Current State of the Surgical Treatment of Terminal Neuromas

Optimizing Surgical Outcomes and the Role of Preventive Surgery: A Scoping Review

BACKGROUND

 Plastic and reconstructive surgeons are often presented with reconstructive challenges as a sequela of complications in high-risk surgical patients, ranging from exposure of hardware, lymphedema, and chronic pain after amputation. These complications can result in significant morbidity, recovery time, resource utilization, and cost. Given the prevalence of surgical complications managed by plastic and reconstructive surgeons, developing novel preventative techniques to mitigate surgical risk is paramount.

METHODS

 Herein, we aim to understand efforts supporting the nascent field of Preventive Surgery, including (1) enhanced risk stratification, (2) advancements in postoperative care. Through an emphasis on four surgical cohorts who may benefit from preventive surgery, two of which are at high risk of morbidity from wound-related complications (patients undergoing sternotomy and spine procedures) and two at high risk of other morbidities, including lymphedema and neuropathic pain, we aim to provide a comprehensive and improved understanding of preventive surgery. Additionally, the role of risk analysis for these procedures and the relationship between microsurgery and prophylaxis is emphasized.

RESULTS

 (1) medical optimization and prehabilitation, (2) surgical mitigation techniques.

CONCLUSION

 Reconstructive surgeons are ideally placed to lead efforts in the creation and validation of accurate risk assessment tools and to support algorithmic approaches to surgical risk mitigation. Through a paradigm shift, including universal promotion of the concept of "Preventive Surgery," major improvements in surgical outcomes may be achieved.

Targeted muscle reinnervation: A narrative review of a novel tool for the management of neuropathic pathology in major lower extremity amputations

OBJECTIVE

The purpose of this narrative review is to provide the vascular surgery community with updated recommendations and information regarding the use of Targeted Muscle Reinnervation (TMR) for both the prevention and treatment of chronic pain and phantom limb pain occurring in patients after undergoing lower extremity amputation for peripheral artery disease.

METHODS

Current available literature discussing TMR is reviewed and included in the article in order to provide a succinct overview on the indications, clinical applications, and surgical technique for TMR. Additionally, early studies showing favorable long-term results after TMR are discussed. Patient consent for publication was obtained for this investigation.

RESULTS

TMR has been demonstrated to be an effective means of both treating and preventing neuroma-related symptoms including chronic pain and phantom limb pain. It has been proven to be technically feasible, and can help patients to have improved utilization of prostheses for ambulation, which can conceivably lead to a reduction in mortality.

CONCLUSIONS

TMR is an important tool to consider for any patient undergoing lower extremity amputation for a vascular-related indication. A vascular-plastic surgeon dual team approach is an effective means to prevent and reduce neuromas and associated chronic pain in this patient population.

Neuromuscular implants: Interfacing with skeletal muscle for improved clinical translation of prosthetic limbs

After an amputation, advanced prosthetic limbs can be used to interface with the nervous system and restore motor function. Despite numerous breakthroughs in the field, many of the recent research advancements have not been widely integrated into clinical practice. This review highlights recent innovations in neuromuscular implants-specifically those that interface with skeletal muscle-which could improve the clinical translation of prosthetic technologies. Skeletal muscle provides a physiologic gateway to harness and amplify signals from the nervous system. Recent surgical advancements in muscle reinnervation surgeries leverage the "bio-amplification" capabilities of muscle, enabling more intuitive control over a greater number of degrees of freedom in prosthetic limbs than previously achieved. We anticipate that state-of-the-art implantable neuromuscular interfaces that integrate well with skeletal muscle and novel surgical interventions will provide a long-term solution for controlling advanced prostheses. Flexible electrodes are expected to play a crucial role in reducing foreign body responses and improving the longevity of the interface. Additionally, innovations in device miniaturization and ongoing exploration of shape memory polymers could simplify surgical procedures for implanting such interfaces. Once implanted, wireless strategies for powering and transferring data from the interface can eliminate bulky external wires, reduce infection risk, and enhance day-to-day usability. By outlining the current limitations of neuromuscular interfaces along with potential future directions, this review aims to guide continued research efforts and future collaborations between engineers and specialists in the field of neuromuscular and musculoskeletal medicine.

Systematic Review and Meta-Analysis of Global Neuroma Incidence in Upper Extremity Amputees

BACKGROUND

Neuromas substantially decrease a patient's quality of life and obstruct the use of prosthetics. This systematic review and meta-analysis aimed to determine the global incidence of neuroma formation in upper extremity amputees.

METHODS

A literature search was performed using 3 databases: Web of Science, MEDLINE, and Cochrane. Inclusion criteria for the systematic review were those studies investigating only upper extremity amputees and reported postamputation neuroma. A random-effects, inverse-variance analysis was conducted to determine the pooled proportion of neuromas within the upper extremity amputation population. Critical appraisal using the JBI Checklist for Studies Reporting Prevalence Data of each individual article were performed for the systematic review.

RESULTS

Eleven studies met the inclusion criteria collating a total of 1931 patients across 8 countries. More than three-fourth of patients are young men (77%; age range, 19-54 years) and had an amputation due to trauma. The random-effects analysis found the pooled combined proportion of neuromas to be 13% (95% confidence interval, 8%-18%). The treatment of neuroma is highly variable, with some patients receiving no treatment.

CONCLUSIONS

The pooled proportion of neuroma incidence in the 1931 patients was 13%. With the known global prevalence of upper extremity amputees, this translates to nearly 3 million amputees suffering from a neuroma globally. Increasing training in preventative surgical methods could contribute to lowering this incidence and improving the outcomes of this patient population.

Surgery for mononeuropathies

Advancement in microsurgical techniques and innovative approaches including greater use of nerve and tendon transfers have resulted in better peripheral nerve injury (PNI) surgical outcomes. Clinical evaluation of the patient and their injury factors along with a shift toward earlier time frame for intervention remain key. A better understanding of the pathophysiology and biology involved in PNI and specifically mononeuropathies along with advances in ultrasound and magnetic resonance imaging allow us, nowadays, to provide our patients with a logical and sophisticated approach. While functional outcomes are constantly being refined through different surgical techniques, basic scientific concepts are being advanced and translated to clinical practice on a continuous basis. Finally, a combination of nerve transfers and technological advances in nerve/brain and machine interfaces are expanding the scope of nerve surgery to help patients with amputations, spinal cord, and brain lesions.

TMR for Peripheral Sensory Nerve Neuroma around the Wrist Utilizing the Distal Anterior Interosseous Nerve

Injury to the peripheral sensory nerves of the hand and wrist is common and can lead to debilitating neuromas and significantly impair patients' quality of life. Target-muscle reinnervation (TMR) is a novel method for treating neuromas that can result in significant clinical improvement. However, TMR for the peripheral sensory nerves in the hand and wrist is restricted by the limited options for motor branches. The adaptability of the anterior interosseous nerve (AIN) as a target for TMR treating peripheral sensory neuroma has not been thoroughly investigated or implemented therapeutically. This study aimed to evaluate the use of AIN as a viable recipient of TMR for treating peripheral sensory neuromas around the wrist. In this retrospective study, eight patients were included over 18 months from June 2021 to January 2023 at Hamad Medical Corporation. The average follow-up time after TMR was 13 months. The peripheral sensory nerves involved were the radial sensory nerve in five cases, the palmar cutaneous branch of the median nerve in one case, and the median nerve in one case. The preoperative average VAS pain score was 7 of 10 compared with the postoperative pain score of 2 of 10. In conclusion, the AIN can be used as a first-choice motor target for all peripheral sensory neuromas around the wrist for the following reasons: first, it can be reached by the peripheral sensory nerves around the wrist; second, the pronator quadratus muscle is expandable; and third, the AIN can be taken with a long proximal tail for flexible coaptation with the peripheral sensory nerves.

