Direct radial to ulnar nerve transfer to restore intrinsic muscle function in combined proximal median and ulnar nerve injury: case report and surgical technique

Three Useful Tips and Tricks for Intraoperative Nerve Stimulation

Disposable handheld nerve stimulators are widely used in peripheral nerve surgery. Such devices stimulate a motor nerve or the motor component of a mixed nerve by applying electrical current to the proximal region, targeting the main nerve trunk. This stimulation then travels along the motor nerve, reaching the distal end to control the corresponding muscle(s). In this study, the authors demonstrate three useful tips and tricks for handheld nerve stimulation during targeted muscle reinnervation and peripheral nerve surgery. The three tips are (1) identification of proximal muscle contraction by retrograde electrical stimulation of a distal sensory nerve; (2) graded stimulation for identifying motor nerves within fibrotic scarred tissue beds or parallel to the major motor/mixed nerve of interest; and (3) proximal stimulation for validation of adequate post-targeted muscle reinnervation coaptation(s).

Bilateral Ulnar Nerve Injury in the Wrist: Comparison of First Webspace Muscle Reconstruction by Opponens Nerve Transfer in the Right Hand Versus Direct Ulnar Nerve Repair in the Left Hand

We report a case of a bilateral glass injury to the wrist with transection of flexor tendons and the ulnar nerve and artery in a 60-year-old male patient. Two days after his accident, we repaired all divided structures, and on the right hand, we added the transfer of the opponens motor branch to the deep terminal division of the ulnar nerve aimed at first dorsal interosseous and adductor pollicis muscle reinnervation. After surgery, the patient was followed over 24 months. Postoperative dynamometry of the hand, which included grasping, key-pinch, subterminal-key-pinch, pinch-to-zoom, and first dorsal interosseous muscle strength, indicated recovery only in the nerve transfer side.

Nerve transfers in tetraplegia: a review and practical guide

INTRODUCTION

Spinal cord injury (SCI) may lead to tetraplegia. Several nerve transfers have been successfully used for the restoration of the upper limb in tetraplegia. Reconstruction of an upper limb is individualized based on the functional level. In this study, the authors reviewed nerve transfers based on the injury level for the restoration of upper limb function in tetraplegia.

EVIDENCE ACQUISITION

We performed this study to review nerve transfers in tetraplegia by searching MEDLINE and EMBASE databases to identify relevant articles published through December 2020. We selected studies that reported cases in tetraplegia and extracted information on demographic data, clinical characteristics, operative details, and strength outcomes based on each injury level after surgery.

EVIDENCE SYNTHESIS

Total of 29 journal articles reporting on 275 nerve transfers in 172 upper limbs of 121 patients were included in the review. The mean time between SCI and nerve transfer surgery was 21.37 months (range: 4-156 months), and the follow-up time was 21.34 months (range: 3-38 months). The best outcomes were achieved for the restoration of wrist/finger extension and elbow extension.

CONCLUSIONS

Nerve transfer can provide a new function in tetraplegic patients' upper limbs to improve daily living activities. The type of surgical procedure should be performed based on the functional level of SCI and the individual's needs. Functional recovery occurs more in extensor muscles than flexors. Nerve transfer is a promising option in the reconstruction of upper limb function in tetraplegia.

Surgery for nerve injury: current and future perspectives

In this review article, the authors offer their perspective on nerve surgery for nerve injury, with a focus on recent evolution of management and the current surgical management. The authors provide a brief historical perspective to lay the foundations of the modern understanding of clinical nerve injury and its evolving management, especially over the last century. The shift from evaluation of the nerve injury using macroscopic techniques of exploration and external neurolysis to microscopic interrogation, interfascicular dissection, and internal neurolysis along with the use of intraoperative electrophysiology were important advances of the past 50 years. By the late 20th century, the advent and popularization of interfascicular nerve grafting techniques heralded a major advance in nerve reconstruction and allowed good outcomes to be achieved in a large percentage of nerve injury repair cases. In the past 2 decades, there has been a paradigm shift in surgical nerve repair, wherein surgeons are not only directing the repair at the injury zone, but also are deliberately performing distal-targeted nerve transfers as a preferred alternative in an attempt to restore function. The peripheral rewiring approach allows the surgeon to convert a very proximal injury with long regeneration distances and (often) uncertain outcomes to a distal injury and repair with a greater potential of regenerative success and functional recovery. Nerve transfers, originally performed as a salvage procedure for severe brachial plexus avulsion injuries, are now routinely done for various less severe brachial plexus injuries and many other proximal nerve injuries, with reliably good to even excellent results. The outcomes from nerve transfers for select clinical nerve injury are emphasized in this review. Extension of the rewiring paradigm with nerve transfers for CNS lesions such as spinal cord injury and stroke are showing great potential and promise. Cortical reeducation is required for success, and an emerging field of rehabilitation and restorative neurosciences is evident, which couples a nerve transfer procedure to robotically controlled limbs and mind-machine interfacing. The future for peripheral nerve repair has never been more exciting.

