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

Surgical treatment of painful neuroma in amputated and non-amputated patients: does the level of neurotomy affect clinical outcomes?

PURPOSE

To compare the outcomes of distal neurotomy (DN) versus proximal neurotomy (PN) for the surgical management of painful neuromas in amputees and non-amputees, whether used in passive or active treatment.

METHODS

A retrospective study was conducted on patients who underwent surgery for painful traumatic neuromas between 2019 and 2022. DN with neuroma excision was performed at the level of the injury or amputation. PN was performed using a separate proximal approach without neuroma excision. Outcomes included a Numerical Rating Scale (NRS) score and Patient-Reported Outcomes Measurement Information System (PROMIS) scores, as well as patients' subjective assessments.

RESULTS

A total of 33 patients were included: 17 amputees and 16 non-amputees. They totalized 43 neuromas treated by DN in 21 cases and PN in 22 cases. At the median follow-up time of 13 months, there were significant decreases in all NRS and PROMIS scores in the whole series. The decrease in limb pain scores was not significantly different between groups, except for the decrease in pain interference and patient satisfaction which were higher in the DN group. Sub-group analyses found the same significant differences in amputees. Targeted muscle reinnervation (TMR) was associated with a higher decrease in PROMIS scores.

CONCLUSION

DN seemed to give better results in amputees but there were confusing factors related to associated lesions. In other situations, the non-inferiority of PN was demonstrated. PN could be of interest for treating neuromas of superficial sensory nerves, for avoiding direct revision of a well-fitted stump and in conjunction with TMR.

Anatomy of the Superficial Radial Nerve and Its Target Nerves for Targeted Muscle Reinnervation: An Anatomical Cadaver Study

BACKGROUND

Targeted muscle reinnervation (TMR) is a surgical procedure for treating symptomatic neuroma, in which the neuroma is removed and the proximal nerve stump is coapted to a donor motor branch innervating a nearby muscle. This study aimed to identify optimal motor targets for TMR of the superficial radial nerve (SRN).

METHODS

Seven cadaveric upper limbs were dissected to describe the course of the SRN in the forearm and motor nerve supply-number, length, diameter, and entry points in muscle of motor branches-for potential recipient muscles.

RESULTS

The radial nerve provided three (three of six) motor branches, two (two of six) motor branches, or one (one of six) motor branch to the brachioradialis muscle, entering the muscle 21.7 ± 17.9 to 10.8 ± 15 mm proximal to the lateral epicondyle. One (one of seven), two (three of seven), three (two of seven), or four (one of seven) motor branches innervated the extensor carpi radialis longus muscle, with entry points 13.9 ± 16.2 to 26.3 ± 14.9 mm distal from the lateral epicondyle. In all specimens, the posterior interosseous nerve gave off one motor branch to the extensor carpi radialis brevis, which divided into two or three secondary branches. The distal anterior interosseus nerve was assessed as a potential recipient for TMR coaptation and had a freely transferable length of 56.4 ± 12.7 mm.

CONCLUSIONS

When considering TMR for neuromas of the SRN in the distal third of the forearm and hand, the distal anterior interosseus nerve is a suitable donor target. For neuromas of the SRN in the proximal two-thirds of the forearm, the motor branches to the extensor carpi radialis longus, extensor carpi radialis brevis, and brachioradialis are potential donor targets.

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.

Use of Supinator Motor Branches in Targeted Muscle Reinnervation of the Superficial Radial Nerve

Symptomatic neuromas of the superficial radial nerve (SRN) can cause debilitating pain. Traditional surgical management options have demonstrated inconsistent outcomes prompting a search for alternatives. Recent reports have emerged on the use of targeted muscle reinnervation (TMR) for neuromas of the SRN using donors that are well established in hand surgery, such as the brachioradialis (BR) or extensor capri radialis longus or brevis. Use of the brachioradialis or extensor capri radialis longus motor targets can require surgery at or above the level of the antecubital fossa, and denervation of these muscle groups may be undesirable in cases of complex upper extremity injury where these donors may be needed for tendon or nerve transfer. The supinator is an expendable and often overlooked donor nerve that has not been assessed as a target for TMR of the SRN. In this case series, three patients with SRN neuromas whose conservative management failed and who did not have an SRN lesion amenable to reconstruction were managed with TMR to the nerves to supinator. At latest follow-up (9-22 months), no patients had deficits in supination or evident donor site morbidity. Two patients reported complete resolution of their SRN neuroma pain, and one patient reported partial improvement. This case series reports early results of TMR of the SRN using nerves to supinator in cases of SRN neuromas not amenable to reconstruction, demonstrating technical feasibility, improvements in neuroma pain, and no discernible donor morbidity.

