End-to-side neurorrhaphy

Treatment of Complete Brachial Plexus Injuries Using Double Free Muscle Transfer

PURPOSE

The purpose of this study was to examine the surgical outcomes of double free muscle transfer (DFMT) performed in patients with complete brachial plexus injury (BPI).

METHODS

We retrospectively analyzed the outcomes of DFMT for 12 patients with complete BPI who were followed up for more than 2 years after the final muscle transplantation. Their mean age was 29 years (range, 18-41). Three patients underwent contralateral C7 nerve root transfer before the DFMT. The range of motion (ROM) of the shoulder, elbow, and fingers was measured. Patient-reported outcome measures, including Disability of the Shoulder, Arm, and Hand (DASH) scores and visual analog scale (VAS) scores for pain, were also examined.

RESULTS

The mean shoulder ROM against gravity was 22° ± 8° in abduction and 33° ± 5° in flexion. Seven patients underwent phrenic nerve (PhN) transfer to the suprascapular nerves, and five exhibited asymptomatic lung impairment on spirography more than 2 years after PhN transfer. The mean elbow ROM against gravity was 111° ± 9° in flexion and -32° ± 7° in extension. All patients obtained elbow flexion >90° against a 0.5-kg weight. All patients obtained touch sensation and two recognized warm and cold sensations in the affected palm. The mean total active motion of the affected fingers was 44° ± 11°. All patients exhibited hook function of the hands. The mean preoperative and postoperative DASH scores were 70.3 ± 13.4 and 51.8 ± 15.9, respectively. The mean pain VAS score was 28 ± 31 at the final follow-up.

CONCLUSIONS

Double free muscle transfer provided patients with complete brachial plexus palsy with good elbow flexion and hand hook functions.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Advances in Biomimetic Nerve Guidance Conduits for Peripheral Nerve Regeneration

Injuries to the peripheral nervous system are a common clinical issue, causing dysfunctions of the motor and sensory systems. Surgical interventions such as nerve autografting are necessary to repair damaged nerves. Even with autografting, i.e., the gold standard, malfunctioning and mismatches between the injured and donor nerves often lead to unwanted failure. Thus, there is an urgent need for a new intervention in clinical practice to achieve full functional recovery. Nerve guidance conduits (NGCs), providing physicochemical cues to guide neural regeneration, have great potential for the clinical regeneration of peripheral nerves. Typically, NGCs are tubular structures with various configurations to create a microenvironment that induces the oriented and accelerated growth of axons and promotes neuron cell migration and tissue maturation within the injured tissue. Once the native neural environment is better understood, ideal NGCs should maximally recapitulate those key physiological attributes for better neural regeneration. Indeed, NGC design has evolved from solely physical guidance to biochemical stimulation. NGC fabrication requires fundamental considerations of distinct nerve structures, the associated extracellular compositions (extracellular matrices, growth factors, and cytokines), cellular components, and advanced fabrication technologies that can mimic the structure and morphology of native extracellular matrices. Thus, this review mainly summarizes the recent advances in the state-of-the-art NGCs in terms of biomaterial innovations, structural design, and advanced fabrication technologies and provides an in-depth discussion of cellular responses (adhesion, spreading, and alignment) to such biomimetic cues for neural regeneration and repair.

End-to-side neurorrhaphy in peripheral nerves: Does it work?

Acute peripheral nerve injuries are common and can cause physical disabilities with sensory and functional sequelae; they therefore require surgery. The aim of this study was to conduct a systematic review to assess the clinical applicability of end-to-side neurorrhaphy in peripheral nerve reconstruction, based on available evidence. We carried out a systematic review of the literature using MEDLINE/PubMed, EMBASE, Cochrane Library, Web of Science, Scielo and Scopus through March 16, 2021. Most of the selected studies were qualitative and employed nonrandomized groups of patients, without standardized scales for assessing outcomes, which made statistical analysis difficult. Efficacy varied from 24% to 81%. Factors for better outcome included the type of injury, type of injured nerve (sensory, motor or mixed), presence of an epineural window, topography, injury extension <1.3 cm, and intervention within 2 weeks of injury. Clinical studies so far lack scientific evidence on end-to-side neurorrhaphy in peripheral nerve lesions.

Stem cells in end-to-side neurorrhaphy. Experimental study in rats

Purpose:

To evaluate the influence of mesenchymal stem cells from adipose tissue in the end-to-side neurorrhaphy, focusing in the nerve regeneration and the muscle reinnervation in acute trauma.

Methods:

140 animals were randomly divided in seven groups: control, denervated, end-to-side neurorrhaphy between distal stump of common peroneal nerve and tibial nerve (ESN), ESN wrapped in fascia, ESN wrapped in fascia and platelet gel, ESN wrapped in platelet gel, ESN wrapped in fascia and platelet gel within stem cells (without culture) removed from the adipose tissue. Mass measurements of the animal and of cranial tibial muscles, electromyography, walking track analysis tests and histological examinations of the nerves and muscles after 180 days was performed.

Results:

In the groups where the ESN was performed, the results were always better when compared to the denervated group, showing reinnervation in all ESN groups. The most sensitive methods were walking track and histological analysis. Only the group with stem cells showed values similar to the control group, as well as the functional indices of peroneal nerve and the number of nerve fibers in the peroneal nerve.

Conclusions:

Stem cells were effective in ESN according with the functional index of the peroneal nerve, evaluated by walking track analysis and the number of nerve fibers in the peroneal nerve.