Peripheral nerve intersectional repair by bi-directional induction and systematic remodelling: biodegradable conduit tubulization from basic research to clinical application

In terms of the clinical effect of peripheral nerve injury repair, the biological degradable conduit 2 mm small gap tubulization is far better than the traditional epineurial or perineurium neurorrhaphy. The assumption of the bi-directional induction between the central system and the terminal effector during peripheral nerve regeneration is purposed and proved in clinical by our group. The surgical approach of transferring a portion of or the whole contralateral C7 nerve to repair a part of or the whole ipsilateral brachial plexus injury is clinically promoted, in which the most important idea and practice is to use the cone conduit designed by the group to repair thick nerves with fine nerves. Some of the patients suffering from cerebral palsy or cerebral haemorrhage and those who got cerebral infarction yet have not reached recovery after 3-6 months could regain some functions of the ipsilateral upper limb and improve the life quality by transfer of a portion of or the whole contralateral C7 nerve and connection by cone conduit.

Transfer of the extensor indicis proprius branch of posterior interosseous nerve to reconstruct ulnar nerve and median nerve injured proximally: an anatomical study

Proximal or middle lesions of the ulnar or median nerves are responsible for extensive loss of hand motor function. This occurs even when the most meticulous microsurgical techniques or nerve grafts are used. Previous studies had proposed that nerve transfer was more effective than nerve grafting for nerve repair. Our hypothesis is that transfer of the posterior interosseous nerve, which contains mainly motor fibers, to the ulnar or median nerve can innervate the intrinsic muscles of hands. The present study sought to investigate the feasibility of reconstruction of the deep branch of the ulnar nerve and the thenar branch of median nerve by transferring the extensor indicis proprius branch of the posterior interosseous nerve obtained from adult cadavers. The results suggested that the extensor indicis proprius branch of the posterior interosseous nerve had approximately similar diameters and number of fascicles and myelinated nerve fibers to those of the deep branch of ulnar nerve and the thenar branch of the median nerve. These confirm the feasibility of extensor indicis proprius branch of posterior interosseous nerve transfer for reconstruction of the deep branch of the ulnar nerve and the thenar branch of median nerve. This procedure could be a novel and effective method for the functional recovery of the intrinsic muscles of hands after ulnar nerve or median nerve injury.

Brain injury in combination with tacrolimus promotes the regeneration of injured peripheral nerves

Both brain injury and tacrolimus have been reported to promote the regeneration of injured peripheral nerves. In this study, before transection of rat sciatic nerve, moderate brain contusion was (or was not) induced. After sciatic nerve injury, tacrolimus, an immunosuppressant, was (or was not) intraperitoneally administered. At 4, 8 and 12 weeks after surgery, Masson's trichrome, hematoxylin-eosin, and toluidine blue staining results revealed that brain injury or tacrolimus alone or their combination alleviated gastrocnemius muscle atrophy and sciatic nerve fiber impairment on the experimental side, simultaneously improved sciatic nerve function, and increased gastrocnemius muscle wet weight on the experimental side. At 8 and 12 weeks after surgery, brain injury induction and/or tacrolimus treatment increased action potential amplitude in the sciatic nerve trunk. Horseradish peroxidase retrograde tracing revealed that the number of horseradish peroxidase-positive neurons in the anterior horn of the spinal cord was greatly increased. Brain injury in combination with tacrolimus exhibited better effects on repair of injured peripheral nerves than brain injury or tacrolimus alone. This result suggests that brain injury in combination with tacrolimus promotes repair of peripheral nerve injury.

