Novel Uses of Nerve Transfers

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.

Combined contralateral C7 to C7 and L5 to S1 cross nerve transfer for treating limb hemiplegia after stroke

BACKGROUND

Contralateral C7 to C7 cross nerve transfer has been proved to be safe and effective for patients with spastic arm paralysis due to stroke and traumatic brain injury. For the lower limb, contralateral L5 to S1 cross nerve transfer serves as a novel surgical approach. In many cases, patients with hemiplegia have both upper and lower limb dysfunction and hope to restore all limb functions within one operation. To cope with this demand, we performed combined contralateral C7 to C7 and L5 to S1 cross nerve transfer in two cases successfully.

CASE DESCRIPTION

Two patients were enrolled in this study. The first patient is a 36-year-old woman who had spasticity and hemiplegia in both upper and lower limbs on the left side after a right cerebral hemorrhage 14 years prior. The second patient is a 64-year-old man who suffered from permanent muscle weakness in his right limbs, especially the leg, after a left cerebral hemorrhage 7 years prior. Both patients underwent the combined nerve transfer to improve upper and lower limb motor functions simultaneously. During the 10-month follow-up after surgery, the limb functions of both patients improved significantly.

CONCLUSIONS

This study demonstrates the safety and benefits of combined contralateral C7 to C7 and L5 to S1 cross nerve transfer for hemiplegic patients after stroke. This novel combined surgical approach could provide an optimal choice for patients suffering from both upper and lower limb dysfunction, to reduce hospital stay while reducing financial burden.

T12-L3 Nerve Transfer-Induced Locomotor Recovery in Rats with Thoracolumbar Contusion: Essential Roles of Sensory Input Rerouting and Central Neuroplasticity

Locomotor recovery after spinal cord injury (SCI) remains an unmet challenge. Nerve transfer (NT), the connection of a functional/expendable peripheral nerve to a paralyzed nerve root, has long been clinically applied, aiming to restore motor control. However, outcomes have been inconsistent, suggesting that NT-induced neurological reinstatement may require activation of mechanisms beyond motor axon reinnervation (our hypothesis). We previously reported that to enhance rat locomotion following T13-L1 hemisection, T12-L3 NT must be performed within timeframes optimal for sensory nerve regrowth. Here, T12-L3 NT was performed for adult female rats with subacute (7-9 days) or chronic (8 weeks) mild (SCImi: 10 g × 12.5 mm) or moderate (SCImo: 10 g × 25 mm) T13-L1 thoracolumbar contusion. For chronic injuries, T11-12 implantation of adult hMSCs (1-week before NT), post-NT intramuscular delivery of FGF2, and environmentally enriched/enlarged (EEE) housing were provided. NT, not control procedures, qualitatively improved locomotion in both SCImi groups and animals with subacute SCImo. However, delayed NT did not produce neurological scale upgrading conversion for SCImo rats. Ablation of the T12 ventral/motor or dorsal/sensory root determined that the T12-L3 sensory input played a key role in hindlimb reanimation. Pharmacological, electrophysiological, and trans-synaptic tracing assays revealed that NT strengthened integrity of the propriospinal network, serotonergic neuromodulation, and the neuromuscular junction. Besides key outcomes of thoracolumbar contusion modeling, the data provides the first evidence that mixed NT-induced locomotor efficacy may rely pivotally on sensory rerouting and pro-repair neuroplasticity to reactivate neurocircuits/central pattern generators. The finding describes a novel neurobiology mechanism underlying NT, which can be targeted for development of innovative neurotization therapies.

Nerve function restoration following targeted muscle reinnervation after varying delayed periods

Targeted muscle reinnervation has been proposed for reconstruction of neuromuscular function in amputees. However, it is unknown whether performing delayed targeted muscle reinnervation after nerve injury will affect restoration of function. In this rat nerve injury study, the median and musculocutaneous nerves of the forelimb were transected. The proximal median nerve stump was sutured to the distal musculocutaneous nerve stump immediately and 2 and 4 weeks after surgery to reinnervate the biceps brachii. After targeted muscle reinnervation, intramuscular myoelectric signals from the biceps brachii were recorded. Signal amplitude gradually increased with time. Biceps brachii myoelectric signals and muscle fiber morphology and grooming behavior did not significantly differ among rats subjected to delayed target muscle innervation for different periods. Targeted muscle reinnervation delayed for 4 weeks can acquire the same nerve function restoration effect as that of immediate reinnervation.

Optimal timing of referral for nerve transfer surgery for postoperative C5 palsy

OBJECTIVE

Cervical nerve 5 palsy can occur following surgery for cervical spine pathology. The prognosis of C5 palsy is generally favorable, and most patients recover useful function. However, some patients do not recover useful strength. Nerve transfers are a potential effective treatment of postoperative severe C5 palsy. This study aimed to further delineate the natural history of recovery from postoperative C5 palsy, determine whether lack of recovery at specific time points predicts poor recovery prognosis, and thereby determine a reasonable time point for referral to a complex peripheral nerve specialist.