Partial Recovery of Limb Function Following End-to-Side Screw Anastomosis of Phrenic Nerve in Rats with Brachial Plexus Injury

Background

Brachial plexus injury (BPI), a severe nervous system injury, is a leading cause of functional damages of the affected upper limb. Patients with BPI manifested with motor weakness or paralysis, sensory deficits, and pain. We established a BPI rat model to explore the in vivo effect of end-to-side screw anastomosis (ETSSA) of phrenic nerve on the recovery of limb function after BPI.

Material/Methods

After modeling, rats were treated with end-to-side anastomosis (ETSA) and ETSSA respectively. After 1 and 3 months, the behavioral changes of rats were observed using the Terzis grooming test, and the compound muscle action potential (CMAP) and muscle tension of biceps brachii were detected. The muscle weight recovery rate (MWRR) and cross-sectional area recovery rate (CARR) were calculated. Toluidine blue staining was used to observe the myelinated nerve fibers in the proximal phrenic nerve and distal musculocutaneous nerve of suture. The ratio of regenerated nerve traversing rate (NTR) was counted and motor endplate area of biceps brachii was measured.

Results

The rats treated with ETSA and ETSSA exhibited elevated grading of Terzis grooming test with time. Although both the ETSSA and ETSA can reduce the MWRR, CARR and motor endplate area in BPI rats, ETSSA showed a better influence on the latency delayed rate (LDR) and amplitude recovery rate (ARR) of CMAP, muscular tension recovery rate (MTRR), MWRR, number of regenerated myelinated nerve fibers, NTR, and motor endplate area in BPI rats.

Conclusions

Our study provided evidence that ETSSA can restore the limb function recovery to a greater extent, and accelerate the regeneration of nerve fibers in rats with BPI; the effect of ETSSA was better than that of ETSA.

Clinical Experience with End-to-Side Nerve Transfer

A retrospective study was undertaken to determine the effectiveness of end-to-side nerve transfer. Twenty patients with peripheral nerve lesions of varying aetiology underwent 23 end-to-side nerve transfers over a 15-month period. The mean patient age was 30 years and 18 were male. The mean delay in presentation was 2.4 months. All underwent end-to-side nerve repairs and were reviewed in outpatients at regular intervals. Ten patients were lost to follow-up before 12 months and were therefore excluded from the study. The remaining ten patients, who had undergone 13 end-to-side procedures, had a mean follow-up period of 16 months. None demonstrated objective evidence of motor recovery at the end of the study period. Four patients had modest recovery of deep protective sensation, and two patients suffered a subtle degree of ”donor“ nerve morbidity. We have abandoned this technique in our centre in preference for standard nerve grafting techniques.

Nerve Regeneration: Understanding Biology and Its Influence on Return of Function After Nerve Transfers

Poor functional outcomes are frequent after peripheral nerve injuries despite the regenerative support of Schwann cells. Motoneurons and, to a lesser extent, sensory neurons survive the injuries but outgrowth of axons across the injury site is slow. The neuronal regenerative capacity and the support of regenerating axons by the chronically denervated Schwann cells progressively declines with time and distance of the injury from the denervated targets. Strategies, including brief low-frequency electrical stimulation that accelerates target reinnervation and functional recovery, and the insertion of cross-bridges between a donor nerve and a recipient denervated nerve stump, are effective in promoting functional outcomes after complete and incomplete injuries.

Epineurial Window Is More Efficient in Attracting Axons than Simple Coaptation in a Sutureless (Cyanoacrylate-Bound) Model of End-to-Side Nerve Repair in the Rat Upper Limb: Functional and Morphometric Evidences and Review of the Literature

End-to-side nerve coaptation brings regenerating axons from the donor to the recipient nerve. Several techniques have been used to perform coaptation: microsurgical sutures with and without opening a window into the epi(peri)neurial connective tissue; among these, window techniques have been proven more effective in inducing axonal regeneration. The authors developed a sutureless model of end-to-side coaptation in the rat upper limb. In 19 adult Wistar rats, the median and the ulnar nerves of the left arm were approached from the axillary region, the median nerve transected and the proximal stump sutured to the pectoral muscle to prevent regeneration. Animals were then randomly divided in two experimental groups (7 animals each, 5 animals acting as control): Group 1: the distal stump of the transected median nerve was fixed to the ulnar nerve by applying cyanoacrylate solution; Group 2: a small epineurial window was opened into the epineurium of the ulnar nerve, caring to avoid damage to the nerve fibres; the distal stump of the transected median nerve was then fixed to the ulnar nerve by applying cyanoacrylate solution. The grasping test for functional evaluation was repeated every 10-11 weeks starting from week-15, up to the sacrifice (week 36). At week 36, the animals were sacrificed and the regenerated nerves harvested and processed for morphological investigations (high-resolution light microscopy as well as stereological and morphometrical analysis). This study shows that a) cyanoacrylate in end-to-side coaptation produces scarless axon regeneration without toxic effects; b) axonal regeneration and myelination occur even without opening an epineurial window, but c) the window is related to a larger number of regenerating fibres, especially myelinated and mature, and better functional outcomes.

Proceedings of the first workshop on Peripheral Machine Interfaces: going beyond traditional surface electromyography

One of the hottest topics in rehabilitation robotics is that of proper control of prosthetic devices. Despite decades of research, the state of the art is dramatically behind the expectations. To shed light on this issue, in June, 2013 the first international workshop on Present and future of non-invasive peripheral nervous system (PNS)-Machine Interfaces (MI; PMI) was convened, hosted by the International Conference on Rehabilitation Robotics. The keyword PMI has been selected to denote human-machine interfaces targeted at the limb-deficient, mainly upper-limb amputees, dealing with signals gathered from the PNS in a non-invasive way, that is, from the surface of the residuum. The workshop was intended to provide an overview of the state of the art and future perspectives of such interfaces; this paper represents is a collection of opinions expressed by each and every researcher/group involved in it.

