Selective Contralateral C7 Transfer in Posttraumatic Brachial Plexus Injuries: A Report of 56 Cases:

Direct Repair of Ruptured Nerve Stump to Middle Trunk for Restoration of Extrinsic Finger Extension in Total Brachial Plexus Injuries

BACKGROUND

Attempts to restore independent hand function in total brachial plexus injuries (TBPIs) have often failed due to inconsistent results of finger extension reconstruction. An innovative technique is described to achieve this effect by direct neurorrhaphy of residual (ruptured) roots with the middle trunk.

METHODS

Direct coaptation of the ruptured roots to the middle trunk and, simultaneously, transferring the anterior division of the middle trunk to the posterior division of the lower trunk was performed in 64 patients with TBPI. The return of extension of the elbow, wrist, and fingers was monitored.

RESULTS

Excellent and good muscle strength of finger extension were noted in 45.3% of cases. The patients were divided into group A (>32 years) and group B (≤32 years) according to receiver operating characteristic curve analysis. The difference of excellent and good rates of finger and wrist extension muscle strengths between the 2 groups was statistically significant (χ 2 = 4.635, P = 0.031; χ 2 = 6.615, P = 0.010).

CONCLUSIONS

Direct neurorrhaphy of ruptured nerve root stumps with the middle trunk could achieve satisfactory results for finger extension in TBPI for patients ≤32 years old. Long nerve defects (4 to 6.5 cm) could be overcome by freeing the nerve and adducting the arm against the trunk.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Risk, III.

Effect of repeated sciatic nerve crush on the conditioning lesion response: Generating an experimental animal model to prolong the denervation period while maintaining peripheral nerve continuity

Peripheral nerves exhibit long-term residual motor dysfunction following injury. The length of the denervation period before nerve and muscle reconnection is an important factor in motor function recovery. We aimed to investigate whether repeated nerve crush injuries to the same site every 7 days would preserve the conditioning lesion (CL) response and to determine the number of nerve crush injuries required to create an experimental animal model that would prolong the denervation period while maintaining peripheral nerve continuity. Rats were grouped according to the number of sciatic nerve crushes. A significant decrease in the soleus muscle fiber cross-sectional area was observed with increased crushes. After a single crush, macrophage accumulation and macrophage chemotaxis factor CCL2 expression in dorsal root ganglia were markedly increased, which aligned with the gene expression of Ccl2 and its receptor Ccr2. Macrophage numbers, histological CCL2 expression, and Ccl2 and Ccr2 gene expression levels decreased, depending on the number of repeated crushes. Histological analysis and gene expression analysis in the group with four repeated crushes did not differ significantly when compared with uninjured animals. Our findings indicated that repeated nerve crushes at the same site every 7 days sustained innervation loss and caused a loss of the CL response. The experimental model did not require nerve stump suturing and is useful for exploring factors causing prolonged denervation-induced motor dysfunction. SIGNIFICANCE STATEMENT: This study elucidates the effects of repeated nerve crush injury to the same site on innervation and conditioning lesion responses and demonstrates the utility of an experimental animal model that recapitulates the persistent residual motor deficits owing to prolonged denervation without requiring nerve transection and transection suturing.

Trends and insights review. Nerve procedures in the management of upper limb spasticity

This article reviews the recent advances or nerve-oriented surgical procedures in the treatment of the spastic upper limb. The idea to intervene on the nerve is not recent, but new trends have developed in nerve surgery over the past few years, stimulating experiments and research. Specific surgical procedures involving the nerves have been described at different levels from proximal to distal: at the cervical spinal cord and the dorsal root entry zone (rhizotomy), at the level of the roots (contralateral C7 transfer) or in the peripheral nerve, within the motor trunk (selective neurectomy) or as its branches penetrate the muscles (hyperselective neurectomy). All of these neurosurgical procedures are only effective on spasticity but do not address the other deformities, such as contractures and motor deficit. Additional procedures may have to be planned in conjunction with nerve procedures to optimize outcomes.

Peripheral nerve transfers for dysfunctions in central nervous system injuries: a systematic review

BACKGROUND

The review highlights recent advancements and innovative uses of nerve transfer surgery in treating dysfunctions caused by central nervous system (CNS) injuries, with a particular focus on spinal cord injury (SCI), stroke, traumatic brain injury, and cerebral palsy.

METHODS

A comprehensive literature search was conducted regarding nerve transfer for restoring sensorimotor functions and bladder control following injuries of spinal cord and brain, across PubMed and Web of Science from January 1920 to May 2023. Two independent reviewers undertook article selection, data extraction, and risk of bias assessment with several appraisal tools, including the Cochrane Risk of Bias Tool, the JBI Critical Appraisal Checklist, and SYRCLE's ROB tool. The study protocol has been registered and reported following PRISMA and AMSTAR guidelines.

RESULTS

Nine hundred six articles were retrieved, of which 35 studies were included (20 on SCI and 15 on brain injury), with 371 participants included in the surgery group and 192 in the control group. These articles were mostly low-risk, with methodological concerns in study types, highlighting the complexity and diversity. For SCI, the strength of target muscle increased by 3.13 of Medical Research Council grade, and the residual urine volume reduced by more than 100 ml in 15 of 20 patients. For unilateral brain injury, the Fugl-Myer motor assessment (FMA) improved 15.14-26 score in upper extremity compared to 2.35-26 in the control group. The overall reduction in Modified Ashworth score was 0.76-2 compared to 0-1 in the control group. Range of motion (ROM) increased 18.4-80° in elbow, 20.4-110° in wrist and 18.8-130° in forearm, while ROM changed -4.03°-20° in elbow, -2.08°-10° in wrist, -2.26°-20° in forearm in the control group. The improvement of FMA in lower extremity was 9 score compared to the presurgery.

CONCLUSION

Nerve transfer generally improves sensorimotor functions in paralyzed limbs and bladder control following CNS injury. The technique effectively creates a 'bypass' for signals and facilitates functional recovery by leveraging neural plasticity. It suggested a future of surgery, neurorehabilitation and robotic-assistants converge to improve outcomes for CNS.

Surgical reconstructions for adult brachial plexus injuries. Part II: Treatments for total arm type

Brachial plexus injuries (BPI) contribute not only to physical dysfunction but also to socioeconomic aspects and psychological disability. Patients with total arm-type BPI will lose not only the shoulder and elbow function but also the hand function, making reconstruction particularly challenging. Reconstructive procedures commonly include nerve repair, grafting, neurotization (nerve transfer), tendon transfer and free functional muscle transfer (FFMT). Although it is difficult to achieve prehensile hand function, most of patients with total arm-type BPI can be treated with satisfied outcomes. In addition to surgical techniques, comprehensive rehabilitation is another important factor for successful outcomes, and efficient communication can help to boost patient morale and eliminate uncertainty.

[Contralateral C7 Nerve Transfer]

Complex brachial plexus injuries with multiple or complete root avulsions make intraplexic reconstruction impossible in some cases. Such cases necessitate the use of extraplexic nerve donors such as the spinal accessory nerve or intercostal nerves. The contralateral C7 root represents a donor with a high axon count and can be used as an axon source in such cases. We summarise current indications, surgical technique and functional results after a contralateral C7 transfer in cases of brachial plexus injury, describing some of our own cases and including a selective literature review.

Prespinal Versus Conventional Hemicontralateral C7 Nerve Transfer in the Treatment of Total Brachial Plexus Roots Avulsion Injuries: A Retrospective Study With a Minimum Follow-Up Period of 4 Years

PURPOSE

Contralateral C7 (CC7)-to-median nerve transfer has been commonly used to restore hand function in brachial plexus injury. To shorten the nerve graft, the prespinal route was described and achieved direct coaptation when combined with humeral shortening osteotomy. The limb was positioned at 0° shoulder abduction and neutral head position. Given our concern about donor-site morbidity when harvesting the whole CC7 nerve and tension across the neurorrhaphy site after mobilization, we aimed to describe our modified prespinal route and compare its outcomes and complications with the conventional hemi-CC7 transfer.

METHODS

From 2004 to 2014, 39 patients with preganglionic total brachial plexus root avulsion injuries, with a minimum of 4 years of follow-up, were included. Overall, 20 and 19 patients underwent the conventional hemi-CC7-to-median nerve and hemi-CC7-to-lower trunk (LT) transfer through the modified prespinal route, respectively. The modified prespinal route was combined with bilateral clavicle shortening osteotomy to achieve direct coaptation to the LT at 45° shoulder abduction.