METHODS

The authors conducted a retrospective review of 72 patients who underwent surgery for cervical spondylosis and stenosis complicated by C5 palsy. Medical Research Council (MRC) motor strength grades were recorded preoperatively; immediately postoperatively; at discharge; and at 2 weeks, 3 months, 6 months, and 12 months postoperatively. Univariate and multivariate logistic regression models were used to identify demographic and clinical risk factors associated with recovery of useful strength after severe C5 palsy.

RESULTS

The mean patient age was 62.5 years, and 36.1% of patients were female. Thirty patients (41.7%) experienced severe C5 palsy with less than antigravity strength (MRC grade 2 or less) at discharge. Twenty-one (70%) of these patients recovered useful strength (MRC grade 3 or greater) at 12 months postoperatively, and 9 patients (30%) did not recover useful strength at 12 months. Of those patients with persistent severe C5 palsy at 3 months postoperatively, 50% recovered useful strength at 12 months. Of those patients with persistent severe C5 palsy at 6 months postoperatively, 25% recovered useful strength at 12 months. No patient with MRC grade 0 or 1 strength at 6 months postoperatively recovered useful strength. A history of diabetes was associated with the occurrence of severe C5 palsy. On multivariate analysis, female sex was associated with recovery of useful strength.

CONCLUSIONS

Most patients with severe C5 palsy recover useful strength in their C5 myotome within 12 months of onset. However, at 3 months postoperatively, patients with persistent severe C5 palsy had only a 50% chance of recovering useful strength by 12 months. Lack of recovery of useful strength at 3 months postoperatively is a reasonable time point for referral to a complex peripheral nerve center to establish care and to determine candidacy for nerve transfer surgery if severe C5 palsy persists.

Surgical Interventions for Lumbosacral Plexus Injuries: A Systematic Review

Background:

Nerve reconstruction techniques for lumbosacral plexus (LSP) injuries vary. There are no clear treatment guidelines available, and summative evaluations of the literature discussing these surgeries are lacking. For these reasons, this investigation aimed to systematically review and consolidate all available literature discussing surgical interventions for LSP injuries and cohesively present patient-reported and objective postoperative outcomes.

Methods:

The authors conducted a systematic review using PubMed, Embase, Web of Science, ProQuest Dissertations and Theses Global (via Proquest.com), and ClinicalTrials.gov databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. After title and abstract screening, identified articles were read in full and selected for inclusion based on prespecified criteria.

Results:

Our literature search identified 8683 potential citations, and after duplicate removal, abstract screening, and full-text review, 62 studies remained meeting inclusion and exclusion criteria. Outcomes were extracted according to the location of injury and type of surgical repair. Injuries were classified into isolated femoral nerve injuries, isolated obturator nerve injuries, isolated sciatic nerve injuries, and multilevel LSP injuries. Surgical treatment was further classified into exploration with neurolysis, direct repair, nerve grafting, and nerve transfer surgery.

Conclusions:

Although results vary based on the location of the injury and the surgical technique used, nerve grafts and transfers demonstrated reasonable success in improving functional and pain outcomes. Overall, isolated femoral and obturator nerve injuries had the best outcomes reported with surgical treatment. Furthermore, incomplete sciatic nerve and multilevel LSP injuries had more reported surgical options and better outcomes than complete sciatic nerve injuries.

Nerve transfers in the forearm: potential use in spastic conditions

PURPOSE

Deformities of the spastic upper limb result frequently from the association of spasticity, muscle contracture and muscle imbalance between strong spastic muscles and weak non-spastic muscles. This study was designed to evaluate the feasibility of combining selective neurectomy of the usual spastic and strong muscles together with transfer of their motor nerves to the usual weak muscles, to improve wrist and fingers motion while decreasing spasticity.

METHODS

Twenty upper limbs from fresh frozen human cadavers were dissected. All motor branches of the radial and median nerve for the forearm muscles were identified. We attempted all possible end-to-end nerve transfers between the usually strong "donor" motor branches, namely FCR and PT, and the usually weak "recipient" motor branches (ERCL, ECRB, PIN, AIN).

RESULTS

 The PT had two nerve branches in 80%, thus allowing selective neurectomy. The proximal PT branch could be anastomosed end-to-end in 45% (AIN) to 85% (ECRL) of cases with the potential recipient branches. The distal PT branch could be anastomosed end to end to all potential recipient nerves. The FCR had a single branch in all cases. End-to-end anastomosis was possible in 90% for the ECRL and in 100% for all other recipient branches, but sacrificed all FCR innervation, ruling out hyperselective neurectomy.