Targeted muscle reinnervation and regenerative peripheral nerve interfaces for pain prophylaxis and treatment: A systematic review

OBJECTIVE

Nerve pain frequently develops following amputations and peripheral nerve injuries. Two innovative surgical techniques, targeted muscle reinnervation (TMR) and regenerative peripheral nerve interfaces (RPNI), are rapidly gaining popularity as alternatives to traditional nerve management, but their effectiveness is unclear.

LITERATURE SURVEY

A review of literature pertaining to TMR and RPNI pain results was conducted. PubMed and MEDLINE electronic databases were queried.

METHODOLOGY

Studies were included if pain outcomes were assessed after TMR or RPNI in the upper or lower extremity, both for prophylaxis performed at the time of amputation and for treatment of postamputation pain. Data were extracted for evaluation.

SYNTHESIS

Seventeen studies were included, with 14 evaluating TMR (366 patients) and three evaluating RPNI (75 patients). Of these, one study was a randomized controlled trial. Nine studies had a mean follow-up time of at least 1 year (range 4-27.6 months). For pain treatment, TMR and RPNI improved neuroma pain in 75%-100% of patients and phantom limb pain in 45%-80% of patients, averaging a 2.4-6.2-point reduction in pain scores on the numeric rating scale postoperatively. When TMR or RPNI was performed prophylactically, many patients reported no neuroma pain (48%-100%) or phantom limb pain (45%-87%) at time of follow-up. Six TMR studies reported Patient-Reported Outcomes Measurement Information System (PROMIS) scores assessing pain intensity, behavior, and interference, which consistently showed a benefit for all measures. Complication rates ranged from 13% to 31%, most frequently delayed wound healing.

CONCLUSIONS

Both TMR and RPNI may be beneficial for preventing and treating pain originating from peripheral nerve dysfunction compared to traditional techniques. Randomized trials with longer term follow-up are needed to directly compare the effectiveness of TMR and RPNI with traditional nerve management techniques.

A Direct Comparison of Targeted Muscle Reinnervation and Regenerative Peripheral Nerve Interfaces to Prevent Neuroma Pain

BACKGROUND AND OBJECTIVES

Targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) surgeries manage neuroma pain; however, there remains considerable discord regarding the best treatment strategy. We provide a direct comparison of TMR and RPNI surgery using a rodent model for the treatment of neuroma pain.

METHODS

The tibial nerve of 36 Fischer rats was transected and secured to the dermis to promote neuroma formation. Pain was assessed using mechanical stimulation at the neuroma site (direct pain) and von Frey analysis at the footpad (to assess tactile allodynia from collateral innervation). Once painful neuromas were detected 6 weeks later, animals were randomized to experimental groups: (a) TMR to the motor branch to biceps femoris, (b) RPNI with an extensor digitorum longus graft, (c) neuroma excision, and (d) neuroma in situ. The TMR/RPNIs were harvested to confirm muscle reinnervation, and the sensory ganglia and nerves were harvested to assess markers of regeneration, pain, and inflammation.

RESULTS

Ten weeks post-TMR/RPNI surgery, animals had decreased pain scores compared with controls ( P < .001) and they both demonstrated neuromuscular junction reinnervation. Compared with neuroma controls, immunohistochemistry showed that sensory neuronal cell bodies of TMR and RPNI showed a decrease in regeneration markers phosphorylated cyclic AMP receptor binding protein and activation transcription factor 3 and pain markers transient receptor potential vanilloid 1 and neuropeptide Y ( P < .05). The nerve and dorsal root ganglion maintained elevated Iba-1 expression in all cohorts.

CONCLUSION

RPNI and TMR improved pain scores after neuroma resection suggesting both may be clinically feasible techniques for improving outcomes for patients with nerve injuries or those undergoing amputation.

The Use of Nerve Caps after Nerve Transection in Headache Surgery: Cadaver and Case Reports

Background

Nerve transection with nerve reconstruction is part of the treatment algorithm for patients with refractory pain after greater occipital nerve (GON) and lesser occipital nerve (LON) decompression or during primary decompression when severe nerve injury or neuroma formation is present. Importantly, the residual nerve stump is often best addressed via contemporary nerve reconstruction techniques to avoid recurrent pain. As a primary aim of this study, nerve capping is explored as a potential viable alternative that can be utilized in certain headache cases to mitigate pain.

Methods

The technical feasibility of nerve capping after GON/LON transection was evaluated in cadaver dissections and intraoperatively. Patient-reported outcomes in the 3- to 4-month period were compiled from clinic visits. At 1-year follow-up, subjective outcomes and Migraine Headache Index scores were tabulated.

Results

Two patients underwent nerve capping as a treatment for headaches refractory to medical therapy and surgical decompressions with significant improvement to total resolution of pain without postoperative complications. These improvements on pain frequency, intensity, and duration remained stable at a 1-year time point (Migraine Headache Index score reductions of -180 to -205).

Conclusions

Surgeons should be equipped to address the proximal nerve stump to prevent neuroma and neuropathic pain recurrence. Next to known contemporary nerve reconstruction techniques such as targeted muscle reinnervation/regenerative peripheral nerve interface and relocation nerve grafting, nerve capping is another viable method for surgeons to address the proximal nerve stump in settings of GON and LON pain. This option exhibits short operative time, requires only limited dissection, and yields significant clinical improvement in pain symptoms.

Regenerative peripheral nerve interface reduces the incidence of neuroma in the lower limbs after amputation: a retrospective study based on ultrasound

BACKGROUND

Amputees suffer from symptomatic neuroma and phantom limb pain. Regenerative peripheral nerve interface (RPNI) has recently been regarded as an effective method to prevent neuroma after amputation. However, the verifications of RPNI efficacy are mostly based on subjective evaluation, lacking objective approaches. This study aims to unveil the effect of RPNI on preventing neuroma formation and provide evidence supporting the efficacy of RPNI based on ultrasound.

METHODS

Amputees of lower limb at Peking University People's Hospital from July 2020 to March 2022 were analyzed retrospectively. The clinical data collected consisted of general information, pathology of primary disease, history of limb-salvage treatment, amputation level of nerve, pain scales such as the Numerical Rating Scale (NRS) and the Manchester Foot Pain and Disability Index (MFPDI). Three months after amputation, the transverse diameter, anteroposterior diameter, and cross-sectional area of neuromas in stump nerves at the end of residual limbs were measured using ultrasound and compared to adjacent normal nerves.

RESULTS

Fourteen patients were enrolled in the study, including 7 in the traditional amputation group (TA group) and 7 in the RPNI group. There was no significant difference in basic information and amputation sites between the two groups. The NRS and MFPDI scores of patients in RPNI group were significantly lower than those in TA group, and decreased with the follow-up time increasing, indicating that RPNI could reduce symptomatic neuroma pain. The comparison of preoperative ultrasound and postoperative pathology showed ultrasound could reflect the size of neuroma in vivo. Independent-sample t tests indicated that the ratios of anteroposterior diameter, transverse diameter and area of the cross section of both the neuroma and adjacent normal nerve obtained via ultrasound were significantly reduced in the RPNI group.

CONCLUSION

This study suggested that RPNI can effectively prevent the formation of symptomatic neuroma after amputation using ultrasound.