Studying axonal degeneration and regeneration using in vitro and in vivo models: the translational potential

ABSTRACT: 

Since the initial studies by Cajal, multiple models of peripheral nerve degeneration and regeneration have been developed to address the ever-increasing complexity of the mechanisms involved in regeneration. In vitro models offer the principal benefit of a system that can be readily manipulated to address specific mechanistic questions in a deconstructed system. However, in vitro models can be overly simplified and intricacies of the interactions between neurons and glia can be lost. In vivo animal models seek to remedy some of these shortcomings, but most in vivo animal systems fail to precisely model human nerve regeneration. Rodent models of chronic nerve regeneration have been developed to better recapitulate human nerve regeneration, but are not widely used. An important development in the field has been the establishment of experimental nerve regeneration in humans, involving the reinnervation of the epidermis after cutaneous axotomy or topical capsaicin application. Use of such human models will likely accelerate the development and evaluation of new drugs that enhance peripheral nerve regeneration.

End-to-Side Interposed Donor Grafting as a Facial Nerve Reinforcement Technique after Vestibular Schwannoma Surgery

Objectives:

This retrospective case review was performed to determine the facial function outcome of an end-to-side interposed donor grafting technique in patients who had a nonresponsive and partially injured facial nerve during a translabyrinthine approach for vestibular schwannoma resection.

Methods:

The study included patients with silent electrophysiological tests after partial injury of the facial nerve during translabyrinthine schwannoma resection surgery in a tertiary referral hospital. The patients underwent end-to-side interposed donor grafting as a facial nerve reinforcement technique, and we evaluated their facial function after 1 year of follow-up.

Results:

Four cases with intact preoperative facial function were included (3 men and 1 woman). All patients had a lack of electrical response from the facial nerve and partial anatomic injury after a translabyrinthine approach. An end-to-side interposed donor grafting technique was performed. The donor grafts used were the sural nerve (2 patients), superior vestibular nerve (1 patient), and greater auricular nerve (1 patient). All patients achieved a good House-Brackmann grade. Ocular adjuvant procedures were performed in all patients.

Conclusions:

Immediate repair of the facial nerve with an interposed donor graft may provide better facial function in patients who have no electrical response from a partially injured facial nerve after vestibular schwannoma surgery.

Re-innervation of the bladder through end-to-side neurorrhaphy of autonomic nerve and somatic nerve in rats

End-to-side neurorrhaphy is widely used in the peripheral nervous system for nerve repair; however, the application of this technique has been limited to somatic nerves. The feasibility of nerve regeneration through end-to-side neurorrhaphy between autonomic and somatic nerves with different characteristics in the peripheral nervous system is still undetermined. In this study, rats were divided into three groups for different treatments (n=10 per group). In the end-to-side neurorrhaphy group, left L6 and S1 were transected in the dura, and the distal stump of L6 ventral root was sutured to the lateral face of L4 ventral root through end-to-side coaptation. In the no repair group, the rats did not undergo neurorrhaphy. In the control group, the left L6 dorsal root and S1 roots were transected, respectively, but the L6 ventral root was kept intact. After 16 weeks, the origin and mechanism of nerve regeneration was evaluated by retrograde double labeling technique as well as histological examination and intravesical pressure measurement. Retrograde double labeling indicated that the reconstructed reflex pathway was successfully established and the primary regeneration mechanism involved axon collateral sprouting. Morphological examination and intravesical pressure measurement indicated prominent nerve regeneration and successful re-innervation of the bladder in the neurorrhaphy group, compared with the "no repair" group (p<0.05). No significant changes were observed in the histology of the donor nerve and the bilateral extensor digitorum longus muscles in the neurorrhaphy group. Nerve regeneration may be achievable for nerve repair through end-to-side neurorrhaphy between autonomic and somatic nerves without apparent impairment of donor somatic nerve.

Avaliação histológica da neurorrafia término-lateral: estudo experimental em ratos

OBJETIVO: Realizar estudo histológico comparando o crescimento axonal após neurorrafia término-lateral com e sem epineurectomia. MÉTODOS: foram utilizados vinte ratos Wistar, machos, divididos em dois grupos de 10 ratos cada. Um segmento de 1,0cm do nervo tibial e, foi transposto para o lado contralateral, sendo suturado no nervo ciático D. No grupo I, a sutura foi realizada diretamente no epineuro, enquanto que no grupo II foi realizado epineurectomia. Após 4 semanas foi realizado avaliação histológica do segmento transposto e no nervo ciático D, no sitio distal à lesão. RESULTADOS: demonstrou-se baixa quantidade de fibras remielinizadas, variando de 7 a 51 fibras no Grupo I e de 10 a 91 fibras no Grupo II. Utilizou-se o teste U de Mann-Whitney, com p=0,31, demonstrando que não há diferença estatisticamente significante entre os dois grupos. Não há relação positiva entre o número de fibras remielinizadas no enxerto e no sitio distal à lesão do ciático. CONCLUSÃO: A neurorrafia término-lateral, com e sem janela epineural, não promove remielinização eficiente. Nivel de evidência: Nível II: Estudo prospectivo comparativo

A successful neurotization of two different muscles using a single intact motor nerve: experimental study on rats

