Targeted Muscle Reinnervation as a Solution for Nerve Pain

Targeted Muscle Reinnervation: Factors Predisposing to Successful Pain Score Reduction

BACKGROUND

Targeted muscle reinnervation (TMR) has demonstrated efficacy in reducing neuroma and chronic pain. In this article, we investigated postoperative outcomes in our patient cohort, with a focus on the role of nonmodifiable factors such as patient age and gender.

METHODS

Patients who had extremity TMR from April 2018 to October 2022 were reviewed. Outcomes of interest included patient age, gender, cause and type of amputation, delayed versus immediate TMR, as well as postoperative improvement in pain as assessed by numerical rating score (NRS).

RESULTS

A total of 40 patients underwent TMR on 47 limbs. Mean age was 46.2 ± 17.0 years. Delayed TMR (27, 57.4%) was most commonly performed, followed by immediate and delayed-immediate at 11 (23.4%) and 9 (19.1%), respectively. Amputation level was most commonly above-knee in 20 (42.6%) patients, followed by below-knee (12, 25.5%), transhumeral (8, 17.0%), transradial (6, 12.8%), and shoulder (1, 2.1%). The median time interval between amputation and TMR was 12 months. The median preoperative NRS assessing residual limb pain (RLP) for patients who underwent delayed TMR was 10. The median postoperative NRS assessing RLP for all patients was 0 (interquartile range25-75: 0-5) and significantly improved compared with preoperative NRS (P < 0.001). At the last follow-up for limbs that had delayed and delayed-immediate TMR (n = 36), 33 (91.7%) limbs had more than 50% resolution of RLP. There was a significant difference in median postoperative NRS by gender (4 in men and 0 in women) (P < 0.05). Postoperative median NRS also favored younger patients (0, <50 years compared with 4.5, >50 years) (P < 0.05). Multiple linear regression analysis showed that, of different variables analyzed, only male gender and older age were predictive of poorer postoperative outcomes.

CONCLUSION

TMR showed high efficacy in our cohort, with improved short-term outcomes in women and younger patients.

The effectiveness of targeted muscle reinnervation in reducing pain and improving quality of life for patients following lower limb amputation

BACKGROUND

Globally, over 1 million lower limb amputations are performed annually, with approximately 75% of patients experiencing significant pain, profoundly impacting their quality of life and functional capabilities. Targeted muscle reinnervation (TMR) has emerged as a surgical solution involving the rerouting of amputated nerves to specific muscle targets. Originally introduced to enhance signal amplification for myoelectric prosthesis control, TMR has expanded its applications to include neuroma management and pain relief. However, the literature assessing patient outcomes is lacking, specifically for lower limb amputees. This systematic review aims to assess the effectiveness of TMR in reducing pain and enhancing functional outcomes for patients who have undergone lower limb amputation.

METHODS

A systematic review was performed by examining relevant studies between 2010 and 2023, focusing on pain reduction, functional outcomes and patient-reported quality of life measures.

RESULTS

In total, 20 studies were eligible encompassing a total of 778 extremities, of which 75.06% (n = 584) were lower limb amputees. Average age was 46.66 years and patients were predominantly male (n = 70.67%). Seven studies (35%) reported functional outcomes. Patients who underwent primary TMR exhibited lower average patient-reported outcome measurement information system (PROMIS) scores for phantom limb pain (PLP) and residual limb pain (RLP). Secondary TMR led to improvements in PLP, RLP and general limb pain as indicated by average numeric rating scale and PROMIS scores.

CONCLUSION

The systematic review underscores TMR's potential benefits in alleviating pain, fostering post-amputation rehabilitation and enhancing overall well-being for lower limb amputees.

Combined Targeted Muscle Reinnervation With Regenerative Peripheral Nerve Interfaces Decreases Long-Term Narcotic Use in Amputees: A Case Control Study

PURPOSE

Combined targeted muscle reinnervation with regenerative peripheral nerve interfaces ("TMRpni") is a recently described nerve management strategy that leverages beneficial elements of targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) techniques. This study aimed to evaluate the effect of TMRpni on long-term opioid consumption after amputation. We hypothesize that TMRpni decreases chronic opioid consumption in amputees.

METHODS

This is a retrospective cohort study of all patients who underwent TMRpni between 2019 and 2021. These patients were age-matched at a 1:1 ratio with a control group of patients who underwent amputation without TMRpni. Statistical analysis was performed using SPSS Version 28.0.