Unmasked Neuropathic Pain After Neurectomy: A Case Series and Review of the Literature

Localization of neuropathic pain to a specific peripheral nerve origin relies on patient history, physical examination, and nerve blocks. Neurectomy of the involved nerve(s) can successfully alleviate patients' pain. However, a subset of patients postoperatively describe persistent pain, but say that the pain "moved" to a new location (eg, from the dorsum of the foot to the lateral foot). This may be viewed as a treatment failure by the patient and surgeon alike. Further investigation, however, may localize the new pain to an additional, separate peripheral nerve injury, which was previously unrecognized by both parties. The mechanism involved is that of pain masking and unmasking. Successful treatment of the more prominent pain stimulus allows for recognition of a second, less-offending peripheral nerve injury. As the field of surgical treatment of chronic peripheral neuropathic pain advances, it is important to identify and define specific nuances of diagnosis and treatment via neurectomy. The term "diffuse noxious inhibitory control," used to describe the pain-inhibits-pain pathway, may help explain the phenomenon of masking, whereby one pain generator is more prominent and shields another site from recognition and subsequent diagnosis. In this context, unmasked pain should be considered as a potential source of surgical treatment failure. We present a series of patients who, following improvement in the initial location of their pain, reported pain in a distinctly new peripheral nerve distribution, leading to reoperation.

Regenerative Peripheral Nerve Interface Surgery: Anatomic and Technical Guide

Regenerative peripheral nerve interface (RPNI) surgery has been demonstrated to be an effective tool as an interface for neuroprosthetics. Additionally, it has been shown to be a reproducible and reliable strategy for the active treatment and for prevention of neuromas. The purpose of this article is to provide a comprehensive review of RPNI surgery to demonstrate its simplicity and empower reconstructive surgeons to add this to their armamentarium. This article discusses the basic science of neuroma formation and prevention, as well as the theory of RPNI. An anatomic review and discussion of surgical technique for each level of amputation and considerations for other etiologies of traumatic neuromas are included. Lastly, the authors discuss the future of RPNI surgery and compare this with other active techniques for the treatment of neuromas.

The Neuroma Startle Sign: A Surgical Indicator of Proximity to an Injured Nerve

During operative intervention for the treatment of symptomatic neuromas, the authors have observed a hypersensitive "startle" response to stimulation in proximity to the painful nerve. This physiologic sign is an indicator of the specific anatomic localization of the painful stimulus, commonly a symptomatic neuroma, that appears to be reproducible. The aim of this article is to describe this "neuroma startle sign," posit the underlying mechanism for this observation, and propose how this phenomenon could be clinically harnessed for innovation and optimization in both surgery and anesthesia for more effective symptomatic neuroma localization.

Hopeless Neuroma-The Neurotized Free Flap Tissue Augmentation as Salvage Therapy-A Concept and Clinical Demonstration

Therapy-resistant neuroma pain is a devastating condition for patients and surgeons. Although various methods are described to surgically deal with neuromas, some discontinuity and stump neuroma therapies have anatomical limitations. It is widely known that a neurotizable target for axon ingrowth is beneficial for dealing with neuromas. The nerve needs "something to do". Furthermore, sufficient soft tissue coverage plays a major role in sufficient neuroma therapy. We aimed, therefore, to demonstrate our approach for therapy of resistant neuromas with insufficient tissue coverage using free flaps, which are sensory neurotized via anatomical constant branches. The central idea is to provide a new target, a new "to do" for the painful mislead axons, as well as an augmentation of deficient soft tissues. As indication is key, we furthermore demonstrate clinical cases and common neurotizable workhorse flaps.

Targeted muscle reinnervation prevents and reverses rat pain behaviors after nerve transection

ABSTRACT

Targeted muscle reinnervation (TMR) is a clinical intervention that is rapidly becoming common in major limb amputation to prevent or reduce amputation-related pain. However, TMR is much less effective when applied long after injury compared with acute TMR. Since the mechanisms governing pain relief in TMR of amputated nerves are unknown, we developed a preclinical model as a platform for mechanistic examination. Following spared nerve injury (SNI), rats underwent either TMR, simple neuroma excision, or a sham manipulation of the injury site. These interventions were performed immediately or delayed (3 or 12 weeks) after SNI. Pain behavior was measured as sensitivity to mechanical stimuli (pin, von Frey, and dynamic brush) and thermal stimuli (acetone and radiant heat). Spared nerve injury produced hypersensitivity to all mechanical stimuli and cold, which persisted after sham surgery. Targeted muscle reinnervation at the time of SNI prevented the development of pain behaviors and performing TMR 3 weeks after SNI reversed pain behaviors to baseline. By contrast, TMR performed at 12 weeks after SNI had no effect on pain behaviors. Neuroma excision resulted in significantly less reduction in hyperalgesia compared with TMR when performed 3 weeks after SNI but had no effect at 12 weeks after SNI. In this model, the pain phenotype induced by nerve transection is reduced by TMR when performed within 3 weeks after injury. However, TMR delayed 12 weeks after injury fails to reduce pain behaviors. This replicates clinical experience with limb amputation, supporting validity of this model for examining the mechanisms of TMR analgesia.

Traumatic neuromas of peripheral nerves: Diagnosis, management and future perspectives

Traumatic neuromas are infrequent in clinical settings but are prevalent following trauma or surgery. A traumatic neuroma is not a true malignancy, rather, it is a hyperplastic, reparative nerve reaction after injury and typically manifests as a nodular mass. The most common clinical manifestations include painful hypersensitivity and the presence of a trigger point that causes neuralgic pain, which could seriously decrease the living standards of patients. While various studies are conducted aiming to improve current diagnosis and management strategies via the induction of emerging imaging tools and surgical or conservative treatment. However, researchers and clinicians have yet to reach a consensus regarding traumatic neuromas. In this review, we aim to start with the possible underlying mechanisms of traumatic neuromas, elaborate on the diagnosis, treatment, and prevention schemes, and discuss the current experiment models and advances in research for the future management of traumatic neuromas.

Mindful SensoriMotor Therapy combined with brain modulation for the treatment of pain in individuals with disarticulation or nerve injuries: a single-arm clinical trial

INTRODUCTION

Neuropathic pain is a complex and demanding medical condition that is often difficult to treat. Regardless of the cause, the impairment, lesion or damage to the nervous system can lead to neuropathic pain, such as phantom limb pain (PLP). No treatment has been found widely effective for PLP, but plasticity-guided therapies have shown the least severe side effects in comparison to pharmacological or surgical interventions. Phantom motor execution (PME) is a plasticity-guided intervention that has shown promising results in alleviating PLP. The potential mechanism underlying the effectiveness of PME can be explained by the Stochastic Entanglement hypothesis for neurogenesis of neuropathic pain resulting from sensorimotor impairment. We have built on this hypothesis to investigate the efficacy of enhancing PME interventions by using phantom motor imagery to facilitate execution and with the addition of sensory training. We refer to this new treatment concept as Mindful SensoriMotor Therapy (MiSMT). In this study, we further complement MiSMT with non-invasive brain modulation, specifically transcranial direct current stimulation (tDCS), for the treatment of neuropathic pain in patients with disarticulation or peripheral nerve injury.

METHODS AND ANALYSIS

This single-arm clinical trial investigates the efficacy of MiSMT and tDCS as a treatment of neuropathic pain resulting from highly impaired extremity or peripheral nerve injury in eight participants. The study consists of 12 sessions of MiSMT with anodal tDCS in the motor cortex, pretreatment and post-treatment assessments, and follow-up sessions (up to 6 months). The primary outcome is the change in pain intensity as measured by the Pain Rating Index between the first and last treatment sessions.

ETHICS AND DISSEMINATION

The study is performed under the approval of the governing ethical committee in Sweden (approval number 2020-07157) and in accordance with the Declaration of Helsinki.

TRIAL REGISTRATION NUMBER

NCT04897425.