RESULTS

The modified prespinal route showed the median period to achieve ≥M3 hand grip assessed in clinical follow-up was shorter (26.5 months vs 45.5 months), and a higher proportion of patients achieved ≥M3 hand grip recovery (63% vs 30%). One patient experienced symptomatic phrenic nerve injury; however, the hemidiaphragm fully recovered after 6 months. The long-term donor-site complication rate was 2.6%, including one sensory abnormality, and no permanent donor-site weakness after hemi-CC7 harvesting was observed.

CONCLUSIONS

The modified prespinal route combined with clavicle osteotomy allowed direct coaptation to the LT and did not require head immobilization. It may allow a higher proportion of patients to achieve ≥M3 hand grip more quickly than conventional hemi-CC7 transfer.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Restoration of intrinsic hand function by superficial radial nerve: an anatomical study

BACKGROUND

The contralateral seventh cervical (cC7) nerve root transfer represents a cornerstone technique in treating total brachial plexus avulsion injury. Traditional cC7 procedures employ the entire ulnar nerve as a graft, which inevitably compromises its restorative capacity.

OBJECTIVE

Our cadaveric study seeks to assess this innovative approach aimed at preserving the motor branch of the ulnar nerve (MBUN). This new method aims to enable future repair stages, using the superficial radial nerve (SRN) as a bridge connecting cC7 and MBUN.

METHODS

We undertook a comprehensive dissection of ten adult cadavers, generously provided by the Department of Anatomy, Histology, and Embryology at Fudan University, China. It allowed us to evaluate the feasibility of our proposed technique. For this study, we harvested only the dorsal and superficial branches of the ulnar nerve, as well as the SRN, to establish connections between the cC7 nerve and recipient nerves (both the median nerve and MBUN). We meticulously dissected the SRN and the motor and sensory branches of the ulnar nerve. Measurements were made from the reverse point of the SRN to the wrist flexion crease and the coaptation point of the SRN and MBUN. Additionally, we traced the MBUN from distal to proximal ends, recording its maximum length. We also measured the diameters of the nerve branches and tallied the number of axons.

RESULTS

Our modified approach proved technically viable in all examined limbs. The distances from the reverse point of the SRN to the wrist flexion crease were 8.24 ± 1.80 cm and to the coaptation point were 6.60 ± 1.75 cm. The maximum length of the MBUN was 7.62 ± 1.03 cm. The average axon diameters in the MBUN and the anterior and posterior branches of the SRN were 1.88 ± 0.42 mm、1.56 ± 0.38 mm、2.02 ± 0.41 mm,respectively. The corresponding mean numbers of axons were 1426.60 ± 331.39 and 721.50 ± 138.22, and 741.90 ± 171.34, respectively.

CONCLUSION

The SRN demonstrated the potential to be transferred to the MBUN without necessitating a nerve graft. A potential advantage of this modification is preserving the MBUN's recovery potential.

Restoration of Grasp after Single-Stage Free Functioning Gracilis Muscle Transfer in Traumatic Adult Pan-Brachial Plexus Injury

BACKGROUND

A variety of approaches have been described to obtain rudimentary grasp after traumatic pan-brachial plexus injury in adults. The aim of this study is to evaluate hand prehension after a gracilis single-stage free functioning muscle transfer.

METHODS

Twenty-seven patients who underwent gracilis single-stage free functioning muscle transfer for elbow flexion and hand prehension after a pan-plexus injury were included. All patients presented with a minimum of 2 years of follow-up. Postoperative finger flexion, elbow flexion strength, preoperative and postoperative Disability of the Arm, Shoulder, and Hand questionnaire scores, secondary hand procedures, complications, and demographic characteristics were analyzed.

RESULTS

Twenty patients (74%) demonstrated active finger pull-through. Only six patients (25%) considered their hand function useful for daily activities. Disability of the Arm, Shoulder, and Hand score improved by 13.1 ± 13.7 ( P < 0.005). All patients were expected to require one secondary procedure (wrist fusion, thumb carpometacarpal fusion, and/or thumb interphalangeal fusion) because no extensor reconstruction was performed. These were performed in 89%, 78%, and 74% of patients, respectively. Four postoperative complications (hematoma, seroma, wound dehiscence, and skin paddle loss) occurred. No flap loss occurred.

CONCLUSIONS

In pan-plexus injuries, the use of a gracilis single-stage free functioning muscle transfer is an alternative to the double free functioning muscle transfer procedure and contralateral C7 transfer, especially for patients who are unable to undergo two to three important operations in a short period of time. Further research and studies are required to improve hand function in these patients.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

Restoring After Central Nervous System Injuries: Neural Mechanisms and Translational Applications of Motor Recovery

Central nervous system (CNS) injuries, including stroke, traumatic brain injury, and spinal cord injury, are leading causes of long-term disability. It is estimated that more than half of the survivors of severe unilateral injury are unable to use the denervated limb. Previous studies have focused on neuroprotective interventions in the affected hemisphere to limit brain lesions and neurorepair measures to promote recovery. However, the ability to increase plasticity in the injured brain is restricted and difficult to improve. Therefore, over several decades, researchers have been prompted to enhance the compensation by the unaffected hemisphere. Animal experiments have revealed that regrowth of ipsilateral descending fibers from the unaffected hemisphere to denervated motor neurons plays a significant role in the restoration of motor function. In addition, several clinical treatments have been designed to restore ipsilateral motor control, including brain stimulation, nerve transfer surgery, and brain–computer interface systems. Here, we comprehensively review the neural mechanisms as well as translational applications of ipsilateral motor control upon rehabilitation after CNS injuries.

Crossing nerve transfer drives sensory input-dependent plasticity for motor recovery after brain injury

Restoring limb movements after central nervous system injury remains a substantial challenge. Recent studies proved that crossing nerve transfer surgery could rebuild physiological connectivity between the contralesional cortex and the paralyzed arm to compensate for the lost function after brain injury. However, the neural mechanism by which this surgery mediates motor recovery remains still unclear. Here, using a clinical mouse model, we showed that this surgery can restore skilled forelimb function in adult mice with unilateral cortical lesion by inducing cortical remapping and promoting corticospinal tract sprouting. After reestablishing the ipsilateral descending pathway, resecting of the artificially rebuilt peripheral nerve did not affect motor improvements. Furthermore, retaining the sensory afferent, but not the motor efferent, of the transferred nerve was sufficient for inducing brain remapping and facilitating motor restoration. Thus, our results demonstrate that surgically rebuilt sensory input triggers neural plasticity for accelerating motor recovery, which provides an approach for treating central nervous system injuries.

Research Progress of Alumina-Forming Austenitic Stainless Steels: A Review

The development of Alumina-Forming Austenitic (AFA) stainless steel is reviewed in this paper. As a new type of heat-resistant steel, AFA steel forms an alumina protective scale instead of chromia in a corrosive environment. This work summarizes the types of developed AFA steels and introduces the methods of composition design. Various precipitates appear in the microstructure that directly determine the performance at high temperatures. It was found that alloy elements and the heat treatment process have an important influence on precipitates. In addition, the corrosion resistance of AFA steel in different corrosive environments is systematically analyzed, and the beneficial or harmful effects of different elements on the formation of alumina protective scale are discussed. In this paper, the short-term mechanical properties, creep properties and influencing factors of AFA steel are also analyzed. This work aims to summarize the research status on this subject, analyze the current research results, and explore future research directions.

Effects of exercise on muscle reinnervation and plasticity of spinal circuits in rat sciatic nerve crush injury models with different numbers of crushes

INTRODUCTION/AIMS

Motor function recovery is frequently poor after peripheral nerve injury. The effect of different numbers of nerve crushes and exercise on motor function recovery is unknown. We aimed to examine how different numbers of crushes of the rat sciatic nerve affects muscle reinnervation and plasticity of spinal circuits and the effect of exercise intervention.

METHODS

Single and multiple sciatic nerve crush models with different numbers of crushes were created in rats. Treadmill exercise was performed at 10 m/min for 60 min, five times a week. Muscle reinnervation and synaptic changes in L4-5 motor neurons were examined by immunofluorescence staining. Behavioral tests were the sciatic functional index (SFI) and the pinprick tests.

RESULTS

The percentage of soleus muscle reinnervation was not significantly increased by the presence of exercise in single or multiple crushes. Exercise after a single crush increased the contact of motor neurons with VGLUT1-containing structures (Exercised vs. Unexercised, 12.9% vs. 8.7%; P < 0.01), but after multiple crushes, it decreased with or without exercise (8.1% vs. 8.6%). Exercise after a single crush significantly improved SFI values from 14 to 24 days, and exercise after multiple crushes from 21 to 35 days (all P < 0.05). The pinprick test showed no difference in recovery depending on the number of crushes or whether or not exercised.