RESULTS

Thirty-one age-matched pairs of patients in the TMRpni and control groups were included. At 30 days after surgery, there was no significant difference in number of patients who required an additional refill of their opioid prescriptions (45% vs 55%, P = 0.45) or patients who continued to actively use opioids (36% vs 42%, P = 0.60). However, at 90 days after surgery, there was a significantly lower number of patients from the TMRpni group who reported continued opioid use compared with the control group (10% vs 32%, P = 0.03).

CONCLUSIONS

This study demonstrates that TMRpni may translate to decreased rates of chronic opiate use. Continued study is indicated to optimize TMRpni techniques and patient selection and to determine its long-term efficacy.

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.

Targeted muscle reinnervation in upper extremity amputation in military hand surgery: A systematic review

INTRODUCTION

Targeted Muscle Reinnervation (TMR) is a surgical technique utilized to alleviate post-amputation neuroma pain, reduce reliance on narcotic pain medication, and enhance control of prosthetic devices. Motor targets for upper extremity TMR vary depending on injury patterns and amputation levels, with conventional transfer patterns serving as general guides. This study aims to summarize the common patterns of TMR in transradial and transhumeral amputations, focusing on anatomic and surgical considerations.

METHODS

A comprehensive systematic review of TMR literature was conducted by two independent physician reviewers (M.H.A. and D.M.G.R.) to identify the prevailing motor targets, while considering injury patterns and amputation levels.

INCLUSION CRITERIA

1) TMR techniques, outcomes, or advancements; 2) Original research, systematic reviews, meta-analyses, or clinical trials; 3) Peer-reviewed journal articles or reputable conference proceedings.

EXCLUSION CRITERIA

non-English resources, editorials, opinion pieces, and case reports. The databases utilized include MEDLINE (PubMed), EMBASE (Scopus) and Cochrane CENTRAL, last searched 01APR2023.

RESULTS

The reviewed literature revealed multiple motor targets described for upper extremity TMR out of our included 51 studies. However, the selection of motor targets is influenced by the availability of viable options based on injury patterns and amputation levels. Conventional transfer patterns provide useful guidance for determining appropriate motor targets in transradial and transhumeral amputations.

DISCUSSION

TMR has played a significant role in military medicine, particularly in addressing the impact of blast-related injuries. The energy associated with such injuries often results in substantial soft tissue defects, higher amputation levels, and increased post-amputation pain. TMR, in conjunction with advancements in prosthetic technology and ongoing military research, offers improved outcomes to help achieve the goals of active-duty service members. The capabilities and applications of TMR continue to expand rapidly due to its high surgical success rate, technological innovations in prosthetic care, and favorable patient outcomes. As technology evolves to include implantable devices, osseointegration techniques, and bidirectional neuroprosthetic devices, the future of amputation surgery and TMR holds immense promise, offering innovative solutions to optimize patient outcomes. It is important to note, this review was limited to the data available in the included resources which was mostly qualitative; thus, it did not involve primary data analysis.

Neuromas cause severe residual problems at long-term despite surgery

Pain, and disabilities after neuroma surgery, using patient reported outcome measurements (PROMs), were evaluated by QuickDASH and a specific Hand Questionnaire (HQ-8). The 69 responding individuals (response rate 61%; 59% women; 41% men; median follow up 51 months) reported high QuickDASH score, pain on load, cold sensitivity, ability to perform daily activities and sleeping difficulties. Individuals reporting impaired ability to perform daily activities and sleeping problems had higher scores for pain, stiffness, weakness, numbness/tingling, cold sensitivity and QuickDASH. Only 17% of individuals reported no limitations at all. No differences were observed between sexes. Surgical methods did not influence outcome. Symptoms and disabilities correlated moderately-strongly to each other and to ability to perform regular daily activities as well as to sleeping difficulties. Pain, cold sensitivity, sleeping difficulties and limitation to perform daily activities were associated to higher QuickDASH. A weak association was found between follow up time and QuickDASH score as well as pain on load, but not cold sensitivity. A major nerve injury was frequent among those with limitations during work/performing other regular daily activities. Despite surgical treatment, neuromas cause residual problems, which affect the capacity to perform daily activities and ability to sleep with limited improvement in long-term.

Surgical treatments for postamputation pain: study protocol for an international, double-blind, randomised controlled trial

BACKGROUND

Painful conditions such as residual limb pain (RLP) and phantom limb pain (PLP) can manifest after amputation. The mechanisms underlying such postamputation pains are diverse and should be addressed accordingly. Different surgical treatment methods have shown potential for alleviating RLP due to neuroma formation - commonly known as neuroma pain - and to a lesser degree PLP. Two reconstructive surgical interventions, namely targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI), are gaining popularity in postamputation pain treatment with promising results. However, these two methods have not been directly compared in a randomised controlled trial (RCT). Here, we present a study protocol for an international, double-blind, RCT to assess the effectiveness of TMR, RPNI, and a non-reconstructive procedure called neuroma transposition (active control) in alleviating RLP, neuroma pain, and PLP.