Update on Upper Limb Neuroma Management

Painful terminal neuromas in the upper limb due to nerve injury are common. Neuroma symptoms include a sharp and burning sensation, cold intolerance, dysesthesia, pain, numbness, and paresthesia. These symptoms could have a negative impact on the functional ability of the patient and quality of life. In addition, Prostheses use might be abandoned by amputees due to neuroma-induced pain. Many clinicians face challenges while managing neuromas. Contemporary "active" methods like regenerative peripheral nerve interface (RPNI), targeted muscle reinnervation (TMR), and processed nerve allograft repair (PNA) are replacing the conventional "passive" approaches such as excision, transposition, and implantation techniques. RPNI involves inducing axonal sprouting by transplanting the free end of a peripheral nerve into a free muscle graft. TMR includes reassigning the role of the peripheral nerve by the transfer of the distal end of a pure sensory or a mixed peripheral nerve to a motor nerve of a nearby muscle segment. To give the peripheral nerve a pathway to re-innervate its target tissue, PNA entails implanting a sterile extracellular matrix prepared from decellularized and regenerated human nerve tissue with preserved epineurium and fascicles. Of these, RPNI and TMR appear to hold a promising treatment for nerve-ending neuromas and prevent their relapse. In contrast, PNA may reduce neuroma pain and allow meaningful nerve repair. The aim of this article is to provide an overview of the newer approaches of TMR, RPNI, and PNA and discuss their implications, surgical techniques, and reported consequences.

[Treatment and prevention phantom pain syndrome in mine-explosive injuries]

Phantom pain syndrome significantly impairs the quality of life and effectiveness of surgical treatment after limb amputations. The authors consider possible strategies for treatment and prevention in elective surgical intervention and mine-explosive injuries.

Local Environment Induces Differential Gene Expression in Regenerating Nerves

INTRODUCTION

Approximately 80% of amputations are complicated by neuromas. Methods for neuroma management include nerve translocation into bone and implantation into skeletal muscle grafts, which have also facilitated the development of regenerative neural interfaces to enable fixation of prosthetics with motor and sensory feedback. However, molecular-level differences between nerves in these environments have not been investigated. This study aimed to elucidate the physiology of regenerating nerves in different settings by assessing gene expression.

MATERIALS AND METHODS

New Zealand white rabbits underwent transfemoral amputation with sciatic nerve transposition into the femur or tacked to skeletal muscle. At 5 wk, ribonucleic acid (RNA) sequencing of samples of distal nerve terminating in bone or muscle and nerve of the contralateral limb (control) identified differentially expressed genes (DEGs) and biochemical pathways (α = 0.05).

RESULTS

Three samples of nerve housed in bone, four of nerve tacked to muscle, and seven naïve controls were analyzed. Relative to controls, nerve housed in bone had little within-group variation and 13,028 DEGs, and nerve tacked to muscle had dramatic within-group variation and 12,811 DEGs. These samples upregulated the following pathways: lysosome, phagosome, antigen processing/presentation, and cell adhesion molecule. Relative to nerve housed in bone, nerve tacked to muscle had 12,526 DEGs, demonstrating upregulation of pathways of B-cell receptor signaling, focal adhesion, natural killer-cell mediated cytotoxicity, leukocyte transendothelial migration, and extracellular matrix-receptor interactions.

CONCLUSIONS

Nerve housed in bone has a more predictable molecular profile than does nerve tacked to muscle. Thus, the intramedullary canal may provide a more reliable setting for neuroma prevention and neural interfacing.

Controlling axonal regeneration with acellular nerve allograft limits neuroma formation in peripheral nerve transection: An experimental study in a swine model

BACKGROUND

Symptomatic neuromata are a common indication for revision surgery following amputation. Previously described treatments, including traction neurectomy, nerve transposition, targeted muscle re-innervation, and nerve capping, have provided inconsistent results or are technically challenging. Prior research using acellular nerve allografts (ANA) has shown controlled termination of axonal regrowth in long grafts. The purpose of this study was to determine the ability of a long ANA to prevent neuroma formation following transection of a peripheral nerve in a swine model.

MATERIALS AND METHODS

Twenty-two adult female Yucatan miniature swine (Sus scrofa; 4-6 months, 15-25 kg) were assigned to control (ulnar nerve transection only, n = 10), treatment (ulnar transection and coaptation of 50 mm ANA, n = 10), or donor (n = 2) groups. Nerves harvested from donor group animals were treated to create the ANA. After 20 weeks, the transected nerves including any neuroma or graft were harvested. Both qualitative (nerve architecture, axonal sprouting) and quantitative histologic analyses (myelinated axon number, cross sectional area of nerve tissue) were performed.

RESULTS

Qualitative histologic analysis of control specimens revealed robust axon growth into dense scar tissue. In contrast, the treatment group revealed dwindling axons in the terminal tissue, consistent with attenuated neuroma formation. Quantitative analysis revealed a significantly decreased number of myelinated axons in the treatment group (1232 ± 540) compared to the control group (44,380 ± 7204) (p < .0001). Cross sectional area of nerve tissue was significantly smaller in treatment group (2.83 ± 1.53 mm² ) compared to the control group (9.14 ± 1.19 mm² ) (p = .0012).

CONCLUSIONS

Aberrant axonal growth is controlled to termination with coaptation of a 50 mm ANA in a swine model of nerve injury. These early results suggest further investigation of this technique to prevent and/or treat neuroma formation.

Target Receptors of Regenerating Nerves: Neuroma Formation and Current Treatment Options

Neuromas form as a result of disorganized sensory axonal regeneration following nerve injury. Painful neuromas lead to poor quality of life for patients and place a burden on healthcare systems. Modern surgical interventions for neuromas entail guided regeneration of sensory nerve fibers into muscle tissue leading to muscle innervation and neuroma treatment or prevention. However, it is unclear how innervating denervated muscle targets prevents painful neuroma formation, as little is known about the fate of sensory fibers, and more specifically pain fiber, as they regenerate into muscle. Golgi tendon organs and muscle spindles have been proposed as possible receptor targets for the regenerating sensory fibers; however, these receptors are not typically innervated by pain fibers, as these free nerve endings do not synapse on receptors. The mechanisms by which pain fibers are signaled to cease regeneration therefore remain unknown. In this article, we review the physiology underlying nerve regeneration, the guiding molecular signals, and the target receptor specificity of regenerating sensory axons as it pertains to the development and prevention of painful neuroma formation while highlighting gaps in literature. We discuss management options for painful neuromas and the current supporting evidence for the various interventions.

Sensory nerve regeneration and reinnervation in muscle following peripheral nerve injury

Sensory afferent fibers are an important component of motor nerves and compose the majority of axons in many nerves traditionally thought of as "pure" motor nerves. These sensory afferent fibers innervate special sensory end organs in muscle, including muscle spindles that respond to changes in muscle length and Golgi tendons that detect muscle tension. Both play a major role in proprioception, sensorimotor extremity control feedback, and force regulation. After peripheral nerve injury, there is histological and electrophysiological evidence that sensory afferents can reinnervate muscle, including muscle that was not the nerve's original target. Reinnervation can occur after different nerve injury and muscle models, including muscle graft, crush, and transection injuries, and occurs in a nonspecific manner, allowing for cross-innervation to occur. Evidence of cross-innervation includes the following: muscle spindle and Golgi tendon afferent-receptor mismatch, vagal sensory fiber reinnervation of muscle, and cutaneous afferent reinnervation of muscle spindle or Golgi tendons. There are several notable clinical applications of sensory reinnervation and cross-reinnervation of muscle, including restoration of optimal motor control after peripheral nerve repair, flap sensation, sensory protection of denervated muscle, neuroma treatment and prevention, and facilitation of prosthetic sensorimotor control. This review focuses on sensory nerve regeneration and reinnervation in muscle, and the clinical applications of this phenomena. Understanding the physiology and limitations of sensory nerve regeneration and reinnervation in muscle may ultimately facilitate improvement of its clinical applications.