The development of microsurgical techniques and better understanding of nerve biology has resulted in significant improvement in the results of nerve repair. Some problems are still present. What would be the method of choice if 2 transected nerves were to be coapted and only one neighboring intact nerve was available? We performed neurotization of 2 different muscles by a single intact nerve, using only one nerve graft by reverse end-to-side coaptation that has already been introduced into the literature. We assessed the results histomorphologically and functionally. Twenty-four adult rats were used in the present study and equally divided into 4 groups. Group 1 (n = 6): Control group; Group 2 (n = 6): Unrepaired nerve damage group; Group 3 (n = 6): End-to-end repair group. The peroneal branch of the sciatic nerve was excised to obtain an approximate size of 2 cm-graft, which was subsequently divided into 2 equal pieces to obtain 2 pieces of grafts each 1 cm long. Then, the tibial branch of the sciatic nerve was also cut to produce a nerve defect. End-to-end coaptation was obtained. A “V” shape was obtained. Group 4 (n = 6): Reverse end-to-side repair group. The peroneal branch of the sciatic nerve was excised as a graft approximately 2-cm in length. Subsequently a defect was produced by cutting the tibial branch of the sciatic nerve. Coaptation was performed by suturing the dissected proximal end of the tibial nerve by reverse end-to-side coaptation. A “U” shape resembling a horse shoe was obtained. The success of Group 4 was demonstrated when both peek-to-peek and latency timing of extensor digitorum and gastrocnemius muscles, determined as the target organ, were evaluated. Besides, an equal distribution was observed in Group 4 when number of myelinated (P = 0.596) and unmyelinated (P = 0.936) axons in both legs of grafts were compared with each other. However, myelinated axons were not equally distributed between the legs of the nerve graft in Group 3 (P = 0.027). In conclusion, reverse end-to-side coaptation is a useful technique for 2 different muscle neurotization via a single nerve graft and a single nerve coaptation with a donor nerve.

Functional recovery following an end to side neurorrhaphy of the accessory nerve to the suprascapular nerve: case report

The use of end-to-side neurrorhaphy remains a controversial topic in peripheral nerve surgery. The authors report the long-term functional outcome following a modified end-to-side motor reinnervation using the spinal accessory to innervate the suprascapular nerve following a C5 to C6 avulsion injury. Additionally, functional outcomes of an end-to-end neurotization of the triceps branch to the axillary nerve and double fascicular transfer of the ulnar and medial nerve to the biceps and brachialis are presented. Excellent functional recoveries are found in respect to shoulder abduction and flexion and elbow flexion.

ELECTRONIC SUPPLEMENTARY MATERIAL

The online version of this article (doi:10.1007/s11552-009-9242-3) contains supplementary material, which is available to authorized users.

Novel model for end-neuroma formation in the amputated rabbit forelimb

BACKGROUND

The forelimb amputee poses many reconstructive challenges in the clinical setting, and there is a paucity of established surgical models for study. To further elucidate the pathogenic process in amputation neuroma formation, we created a reproducible, well-tolerated rabbit forelimb amputation model.

METHODS

Upon approval from the Institutional Animal Care and Use Committee, 5 New Zealand White rabbits underwent left forelimb amputation. During this initial surgery, the median, radial and ulnar nerves were transected 1.6-2.5 (mean 2.0) cm distal to the brachial plexus, transposed onto the anterior chest wall and preserved at length. Six weeks subsequent to the amputation, the distal 5 mm of each neuroma was excised, and the remaining stump underwent histomorphometric analysis.

RESULTS

The nerve cross sectional areas increased by factors of 1.99, 3.17, and 2.59 in the median (p = 0.077), radial (p < 0.0001) and the ulnar (p = 0.0026) nerves, respectively. At the axonal level, the number and cross-sectional area of myelinated fibers demonstrated an inverse relationship whereby the number of myelinated fibers in the median, radial and ulnar nerves increased by factors of 5.13 (p = 0.0043), 5.25 (p = 0.0056) and 5.59 (p = 0.0027), and the cross-sectional areas of these myelinated fibers decreased by factors of 4.62 (p < 0.001), 3.51 (p < 0.01), and 4.29 (p = 0.0259), respectively.

CONCLUSION

Given that the surgical model appears well-tolerated by the rabbits and that patterns of morphologic change are consistent and reproducible, we are encouraged to further investigate the utility of this model in the pathogenesis of neuroma formation.

Termino-lateral nerve suture in lesions of the digital nerves: clinical experience and literature review

Documented experience of treatment of digital nerve lesions with the termino-lateral (end-to-side) nerve suture is limited. Our clinical experience of this technique is detailed here alongside a systematic review of the previous literature. We performed, from 2002 to 2008, seven termino-lateral sutures with epineural window opening for digital nerve lesions. Functional outcome was analysed using the two-point discrimination test and the Semmes-Weinstein monofilament test. The results showed a sensory recovery of S3+ in six cases and S3 in one case. The mean distance found in the two-point discrimination test was 12.7 mm (range 8-18 mm). After a review of the literature, we were able to obtain homogeneous data from 17 additional patients operated by termino-lateral coaptation. The overall number of cases included in our review was 24. A sensory recovery was observed in 23 out of 24 patients. The functional results were S0 in one case, S3 in one case, S3+ in twenty cases and S4 in two cases. Excluding the one unfavourable case, the mean distance in the two-point discrimination test was 9.7 mm (range 3-18 mm). It can thus be concluded that the treatment of digital nerve lesions with termino-lateral suture showed encouraging results. Based on the results obtained in this current study we believe that in case of loss of substance, end-to-side nerve coaptation may be an alternative to biological and synthetic tubulisation when a digital nerve reconstruction by means of nerve autograft is declined by the patient.