METHODS

One hundred ten upper and lower limb amputees suffering from RLP will be recruited and assigned randomly to one of the surgical interventions (TMR, RPNI, or neuroma transposition) in an equal allocation ratio. Complete evaluations will be performed during a baseline period prior to the surgical intervention, and follow-ups will be conducted in short term (1, 3, 6, and 12 months post-surgery) and in long term (2 and 4 years post-surgery). After the 12-month follow-up, the study will be unblinded for the evaluator and the participants. If the participant is unsatisfied with the outcome of the treatment at that time, further treatment including one of the other procedures will be discussed in consultation with the clinical investigator at that site.

DISCUSSION

A double-blind RCT is necessary for the establishment of evidence-based procedures, hence the motivation for this work. In addition, studies on pain are challenging due to the subjectivity of the experience and the lack of objective evaluation methods. Here, we mitigate this problem by including different pain evaluation methods known to have clinical relevance. We plan to analyse the primary variable, mean change in NRS (0-10) between baseline and the 12-month follow-up, using the intention-to-treat (ITT) approach to minimise bias and keep the advantage of randomisation. The secondary outcomes will be analysed on both ITT and per-protocol (PP). An adherence protocol (PP population) analysis will be used for estimating a more realistic effect of treatment.

TRIAL REGISTRATION

ClincialTrials.gov NCT05009394.

Targeted Muscle Reinnervation: A Systematic Review of Nerve Transfers for the Upper Extremity

INTRODUCTION/BACKGROUND

Despite inspiring improvements in postamputation pain and prosthetic control, targeted muscle reinnervation (TMR) continues to be underused. With some consistency for recommended nerve transfers developing in the literature, it is necessary to systematize these techniques and simplify their incorporation into routine amputation and neuroma care. This systematic review explores the coaptations reported in the literature to date.

METHODS

A systematic review of the literature was performed to collect all reports describing nerve transfers in the upper extremity. The preference was directed toward original studies presenting surgical techniques and coaptations used in TMR. All target muscle options were presented for each nerve transfer in the upper extremity.

RESULTS

Twenty-one original studies describing TMR nerve transfers throughout the upper extremity met inclusion criteria. A comprehensive list of transfers reported for major peripheral nerves at each upper extremity amputation level was included in tables. Ideal nerve transfers were suggested based on convenience and frequency with which certain coaptations were reported.

CONCLUSIONS

Increasingly frequent studies are published with convincing outcomes with TMR and numerous options for nerve transfers and target muscles. It is prudent to appraise these options to provide patients with optimal outcomes. Certain muscles are more consistently targeted and can serve as a baseline plan for the reconstructive surgeon interested in incorporating these techniques.

Demystifying Targeted Muscle Reinnervation: A Systematic Review of Nerve Transfers for the Lower Extremity

Targeted muscle reinnervation (TMR) outcome studies reveal the benefit amputees experience and the potential functional improvement by optimizing neurocutaneous signaling for myoelectric prosthesis control. However, there are still many settings where these techniques are not offered to patients requiring lower extremity amputations or neuroma reconstruction. With growing consistency in the literature, it is helpful to systematize the nerve transfers described for lower extremity TMR and to simplify its integration into reconstructive care.

Methods

A systematic literature review was performed and contained the following inclusion criteria: original cases of primary or secondary lower extremity amputation defects or nerve-related pain that underwent TMR with clearly described target muscles for each nerve transfer. Studies were excluded if the cases had been previously described or contained incomplete data. The primary outcomes were nerves transferred and muscles targeted. Target muscle options were presented in tables specific to anatomic region, and cross-sectional schematics were created for intraoperative assistance.

Results

Seventeen studies presenting original cases with clearly described nerve transfers and target muscles in the lower extremity were included in the review. Target muscle selection for all nerve transfers at the transfemoral and transtibial levels were presented in separate tables.

Conclusions

Reports of early experience at multiple institutions identify trends in the selection of certain target muscles for nerve transfers in transfemoral and transtibial TMR. Familiarity with these common target muscles and nerve transfers can simplify intraoperative decision-making and enhance integration of lower extremity TMR in amputation care and in the treatment of nerve-related pain.

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.

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.