Peripheral Nerve Management in Extremity Amputations

The effective management of peripheral nerves in amputation surgery is critical to optimizing patient outcomes. Nerve-related pain after amputation is common, maybe a source of dissatisfaction and functional impairment, and should be considered in all amputees presenting with pain and dysfunction. While traction neurectomy or transposition has long been the standard of care, both regenerative peripheral nerve interface (RPNI) and targeted muscle reinnervation (TMR) have emerged as promising techniques to improve neuroma-related and phantom pain. A multi-disciplinary and multi-modal approach is essential for the optimal management of amputees both acutely and in the delayed or chronic setting.

Neurorrhaphy of anterior and posterior interosseous nerves in the prevention of neuroma following a radical neurectomy: A case report

Selective wrist denervation is a surgical technique frequently performed for the treatment of chronic wrist pain. While this technique is often effective in pain reduction, it is still associated with certain complications such as pain recurrence secondary to neuroma formation. We present a case report that details the clinical case of a young yoga teacher suffering from debilitating chronic wrist pain, refractory to conservative treatments. We describe a new surgical technique for the treatment of chronic wrist pain: posterior interosseous nerve and anterior interosseous nerve neurectomy followed by neurorrhaphy in preventing neuroma formation. Post-operatively, the patient’s wrist pain continuously improved and completely resolved without any signs of recurrence. Posterior interosseous nerve and anterior interosseous nerve neurectomy followed by an end-to-end neurorrhaphy can be used as an effective novel surgical technique in the management of chronic wrist pain with prevention of neuroma formation.

Typical and atypical properties of peripheral nerve allografts enable novel strategies to repair segmental-loss injuries

We review data showing that peripheral nerve injuries (PNIs) that involve the loss of a nerve segment are the most common type of traumatic injury to nervous systems. Segmental-loss PNIs have a poor prognosis compared to other injuries, especially when one or more mixed motor/sensory nerves are involved and are typically the major source of disability associated with extremities that have sustained other injuries. Relatively little progress has been made, since the treatment of segmental loss PNIs with cable autografts that are currently the gold standard for repair has slow and incomplete (often non-existent) functional recovery. Viable peripheral nerve allografts (PNAs) to repair segmental-loss PNIs have not been experimentally or clinically useful due to their immunological rejection, Wallerian degeneration (WD) of anucleate donor graft and distal host axons, and slow regeneration of host axons, leading to delayed re-innervation and producing atrophy or degeneration of distal target tissues. However, two significant advances have recently been made using viable PNAs to repair segmental-loss PNIs: (1) hydrogel release of Treg cells that reduce the immunological response and (2) PEG-fusion of donor PNAs that reduce the immune response, reduce and/or suppress much WD, immediately restore axonal conduction across the donor graft and re-innervate many target tissues, and restore much voluntary behavioral functions within weeks, sometimes to levels approaching that of uninjured nerves. We review the rather sparse cellular/biochemical data for rejection of conventional PNAs and their acceptance following Treg hydrogel and PEG-fusion of PNAs, as well as cellular and systemic data for their acceptance and remarkable behavioral recovery in the absence of tissue matching or immune suppression. We also review typical and atypical characteristics of PNAs compared with other types of tissue or organ allografts, problems and potential solutions for PNA use and storage, clinical implications and commercial availability of PNAs, and future possibilities for PNAs to repair segmental-loss PNIs.

Treatment of Refractory Radial Sensory Neuroma With Function-Sparing Targeted Muscle Reinnervation to the Extensor Carpi Radialis Brevis

The radial sensory nerve can be injured during many common procedures, including intravenous cannulation, first extensor compartment release, and radial-sided wrist surgery. Injury to the nerve may result in neuroma formation that can lead to chronic and debilitating pain. Nonsurgical treatments and surgical interventions, including excision of the neuroma and burying the nerve into local muscle, are frequently ineffective. Here, we present a technique for treating recalcitrant neuromas of the radial sensory nerve with targeted muscle reinnervation to a redundant motor nerve branch of the extensor carpi radialis brevis.

Prevention is better than cure: Surgical methods for neuropathic pain prevention following amputation - A systematic review

BACKGROUND

Pain after amputation can be known as residual limb pain (RLP) or phantom limb pain (PLP); however, both can be disabling in daily life with reported incidences of 8% for finger amputations and up to 85% for major limb amputations. The current treatment is focused on reducing the pain after neuropathic pain occurs. However, surgical techniques to prevent neuropathic pain after amputation are available and effective, but they are underutilized. The purpose of the review is to investigate the effects of techniques during amputation to prevent neuropathic pain.

METHODS

A systematic review was performed in multiple databases (Embase, Medline, Web of Science, Scopus, Cochrane, and Google Scholar) and following the PRISMA guidelines. Studies that reported surgical techniques to prevent neuropathic pain during limb amputation were included.

RESULTS

Of the 6188 selected studies, 13 eligible articles were selected. Five articles reported techniques for finger amputation: neurovascular island flap, centro-central union (CCU), and epineural ligatures, and flaps. For finger amputations, the use of prevention techniques resulted in a decrease of incidences from 8% to 0-3% with CCU being the most beneficial. For major limb amputations, the incidences for RLP were decreased to 0 to 55% with TMR and RPNI and compared to 64-91% for the control group. Eight articles reported techniques for amputations on major limbs: targeted muscle reinnervation (TMR), targeted nerve implantation, concomitant nerve coaptation, and regenerative peripheral nerve interface (RPNI).

CONCLUSIONS

Based on the current literature, we state that during finger and major limb amputation, the techniques to prevent neuropathic pain and PLP should be performed.

Stump-plasty: An Operation Born of Necessity in Gaza

Aim and objective

The most recent wave of lower limb amputees in Gaza arises from ballistic injuries sustained during protests. This study evaluates the requirement for surgical revision of these mature stumps to allow prosthetic fit and mobility.

Materials and methods

A multidisciplinary team (MDT) comprising a prosthetist, orthopaedic and plastic surgeons and a physiotherapist screened 104 amputee stumps (103 cases). The 27 cases selected for surgical revision (stump-plasty) are the subject of this study.

The MDT prescriptions of care issued at screening were compared to surgical procedures performed at stump-plasty and the findings. Compliance with the MDT prescription was recorded. Stump issues are identified to propose modifications of primary amputation technique to mitigate future revisions.

Patients’ healthcare status was assessed by questionnaire (EQ-5D-L5) at screening, then subsequently post-stump-plasty.

Results

More below-knee amputees (BKAs) than above-knee amputees (AKAs) required stump-plasty. Revisions varied according to the quality of tissue present at the amputation level. AKA revisions addressed bulk and contour issues whereas BKA revisions related to bone prominence, neuroma formation and lack of soft tissue cover. Despite many variations in tissue-targeted procedures being possible, the MDT prescription was followed accurately at surgery.

Suggested modifications at primary amputation to decrease revisions include improved bone tip bevelling at BKA and greater soft tissue reduction at AKA. Severed nerve management needs to be rationalised to reduce primary neuroma formation and neuroma revision at stump-plasty requires consideration to attempt to reduce the recurrent risk. Removal of the fibular remnant in short BKA stumps at primary amputation could mitigate common peroneal nerve hypersensitivity later.