End-to-side nerve suture in traumatic injuries of brachial plexus: review of the literature and personal case series

We used end-to-side nerve coaptation combined with standard end-to-end neurotisations to treat 11 patients who presented with complete (six cases) or incomplete (five cases) traumatic brachial plexus injuries. All patients were available for functional evaluation at a minimum of 2 years postoperatively. In three patients with shoulder abduction recovery, electromyographical studies (EMG) showed a contribution from the end-to-side neurotisation. In the remaining cases end-to-side neurotisations were unsuccessful. Our study did not demonstrate a reliable role for end-to-side nerve suture in brachial plexus surgery. We believe that at present end-to-side suture must not be a substitute for standard reconstructive techniques in brachial plexus surgery. Occasionally termino-lateral nerve sutures may represent a support to standard reconstructive procedures especially in case of severe injuries when few undamaged donor nerves are available.

Can end-to-side neurorrhaphy bridge large defects? An experimental study in rats

This study was undertaken to evaluate collateral sprouting capability in an end-to-side repair model with long regenerative distance. Forty-five rats were used and divided into four groups, according to the reparative procedure following peroneal nerve division: (A) "double" end-to-side neurorrhaphy with a regenerative distance of 0.6 cm; (B) "double" end-to-side neurorrhaphy with a regenerative distance of 1.2 cm; (C) end-to-end neurorrhaphy; and (D) nerve stumps buried into neighboring muscles. In all animals the contralateral healthy side served as a control. Functional assessment of nerve regeneration was performed at intervals up to 5 months using the Peroneal Function Index (PFI). Evaluation 150 days after surgery included peroneal and tibial nerve histologic and morphometric examination and wet weights of the tibialis anterior muscle. Functional evaluation and axonal counting data demonstrated that there was no statistically significant difference between groups A and B, or between groups A and C. There was no functional or histologic evidence of donor nerve deterioration. In conclusion, the present study confirms that "double" end-to-side neurorrhaphy may be useful for the repair of divided human nerves with long gaps.

Functional recovery and mechanisms in end-to-side nerve repair in rats

BACKGROUND

End-to-side nerve repair is attachment of a single distal nerve segment (recipient nerve) end-to-side to an intact donor nerve when there is a lack of proximal nerve segment after injury. The technique is currently used clinically but the mechanism(s) behind this technique are essentially unknown.

METHODS

We have studied end-to-side nerve repair in the forelimb of rats, where a single distal radial nerve or an ulnar or a median, or both, nerves are attached end-to-side to an intact musculocutaneous nerve. We have studied functional recovery, origin of the regenerating axons and cell activation by the end-to-side nerve repair.

FINDINGS

Functional recovery occurs after end-to-side nerve repair but is less sufficient than conventional end-to-end nerve repair or a nerve graft procedure. Sensory and motor axons grow from the musculocutaneous nerve out into the attached nerve segment(s). An injury is required to the musculocutaneous nerve to activate sensory and motor neurons as well as Schwann cells in the musculocutaneous nerve for initiation of regeneration.

CONCLUSIONS

End-to-side nerve repair may be an alternative method in specific cases of complex nerve injuries to reconstruct nerve trunks when no other repair options are possible. Some functional recovery does occur but regeneration of sensory and motor axons require an injury to the neurons of the donor nerve.

Achilles tendon reconstruction after electrical injury with a neurotized cross-leg fillet flap

The authors present a case where a cross-leg fillet flap from an amputated limb allowed reconstruction of the contralateral disrupted Achilles tendon and provided neurotized soft tissue. Achilles tendon reconstruction of the left leg was achieved by utilizing vascularized extensor tendons from the dorsum of the right foot based on the dorsalis pedis circulation. Neurotization was accomplished end to side between a cutaneous nerve from the dorsum of the foot and the recipient sural nerve. Healing was complete and without complication. Cross-leg flaps including tendon and nerve may be used to reconstruct complex lower-extremity injuries, even when free flaps are not feasible.

Quantitative Characterization of Regenerating Axons after End-to-Side and End-to-End Coaptation in a Rat Brachial Plexus Model: A Retrograde Tracer Study

The efficacy of end-to-side repair as a method of nerve reconstruction has been questioned, and most studies that characterize the mode of re-innervation are marred by inappropriate experimental design and lack quantitative analysis. This makes characterization of re-innervating neurons confusing and consequently controversy remains as to the extent and source of reinnervating axons. In an experimental brachial plexus rat model, we transected the musculocutaneous nerve, labeled its neuron pool with Fast-Blue and joined the distal stump to the side of the intact ulnar nerve, or to the proximal stump of the divided ulnar nerve, to characterize neurons that reinnervate the recipient nerve. Tetramethyl-rhodamine dextran (TMRD) or fluoro-gold was used to map the reinnervating motor and sensory neurons at 12 weeks post-transection. No neurons originally labeled from musculocutaneous nerve were subsequently labeled with TMRD or fluoro-gold, showing that this original neuron pool does not contribute to re-innervation of the distal musculocutaneous nerve, but that reinnervation occurs solely by ulnar nerve motor and sensory axons. In the end-to-side group, 16.4% of the motor and 7% of the sensory donor ulnar nerve neurons re-innervated the musculocutaneous nerve exclusively, and a further 10% motor and 11.6% sensory innervated the musculocutaneous nerve by collateral sprouting of their axons. This compared to re-innervation by 62.6% of motor and 70.4% of ulnar nerve sensory neurons in the positive control that underwent end-to-end repair. Our results confirm the concept of collateral sprouting and support the use of end-to-side repair.