CONCLUSION

 Selective neurectomies can be associated with distal nerve transfers at the forearm level in selected cases. The motor nerve to the PT is the best donor for nerve transfer combined with selective neurectomy, transferred to the ECRL, ECRB, PIN or AIN.

Técnica de reconstrução do pé com prótese de calcâneo feita sob medida em câncer primário – Relato de caso

O pé é um local incomum para tumores ósseos, e compreende cerca de 3% de todos os tumores esqueléticos, em especial ao redor do calcâneo. A cirurgia radical cria um vazio no pé, o que afeta de forma negativa a capacidade de resgate do membro. As cirurgias de reconstrução do calcâneo não são comumente realizadas por causa da instabilidade da prótese, defeito de partes moles, e consequente possibilidade de insucesso pós-operatório. Assim, apresentamos aqui um caso raro de sarcoma sinovial originário da bainha do tendão tibial posterior com acometimento secundário do osso calcâneo. Considerando as experiências prévias de diferentes cirurgiões, projetamos uma prótese sob medida com modificações relevantes.

Plasticity of the Central Nervous System Involving Peripheral Nerve Transfer

Peripheral nerve injury can lead to partial or complete loss of limb function, and nerve transfer is an effective surgical salvage for patients with these injuries. The inability of deprived cortical regions representing damaged nerves to overcome corresponding maladaptive plasticity after the reinnervation of muscle fibers and sensory receptors is thought to be correlated with lasting and unfavorable functional recovery. However, the concept of central nervous system plasticity is rarely elucidated in classical textbooks involving peripheral nerve injury, let alone peripheral nerve transfer. This article is aimed at providing a comprehensive understanding of central nervous system plasticity involving peripheral nerve injury by reviewing studies mainly in human or nonhuman primate and by highlighting the functional and structural modifications in the central nervous system after peripheral nerve transfer. Hopefully, it will help surgeons perform successful nerve transfer under the guidance of modern concepts in neuroplasticity.

Restoration of the penile sensory pathway through end-to-side dorsal root neurorrhaphy in rats

Objective: Spinal cord injury often leads to the loss of penile sensation, and severely affects the individual's sexual function. The present study aimed to restore the penile sensory pathway through end-to-side dorsal root (DR) transfer neurorrhaphy in rats, and preliminarily verified the feasibility of the operation.Design: 40 male adult Sprague-Dawley rats were divided into three groups. In the model (n = 20) and resection (n = 10) groups, the right L6 DR, S1 DR, and the contralateral branch of the dorsal nerve of the penis (DNP) were transected. The distal stump of L6 DR in the model group was then anastomosed to the intact L4 DR. The sham group (n = 10) was not subjected to neural damage. Four months later, retrograde and transganglionic neural labeling, morphological examination, immunofluorescence (IF), and ultrastructural observation were carried out to test the reconstruction of the afferent pathway. Reflective erection (RE) was assessed by detecting the intracavernous pressure elicited by DNP stimulation.Results: The neural labeling tests indicated the integrity of the entire rebuilt penile afferent pathway. The morphological studies, IF, and ultrastructural observation showed that the regeneration of L6 axons in the model group was significantly better than that in the resection group; however, it had not reached the level of the sham group. The sham group rats exhibited typical RE following DNP stimulation, while the model and resection groups produced negative results.Conclusion: Our studies demonstrated the feasibility of end-to-side DR transfer neurorrhaphy for restoring the penile sensory pathway in rats.

Optimizing the timing of peripheral nerve transfers for functional re-animation in cervical spinal cord injury: a conceptual framework

Loss of upper extremity function following spinal cord injury (SCI) can have devastating consequences on quality of life. Peripheral nerve transfer surgery aims to restore motor control of upper extremities following cervical SCI and is poised to revolutionize surgical management in this population. The surgery involves dividing an expendable donor nerve above the level of the spinal lesion and coapting it to a recipient nerve arising from the lesional or infralesional segment of the injured cord. In order to maximize outcomes in this complex patient population, refinements in surgical technique need to be integrated with principles of spinal cord medicine and basic science. Deciding on the ideal timing of nerve transfer surgery is one aspect of care that is critical to maximizing recovery and has received very little attention to date in the literature. This complex topic is reviewed, with a focus on expectations for spontaneous recovery within upper motor neuron components of the injury, balanced against the need for expeditious reinnervation for lower motor neuron elements of the injury. The discussion also considers the case of a patient with C6 motor complete SCI where myotomes without electrodiagnostic evidence of denervation spontaneously improved by 6 months post-injury, thereby adjusting the surgical plan. The relevant concepts are integrated into a clinical algorithm with recommendations that consider maximal opportunity for spontaneous clinical improvement post-injury while avoiding excessive delays that may adversely affect patient outcomes.