Following stump-plasty, amputees recorded a significantly improved score in three of five dimensions of the EQ-5D-L5 questionnaire: activities, anxiety levels and pain.

Conclusion and clinical significance

Primary ballistic injury dictates the level of amputation and the resultant stump quality. Issues arising in these complex amputee stumps benefited from measured decisions and specialist care delivered by the MDT. Stump-plasty aims to improve the amputees’ prosthetic fit, mobility and health.

How to cite this article

Godwin Y, Almaqadma A, Abukhoussa H, et al. Stump-plasty: An Operation Born of Necessity in Gaza. Strategies Trauma Limb Reconstr 2021;16(2):102–109.

Amputation Revision Surgery - Refining the surgical approach. Ten years of experience and 250 cases, impressions, outcomes, and thoughts for the future

INTRODUCTION

The decision for revision amputation surgery requires a multi-disciplinary approach and the evidence on outcome data available in the current literature is limited. The aim of this observational, retrospective study was to investigate in patients undergoing stump revision, whether factors such as pathology and reason for the revision surgery affect surgical 'success' rates as primary outcomes. Secondary outcomes of interest include rehabilitation outcomes and complication rates.

METHODS

From December 2008 to November 2018, 250 amputation revision procedures were performed at our centre. Surgical and rehabilitation outcomes and indication for revision surgery were measured for each patient.

RESULTS

There was an overall surgical success rate of 81% and an overall rehabilitation success rate of 63%, with variable outcomes related to the indication for surgery. Revisions for bony pathology had excellent results from a surgical perspective (100%) and good results from a rehabilitation perspective (71%). Revisions for soft tissue pathology and neuroma had satisfactory results from a surgical perspective (81% and 74% respectively) and rehabilitation perspective (56% and 71% respectively). Surgical success rates for those undergoing revision surgery due to non-neuroma pain were poor.

CONCLUSIONS

We found that revision surgery for defined anatomical abnormalities, such as bone pathology or neuromata are associated with good outcomes. Surgical techniques, specifically related to the management of neuromas are continuing to develop, with promising results from the application of targeted muscle reinnervation (TMR) in the treatment of neuromata. The primary amputation surgeon should exercise caution when considering compromising bone length for soft tissue or skin coverage, as revision surgery can address the excision of skin graft or refashioning of the soft tissue envelope at a later stage. Careful patient selection is key to ensure we advocate offering our patients the right operation at the right time, for the right pathology.

"Decreasing Postamputation Pain with the Regenerative Peripheral Nerve Interface (RPNI)"

Over 185,000 limb amputations are performed in the United States annually, many of which are due to the sequelae of peripheral vascular disease. Symptomatic neuromas remain a significant source of postamputation morbidity and contribute to both phantom limb (PLP) and residual limb pain (RLP). While many interventions have been proposed for the treatment of symptomatic neuromas, conventional methods lead to a high incidence of neuroma recurrence. Furthermore, these existing methods do not facilitate an ability to properly interface with myoelectric prosthetic devices. The Regenerative Peripheral Nerve Interface (RPNI) was developed to overcome these limitations. The RPNI consists of an autologous free muscle graft secured around the end of a transected nerve. The muscle graft provides regenerating axons with end organs to reinnervate, thereby preventing neuroma formation. We have shown that this simple, reproducible, and safe surgical technique successfully treats and prevents neuroma formation in major limb amputations. In this paper, we describe RPNI surgery in the setting of major limb amputation and highlight the promising results of RPNIs in our animal and clinical studies.

Clinical Outcomes of Symptomatic Neuroma Resection and Reconstruction with Processed Nerve Allograft

Background:

Neuromas causing sensory disturbance can substantially affect nerve function and quality of life. Historically, passive termination of the nerve end and proximal relocation to muscle or bone has been performed after neuroma resection, but this method does not allow for neurologic recovery or prevent recurrent neuromas. The use of processed nerve allografts (PNAs) for intercalary reconstruction of nerve defects following neuroma resection is reasonable for neuroma management, although reported outcomes are limited. The purpose of this study was to assess the outcomes of pain reduction and functional recovery following neuroma resection and intercalary nerve reconstruction using PNA.

Methods:

Data on outcomes of PNA use for peripheral nerve reconstruction were collected from a multicenter registry study. The registry database was queried for upper extremity nerve reconstruction with PNA after resection of symptomatic neuroma. Patients completing both pain and quantitative sensory assessments were included in the analysis. Improvement in pain-related symptoms was determined via patient self-reported outcomes and/or the visual analog scale. Meaningful sensory recovery was defined as a score of at least S3 on the Medical Research Council Classification scale.

Results:

Twenty-five repairs involving 21 patients were included in this study. The median interval from injury to reconstruction was 386 days, and the average nerve defect length was 31 mm. Pain improved in 80% of repairs. Meaningful sensory recovery was achieved in 88% of repairs.

Conclusion:

Neuroma resection and nerve reconstruction using PNA can reduce or eliminate chronic peripheral nerve pain and provide meaningful sensory recovery.

Peripheral Nerve Healing: So Near and Yet So Far

Peripheral nerve injuries represent a considerable portion of chronic disability that especially affects the younger population. Prerequisites of proper peripheral nerve injury treatment include in-depth knowledge of the anatomy, pathophysiology, and options in surgical reconstruction. Our greater appreciation of nerve healing mechanisms and the development of different microsurgical techniques have significantly refined the outcomes in treatment for the past four decades. This work reviews the peripheral nerve regeneration process after an injury, provides an overview of various coaptation methods, and compares other available treatments such as autologous nerve graft, acellular nerve allograft, and synthetic nerve conduits. Furthermore, the formation of neuromas as well as their latest treatment options are discussed.

Regenerative Peripheral Nerve Interfaces for the Treatment and Prevention of Neuromas and Neuroma Pain

A neuroma occurs when a regenerating transected peripheral nerve has no distal target to reinnervate. This situation can result in a hypersensitive free nerve ending that causes debilitating pain to affected patients. No techniques to treat symptomatic neuromas have shown consistent results. One novel physiologic solution is the regenerative peripheral nerve interface (RPNI). RPNI consists of a transected peripheral nerve that is implanted into an autologous free skeletal muscle graft. Early clinical studies have shown promising results in the use of RPNIs to treat and prevent symptomatic neuromas. This review article describes the rationale behind the success of RPNIs and its clinical applications.

Revision Peripheral Nerve Surgery of the Upper Extremity

Peripheral nerve injuries of the upper extremity can result from a wide array of etiologies, with the two most common being compression neuropathy and traumatic injuries. These types of injuries are common and can be psychologically, functionally, and financially devastating to the patient. A detailed preoperative evaluation is imperative for appropriate management. Traumatic injuries can typically be treated with local burial techniques, targeted muscle reinnervation, and regenerative peripheral nerve interfaces. Median nerve compression is frequently managed with complete release of the antebrachial fascia/transverse carpal ligament and/or use of flap coverage such as the hypothenar fat pad flap and local muscle flaps. Ulnar nerve compression is commonly managed via submuscular transposition, subcutaneous transposition, neurolysis, and nerve wrapping. In this review, we discuss the preoperative evaluation, surgical techniques, and advantages and disadvantages of each treatment modality for patients with compressive and traumatic upper extremity nerve injuries.

Long Acellular Nerve Allografts Cap Transected Nerve to Arrest Axon Regeneration and Alter Upstream Gene Expression in a Rat Neuroma Model

BACKGROUND

Treatments to manage painful neuroma are needed. An operative strategy that isolates and controls chaotic axonal growth could prevent neuroma. Using long acellular nerve allograft to "cap" damaged nerve could control axonal regeneration and, in turn, regulate upstream gene expression patterns.