Origin and history of end-to-side neurorrhaphy

This historical note offers a perspective concerning the origin of the employment of end-to-side (termino-lateral) anastomosis for nerve repair and summarizes the works that have been published on this surgical technique through the first part of the 20th Century. While the origin of end-to-side neurorrhaphy is usually dated to the beginning of the 20th Century, some works referring to this technique were published earlier, the first of which dates as far back as 1873. A number of interesting clinical and experimental studies have been carried out on end-to-side nerve anastomosis during the first years of the twentieth century. However, this literature is not easily detectable through current online scientific databases. In this paper we will give an overview of these early works. This history contributes interesting information to the debate surrounding this surgical concept and adds perspective to the use of a technique that has attracted a great deal of attention over the last 15 years.

Using an end-to-side interposed sural nerve graft for facial nerve reinforcement after vestibular schwannoma resection

✓ Increasing rates of facial and cochlear nerve preservation after vestibular schwannoma surgery have been achieved in the last 30 years. However, the management of a partially or completely damaged facial nerve remains an important issue. In such a case, several immediate or delayed repair techniques have been used.

On the basis of recent studies of successful end-to-side neurorrhaphy, the authors applied this technique in a patient with an anatomically preserved but partially injured facial nerve during vestibular schwannoma surgery. The authors interposed a sural nerve graft to reinforce the facial nerve whose partial anatomical continuity had been preserved. On follow-up examinations 18 months after surgery, satisfactory cosmetic results for facial nerve function were observed.

The end-to-side interposed nerve graft appears to be a reasonable alternative in cases of partial facial nerve injury, and might be a future therapeutic option for other cranial nerve injuries.

End-to-side (terminolateral) nerve regeneration: a challenge for neuroscientists coming from an intriguing nerve repair concept

The last 15 years have seen a growing interest regarding a technique for nerve repair named end-to-side (terminolateral) neurorrhaphy. This technique is based on the concept that nerve fiber regeneration along the distal stump of a transected nerve, the proximal stump of which was lost, can be obtained by just suturing the proximal end of its distal stump to the epinerium of a neighbor healthy and undamaged donor nerve. A large body of experimental studies have shown that end-to-side neurorrhaphy, in fact, is able to induce collateral sprouting from donor nerve's axons which is at the basis of the massive repopulation of the distal nerve stump. The regenerating nerve fibers eventually reinnervate the periphery of the severed nerve leading to a recovery of the lost function the degree of which varies depending on factors that still have to be elucidated. Surprisingly, this puzzling concept of nerve regeneration has attracted very little attention from basic neuroscientists so far and, thus, the present paper is intended to call for more biological research on it by overviewing the relevant literature and indicating the several unanswered questions that this concept asks to the neuroscience community.

Influence of Aging on Regeneration in End-to-Side Neurorrhaphy

Aging profoundly affects the structural and functional characteristics of the peripheral nervous system. Although several experiments have investigated the effect of aging on nerve regeneration after crush and transection nerve injuries, little is known about the influence of age on end-to-side nerve repairs. It was hypothesized that decreased terminal and collateral sprouting in older animals would be associated with less robust regeneration through end-to-side nerve repairs. In this study, 27 Lewis rats underwent end-to-side repair at ages 2 weeks, 3 months, or 1 year. Histomorphometric assessments at 12 weeks demonstrated increased fiber width, percent neural tissue, and neural density in animals undergoing nerve reconstruction at the age of 2 weeks (P < 0.05). A trend toward further decline in regeneration was noted at ages 1 year versus 3 months. After end-to-side nerve repair, younger animals exhibit a more robust regenerative response, consistent with prior experience in other nerve injury models.

Repair of brachial plexus lesions by end-to-side side-to-side grafting neurorrhaphy: experience based on 11 cases