DISCUSSION

Different numbers of sciatic nerve crushes affect muscle reinnervation and motor neuron synaptic changes differently, but motor function recovery may improve with exercise regardless of the number of crushes. This article is protected by copyright. All rights reserved.

Functional outcome of contralateral C7 nerve transfer combined with free functional gracilis transplantation to repair total brachial plexus avulsion: a report of thirty-nine cases

Purpose

Treatment of total brachial plexus avulsion (TBPA) is a challenge in the clinic, especially the restoration of hand function. The current main surgical order is from proximal to distal joints. The purpose of this study was to demonstrate the outcomes of “distal to proximal” surgical method.

Methods

Thirty-nine patients underwent contralateral C7 (CC7) nerve transfer to directly repair the lower trunk (CC7-LT) and phrenic nerve transfer to the suprascapular nerve (PN-SSN) during the first stage, followed by free functional gracilis transplantation (FFGT) for elbow flexion and finger extension. Muscle strength of upper limb, degree of shoulder abduction and elbow flexion, and Semmes–Weinstein monofilament test and static two-point discrimination of the hand were examined according to the modified British Medical Research Council (mBMRC) scoring system.

Results

The results showed that motor recovery reached a level of M3 + or greater in 66.7% of patients for shoulder abduction, 87.2% of patients for elbow flexion, 48.7% of patients for finger extension, and 25.6% of patients for finger flexion. The mean shoulder abduction angle was 45.5° (range 0–90°), and the average elbow flexion angle was 107.2° (range 0–142°), with 2.5 kg average flexion strength (range 0.5–5 kg). In addition, protective sensibility (≥ S2) was found to be achieved in 71.8% of patients.

Conclusion

In reconstruction of TBPA, CC7 transfer combined with free functional gracilis transplantation is an available treatment method. It could help patients regain shoulder joint stability and the function of elbow flexion and finger extension and, more importantly, provide finger sensation and partial finger flexion function. However, the pick-up function was unsatisfied, which needed additional surgery.

Analysis of Results of Contralateral Hemi-C7 Root Used for Restoring Hand Function in Global Birth Brachial Plexus Palsy

PURPOSE

To analyze the outcome of the use of contralateral hemi-C7 for the restoration of hand function in patients with birth brachial plexus global palsy.

METHODS

From 2004 to 2017, 19 infants with Narakas types III and IV birth brachial plexus palsy underwent transfer of contralateral hemi-C7 (posterior division of the contralateral C7 root) to the lower trunk or medial cord on the affected side. All the patients were evaluated for shoulder function using the Gilbert and Mallet scores, elbow flexion using the modified Medical Research Council score for children, and hand function using the Raimondi score. After the surgery, the children were followed-up at 3-month intervals for the first year and 6-month intervals thereafter. Hand function achieving Raimondi scores of 3-5 was considered a useful outcome.

RESULTS

The patients were followed-up for a mean duration of 88 months, with a minimum of 35 and a maximum of 192 months of follow-up. All patients attained a Gilbert score of ≥3, whereas 9 patients attained a score of ≥4. Similarly, all patients attained a minimum aggregate Mallet score of 15, and 9 patients attained a score of ≥20. All patients attained a modified Medical Research Council score of ≥3, used for assessing elbow flexion. Useful hand function was attained in 73% (14/19) of the cases (a Raimondi score of ≥3). There was no clinically recorded deficit on the donor side.

CONCLUSIONS

Contralateral hemi-C7 transfer in infants with brachial plexus root avulsions helped regain useful hand function in 73% (14/19) of the children treated.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Contralateral C7 nerve transfer in the treatment of upper-extremity paralysis: a review of anatomical basis, surgical approaches, and neurobiological mechanisms

The previous three decades have witnessed a prosperity of contralateral C7 nerve (CC7) transfer in the treatment of upper-extremity paralysis induced by both brachial plexus avulsion injury and central hemiplegia. From the initial subcutaneous route to the pre-spinal route and the newly-established post-spinal route, this surgical operation underwent a series of innovations and refinements, with the aim of shortening the regeneration distance and even achieving direct neurorrhaphy. Apart from surgical efforts for better peripheral nerve regeneration, brain involvement in functional improvements after CC7 transfer also stimulated scientific interest. This review summarizes recent advances of CC7 transfer in the treatment of upper-extremity paralysis of both peripheral and central causes, which covers the neuroanatomical basis, the evolution of surgical approach, and central mechanisms. In addition, motor cortex stimulation is discussed as a viable rehabilitation treatment in boosting functional recovery after CC7 transfer. This knowledge will be beneficial towards improving clinical effects of CC7 transfer.

Optimal Donor Nerve to Restore Elbow Flexion After Traumatic Brachial Plexus Injury: A Systematic Review and Meta-Analysis

BACKGROUND

Traumatic brachial plexus injuries (BPIs) often lead to devastating upper extremity deficits. Treatment frequently prioritizes restoring elbow flexion through transfer of various donor nerves; however, no consensus identifies optimal donor nerve sources.

OBJECTIVE

To complete a meta-analysis to assess donor nerves for restoring elbow flexion after partial and total BPI (TBPI).

METHODS

Original English language articles on nerve transfers to restore elbow flexion after BPI were included. Using a random-effects model, we calculated pooled, weighted effect size of the patients achieving a composite motor score of ≥M3, with subgroup analyses for patients achieving M4 strength and with TBPI. Meta-regression was performed to assess comparative efficacy of each donor nerve for these outcomes.

RESULTS

Comparison of the overall effect size of the 61 included articles demonstrated that intercostal nerves and phrenic nerves were statistically superior to contralateral C7 (cC7; P = .025, <.001, respectively) in achieving ≥M3 strength. After stratification by TBPI, the phrenic nerve was still superior to cC7 in achieving ≥M3 strength (P = .009). There were no statistical differences among ulnar, double fascicle, or medial pectoral nerves in achieving ≥M3 strength. Regarding M4 strength, the phrenic nerve was superior to cC7 (P = .01) in patients with TBPI and the ulnar nerve was superior to the medial pectoral nerve (P = .036) for partial BPI.

CONCLUSION

Neurotization of partial BPI or TBPI through the intercostal nerve or phrenic nerve may result in functional advantage over cC7. In patients with upper trunk injuries, neurotization using ulnar, median, or double fascicle nerve transfers has similarly excellent functional recovery.

Contralateral C7 Nerve Transfer for Stroke Recovery: New Frontier for Peripheral Nerve Surgery

Ischemic stroke remains a major cause of disability in the United States and worldwide. Following the large-scale implementation of stroke thrombectomy and the optimization of treatment protocols for acute stroke, the reduction in stroke-associated mortality has resulted in an increased proportion of stroke survivors, many of whom have moderate to severe disability. To date, the treatment of subacute and chronic stroke has remained a challenge. Several approaches, involving pharmacological interventions to promote neuroplasticity, brain stimulation strategies and rehabilitative interventions, are currently being explored at different stages of the translational spectrum, yet level 1 evidence is still limited. In a recent landmark study, surgical intervention using contralateral C7 nerve transfer, an approach used to treat brachial plexus injury, was implemented in patients with chronic stroke, demonstrating an added benefit to standard rehabilitation strategies, leading to improved motor performance and reduced spasticity. The procedure involved the transfer of the C7 nerve root and middle trunk from the uninjured extremity to the injured extremity using a short conduit that allows for faster regeneration and innervation of the injured upper extremity via the ipsilateral (contralesional) hemisphere. In this work, we review the rationale for using contralateral C7 nerve transfer in stroke, describe the surgical intervention with associated variations and limitations, and discuss the current evidence for the efficacy of this technique in ischemic stroke research.

Clinical Anatomy of Human Donor C7 Nerve Roots for Surgical Transfer in Patients with Spastic Arm Paralysis

BACKGROUND

Contralateral C7 (CC7) nerve transfer has successfully restored hand function in patients with spastic hemiplegia from chronic central nervous system injuries. However, little is known about the morphology and anatomy of the donor C7 nerve root in patients undergoing this procedure. This study quantified intraoperative measurements of donor C7 nerve roots during CC7 transfer surgery for spastic hemiplegia in patients treated at a high-volume center to describe observed anatomical variations for successful direct anastomosis.

METHODS

A database of images from 21 patients (2 females, 19 males) undergoing CC7 surgery was searched for photographic data that contained a standard ruler measuring donor C7 nerve root length after surgical sectioning and before transfer. Two independent observers analyzed these images and recorded C7 nerve root diameter, length, and branch lengths.