METHODS

Rat sciatic nerve was transected, and the distal nerve end was reversed and ligated to generate a model end-neuroma. Three groups were used to assess their effects immediately following this nerve injury: no treatment (control), traction neurectomy, or 5-cm acellular nerve allograft cap attached to the proximal nerve. Regeneration of axons from the injured nerve was assessed over 5 months and paired with concurrent measurements of gene expression from upstream affected dorsal root ganglia.

RESULTS

Both control and traction neurectomy groups demonstrated uncontrolled axon regeneration revealed using Thy1-GFP rat axon imaging and histomorphometric measures of regenerated axons within the most terminal region of regenerated tissue. The acellular nerve allograft group arrested axons within the acellular nerve allograft, where no axons reached the most terminal region even after 5 months. At 5 months, gene expression associated with regeneration and pain sensitization, including Bdnf, cfos, and Gal, was decreased within dorsal root ganglia obtained from the acellular nerve allograft group compared to control or traction neurectomy group dorsal root ganglia.

CONCLUSIONS

Long acellular nerve allografts to cap a severed nerve arrested axon regeneration within the acellular nerve allograft. This growth arrest corresponded with changes in regenerative and pain-related genes upstream. Acellular nerve allografts may be useful for surgical intervention of neuroma.

Surgical prevention of terminal neuroma and phantom limb pain: a literature review

The incidence of extremity amputation is estimated at about 200,000 cases annually. Over 25% of patients suffer from terminal neuroma or phantom limb pain (TNPLP), resulting in pain, inability to wear a prosthetic device, and lost work. Once TNPLP develops, there is no definitive cure. Therefore, there has been an emerging focus on TNPLP prevention. We examined the current literature on TNPLP prevention in patients undergoing extremity amputation. A literature review was performed using Ovid Medline, Cochrane Collaboration Library, and Google Scholar to identify all original studies that addressed surgical prophylaxis against TNPLP. The search was conducted using both Medical Subject Headings and free-text using the terms “phantom limb pain,” “amputation neuroma,” and “surgical prevention of amputation neuroma.” Fifteen studies met the inclusion criteria, including six prospective trials, two comprehensive literature reviews, four retrospective chart reviews, and three case series/technique reviews. Five techniques were identified, and each was incorporated into a target-based classification system. A small but growing body of literature exists regarding the surgical prevention of TNPLP. Targeted muscle reinnervation (TMR), a form of physiologic target reassignment, has the greatest momentum in the academic surgical community, with multiple recent prospective studies demonstrating superior prevention of TNPLP. Neurorrhaphy and transposition with implantation are supported by less robust evidence, but merit future study as alternatives to TMR.

Targeted Muscle Reinnervation to Expendable Motor Nerves for the Treatment of Refractory Symptomatic Neuromas in Nonamputees

Symptomatic neuromas can cause debilitating pain, significantly impairing patients’ quality of life. There are numerous medical and surgical options for management. Targeted muscle reinnervation (TMR) is a nerve transfer procedure that is now commonly used to prevent or treat symptomatic neuromas or phantom limb pain in amputees. There are a few reports in the current literature about performing TMR in the nonamputee, but no cohort studies to date that report pain outcomes. This study evaluates TMR to treat symptomatic neuromas in nonamputee patients. This is a retrospective cohort study of all patients with symptomatic neuromas treated with TMR over a 1-year period from January 1,2019, to January 1, 2020, at MedStar Georgetown University Hospital. The neuromas are excised to healthy nerve fascicles, and a redundant donor motor fascicle is selected for nerve transfer. Patients were asked in clinic or via telephone about their preoperative and postoperative pain, function, and quality of life, and postoperative clinic notes were reviewed for complications and motor deficits. Fifteen patients were included in this study. Patients had symptomatic neuromas involving the upper extremity, lower extremity, and trunk. Pain frequency decreased from 6.7 times per week to 3.9 (P < 0.01) and from 9.1 times per day to 5.1 (P < 0.01). Pain severity decreased from an average of 7.9/10 to 4.3/10 (P < 0.01). Overall physical function increased from 3.7/10 to 5.8/10 (P = 0.01), and overall quality of life increased from 4.9/10 to 7.0/10 (P < 0.01). No patients had demonstrable weakness of the motor function of the donor nerve. Targeted muscle reinnervation is a viable surgical option for the treatment of symptomatic neuromas, particularly in those patients who have previously failed prior neuroma excisions.

[Surgical management of peripheral nerves after extremity loss]

Hintergrund

Nach Verlust einer Gliedmaße ist es die Aufgabe des Chirurgen, einen möglichst schmerzfreien und belastbaren Stumpf zu formen. Hierbei kommt insbesondere an der oberen Extremität ein funktioneller Aspekt hinzu, da zur Steuerung myoelektrischer Prothesen entsprechende Muskelsignale notwendig sind. Der Umgang mit peripheren Nerven im Stumpfbereich nimmt sowohl hinsichtlich der Schmerztherapie als auch der funktionellen Mensch-Maschinen-Anbindung eine zentrale Rolle ein.

Ziel der Arbeit

Die Darstellung aktueller chirurgischer Verfahren zum Umgang mit peripheren Nerven nach Extremitätenamputation.

Material und Methoden

Es erfolgt eine Literaturrecherche bzgl. chirurgischer Prophylaxe und Therapie von Neurom- und Phantomschmerzen, sowie zu Techniken zur Verbesserung der funktionellen Schnittstelle zwischen Stumpf und Prothese. Anhand relevanter Arbeiten sowie der Erfahrungen der Autoren werden entsprechende Empfehlungen formuliert.

Ergebnisse und Diskussion

Es gibt eine große Anzahl an verschiedenen Operationstechniken, insbesondere im Umgang mit schmerzhaften Neuromen. Von den klassischen Verfahren findet besonders häufig die intramuskuläre Verlagerung der endständiger Nerven Anwendung. Neuere Techniken wie Targeted Muscle Reinnervation (TMR) und Regenerative Peripheral Nerve Interface (RPNI) zielen erstmals darauf ab, dem Nerven auch nach Amputation funktionelle Endorgane zu liefern. Neben der verbesserten Steuerung myoelektrischer Prothesen zeigen diese Verfahren auch exzellente Ergebnisse in Bezug auf Neurom- und Phantomschmerzen.

Regenerative peripheral nerve interface free muscle graft mass and function

BACKGROUND

Regenerative peripheral nerve interfaces (RPNIs) transduce neural signals to provide high-fidelity control of neuroprosthetic devices. Traditionally, rat RPNIs are constructed with ~150 mg of free skeletal muscle grafts. It is unknown whether larger free muscle grafts allow RPNIs to transduce greater signal.

METHODS

RPNIs were constructed by securing skeletal muscle grafts of various masses (150, 300, 600, or 1200 mg) to the divided peroneal nerve. In the control group, the peroneal nerve was transected without repair. Endpoint assessments were conducted 3 mo postoperatively.

RESULTS

Compound muscle action potentials (CMAPs), maximum tetanic isometric force, and specific muscle force were significantly higher for both the 150 and 300 mg RPNI groups compared to the 600 and 1200 mg RPNIs. Larger RPNI muscle groups contained central areas lacking regenerated muscle fibers.

CONCLUSIONS

Electrical signaling and tissue viability are optimal in smaller as opposed to larger RPNI constructs in a rat model.

Resolution of persistent traumatic supraorbital pain after neuroma excision

We describe a case of an 18-year-old male who developed a supraorbital neuroma following facial trauma that occurred 2 years earlier. He presented with complaints of persistent facial pain and migraines despite successful laceration repair and removal of foreign bodies at the time of injury. A non-contrast computed tomography (CT) scan of the orbits revealed an enlarged supraorbital nerve with remodeling and expansion of the supraorbital notch, suggesting a neuroma. The patient underwent orbitotomy with excision of neuroma (confirmed histologically) and experienced a complete resolution of periorbital pain.