Targeted muscle reinnervation in above knee amputation: surgical technique

In the United States, an estimated 185,000 individuals undergo amputation of their upper or lower limb. This results in residual limb pain in up to 85% of cases. Targeted muscle reinnervation (TMR) is a technique that has been shown to prevent symptomatic neuroma formation. In this video, the authors demonstrate their technique utilizing TMR at the time of above-the-knee amputation. Coaptations are made to provide motor targets for branches of the saphenous, tibial, and peroneal sensory nerves. At the featured patient's most recent follow-up visit 3 months postoperatively, she reported no stump pain or phantom limb pain. The video can be found here: https://stream.cadmore.media/r10.3171/2022.10.FOCVID2293.

Practical Strategies in Reconstruction of Soft-Tissue Sarcoma

LEARNING OBJECTIVES

After studying this article, the participant should be able to: 1. Discuss the natural history and pathophysiology of sarcoma. 2. Summarize the most up-to-date multidisciplinary management of soft-tissue sarcoma. 3. Provide a synopsis of reconstructive modalities based on anatomical location. 4. Highlight some novel strategies for treatment of lymphedema and phantom limb pain that are common sequelae following treatment and resection of soft-tissue sarcomas.

SUMMARY

The management of soft-tissue sarcoma presents unique challenges to the reconstructive surgeon. The optimal management mandates a multidisciplinary approach; however, reconstruction must take into account the extent of the resection and exposed vital structures, but often occurs in the setting of adjuvant treatments including chemotherapy and radiation therapy. Reconstruction is based on the extent of the defect and the location of the primary tumor. As such, an evidence-based, algorithmic approach following the reconstructive ladder is warranted to minimize the risks of complications and maximize success, which varies from head and neck to torso to breast to extremity sarcomas. Aside from reconstruction of the defect, advances in the surgical treatment of lymphedema and neuropathic pain resulting from treatment and extirpation of soft-tissue sarcoma are critical to maintain function and patients' quality of life.

Targeted Muscle Reinnervation of the Supraclavicular Nerve to the Motor Branch of the Omohyoid Muscle in Patients Undergoing Thoracic Outlet Syndrome Procedures

Transection of the supraclavicular nerve (SCN) through supraclavicular incisions can lead to debilitating neuroma formation. Targeted muscle reinnervation (TMR) proved to be an effective technique for the prevention and treatment of neuroma. In this case series, we propose the TMR of the SCN to the motor branch of the omohyoid muscle (OM) to prevent the formation of neuroma and avoid chronic pain at the supraclavicular area after thoracic outlet syndrome (TOS) procedures. A total of 10 patients underwent the procedure. Dissection of the SCN and its branches was performed through a supraclavicular incision. The branches were transected close to the clavicle. The inferior belly of the OM was identified and its motor branch isolated. Coaptation of the SCN branches with the motor branch of the OM was performed under the microscope and the wound was closed in layers. All the patients denied pain or hypersensitivity at the supraclavicular area on follow-up. In summary, the motor branch of the OM is a viable recipient for the TMR of the SCN and can prevent and treat painful neuromas at the supraclavicular area with minimal morbidity.

Failed Targeted Muscle Reinnervation: Findings at Revision Surgery and Concepts for Success

Although it was initially described for improved myoelectric control, targeted muscle reinnervation (TMR) has quickly gained popularity as a technique for neuroma control. With this rapid increase in utilization has come broadening indications and variability in the described technique. As a result, it becomes difficult to interpret published outcomes. Furthermore, there is no literature discussing the management of failed cases which are undoubtedly occurring.

Trigeminal Traumatic Neuroma: a Comprehensive Review of the Literature Based On a Rare Case

PURPOSE OF REVIEW

Traumatic neuromas in general, and trigeminal traumatic neuromas in particular, are relatively rare entities originating from a damage to a corresponding nerve or its branches. This manuscript is a comprehensive review of the literature on trigeminal traumatic neuromas based on an interesting and challenging case of bilateral intraoral lesions.

RECENT FINDINGS

The diagnosis for this patient was bilateral trigeminal traumatic neuromas. It is possible that these patients have a genetic predisposition to the development of these lesions. It is a neuropathic pain condition and may mimic dental and other trigeminal pain entities. Topical treatment with lidocaine gel, utilizing a custom-made neurosensory stent, rendered the patient significant and sustained pain relief. Trigeminal traumatic neuromas present a diagnostic challenge even to a seasoned clinician, due to the complex clinical features that may mimic other entities. Topical medications such as local anesthetics may be a good viable alternative to systemic medications to manage the pain associated with the condition. Early identification of the lesion and the associated pain helps in the succinct management of symptomatic trigeminal traumatic neuromas.

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.