Eleven brachial plexus lesions were repaired using end-to-side side-to-side grafting neurorrhaphy in root ruptures, in phrenic and spinal accessory nerve neurotizations, in contralateral C7 neurotization, and in neurotization using intact interplexus roots or cords. The main aim was to approximate donor and recipient nerves and promote regeneration through them. Another indication was to augment the recipient nerve, when it had been neurotized or grafted to donors of dubious integrity, when it was not completely denervated, when it had been neurotized to a nerve with a suboptimal number of fibers, when it had been neurotized to distant donors delaying its regeneration, and when it had been neurotized to a donor supplying many recipients. In interplexus neurotization, the main indication was to preserve the integrity of the interplexus donors, as they were not sacrificeable. The principles of end-to-side neurorrhaphy were followed. The epineurium was removed. Axonal sprouting was induced by longitudinally slitting and partially transecting the donor and recipient nerves, by increasing the contact area between both of them and the nerve grafts, and by embedding the grafts into the split predegenerated injured nerve segments. Agonistic donors were used for root ruptures and for phrenic and spinal accessory neurotization, but not for contralateral C7 or interplexus neurotization. Single-donor single-recipient neurotization was successfully followed in phrenic neurotization of the suprascapular (3 cases) and axillary (1 case) nerves, spinal accessory neurotization of the suprascapular nerve (1 case), and dorsal part of contralateral C7 neurotization of the axillary nerve (2 cases). Apart from this, recipient augmentation necessitated many donor to single-recipient neurotizations. This was successfully performed using phrenic-interplexus root to suprascapular transfers (2 cases), phrenic-contralateral C7 to suprascapular transfer (1 case), and spinal accessory-interplexus root to musculocutaneous transfer (1 case). Both recipient augmentation and increasing the contact area between grafts and recipients necessitated single or multiple donor to many recipient neurotizations. This was applied in root ruptures (3 cases), with results comparable to those obtained in classical nerve-grafting techniques. It was also applied in ventral C7 transfer to the lateral or medial cords (3 cases) with functional recovery occurring in the biceps and pronator teres muscles, but not in dorsal C7 transfer to the axillary and radial nerves (3 cases) with functional recovery occurring in the deltoid and triceps muscles, and in whole C7 transfer to C5, 6, 7, 8T1 roots with functional recovery occurring in the deltoid (M4), biceps (M4), pronator teres (M4), and triceps (M3) (3 cases), and less so in the flexor carpi ulnaris and FDP (M3) (1 case) and the extensor digitorum longus (M3) (1 case). Contralateral C7 transfer to the lateral and posterior cords (4 cases) was followed by cocontractions that took 1 year to improve and that involved the rotator cuff, deltoid, biceps, and pronator teres (all agonists). Functional recovery in the triceps muscle was less than in the above muscles. Contralateral C7 transfer to C5-7 (1 case) was followed by cocontractions that took 1 year to resolve and that occurred between the deltoid, biceps, and flexor digitorum profundus. Interplexus root neurotization was done only in conjunction with other neurotization techniques, and so its role is difficult to judge. Though the same applies to regenerated lateral cord transfer to the posterior cord (2 cases), the successful results obtained from medial cord neurotization to the axillary, musculocutaneous, and radial nerves (1 case), and from ulnar and median nerve neurotization to the radial nerve (1 case), show that neurotization at the interplexus cord level may play a role in brachial plexus regeneration and may even be used to neurotize nerves and muscles distal to the elbow. The timing of repair was within 6 months after injury, except for 2 cases. In the first case, contralateral C7 transfer was successfully performed more than 1 year after injury. The second case was an obstetric palsy operated upon at age 8. Deterioration in motor power of the donor muscles that improved in 6 months was observed in 2 cases of interplexus neurotization at the cord level, because of looping the sural nerve grafts tightly around the donor nerves. Deterioration in donor-muscle motor power as a consequence of end-to-side neurorrhaphy was noted in the obstetric palsy case, when the flexor carpi radialis (donor) became grade 3 instead of grade 4. This was associated with cocontractions between it and the extensors. It took nearly 1 year to improve.

End-to-side neurorrhaphy for defects of palmar sensory digital nerves

Ten traumatic nerve defects at the palm or digit level were treated by end-to-side (ETS) neurorrhaphy. The technique included removal of an epineurial window on the donor nerve and coaptation of the sharply cut distal end of the injured nerve by epineurial stitches under microscopic magnification. At final follow-up, the static two-point discrimination test (2 pd) scored at an average of 9.1 mm (range, 6-12 mm) on the repaired nerve, compared to an average of 4.6 mm (range, 4-6 mm) on the contralateral uninjured control side. Moving 2 pd scored at an average of 7 mm (range, 4-9 mm) on the repaired nerve compared to an average of 2.6 mm (range, 2-4 mm) on the control side. This short series showed that ETS neurorrhaphies are effective and give comparable results with those of nerve grafts or vein conduits.

End-to-side nerve repair in the upper extremity of rat

The end-to-side nerve-repair technique, i.e., when the distal end of an injured nerve is attached end-to-side to an intact nerve trunk in an attempt to attract nerve fibers by collateral sprouting, has been used clinically. The technique has, however, been questioned. The aim of the present study was to investigate end-to-side repair in the upper extremity of rats with emphasis on functional recovery, source, type, and extent of regenerating fibers. End-to-side repair was used in the upper limb, and the radial or both median/ulnar nerves were attached end-to-side to the musculocutaneous nerve. Pawprints and tetanic muscle force were used to evaluate functional recovery during a 6-month recovery period, and double retrograde labeling was used to detect the source of the regenerated nerve fibers. The pawprints showed that, in end-to-side repair of either one or two recipient nerves, there was a recovery of toe spreading to 60-72% of the preoperative value (lowest value around 47%). Electrical stimulation of the end-to-side attached radial or median/ulnar nerves 6 months after repair resulted in contraction of muscles in the forearm innervated by these nerves (median tetanic muscle force up to 70% of the contralateral side). Retrograde labeling showed that both myelinated (morphometry) sensory and motor axons were recruited to the end-to-side attached nerve and that these axons emerged from the motor and sensory neuronal pool of the brachial plexus. Double retrograde labeling indicated that collateral sprouting was one mechanism by which regeneration occurred. We also found that two recipient nerves could be supported from a single donor nerve. Our results suggest that end-to-side repair may be one alternative to reconstruct a brachial plexus injury when no proximal nerve end is available.

Two applications of end-to-side nerve neurorrhaphy in severe upper-extremity nerve injuries

End-to-side and side-to-side techniques (what we call alternative nerve repair techniques) have been investigated in detail in both experimental and clinical studies. There have not been any large series, but only some case reports describing either successful or disappointing functional results in the recent literature. Two cases presented here were of two extreme examples of nerve injuries that had no chance for direct repair; alternative choices were performed. One was a side-to-side neurorrhaphy between the ulnar and median nerves, and the other was an end-to-side nerve repair of the median and radial nerves to the ulnar nerve. Both patients regained their diminished protective sensation and returned to their occupations. Based on these results and our review of the current literature, we consider alternative nerve repair techniques to be reasonable, prudent, and scientific choices for the treatment of some challenging nerve injury cases.