RESULTS

Mean (SD) values of donor C7 nerve measurements were length, 53.5 (8.0) mm; diameter, 5.1 (0.9) mm; branch length following surgical sectioning, 18.3 (6.3) mm. Right-sided donor C7 nerve roots yielded significantly longer branches compared with left-sided donor C7 nerve roots (P = 0.01). Other patient factors such as age, sex, or laterality of brain injury did not influence intraoperative anatomy.

CONCLUSIONS

We report detailed intraoperative measurements of the donor C7 root during CC7 nerve transfer for spastic hemiplegia. These findings describe existing variation in surgical C7 nerve root anatomy in patients undergoing this procedure and may serve as a general reference for the expected donor C7 length in successful direct anastomosis.

The Atr-Chek1 pathway inhibits axon regeneration in response to Piezo-dependent mechanosensation

Atr is a serine/threonine kinase, known to sense single-stranded DNA breaks and activate the DNA damage checkpoint by phosphorylating Chek1, which inhibits Cdc25, causing cell cycle arrest. This pathway has not been implicated in neuroregeneration. We show that in Drosophila sensory neurons removing Atr or Chek1, or overexpressing Cdc25 promotes regeneration, whereas Atr or Chek1 overexpression, or Cdc25 knockdown impedes regeneration. Inhibiting the Atr-associated checkpoint complex in neurons promotes regeneration and improves synapse/behavioral recovery after CNS injury. Independent of DNA damage, Atr responds to the mechanical stimulus elicited during regeneration, via the mechanosensitive ion channel Piezo and its downstream NO signaling. Sensory neuron-specific knockout of Atr in adult mice, or pharmacological inhibition of Atr-Chek1 in mammalian neurons in vitro and in flies in vivo enhances regeneration. Our findings reveal the Piezo-Atr-Chek1-Cdc25 axis as an evolutionarily conserved inhibitory mechanism for regeneration, and identify potential therapeutic targets for treating nervous system trauma.

Direct Repair of the Lower Trunk to Residual Nerve Roots for Restoration of Finger Flexion After Total Brachial Plexus Injury

PURPOSE

Residual nerve root stumps have been used to neurotize the median nerve in an attempt to restore finger flexion function in patients suffering from total brachial plexus injury. However, the results have been unsatisfactory mainly because of the need to use a long nerve graft. The authors have tried to improve the quality of restored finger flexion by direct approximation of available (ruptured) ipsilateral root stumps to the lower trunk (LT). We sought to validate these results using objective outcome measures.

METHODS

This is a study of 27 cases of total posttraumatic brachial plexus palsies. In each case, the neck was explored and ruptured root stumps identified. The LT was mobilized by separating it from the posterior division and the medial cutaneous nerve of the forearm distally. The mobilized LT was then approximated directly to an ipsilateral root stump. The arm was immobilized against the trunk for 2 months. The patients were observed for return of function in the paralyzed upper limb. The presence and strength of finger flexion was measured using the British Medical Council grading.

RESULTS

The follow-up period was 36 to 74 months (average, 56.9 ± 13.7 months). Recovery of active finger flexion was M4 in 10 patients, M3 in 8 patients, and M2 to M0 in 9 patients. Meaningful recovery (M3 or greater) of finger flexion was achieved in 18 of 27 patients.

CONCLUSIONS

The results of active finger flexion can be improved by direct approximation of the LT to an ipsilateral root stump.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Why It Is Necessary to Use the Entire Root rather than Partial Root When Doing Contralateral C7 Nerve Transfer: Cortical Plasticity Also Matters besides the Amount of Nerve Fibers

Previous studies suggested that the mode of donor transection is a critical factor affecting the efficacy of the contralateral C7 (CC7) nerve transfer. Nevertheless, the mechanism underlying this phenomenon remains elusive. The aim of this study was to investigate the relationship between the division modes of the CC7 nerve and cortical functional reorganization of Sprague-Dawley rats. We hypothesized that different methods of CC7 nerve transection might induce differences in cortical functional reorganization, thus resulting in differences in surgery efficacy. BDNF, TNF-α/IL-6, and miR-132/134 were selected as indicators of cortical functional reorganization. No significant differences in all these indicators were noted between the entire group and the entire root+posterior division group (P > 0.05). BDNF and miR-132/134 levels in the entire group and the entire root+posterior division group were significantly increased compared with their levels in the posterior group and the blank control group (P < 0.001). In all groups, BDNF, TNF-α/IL-6, and miR-132/134 levels in both hemispheres initially increased and subsequently decreased until week 40. In conclusion, this study provided the evidence of dynamic changes in BDNF, TNF-α/IL-6, and miR-132/134 in the cortex of rats after CC7 nerve transfer using different transecting modes, demonstrating that different CC7 nerve divisions might result in different surgical effects through modulation of cortical reorganization.

Transfer of the peroneal component of the sciatic nerve in total brachial plexus lesion: An anatomical feasibility study

Closed brachial plexus lesions (BPLs) are generally associated with a traumatic mechanism of forced traction between the neck and the shoulder-arm complex. For brachial plexus reconstruction different techniques have been proposed with donor motor nerves like intercostal nerves, or the ipsilateral cervical plexus, the phrenic nerve, the contralateral C7 root, and many others. Despite all these surgical possibilities, the overall recovery is generally poor and not satisfactory. The principal drawback is linked to the loss of upper limb proprioception, in a way that dramatically influences even a good motor recovery, so in complete BPLs the sensory loss still represents a debilitating problem. In this anatomical feasibility study, the possibility to transfer the peroneal component of the sciatic nerve as a donor for complete BPLs has been evaluated. This technique would conceptually bring an important motor and sensory contribution to the upper limb using pure motor and sensory branches of the sciatic nerve. Performing immediate tendon transfer for foot drop palsy could significantly decrease the morbidity of the surgical procedure.

Approach to the Pan-brachial Plexus Injury: Variation in Surgical Strategies among Surgeons

Treatment of pan-brachial plexus injuries has evolved significantly over the past 2 decades, with refinement and introduction of new surgical techniques, particularly free functional muscle transfer. The extent to which contemporary brachial plexus surgeons utilize various techniques as part of their treatment algorithm for pan-plexus injuries and the rationale underlying these choices remain largely unknown.

Methods

A case scenario was posed to 12 brachial plexus surgeons during semi-structured qualitative interviews. The case involved a young patient presenting 6 weeks after a pan-plexus injury from a motorcycle accident. Surgeons were asked to formulate a treatment plan. Inductive thematic analysis was used to identify commonalities and variation in approach to treatment.

Results

For shoulder function, the majority of surgeons would graft from a viable C5 nerve root, if possible, though the chosen target varied. Two-thirds of the surgeons would address elbow flexion with nerve transfers, though half would combine this with a free functional muscle transfer to increase elbow flexion strength. Free functional muscle transfer was the technique of choice to restore finger flexion. Finger extension, intrinsic function, and sensation were not prioritized.

Conclusions

Our study sheds light on current trends in the approach to pan-plexus injuries in the U.S. and identifies areas of variability that would benefit from future study. The optimal shoulder target and the role for grafting to the MCN for elbow flexion merit further investigation. The role of FFMT plays an increasingly prominent role in treatment algorithms.

NLRP3 inflammasome is involved in nerve recovery after sciatic nerve injury

The activation of the inflammasome plays an important role in the central nervous system. However, only a few studies have investigated the effects of inflammasome activation in the peripheral nerve, especially in the sciatic nerve, and the mechanism of this activation remains elusive. Moreover, how interleukin-1 beta (IL-1β) is produced after sciatic nerve injury is also unknown. In our study, we aimed to investigate whether the nucleotide-binding oligomerization domain-like pyrin domain containing protein 3 (NLRP3) inflammasome is activated after sciatic nerve injury and to explore its role in sciatic nerve injury. The results of immunoblotting and immunofluorescence microscopy indicate that the NLRP3 inflammasome was activated after sciatic nerve injury in wild-type (WT) mice, as demonstrated by upregulated inflammasome-related components, e.g., NLRP3, procaspase-1 and ASC. Furthermore, upregulated inflammasome-related components cis-cleavage precursor IL-1β (proIL-1β) and precursor interleukin-18 (proIL-18) to IL-1β and IL-18, contributing to the inflammatory response. Consequently, the inflammatory response after sciatic nerve injury in NLRP3 knockout (NLRP3-KO) mice was less severe than that in WT mice. Moreover, NLRP3-KO mice exhibited an increased sciatic functional index (SFI), which was determined by footprint analysis, suggesting that NLRP3 deficiency is beneficial to sciatic nerve recovery after injury. Therefore, our results indicate that NLRP3 is involved in the recovery from sciatic nerve injury and mediates the production of inflammatory factors, such as IL-1β, after sciatic nerve injury.