Risk Factors for Neuropathic Pain Following Major Upper Extremity Amputation

BACKGROUND

 Active treatment (targeted muscle reinnervation [TMR] or regenerative peripheral nerve interfaces [RPNIs]) of the amputated nerve ends has gained momentum to mitigate neuropathic pain following amputation. Therefore, the aim of this study is to determine the predictors for the development of neuropathic pain after major upper extremity amputation.

METHODS

 Retrospectively, 142 adult patients who underwent 148 amputations of the upper extremity between 2000 and 2019 were identified through medical chart review. All upper extremity amputations proximal to the metacarpophalangeal joints were included. Patients with a follow-up of less than 6 months and those who underwent TMR or RPNI at the time of amputation were excluded. Neuropathic pain was defined as phantom limb pain or a symptomatic neuroma reported in the medical charts at 6 months postoperatively. Most common indications for amputation were oncology (n = 53, 37%) and trauma (n = 45, 32%), with transhumeral amputations (n = 44, 30%) and shoulder amputations (n = 37, 25%) being the most prevalent.

RESULTS

 Neuropathic pain occurred in 42% of patients, of which 48 (32%) had phantom limb pain, 8 (5.4%) had a symptomatic neuroma, and 6 (4.1%) had a combination of both. In multivariable analysis, traumatic amputations (odds ratio [OR]: 4.1, p = 0.015), transhumeral amputations (OR: 3.9, p = 0.024), and forequarter amputations (OR: 8.4, p = 0.003) were independently associated with the development of neuropathic pain.

CONCLUSION

 In patients with an upper extremity amputation proximal to the elbow or for trauma, there is an increased risk of developing neuropathic pain. In these patients, primary TMR/RPNI should be considered and this warrants a multidisciplinary approach involving general trauma surgeons, orthopaedic surgeons, plastic surgeons, and vascular surgeons.

Out of the Clinic, into the Home: The in-Home Use of Phantom Motor Execution Aided by Machine Learning and Augmented Reality for the Treatment of Phantom Limb Pain

Purpose

Phantom motor execution (PME) facilitated by augmented/virtual reality (AR/VR) and serious gaming (SG) has been proposed as a treatment for phantom limb pain (PLP). Evidence of the efficacy of this approach was obtained through a clinical trial involving individuals with chronic intractable PLP affecting the upper limb, and further evidence is currently being sought with a multi-sited, international, double blind, randomized, controlled clinical trial in upper and lower limb amputees. All experiments have been conducted in a clinical setting supervised by a therapist. Here, we present a series of case studies (two upper and two lower limb amputees) on the use of PME as a self-treatment. We explore the benefits and the challenges encountered in translation from clinic to home use with a holistic, mixed-methods approach, employing both quantitative and qualitative methods from engineering, medical anthropology, and user interface design.

Patients and Methods

All patients were provided with and trained to use a myoelectric pattern recognition and AR/VR device for PME. Patients took these devices home and used them independently over 12 months.

Results

We found that patients were capable of conducting PME as a self-treatment and incorporated the device into their daily life routines. Use patterns and adherence to PME practice were not only driven by the presence of PLP but also influenced by patients' perceived need and social context. The main barriers to therapy adherence were time and availability of single-use electrodes, both of which could be resolved, or attenuated, by informed design considerations.

Conclusion

Our findings suggest that adherence to treatment, and thus related outcomes, could be further improved by considering disparate user types and their utilization patterns. Our study highlights the importance of understanding, from multiple disciplinary angles, the tight coupling and interplay between pain, perceived need, and use of medical devices in patient-initiated therapy.

Surgery for lower extremity symptomatic neuroma: Long-term outcomes

INTRODUCTION

Traumatic neuroma caused by injuries or surgery can result in neuropathic pain, functional impairment, and psychological distress, which has an impact on quality of life. The aim of this study was to identify the factors related to successful treatment of symptomatic lower extremity symptomatic neuromas using patient-reported outcome measures (PROMs).

METHODS

Thirty-two patients with 48 symptomatic neuromas completed the PROMIS mobility, PROMIS pain interference (PI), Numeric Rating Scale (NRS) for pain (0-10) for both pre- and post-operative pain, and the PROMIS depression at a mean of 8.9±4.5 years following neuroma surgery. Neuromas were located around the foot and ankle (n=18, 38%), leg (n=14, 29%), around the knee (n=13, 27%), and in the thigh (n=3, 6.3%). Surgical treatment included neuroma excision and implantation (n=29, 60%) followed by neuroma excision alone or excision with placement in the subcutaneous tissue (n=12, 25%). We performed multivariable analysis to identify the factors influencing the PROMs.

RESULTS

Patients reported significant reduction in mean NRS pain after surgery (7.3 vs 4.9, p=0.0013). Higher PROMIS depression scores were independently associated with inferior PROMIS mobility scores (β=-0.38, p=0.001), higher PROMIS PI scores (β=0.68, p<0.001), and higher NRS pain scores (β=0.1, p=0.001). Additionally, smoking was independently associated with higher NRS pain scores (β=1.59, p=0.049) CONCLUSION: Surgical treatment of symptomatic neuromas of the lower extremity provides a long-term improvement in 59% of patients, but 19% of patients still reported severe persistent pain despite surgical treatment. Smoking and negative mood have negative effects on patient-reported outcomes after neuroma surgery.

Restoring Finger-Specific Sensory Feedback for Transradial Amputees via Non-Invasive Evoked Tactile Sensation

Objective: This study assessed the feasibility to restore finger-specific sensory feedback in transradial amputees with electrical stimulation of evoked tactile sensation (ETS). Methods: Here we investigated primary somatosensory cortical (SI) responses of ETS using Magnetoencephalography. Results: SI activations revealed a causal correlation with peripheral stimulation of projected finger regions on the stump skin. Peak latency was accountable to neural transmission from periphery to SI. Peak intensity of SI response was proportional to the strength of peripheral stimulation, manifesting a direct neural pathway from skin receptors to SI neurons. Active regions in SI at the amputated side were consistent to the finger/hand map of homunculus, forming a mirror imaging to that of the contralateral hand. With sensory feedback, amputees can recognize a pressure at prosthetic fingers as that at the homonymous lost fingers. Conclusions: Results confirmed that the direct neural pathway from periphery to SI allows effective communication of finger-specific sensory information to these amputees.

A Surgical Approach to Treat Painful Neuromas of the Supraorbital and Supratrochlear Nerves with Implantation of the Proximal Stump into the Orbit

Frontal neuralgia causally related to trauma to the supraorbital and supratrochlear nerves remains a difficult problem to resolve. A peripheral nerve approach to this problem would involve neuroma resection and relocation of the proximal nerve stump to a location away from the vulnerable supraorbital ridge. A retrospective chart review was done to identify patients with frontal pain related to supraorbital trauma who underwent operative interventions to solve this problem by neuroma resection and relocation of the proximal stumps into the orbit. Eight patients were identified for inclusion in this study. At a mean of 16 months after surgery, there was a significant change in the visual analog score from a mean of 9.4 to 2.8 ( p  < 0.05), with 88% of the patients reporting a >50% reduction in pain postoperatively. There was one treatment failure. There were no postoperative complications. The strategy of relocating the proximal end of the supraorbital and supratrochlear nerves into the posterior orbit after resecting the painful neuromas can successfully manage posttraumatic craniofacial pain related to these injured nerves.