End-to-side nerve grafting of the tibial nerve to bridge a neuroma-in-continuity

Standard treatment for a neuroma-in-continuity with partial retained function is neurolysis with or without grafting. The present study tests the outcome of a novel partial nerve lesion bypassed with an end-to-side bridge graft, intended to increase the number of axons crossing the defect while not disturbing intact axons. An 8-mm portion of tibial nerve was resected in 20 rats. Three weeks later, half had the defect repaired with an end-to-side bridge allograft and perineurial windows; controls had only neurolysis. Recovery was evaluated using walking-track analysis, allodynia testing, muscle weight ratios, and histology at 8 weeks. No significant differences in motor or sensory functional recovery were noted between the two groups. Histology showed good axonal regeneration through the defect in all specimens. The experimental group also had regenerated axons in the bridge graft, but their maturity was less advanced, presumably due to delays in regeneration.

Low-power laser biostimulation enhances nerve repair after end-to-side neurorrhaphy: a double-blind randomized study in the rat median nerve model

Previous studies have shown that low-power laser biostimulation (lasertherapy) promotes posttraumatic nerve regeneration. The objective of the present study was to investigate the effects of postoperative lasertherapy on nerve regeneration after end-to-side neurorrhaphy, an innovative technique for peripheral nerve repair. After complete transection, the left median nerve was repaired by end-to-side neurorrhaphy on the ulnar "donor" nerve. The animals were then divided into four groups: one placebo group, and three laser-treated groups that received lasertherapy three times a week for 3 weeks starting from postoperative day 1. Three different types of laser emission were used: continuous (808 nm), pulsed (905 nm), and a combination of the two. Functional testing was carried out every 2 weeks after surgery by means of the grasping test. At the time of withdrawal 16 weeks postoperatively, muscle mass recovery was assessed by weighing the muscles innervated by the median nerve. Finally, the repaired nerves were withdrawn, embedded in resin and analyzed by light and electron microscopy. Results showed that laser biostimulation induces: (1) a statistically significant faster recovery of the lesioned function; (2) a statistically significant faster recovery of muscle mass; (3) a statistically significant faster myelination of the regenerated nerve fibers. From comparison of the three different types of laser emissions, it turned out that the best functional outcome was obtained by means of pulsed-continuous-combined laser biostimulation. Taken together, the results of the present study confirm previous experimental data on the effectiveness of lasertherapy for the promotion of peripheral nerve regeneration and suggest that early postoperative lasertherapy should be considered as a very promising physiotherapeutic tool for rehabilitation after end-to-side neurorrhaphy.

Collateral sprouting occurs following end-to-side neurorrhaphy

Recent evidence supports the use of end-to-side neurorrhaphy for the treatment of certain peripheral nerve disorders. However, the mechanism by which nerves regenerate following this procedure is still unclear. To address this question, the authors designed a new end-to-side coaptation model in rats in which the donor nerves were uninjured. The regenerated axons at the coaptation site were observed directly using fluorescent dye as the neural tracer. The sciatic nerve from adult Wistar rats was transplanted between the left and right median nerves. Fifteen rats were divided into three groups. In group I, the donor (right median) nerve was sutured end to side to the divided grafted nerve using a noninjury technique. In group II, the aponeurosis of the spinal muscles was harvested and the sciatic and right median nerves were coapted end to side noninjuriously by wrapping them in the excised aponeurosis. In group III, a perineurial window was created and a partial neurectomy was carried out at the suture site, after which the sciatic and right median nerves were sutured end to side. Sixty days after the operation, nerve regeneration was evaluated by recording action potentials in the grafted nerve, by performing electromyography in the flexor muscles in the forearm, and by histological examination. The grafted nerves were fixed and sectioned, the number of regenerated nerve fibers was counted, and axonal diameters were measured. Fluorescent dye crystal was used, in conjunction with confocal microscopy, to observe the regenerated axons at the co-aptation site. The results showed that nerve regeneration had occurred in the animals, as determined electrophysiologically and histologically. Both the right and left flexor muscles of the forearm contracted simultaneously as a result of indirect electric stimulation of the grafted nerve, which suggests that the regenerated nerve was physiologically connected with the donor nerve. Nerve fiber counts did not show any differences among groups (p > 0.05), but axonal diameters were significantly greater in group III than in the other two groups. Fluorescent dye staining revealed the presence of regenerated nerve fibers beyond the coaptation site. In group III, the regenerating nerves were observed within the whole section of the coaptation site and collateral sprouting was found to occur even at a site distal to the suture. From these results, the authors conclude that in end-to-side neurorrhaphy, nerve regeneration occurs by collateral sprouting from the donor nerve.

Effect of Perineurial Window Size on Nerve Regeneration, Blood–Nerve Barrier Integrity, and Functional Recovery

End-to-side neurorrhaphy is used clinically to reconstruct nerve injuries when the lack of a suitable proximal nerve stump precludes conventional approaches to microsurgical repair. In end-to-side neurorrhaphy, the distal stump of a transected nerve is sutured to the side of an intact nerve that serves as an axon donor. Prior studies suggest that this perineurial window is a prerequisite for effective nerve regeneration into the recipient nerve. However, the optimal size for this perineurial window remains uncertain. This study evaluated the effect of perineurial window size on collateral axonal sprouting, blood-nerve barrier architecture, and functional impairment of the donor nerve. One hundred twenty Lewis rats were randomized to 1 and 5 mm perineurial window groups and examined at serial time points. The 5 mm perineurial window group exhibited significantly greater fiber counts at the repair zone than the 1mm group within 4 weeks (p < 0.005). Marked breakdown of the blood-nerve barrier was present 2 week postoperatively and resolved by 4 weeks regardless of 1 versus 5 mm perineurial window size. Tibial function indices in both groups normalized between 4 and 6 weeks postoperatively. A large (5 mm) perineurial window induced greater collateral sprouting or regenerative response than a small (1 mm) perineurial window without increasing cross sectional nerve injury or delaying functional recovery.