Intraoperative single administration of neutrophil peptide 1 accelerates the early functional recovery of peripheral nerves after crush injury

Neutrophil peptide 1 belongs to a family of peptides involved in innate immunity. Continuous intramuscular injection of neutrophil peptide 1 can promote the regeneration of peripheral nerves, but clinical application in this manner is not convenient. To this end, the effects of a single intraoperative administration of neutrophil peptide 1 on peripheral nerve regeneration were experimentally observed. A rat model of sciatic nerve crush injury was established using the clamp method. After model establishment, a normal saline group and a neutrophil peptide 1 group were injected with a single dose of normal saline or 10 μg/mL neutrophil peptide 1, respectively. A sham group, without sciatic nerve crush was also prepared as a control. Sciatic nerve function tests, neuroelectrophysiological tests, and hematoxylin-eosin staining showed that the nerve conduction velocity, sciatic functional index, and tibialis anterior muscle fiber cross-sectional area were better in the neutrophil peptide 1 group than in the normal saline group at 4 weeks after surgery. At 4 and 8 weeks after surgery, there were no differences in the wet weight of the tibialis anterior muscle between the neutrophil peptide 1 and saline groups. Histological staining of the sciatic nerve showed no significant differences in the number of myelinated nerve fibers or the axon cross-sectional area between the neutrophil peptide 1 and normal saline groups. The above data confirmed that a single dose of neutrophil peptide 1 during surgery can promote the recovery of neurological function 4 weeks after sciatic nerve injury. All the experiments were approved by the Medical Ethics Committee of Peking University People’s Hospital, China (approval No. 2015-50) on December 9, 2015.

Contralateral C7 transfer to axillary and median nerves in rats with total brachial plexus avulsion

Background

Contralateral cervical 7 nerve (cC7) was used to repair two recipient nerves simultaneously for patients with total brachial plexus avulsion (TBPA).

Objective

To evaluate the effect of cC7 transfer to axillary and median nerves in rats with TBPA.

Methods

Eighty S-D rats were divided into 4 groups randomly on average. Group A: cC7-median nerve, Group B: cC7-axillary nerve, Group C: cC7-median and axillary nerves, Group D: TBPA without repair. The evaluation tools included behavioral tests, electromyogram (EMG), measurement of cross-sectional area of muscle fiber, nerve fiber count and gene expression assay.

Results

The effective rates of EMG were 90 and 70% in Flexor Carpi Radialis (FCR) in Group A and C, while 70 and 60% in deltoid (DEL) in Group B and C, respectively. In behavioral test, the differences of effective rates between groups were not significant. The mean cross-sectional area of FCR in Group A or C was significantly larger than that in Group D. Either the number of median or axillary nerve fibers in Group A, B or C was statistically more than that in Group D. No matter for FCR or DEL, there were no significant differences in the ratios of relative expression of Muscle Atrophy F-box(MAFBOX)and Muscle RING Finger 1(MURF1)among these groups.

Conclusion

Compared with cC7 transfer to median nerve, cC7 transfer to both median and axillary nerves did not affect median nerve recovery. The deltoid muscle also could be restored. The recovery proportion of axillary nerve was less than that of median nerve.

Comparative Study of Intercostal Nerve and Contralateral C7 Nerve Transfers for Elbow Extension After Global Brachial Plexus Avulsion

INTRODUCTION

Elbow extensive reconstruction was essential for the patients with brachial plexus avulsion. Nerve transfer was applied to repair elbow extension, but the ultimate recovery was quite different. The purpose of this study was to compare the effects of elbow extension in patients with global brachial plexus avulsion after repaired by intercostal nerve (ICN) and contralateral cervical 7 (cC7) nerve transfer to the long head branch of triceps and to analyze the possible influencing factors.

MATERIALS AND METHODS

A retrospective review of 24 patients treated with ICN and cC7 nerve transfer for elbow extension in posttraumatic global brachial plexus avulsion was carried out. Two ICNs were used as donors in 17 patients, and cC7 nerve was used in the other 7 patients. We evaluated the recovery of elbow extension by the British Medical Research Council grading system and electromyography. The correlation between age, preoperative interval, and prognosis was analyzed in this study.

RESULTS

Efficiency of elbow extensor strength in the ICN transfer group was 47.06%, and it was 28.57% in the cC7 nerve transfer group, but there was no significant difference (P = 0.653). The effective recovery of electromyography in ICN transfer group was 82.35%, whereas in the group cC7 nerve transfer, it was 28.57%, there was a statistical difference between the 2 groups (P = 0.021). Age and interval were negatively correlated with prognosis.

CONCLUSIONS

Intercostal nerve or cC7 nerve transfer to the long head branch of triceps could reconstruct elbow extension to some extent. Compared with cC7 nerve transfer, ICN transfer had a greater result for elbow extension, but the difference in extension power was not significant, whereas there was difference in electromyography recovery. Patient's age and interval were negatively correlated with the results.

Contralateral C7 transfer via both ulnar nerve and medial antebrachial cutaneous nerve to repair total brachial plexus avulsion: a preliminary report

Aim: After brachial plexus injuries, sacrifice of the contralateral C7 (cC7) root from the non-injured side is well tolerated and various schemes to innervate the injured side from the cC7 root have been used. Objective: To demonstrate the surgical outcomes from transferring the cC7 to the affected side via both the ulnar nerve and medial antebrachial cutaneous nerve (MACN).Methods: A retrospective study of 16 adult patients sustaining total brachial plexus avulsion who underwent this procedure. The British Medical Research Council (MRC) grading system and the disabilities of the arm, shoulder, and hand (DASH) questionnaire scoring were used to evaluate the recovery.Results: About 68.75% of the patients achieved functional recovery of elbow flexion to M3 or better and 43.75% achieved motor recovery of wrist and finger flexion to M3 or better. Sensation in the median nerve territory recovered to S2 or better in 68.75%. The DASH scores after surgery were significantly lower than those before surgery.Conclusions: cC7 transfer via both ulnar and MACNs is an effective and safe procedure in patients sustaining total injuries of brachial plexus.

Modified contralateral C7 nerve transfer: the possibility of permitting ulnar nerve recovery is confirmed by 10 cases of autopsy

Contralateral C7 nerve transfer surgery is one of the most important surgical techniques for treating total brachial plexus nerve injury. In the traditional contralateral C7 nerve transfer surgery, the whole ulnar nerve on the paralyzed side is harvested for transfer, which completely sacrifices its potential of recovery. In the present, novel study, we report on the anatomical feasibility of a modified contralateral C7 nerve transfer surgery. Ten fresh cadavers (4 males and 6 females) provided by the Department of Anatomy, Histology, and Embryology at the Medical College of Fudan University, China were used in modified contralateral C7 nerve transfer surgery. In this surgical model, only the dorsal and superficial branches of the ulnar nerve and the medial antebrachial cutaneous nerve on the paralyzed side (left) were harvested for grafting the contralateral (right) C7 nerve and the recipient nerves. Both the median nerve and deep branch of the ulnar nerve on the paralyzed (left) side were recipient nerves. To verify the feasibility of this surgery, the distances between each pair of coaptating nerve ends were measured by a vernier caliper. The results validated that starting point of the deep branch of ulnar nerve and the starting point of the medial antebrachial cutaneous nerve at the elbow were close to each other and could be readily anastomosed. We investigated whether the fiber number of donor and recipient nerves matched one another. The axons were counted in sections of nerve segments distal and proximal to the coaptation sites after silver impregnation. Averaged axon number of the ulnar nerve at the upper arm level was approximately equal to the sum of the median nerve and proximal end of medial antebrachial cutaneous nerve (left: 0.94:1; right: 0.93:1). In conclusion, the contralateral C7 nerve could be transferred to the median nerve but also to the deep branch of the ulnar nerve via grafts of the ulnar nerve without deep branch and the medial antebrachial cutaneous nerve. The advantage over traditional surgery was that the recovery potential of the deep branch of ulnar nerve was preserved. The study was approved by the Ethics Committee of Fudan University (approval number: 2015-064) in July, 2015.

Outcomes of Elbow Flexion Reconstruction in Patients Older than 50 with Traumatic Brachial Plexus Injury

BACKGROUND

There is controversy regarding the effectiveness of brachial plexus reconstruction for elbow function in older patients, as reported outcomes are generally poor. The purpose of this study was to evaluate elbow function outcomes in patients older than 50.