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.

Targeted muscle reinnervation in upper extremity amputations

PURPOSE

Targeted muscle reinnervation (TMR) is a relatively recent surgical innovation that involves the coaptation of major peripheral nerves to a recipient motor branch that innervates an expendable muscle target. The original indication for TMR was augmentation and optimization of myoelectric signals in the amputated limb for use of myoelectric prosthetics. Incidentally, surgeons and patients discovered that the technique also could treat and prevent phantom and residual limb pain. TMR is performed at the time of amputation or delayed any time after the amputation, and TMR can also be performed at any level of amputation. In the upper extremity, studies have detailed the various techniques and coaptations possible at each amputation level to create intuitive myoelectric signals and treat neurogenic pain. Treatment of peripheral nerves in the amputee with TMR should be a consideration for all patients with major upper extremity amputations, especially at large institutions able to support multidisciplinary limb salvage teams. This review article summarizes the current literature and authors' techniques and recommendations surrounding TMR in the upper extremity amputee including techniques relevant to each level of upper extremity amputation.

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.

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.

Pronator Quadratus: A Preferable Recipient for Targeted Muscle Reinnervation of Neuromas in the Hand

Targeted muscle reinnervation (TMR) has emerged as a useful solution to the problem of painful neuromas and is increasingly being applied in many clinical circumstances. Relatively little has been written about TMR for painful neuromas of the hand, and what has been written describes use of the intrinsic muscles as recipients for the nerve transfer. Except in cases of amputation, intrinsic muscle sacrifice carries morbidity. Furthermore, TMR to intrinsic muscles will place the nerve coaptation in areas subject to pressure with loading of the palm. For these reasons, the pronator quadratus may be a preferable target muscle when performing TMR for painful neuromas of the hand. In this report, we describe the rationale for its use and demonstrate the surgical technique and outcomes with case examples.

Targeted muscle reinnervation for a recurrent traumatic neuroma of the sural nerve: illustrative case

BACKGROUND

Traumatic neuromata often recur after resection. Recently, targeted muscle reinnervation (TMR) has been shown to be a promising alternative for the treatment of traumatic neuroma, also in nonamputees. This case shows that TMR can also be applied for this indication in recurrent traumatic neuroma.

OBSERVATIONS

A 55-year-old patient with a history of cerebral palsy presented with a painful swelling in his right knee, 40 years after multiple Achilles tendon surgeries for contractures. On imaging, the lesion was suspect for a traumatic neuroma of the posterior sural nerve. After two failed resections, TMR was performed by connecting the proximal end of the sural nerve to the motor branch of the lateral gastrocnemius muscle. During outpatient visits at 3, 6, and 12 months, the patient reported significantly less pain compared to before the TMR. He had no weakness of plantar flexion. Postoperative imaging, however, showed atrophy of the lateral gastrocnemius muscle.

LESSONS

This case shows that TMR can be a successful strategy to treat recurrent traumatic neuroma after previous failed transection of single neuromata in nonamputee cases. In the authors’ patient, TMR did not result in motor deficit, but more research is needed to investigate this consequence of TMR for this indication.

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.

Challenges and Potential in Targeted Muscle Reinnervation in Pediatric Amputees

Targeted muscle reinnervation (TMR) is a powerful new tool in preventing and treating residual limb and phantom limb pain. In the adult population, TMR is rapidly becoming standard of care; however, there is a paucity of literature regarding indications and outcomes of TMR in the pediatric population. We present 2 cases of pediatric patients who sustained amputations and the relevant challenges associated with TMR in their cases. One is a 7-year-old patient who developed severe phantom and residual limb pain after a posttraumatic above-knee amputation. He failed pharmacologic measures and underwent TMR. He obtained complete relief of his symptoms and is continuing to do well 1.5 years postoperatively. The other is a 2-year-old boy with bilateral wrist and below-knee amputations as sequelae of sepsis. TMR was not performed because the patient never demonstrated evidence of phantom limb pain or symptomatic neuroma formation. We use these 2 cases to explore the challenges particular to pediatric patients when considering treatment with TMR, including capacity to report pain, risks of anesthesia, and cortical plasticity. These issues will be critical in determining how TMR will be applied to pediatric patients.