurological injury.Although orthopaedic surgeons may consider CPN exploration at the time of ligament reconstruction, there is no standardised approach to the management of this complex and debilitating complication.This review focusses on published evidence of the outcomes of common peroneal nerve (CPN) injuries associated with knee dislocation, and proposes an algorithm for the management. Cite this article: Deepak Samson, Chye Yew Ng, Dominic Power. An evidence-based algorithm for the management of common peroneal nerve injury associated with traumatic knee dislocation. EFORT Open Rev 2016;1:362-367. DOI: 10.1302/2058-5241.160012.

Useful Functional Outcome Can Be Achieved After Motor Nerve Transfers in Management of the Paralytic Hand. An Observational Study

BACKGROUND

Nerve transfers have demonstrated encouraging outcomes in peripheral nerve reconstructions compared with the conventional direct repair or grafting.

QUESTIONS/PURPOSES

We aimed to identify whether the patient's demographics, delay to surgery, degree of loss of grip and pinch strengths, mechanism of injury, and compliance to hand therapy have an impact on the functional outcome of motor nerve transfers in patients with paralytic hand.

METHODS

Fifty-five patients with a mean age of 31.05 (18-48) years with complete isolated high injuries of radial, ulnar, and median nerves, who underwent motor nerve transfers, were reviewed. The outcome was assessed using the Medical Research Council (MRC) scale and measurement of grip and pinch strengths of the hand at minimum 1-year follow-up (mean of 14.4 (12-18) months). Patient's age and gender, delay to surgery, body mass index (BMI), degree of loss of grip and pinch strengths, educational level, occupation, mechanism of injury, and compliance to hand therapy were analyzed to determine their impact on the extent of recovery of hand function.

RESULTS

Forty of fifty five (72.73%) patients regained useful functional recovery (M3-M4) with satisfactory grip hand functions. Worse motor recovery was observed in older ages, delayed surgical intervention, higher BMI, and greater postoperative loss of grip and pinch strengths in comparison to the healthy opposite hand. Better outcomes are significantly associated with higher educational level and postoperative compliance to hand therapy. Contrarily, there was no significant association between gender, occupation, mechanism of injury, and achievement of useful functional recovery.

CONCLUSIONS

Successful nerve transfers are expected with experienced skilled surgeons. However, outstanding outcomes are not the standard, with about one fourth failing to achieve M3 grade. The educational level, hand dominance, compliance to hand therapy, loss of grip and pinch strengths, age, injury-surgery interval, and BMI are possible predictors of patients' outcome.

A Cadaver Study of Median-to-Radial Nerve Transfer for Radial Nerve Injuries

PURPOSE

To assess the anatomic feasibility of a median-to-radial nerve transfer in cadaver limbs and to quantify the number of axons present in the cut ends of the involved donor and recipient nerves.

METHODS

Ten fresh frozen cadaveric upper limbs were dissected. We investigated whether the flexor carpi radialis (FCR) branch/flexor digitorum superficialis (FDS) branch (donor nerve) reached the posterior interosseous nerve (PIN)/extensor carpi radialis brevis (ECRB) branch (recipient nerve) without tension. We also investigated the length of the transected supinator fascia for FCR-posterior interosseous nerve transfer and the FDS-ECRB positional relationship using the epicondyle line and the midline of the forearm as axes. The findings were used for these 2 types of nerve transfer with evaluation closer to the target muscles. The distance between the point at which the FDS and ECRB branches met and the point at which the ECRB branch entered the muscle was measured. After nerve coaptation, the axon number was determined by histological evaluation.

RESULTS

In all limbs, the FCR and FDS branches reached the PIN and the ECRB branch without tension. The transected supinator fascia was 17 (3-25) mm long. The point at which the FDS branch reached the ECRB branch [corrected] was 48 (23-65) mm distal to the epicondyle line and approximately 23 (18-27) mm radial to the midline of the forearm. The distance between the point at which the FDS and ECRB branches met and the point at which the ECRB branch entered the muscle was 27 (17-40) mm. The mean axon numbers were FCR, 1501 (932-3022); PIN, 5162 (4325-7732); FDS, 885 (558-962); and ECRB, 548 (433-723).

CONCLUSIONS

The FCR branch could be transferred to the PIN [corrected] and the FDS to the ECRB branch in all limbs without tension.

CLINICAL RELEVANCE

We provide anatomical and histological information for median-to-radial nerve transfer.

Principles of nerve repair in complex wounds of the upper extremity

Peripheral nerve injuries are common in the setting of complex upper extremity trauma. Early identification of nerve injuries and intervention is critical for maximizing return of function. In this review, the principles of nerve injury, patient evaluation, and surgical management are discussed. An evidence-based approach to nerve reconstruction is reviewed, including the benefits and limitations of direct repair and nerve gap reconstruction with the use of autografts, processed nerve allografts, and conduits. Further, the principles and indications of commonly used nerve transfers in proximal nerve injuries are also addressed.