METHODS

Fifty-eight patients older than 50 years underwent nerve grafting, transfers, or free functioning muscle transfer to improve elbow function after traumatic brachial plexus injury. Patients were evaluated preoperatively and postoperatively for elbow flexion strength and range of motion; Disabilities of the Arm, Shoulder and Hand scores; pain; concomitant trauma; severity of trauma; and type of reconstruction.

RESULTS

The average age of the patients was 57.8 years, and the average follow-up was 24.0 months. The average modified British Medical Research Council elbow flexion grade improved significantly from 0.26 to 2.63. Thirty-three patients (60 percent) achieved functional flexion greater than or equal to M3 postoperatively, compared to zero patients preoperatively. There was no correlation between age and modified British Medical Research Council grade. Active elbow range of motion improved significantly postoperatively, with no effect of age on flexion motion. More patients achieved greater than or equal to M3 flexion with nerve transfers (69 percent) compared to free functioning muscle transfer (43 percent). Patients had worse outcomes with high-energy injuries. The mean Disabilities of the Arm, Shoulder and Hand score decreased from 51.5 to 49.6 postoperatively, and the average pain score decreased from 5.0 to 4.3.

CONCLUSION

Brachial plexus reconstruction for elbow function in patients older than 50 can yield useful flexion.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, IV.

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.

C7 transfer in a posterior intradural approach for treating hemiplegic upper-limbs: hypothesis and a cadaver feasibility study

Objective: Contralateral C7 nerve root transfer surgery has been successfully applied to rescue motor function of a hemiplegic upper extremity in patients with central neurological injury. This surgical technique is challenging, and limited anatomical space makes it difficult to manipulate tissues and may lead to higher complication rates. The authors hypothesis a new surgical route in which cervical nerve roots of both donor and recipient sides are exposed from a posterior intradural approach and neurorrhaphy is performed easily and clearly. The feasibility of this operation is tested in a cadaver model. Methods: A fresh cadaver was placed prone. After a standard midline incision and extensive cervical laminectomy, the dura and arachnoid were widely opened, and the spinal nerve roots of C6, C7, and C8 were exposed bilaterally. Nerve grafting was attempted between pairs of donor and recipient nerve roots on contralateral sides of the spinal cord. After completion of neurorrhaphy, the dura was closed. Results: Precise neurorrhaphy could be performed intradurally between posterior and anterior nerve roots of C7 on both sides. Multiple anastomoses of C7 to various nerve roots on the contralateral side could also be performed within the same surgical field with an interposition nerve graft. Conclusion: The posterior intradural repair idea affords many advantages, the pathway is shorter and more straightforward, which provides more access to multiple nerve roots repair in one surgical field, and is more familiar to many neurosurgeons and spine surgeons. It may potentially be adapted for clinical use.

Outcome of contralateral C7 transfers to different recipient nerves after global brachial plexus avulsion

INTRODUCTION

Contralateral cervical seventh nerve root (CC7) transfer has been widely applied for treatment of traumatic brachial plexus injury. The purpose of the study was to evaluate outcomes of patients with global brachial plexus avulsion (GBPA) after CC7 transfer and compare the recoveries of median nerve as the only recipient nerve and one of the multiple recipient nerves.

METHODS

A retrospective review of 51 patients treated with CC7 transfers after GBPA was carried out. The British Medical Research Council (MRC) grading system and range of joint motion (ROM) were used for motor and sensory assessment.

RESULTS

The effective rates of FCR were 57.7%, 45.5%, and 36.4% in CC7 transfer to median nerve (CC7-Md), CC7 transfer to median nerve and biceps branch (CC7-Md+Bic) and CC7 transfer to median nerve and triceps branch (CC7-Md+Tric) groups, respectively. There were no statistical differences no matter in FCR or FDS among groups. The effective rate in biceps had no significant difference with that in triceps. The effective sensory recovery rate was 65.4%, 54.5%, and 36.4% in CC7-Md, CC7-Md+Bic, and CC7-Md+Tric groups. There were no statistical differences in the sensory effective recovery rate among groups. All the ROMs were improved significantly after surgery. The improvement of ROM of elbow flexion after surgery in CC7-Md+Bic group was significantly larger than that of elbow extension after surgery in CC7-Md+Tric group (p = 0.047).

CONCLUSIONS

The CC7 transfer contributed to the functional improvement of the hand and wrist for the patients with global brachial plexus avulsion. The whole CC7 could be used to repair more than one recipient nerve (including median nerve) without affecting the recovery of median nerve. When CC7 was used to repair two nerves, biceps branch might be preferred to choose as one recipient nerve rather than triceps branch.

Contralateral C7 to C7 nerve root transfer in reconstruction for treatment of total brachial plexus palsy: anatomical basis and preliminary clinical results

OBJECTIVEContralateral C7 (CC7) nerve root has been used as a donor nerve for targeted neurotization in the treatment of total brachial plexus palsy (TBPP). The authors aimed to study the contribution of C7 to the innervation of specific upper-limb muscles and to explore the utility of C7 nerve root as a recipient nerve in the management of TBPP.METHODSThis was a 2-part investigation. 1) Anatomical study: the C7 nerve root was dissected and its individual branches were traced to the muscles in 5 embalmed adult cadavers bilaterally. 2) Clinical series: 6 patients with TBPP underwent CC7 nerve transfer to the middle trunk of the injured side. Outcomes were evaluated with the modified Medical Research Council scale and electromyography studies.RESULTSIn the anatomical study there were consistent and predominantly C7-derived nerve fibers in the lateral pectoral, thoracodorsal, and radial nerves. There was a minor contribution from C7 to the long thoracic nerve. The average distance from the C7 nerve root to the lateral pectoral nerve entry point of the pectoralis major was the shortest, at 10.3 ± 1.4 cm. In the clinical series the patients had been followed for a mean time of 30.8 ± 5.3 months postoperatively. At the latest follow-up, 5 of 6 patients regained M3 or higher power for shoulder adduction and elbow extension. Two patients regained M3 wrist extension. All regained some wrist and finger extension, but muscle strength was poor. Compound muscle action potentials were recorded from the pectoralis major at a mean follow-up of 6.7 ± 0.8 months; from the latissimus dorsi at 9.3 ± 1.4 months; from the triceps at 11.5 ± 1.4 months; from the wrist extensors at 17.2 ± 1.5 months; from the flexor carpi radialis at 17.0 ± 1.1 months; and from the digital extensors at 22.8 ± 2.0 months. The average sensory recovery of the index finger was S2. Transient paresthesia in the hand on the donor side, which resolved within 6 months postoperatively, was reported by all patients.CONCLUSIONSThe C7 nerve root contributes consistently to the lateral pectoral nerve, the thoracodorsal nerve, and long head of the triceps branch of the radial nerve. CC7 to C7 nerve transfer is a reconstructive option in the overall management plan for TBPP. It was safe and effective in restoring shoulder adduction and elbow extension in this patient series. However, recoveries of wrist and finger extensions are poor.

Contralateral C7 Nerve Root Transfer for Function Recovery in Adults: A Meta-analysis

Background:

Root avulsion to all 5 roots of the brachial plexus is a common presentation and keeps a major reconstructive challenge. The contralateral C7 (CC7) nerve transfer has been used in treating brachial plexus avulsion injury (BPAI) since 1986. However, the effectiveness of the procedure remains a subject of controversy. The aim of this meta-analysis was to study surgical outcomes regarding motor and sensory recovery after CC7 nerve transfer.

Methods:

Chinese or English (i.e., “contralateral c-7”, “contralateral c7”, “c7 nerve root”, and “seventh cervical nerve root”) keywords were used for a literature search for articles related to CC7 nerve transfer in several databases (i.e., PubMed, Cochrane, Embase, CNKI, CQVIP, and Wanfang Data). Clinical research articles were screened, and animal studies as well as duplicate publications were excluded. Muscle strength and sensory recovery were considered to be effective only when the scores on the United Kingdom Medical Research Council scale were equal to or higher than M3 and S3, respectively.

Results:

The overall ipsilateral recipient nerve recovery rates were as follows: the efficiency rate for muscle strength recovery after CC7 nerve transfer was 0.57 (95% confidence interval [CI]: 0.48–0.66) and for sensory recovery was 0.52 (95% CI: 0.46–0.58). When the recipient nerve was the median nerve, the efficiency rate for muscle strength recovery was 0.50 (95% CI: 0.39–0.61) and for sensory was 0.56 (95% CI: 0.50–0.63). When the recipient nerve was the musculocutaneous nerve and the radial nerve, the efficiency rate for muscle strength recovery was 0.74 (95% CI: 0.65–0.82) and 0.50 (95% CI: 0.31–0.70), respectively.