Restoration of Penile Sensation Through Neurological Bypass in Rats

OBJECTIVE

To explore the feasibility of the penile afferent pathway by the cutaneous branch of the genitofemoral nerve to the dorsal nerve of penile transfer in rats.

METHODS

A total of 54 male rats were randomly divided into model group (n = 18), resection group (n = 18), and sham group (n = 18). In the model group, the distal stump of bilateral DNP was anastomosed to the proximal stump of the bilateral CGN through end-to-end neurorrhaphy. In the resection group, bilateral DNP was severed and ligated, and no end-to-end anastomosis was performed. Only a surgical incision was made in the sham group, and no nerve injury was caused. After the operation, the feasibility of reconstructing the penile afferent pathway was explored by fluorescent-gold retrograde neural labeling. The intracavernous pressure assessment was then carried out. The morphological examination, histological staining of nerves, and ultrastructural observation were performed accordingly.

RESULTS

Fluorescent-gold labeled L1 and L2 neurons in the model group were positive. The mean ICP in the model group was (12.02 ± 2.03 mmHg), which is higher than the mean value in the resection group (0 mmHg, P < .05) but lower than that in the sham group (36.95 ± 5.33 mmHg; P < .05). The morphological studies, HE, and ultrastructure observation revealed that the regeneration of DNP axons in the model group was significantly better than that in the resection group yet did not reach the level of the sham group.

CONCLUSION

This experiment preliminarily proved the feasibility of restoration of the penile afferent pathway by CGN to DNP transfer in Rats.

Research progress on limb spasmolysis, orthopedics and functional reconstruction of brain-derived paralysis

Brain-derived paralysis is a disease dominated by limb paralysis caused by various brain diseases. The damage of upper motor neurons can lead to spastic paralysis of the limbs in different parts. If it cannot be treated in time and effectively, it will severely affect the motor function and ability of daily living. Treating limb spastic dysfunction in patients with brain-derived paralysis is a global problem. Presently, there are many alternative surgical methods. This article mainly reviews the treatment of limb spastic dysfunction with brain-derived paralysis, focusing on three aspects: limb spasmolysis, orthopedics, and functional reconstruction. Among them, the transposition of the peripheral nerve helps limb function with spastic paralysis and can effectively alleviate limb spasticity.

Treatment of Neuroma of the Dorsal Branch of the Ulnar Nerve With Transfer to the Distal Anterior Interosseous Nerve

Painful neuromas of the dorsal branch of the ulnar nerve may be difficult to treat. Proximal transposition is the standard treatment, but pain may recur. Sensory-to-motor nerve transfer as an evolution of targeted muscle reinnervation is a recently described technique to reduce neuroma formation in the treatment of painful neuromas. This report describes sensory-to-motor transfer of the dorsal branch of the ulnar nerve to the distal anterior interosseous nerve to treat a painful neuroma.

Nogo-A/Pir-B/TrkB Signaling Pathway Activation Inhibits Neuronal Survival and Axonal Regeneration After Experimental Intracerebral Hemorrhage in Rats

Intracerebral hemorrhage (ICH) leads to widespread pathological lesions in the brain, especially impacting neuronal survival and axonal regeneration. This study aimed to elucidate whether the Nogo-A (a myelin-related protein)/paired immunoglobulin-like receptor B (Pir-B)/tropomyosin receptor kinase B (TrkB) pathway could exert a regulatory effect in ICH. An ICH model was first established in Sprague Dawley rats, followed by different administrations of vehicle, k252a, or NSC 87877. The Morris water maze test was performed to observe ICH-induced cognitive dysfunction in rats. Rats in the ICH + NSC 87877 group showed better cognitive performance compared with those injected with vehicle or k252a. Neurobehavioral scores were identical. By harvesting brain tissues at different time points after ICH, we detected the expression levels of Nogo-A and PirB with western blot and immunofluorescence and found that they were markedly upregulated at 48 h after ICH. TUNEL and Fluoro-Jade B staining showed that NSC 87877 treatment attenuated ICH-induced apoptosis and neuronal death, whereas k252a treatment aggravated these pathological changes. The expression levels of growth-associated protein 43 (GAP43) and neurofilament 200 (NF200) were higher in the ICH + NSC 87877 group compared with the ICH + vehicle group, but were lower in the ICH + k252a group. Finally, we confirmed the protective role of p-TrkB/TrkB in ICH by western blot. To sum up, our study identified the inhibitory role of the Nogo-A/PirB/TrkB pathway in ICH; however, p-TrkB/TrkB may serve as a potential target for secondary brain injury post-ICH.