Supinator to ulnar nerve transfer via in situ anterior interosseous nerve bridge to restore intrinsic muscle function in combined proximal median and ulnar nerve injury: a novel cadaveric study

BACKGROUND

In cases of high ulnar nerve palsy, result of nerve repair in term of intrinsic muscle recovery is unsatisfactory. Distal nerve transfer can diminish the regeneration time and improve the results. But, there was no perfect distal nerve transfer for restoring intrinsic hand function in combined proximal median and ulnar nerve injuries. This cadaveric study aims to evaluate the possibility and feasibility of supinator nerve transfer to motor branch of ulnar nerve (MUN).

METHODS

Ten cadaveric upper limbs dissected to identify the location of the supinator branch, anterior interosseous nerve (AIN), and MUN. The AIN was cut from its origin and transferred to the supinator branches. Also, the AIN was distally cut and transferred to the MUN. After nerve coaptation, surface area, fascicle count, and axon number were determined by histologic methods.

RESULTS

In all limbs, the proximal and distal stumps of AIN reached the supinator branch and the MUN without tension, respectively. The mean of axon number in the supinator, proximal stump of AIN, distal stump of AIN and MUN branches were 32,426, 45,542, 25,288, and 35,426, respectively.

CONCLUSIONS

This study showed that transfer of the supinator branches to the MUN is possible via the in situ AIN bridge. The axon count data showed a favorable match between the supinator branches, AIN, and MUN. Therefore, it is suggested that this technique can be useful for patients with combined high median and ulnar nerve injuries.

Peripheral Nerve Injury: Stem Cell Therapy and Peripheral Nerve Transfer

Peripheral nerve injury can lead to great morbidity in those afflicted, ranging from sensory loss, motor loss, chronic pain, or a combination of deficits. Over time, research has investigated neuronal molecular mechanisms implicated in nerve damage, classified nerve injury, and developed surgical techniques for treatment. Despite these advancements, full functional recovery remains less than ideal. In this review, we discuss historical aspects of peripheral nerve injury and introduce nerve transfer as a therapeutic option, as well as an adjunct therapy to transplantation of Schwann cells and their stem cell derivatives for repair of the damaged nerve. This review furthermore, will provide an elaborated discussion on the sources of Schwann cells, including sites to harvest their progenitor and stem cell lines. This reflects the accessibility to an additional, concurrent treatment approach with nerve transfers that, predicated on related research, may increase the efficacy of the current approach. We then discuss the experimental and clinical investigations of both Schwann cells and nerve transfer that are underway. Lastly, we provide the necessary consideration that these two lines of therapeutic approaches should not be exclusive, but conversely, should be pursued as a combined modality given their mutual role in peripheral nerve regeneration.

Free Functional Muscle Transfers to Restore Upper Extremity Function

Free functional muscle transfer provides an option for functional restoration when nerve reconstruction and tendon transfers are not feasible. To ensure a successful outcome, many factors need to be optimized, including proper patient selection, timing of intervention, donor muscle and motor nerve selection, optimal microneurovascular technique and tension setting, proper postoperative management, and appropriate rehabilitation. Functional outcomes of various applications to the upper extremity and the authors' algorithm for the use of free functional muscle transfer are also included in this article.

High Ulnar Nerve Injuries: Nerve Transfers to Restore Function

Peripheral nerve injuries are challenging problems. Nerve transfers are one of many options available to surgeons caring for these patients, although they do not replace tendon transfers, nerve graft, or primary repair in all patients. Distal nerve transfers for the treatment of high ulnar nerve injuries allow for a shorter reinnervation period and improved ulnar intrinsic recovery, which are critical to function of the hand.

Motor Nerve Transfers

Brachial plexus and peripheral nerve injuries are exceedingly common. Traditional nerve grafting reconstruction strategies and techniques have not changed significantly over the last 3 decades. Increased experience and wider adoption of nerve transfers as part of the reconstructive strategy have resulted in a marked improvement in clinical outcomes. We review the options, outcomes, and indications for nerve transfers to treat brachial plexus and upper- and lower-extremity peripheral nerve injuries, and we explore the increasing use of nerve transfers for facial nerve and spinal cord injuries. Each section provides an overview of donor and recipient options for nerve transfer and of the relevant anatomy specific to the desired function.

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.