Conclusions:

Transfer of CC7 nerves to musculocutaneous nerves leads to the best results. CC7 is a reliable donor nerve, which can be safely used for upper limb function reconstruction, especially for entirely BPAI. When modifying procedures, musculocutaneous nerves and median nerve can be combined as recipient nerves.

Retropharyngeal Contralateral C7 Nerve Transfer to the Lower Trunk for Brachial Plexus Birth Injury: Technique and Results

PURPOSE

Brachial plexus birth injuries with multiple nerve root avulsions present a particularly difficult reconstructive challenge because of the limited availability of donor nerves. The contralateral C7 has been described for brachial plexus reconstruction in adults but has not been well-studied in the pediatric population. We present our technique and results for retropharyngeal contralateral C7 nerve transfer to the lower trunk for brachial plexus birth injury.

METHODS

We performed a retrospective review. Any child aged less than 2 years was included. Charts were analyzed for patient demographic data, operative variables, functional outcomes, complications, and length of follow-up.

RESULTS

We had a total of 5 patients. Average nerve graft length was 3 cm. All patients had return of hand sensation to the ulnar nerve distribution as evidenced by a pinch test, unprompted use of the recipient limb without mirror movement, and an Active Movement Scale (AMS) of at least 2/7 for finger and thumb flexion; one patient had an AMS of 7/7 for finger and thumb flexion. Only one patient had return of ulnar intrinsic hand function with an AMS of 3/7. Two patients had temporary triceps weakness in the donor limb and one had clinically insignificant temporary phrenic nerve paresis. No complications were related to the retropharyngeal nerve dissection in any patient. Average follow-up was 3.3 years.

CONCLUSIONS

The retropharyngeal contralateral C7 nerve transfer is a safe way to supply extra axons to the severely injured arm in brachial plexus birth injuries with no permanent donor limb deficits. Early functional recovery in these patients, with regard to hand function and sensation, is promising.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic V.

Functional recovery from sciatic nerve crush injury is delayed because of increased distal atrophy in mice lacking the p75 receptor

Peripheral nerve injuries are becoming more common, but without effective treatment, the outcome is often very poor. Recent research shows that p75 plays an important role in nerve regeneration, but its mechanisms of action during behavioral recovery and axon regrowth remain unclear. To investigate these mechanisms, we examined recovery from sciatic nerve crush injury in wild-type and p75 knockout mice. We found that sciatic nerve crush injury upregulates mRNA and protein expressions of p75 and p75 deficiency alters gene and protein expression of molecules associated with distal portion atrophy. However, p75 deletion did not alter gene and protein expression in the spinal cord of molecules related to neuronal intrinsic growth capacity. Behavioral testing showed that functional recovery was delayed in mice lacking p75. These results suggest that p75 regulates gene and protein expression that limits the distal atrophy after sciatic nerve injury, thereby regulating axonal growth and functional recovery.

Trial of Contralateral Seventh Cervical Nerve Transfer for Spastic Arm Paralysis

BACKGROUND

Spastic limb paralysis due to injury to a cerebral hemisphere can cause long-term disability. We investigated the effect of grafting the contralateral C7 nerve from the nonparalyzed side to the paralyzed side in patients with spastic arm paralysis due to chronic cerebral injury.

METHODS

We randomly assigned 36 patients who had had unilateral arm paralysis for more than 5 years to undergo C7 nerve transfer plus rehabilitation (18 patients) or to undergo rehabilitation alone (18 patients). The primary outcome was the change from baseline to month 12 in the total score on the Fugl-Meyer upper-extremity scale (scores range from 0 to 66, with higher scores indicating better function). Results The mean increase in Fugl-Meyer score in the paralyzed arm was 17.7 in the surgery group and 2.6 in the control group (difference, 15.1; 95% confidence interval, 12.2 to 17.9; P<0.001). With regard to improvements in spasticity as measured on the Modified Ashworth Scale (an assessment of five joints, each scored from 0 to 5, with higher scores indicating more spasticity), the smallest between-group difference was in the thumb, with 6, 9, and 3 patients in the surgery group having a 2-unit improvement, a 1-unit improvement, or no change, respectively, as compared with 1, 6, and 7 patients in the control group (P=0.02). Transcranial magnetic stimulation and functional imaging showed connectivity between the ipsilateral hemisphere and the paralyzed arm. There were no significant differences from baseline to month 12 in power, tactile threshold, or two-point discrimination in the hand on the side of the donor graft.

RESULTS

The mean increase in Fugl-Meyer score in the paralyzed arm was 17.7 in the surgery group and 2.6 in the control group (difference, 15.1; 95% confidence interval, 12.2 to 17.9; P<0.001). With regard to improvements in spasticity as measured on the Modified Ashworth Scale (an assessment of five joints, each scored from 0 to 5, with higher scores indicating more spasticity), the smallest between-group difference was in the thumb, with 6, 9, and 3 patients in the surgery group having a 2-unit improvement, a 1-unit improvement, or no change, respectively, as compared with 1, 6, and 7 patients in the control group (P=0.02). Transcranial magnetic stimulation and functional imaging showed connectivity between the ipsilateral hemisphere and the paralyzed arm. There were no significant differences from baseline to month 12 in power, tactile threshold, or two-point discrimination in the hand on the side of the donor graft.

CONCLUSIONS

In this single-center trial involving patients who had had unilateral arm paralysis due to chronic cerebral injury for more than 5 years, transfer of the C7 nerve from the nonparalyzed side to the side of the arm that was paralyzed was associated with a greater improvement in function and reduction of spasticity than rehabilitation alone over a period of 12 months. Physiological connectivity developed between the ipsilateral cerebral hemisphere and the paralyzed hand. (Funded by the National Natural Science Foundation of China and others; Chinese Clinical Trial Registry number, 13004466 .).

Is it necessary to use the entire root as a donor when transferring contralateral C7 nerve to repair median nerve?

If a partial contralateral C₇ nerve is transferred to a recipient injured nerve, results are not satisfactory. However, if an entire contralateral C₇ nerve is used to repair two nerves, both recipient nerves show good recovery. These findings seem contradictory, as the above two methods use the same donor nerve, only the cutting method of the contralateral C₇ nerve is different. To verify whether this can actually result in different repair effects, we divided rats with right total brachial plexus injury into three groups. In the entire root group, the entire contralateral C₇ root was transected and transferred to the median nerve of the affected limb. In the posterior division group, only the posterior division of the contralateral C₇ root was transected and transferred to the median nerve. In the entire root + posterior division group, the entire contralateral C₇ root was transected but only the posterior division was transferred to the median nerve. After neurectomy, the median nerve was repaired on the affected side in the three groups. At 8, 12, and 16 weeks postoperatively, electrophysiological examination showed that maximum amplitude, latency, muscle tetanic contraction force, and muscle fiber cross-sectional area of the flexor digitorum superficialis muscle were significantly better in the entire root and entire root + posterior division groups than in the posterior division group. No significant difference was found between the entire root and entire root + posterior division groups. Counts of myelinated axons in the median nerve were greater in the entire root group than in the entire root + posterior division group, which were greater than the posterior division group. We conclude that for the same recipient nerve, harvesting of the entire contralateral C₇ root achieved significantly better recovery than partial harvesting, even if only part of the entire root was used for transfer. This result indicates that the entire root should be used as a donor when transferring contralateral C₇ nerve.

Evaluation of nerve transfer options for treating total brachial plexus avulsion injury: A retrospective study of 73 participants

Despite recent great progress in diagnosis and microsurgical repair, the prognosis in total brachial plexus-avulsion injury remains unfavorable. Insufficient number of donors and unreasonable use of donor nerves might be key factors. To identify an optimal treatment strategy for this condition, we conducted a retrospective review. Seventy-three patients with total brachial plexus avulsion injury were followed up for an average of 7.3 years. Our analysis demonstrated no significant difference in elbow-flexion recovery between phrenic nerve-transfer (25 cases), phrenic nerve-graft (19 cases), intercostal nerve (17 cases), or contralateral C₇-transfer (12 cases) groups. Restoration of shoulder function was attempted through anterior accessory nerve (27 cases), posterior accessory nerve (10 cases), intercostal nerve (5 cases), or accessory + intercostal nerve transfer (31 cases). Accessory nerve + intercostal nerve transfer was the most effective method. A significantly greater amount of elbow extension was observed in patients with intercostal nerve transfer (25 cases) than in those with contralateral C₇ transfer (10 cases). Recovery of median nerve function was noticeably better for those who received entire contralateral C₇ transfer (33 cases) than for those who received partial contralateral C₇ transfer (40 cases). Wrist and finger extension were reconstructed by intercostal nerve transfer (31 cases). Overall, the recommended surgical treatment for total brachial plexus-avulsion injury is phrenic nerve transfer for elbow flexion, accessory nerve + intercostal nerve transfer for shoulder function, intercostal nerves transfer for elbow extension, entire contralateral C₇ transfer for median nerve function, and intercostal nerve transfer for finger extension. The trial was registered at ClinicalTrials.gov (identifier: NCT03166033).