The clinical practice of reconstructive neurosurgery

Surgical interventions to improve function following nervous system injury have been in development since the early 1900s. Only recently these have been assimilated into a coherent approach which can be applied to injuries of the brain, spinal cord and peripheral nerves. In addition to pharmacological and stimulation based interventions, surgical manipulation of the peripheral nerves and muscles of the extremity can offer functional enhancement for a variety of limb impairments. In order to plan an effective surgical intervention, neurophysiological assessment of the injury and residual motor control is essential. Effective implementation of these surgical interventions can enhance function and quality of life for many individuals whose activity has been limited as a result of nervous system injury.

Nerve transfers in tetraplegia I: Background and technique

BACKGROUND

The recovery of hand function is consistently rated as the highest priority for persons with tetraplegia. Recovering even partial arm and hand function can have an enormous impact on independence and quality of life of an individual. Currently, tendon transfers are the accepted modality for improving hand function. In this procedure, the distal end of a functional muscle is cut and reattached at the insertion site of a nonfunctional muscle. The tendon transfer sacrifices the function at a lesser location to provide function at a more important location. Nerve transfers are conceptually similar to tendon transfers and involve cutting and connecting a healthy but less critical nerve to a more important but paralyzed nerve to restore its function.

METHODS

We present a case of a 28-year-old patient with a C5-level ASIA B (international classification level 1) injury who underwent nerve transfers to restore arm and hand function. Intact peripheral innervation was confirmed in the paralyzed muscle groups corresponding to finger flexors and extensors, wrist flexors and extensors, and triceps bilaterally. Volitional control and good strength were present in the biceps and brachialis muscles, the deltoid, and the trapezius. The patient underwent nerve transfers to restore finger flexion and extension, wrist flexion and extension, and elbow extension. Intraoperative motor-evoked potentials and direct nerve stimulation were used to identify donor and recipient nerve branches.

RESULTS

The patient tolerated the procedure well, with a preserved function in both elbow flexion and shoulder abduction.

CONCLUSIONS

Nerve transfers are a technically feasible means of restoring the upper extremity function in tetraplegia in cases that may not be amenable to tendon transfers.

Nerve transfer to the triceps after brachial plexus injury: report of four cases

These case reports review the clinical outcomes of 4 patients who underwent nerve transfer to a triceps motor branch of the radial nerve. Mean follow-up was 26 ± 15 months. Two patients had a transfer using an ulnar nerve fascicle to the flexor carpi ulnaris muscle, yielding a motor recovery of grade M5 elbow extension strength in one case and M4+ in the other. In 1 patient, a thoracodorsal nerve branch was used as the donor; this patient recovered M4 strength. One patient had a transfer using a radial nerve fascicle to the extensor carpi radialis longus muscle and recovered M5 strength. These outcomes indicate that expendable fascicles of the ulnar, thoracodorsal, and radial nerves are viable donors in the surgical reconstruction of elbow extension.

Clinical outcomes following median to radial nerve transfers

PURPOSE

To evaluate the clinical outcomes in patients with radial nerve palsy who underwent nerve transfers using redundant fascicles of median nerve (innervating the flexor digitorum superficialis and flexor carpi radialis muscles) to the posterior interosseous nerve and the nerve to the extensor carpi radialis brevis.

METHODS

This was a retrospective review of the clinical records of 19 patients with radial nerve injuries who underwent nerve transfer procedures using the median nerve as a donor nerve. All patients were evaluated using the Medical Research Council (MRC) grading system. The mean age of patients was 41 years (range, 17-78 y). All patients received at least 12 months of follow-up (range, 20.3 ± 5.8 mo). Surgery was performed at a mean of 5.7 ± 1.9 months postinjury.

RESULTS

Postoperative functional evaluation was graded according to the following scale: grades MRC 0/5 to MRC 2/5 were considered poor outcomes, whereas an MRC grade of 3/5 was a fair result, 4/5 was a good result, and 4+/5 was an excellent outcome. Postoperatively, all patients except one had good to excellent recovery of wrist extension. A total of 12 patients recovered good to excellent finger and thumb extension, 2 had fair recovery, and 5 had poor recovery.

CONCLUSIONS

The radial nerve is commonly injured, causing severe morbidity in affected patients. The median nerve provides a reliable source of donor nerve fascicles for radial nerve reinnervation. The important nuances of both surgical technique and motor reeducation critical for the success of this transfer have been identified and are discussed.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.