Super-selective cervical nerve root stimulation in contralateral C7 transfer: An intraoperative study

OBJECTIVE

We designed this study using super-selective intraoperative cervical nerve root stimulation aiming to support decision making about complete or partial contralateral C7 (cC7) nerve root transfer in patients with multiple cervical root avulsion injury.

METHODS

Super-selective intraoperative stimulations of anterior, lateral, medial and posterior aspect of C5-C8 nerve roots were performed. Compound muscle action potentials (CMAP) were recorded in the lateral part of the deltoid (DM), long head of biceps brachii (BCM), brachioradial (BRM), long head of triceps brachii (TCM), and extensor digitorum communis (EDC) muscle. Muscle strength was documented immediately after cC7 transfer procedures and on scheduled follow-up visits according to the Medical Research Council (MRC) scale.

RESULTS

In the DM, stimulation of the posterior aspect of C5 resulted in the largest CMAP amplitudes (2.0 mV ± 1.9; 80% ± 28.3). The BCM CMAPs induced by the different aspects of C6 all revealed homogenous stimulation results. Stimulation of the lateral aspect of C7 induced the largest amplitude of TCM CMAPs (1.3 mV ± 1.0; 67.1% ± 43.3). CMAP amplitudes of individual muscles and individual contributions of cervical nerve roots to the TCM varied between subjects. Overall donor side morbidity was low, no permanent motor deficit occurred.

CONCLUSION

A super-selective intraoperative cervical nerve root stimulation may help minimize donor side morbidity in transfer procedures. Individual differences of cervical nerve root innervation pattern need to be addressed in future electrophysiological studies.

SIGNIFICANCE

Our study outlines individual differences of cervical nerve root innervation pattern.

A systematic review of outcomes of contralateral C-7 transfer for the treatment of traumatic brachial plexus injury: an international comparison

OBJECTIVE

The effectiveness of contralateral C-7 (CC7) transfer is controversial, yet this procedure has been performed around the world to treat brachial plexus injuries. The authors performed a systematic review to study whether Asian countries reported better outcomes after CC7 transfer compared with “other” countries.

METHODS

A systematic literature search using PubMed, EMBASE, and 3 Chinese databases was completed. Patient outcomes of CC7 transfer to the median and musculocutaneous (MC) nerves were collected and categorized into 2 groups: Asia and “other” countries. China was included as a subcategory of Asia because investigators in China published the majority of the collected studies. To compare outcomes among studies, we created a normalized Medical Research Council (MRC) scale.

RESULTS

For median nerve outcomes, Asia reported that 41% of patients achieved an MRC grade of ≥ M3 of wrist flexion compared with 62% in “other” countries. For finger flexion, Asia found that 41% of patients reached an MRC grade of ≥ M3 compared with 38% in “other” countries. Asia reported that 60% of patients achieved ≥ S3 sensory recovery, compared with 32% in “other” countries. For MC nerve outcomes, 75% of patients from both Asia and “other” countries reached M4 and M3 in elbow flexion.

CONCLUSIONS

Current data did not demonstrate that studies from Asian countries reported better outcomes of CC7 transfer to the median and MC nerves. Future studies should focus on comparing outcomes of different surgical strategies for CC7 transfer.

Functional connectivity of motor cortical network in patients with brachial plexus avulsion injury after contralateral cervical nerve transfer: a resting-state fMRI study

Introduction

The purpose of this study is to assess the functional connectivity of the motor cortical network in patients with brachial plexus avulsion injury (BPAI) after contralateral C7 nerve transfer, using resting-state functional magnetic resonance imaging (RS-fMRI).

Methods

Twelve patients with total brachial plexus root avulsion underwent RS-fMRI after contralateral C7 nerve transfer. Seventeen healthy volunteers were also included in this fMRI study as controls. The hand motor seed regions were defined as region of interests in the bilateral hemispheres. The seed-based functional connectivity was calculated in all the subjects. Differences in functional connectivity of the motor cortical network between patients and healthy controls were compared.

Results

The inter-hemispheric functional connectivity of the M1 areas was increased in patients with BPAI compared with the controls. The inter-hemispheric functional connectivity between the supplementary motor areas was reduced bilaterally.

Conclusions

The resting-state inter-hemispheric functional connectivity of the bilateral M1 areas is altered in patients after contralateral C7 nerve transfer, suggesting a functional reorganization of cerebral cortex.

Electronic supplementary material

The online version of this article (doi:10.1007/s00234-017-1796-0) contains supplementary material, which is available to authorized users.

Hindlimb spasticity after unilateral motor cortex lesion in rats is reduced by contralateral nerve root transfer

Transfer of nerve root from normal side to the spastic side could reduce unilateral motor cortex lesion-induced contralateral hindlimb spasticity in rats.

Lower extremity spasticity is a common sequela among patients with acquired brain injury. The optimum treatment remains controversial. The aim of our study was to test the feasibility and effectiveness of contralateral nerve root transfer in reducing post stroke spasticity of the affected hindlimb muscles in rats. In our study, we for the first time created a novel animal hindlimb spastic hemiplegia model in rats with photothrombotic lesion of unilateral motor cortex and we established a novel surgical procedure in reducing motor cortex lesion-induced hindlimb spastic hemiplegia in rats. Thirty six rats were randomized into three groups. In group A, rats received sham operation. In group B, rats underwent unilateral hindlimb motor cortex lesion. In group C, rats underwent unilateral hindlimb cortex lesion followed by contralateral L4 ventral root transfer to L5 ventral root of the affected side. Footprint analysis, Hoffmann reflex (H-reflex), cholera toxin subunit B (CTB) retrograde tracing of gastrocnemius muscle (GM) motoneurons and immunofluorescent staining of vesicle glutamate transporter 1 (VGLUT1) on CTB-labelled motoneurons were used to assess spasticity of the affected hindlimb. Sixteen weeks postoperatively, toe spread and stride length recovered significantly in group C compared with group B (P<0.001). H_max (H-wave maximum amplitude)/M_max (M-wave maximum amplitude) ratio of gastrocnemius and plantaris muscles (PMs) significantly reduced in group C (P<0.01). Average VGLUT1 positive boutons per CTB-labelled motoneurons significantly reduced in group C (P<0.001). We demonstrated for the first time that contralateral L4 ventral root transfer to L5 ventral root of the affected side was effective in relieving unilateral motor cortex lesion-induced hindlimb spasticity in rats. Our data indicated that this could be an alternative treatment for unilateral lower extremity spasticity after brain injury. Therefore, contralateral neurotization may exert a potential therapeutic candidate to improve the function of lower extremity in patients with spastic hemiplegia.

Passage through the carotid sheath: An alternative path to the pre-spinal route for direct repair of contralateral C7 to the lower trunk in total brachial plexus root avulsion injury

Context:

In surgical management of global brachial plexus injuries, direct repair of contralateral C7 (cC7) to the anterior division of the lower trunk, can produce good extrinsic finger flexion. The pitfalls associated with the pre-spinal passage have, perhaps, proved to be a deterrent for using this technique routinely.

Aims:

The aim of this study is to demonstrate an alternative to pre-spinal route for cC7 transfer in brachial plexus avulsion injuries.

Methods:

We noted that the mobilised lower trunk, which reaches the level of the scalenus anterior by passage deep to the clavicle, can be brought to the suprasternal notch when brought out from below the clavicle. This area was dissected in two cadavres, and safe passage was found through the carotid sheath with the common carotid artery medially and the internal jugular vein with the vagus nerve laterally. The cC7 root dissected medial to the scalenus anterior muscle can be directly transferred along this path to the subcutaneous plane at the suprasternal notch. This study allowed us to execute a direct repair in ten clinical cases of global brachial plexus injuries. In each case, the passage was prepared rapidly and uneventfully. The repair was technically simple and could be performed comfortably using suitable fine suture materials. In none of these cases, did we need to shorten the humerus.

Results:

The clinical outcome of this technique is awaited.

Conclusions:

We advocate carotid sheath route to approximate the cC7 to the injured lower trunk in global palsies, as the risks associated with the pre-spinal route can be readily avoided.