Muscle Reinnervation Research Articles

Nerve transfer of the median flexor pollicis brevis branch to the deep branch of the ulnar nerve for ulnar nerve palsy: a cadaveric feasibility study.

An ulnar nerve (UN) palsy is devastating for hand function, resulting in an intrinsic minus position or claw hand with a loss of pinch grip. Distal nerve transfers facilitate faster reinnervation of hand intrinsic muscles in cases of proximal ulnar nerve lesions. The traditional anterior interosseous nerve (AIN) to UN motor transfer is commonly used, however, this still leads to long reinnervation times for the distal intrinsic muscles, important for the thumb to index pinch grip. This study investigated the feasibility of a more distal nerve transfer, from the median thenar to the deep branch of the UN (DBUN), in six cadaveric hands. A separate branch of the median nerve to the superficial head of flexor pollicis brevis (sFPB) arose distally of the thenar branch from the common digital nerve of the thumb shortly before the bifurcation of the ulnar palmar digital nerve to the thumb in all specimens, with a mean distance to the thenar branch of 8.3 ± 5.3 mm. The sFPB motor branch had a mean length of 11.5 ± 1.5 mm. The mean distance between the division of the dorsal cutaneous branch of the UN, where the AIN to UN motor transfer is usually performed, and the transfer between the sFPB branch to the DBUN was 132 ± 11 mm. A distal nerve transfer between the median innervated motor branch to the sFPB to the DBUN shortens the reinnervation distance for the first dorsal interosseous, the adductor pollicis, and the deep head of the FPB muscles, which is a prerequisite for restoration of the pinch grip.

FK506 Enhancement of Neuromuscular Junction Recovery After Nerve Injury Is Macrophage-Dependent.

Motor recovery following nerve injury is dependent on time required for muscle reinnervation. This process is imperfect, however, and recovery is often incomplete. At the neuromuscular junction (NMJ), macrophage signaling aids muscle reinnervation. Tacrolimus (FK506) treatment speeds functional recovery through unknown mechanisms. This study investigated whether macrophages were required for FK506 neuroenhancing effects. Wildtype (WT) mice and mice with impaired macrophage recruitment to injury sites (Ccr2-/-) were injected subcutaneously with either saline or FK506 for 3 days prior to sciatic nerve transection and immediate repair and then daily for 4 weeks. Functional recovery was assessed by grid walk and muscle force. Morphometric NMJ and macrophage analyses were conducted in extensor digitorum longus muscles. FK506-injected WT mice showed increased proportions of fully reinnervated NMJs and terminal Schwann cells/NMJ (p < 0.05), improved recovery of tetanic muscle force (p < 0.05), and improved grid walking (p < 0.05) relative to controls. Ccr2-/- mice showed no enhancements in recovery; Ccr2-/- mice treated with FK506 did not differ from controls on any tested metric. We also observed at the NMJ of WT mice increased macrophage numbers with FK506 treatment and increased macrophages expressing FK506 binding protein, FKBP52, after nerve injury. These results show that macrophages are required for FK506-mediated improvements in NMJ reinnervation and muscle function. These data implicate macrophages in the mechanism underlying FK506-mediated enhancement of motor recovery after nerve injury. Enhanced knowledge of the neuroenhancing mechanism of FK506 may identify new clinically relevant therapeutic targets.

Adenosine A2A receptor activation is necessary to gate the TrkB-dependent intramuscular nerve sprouting during muscle reinnervation after a nerve crush

Adenosine A2A receptor activation is necessary to gate the TrkB-dependent intramuscular nerve sprouting during muscle reinnervation after a nerve crush

No penalty for blocking: Preoperative nerve blocks do not prevent motor nerve stimulation during TMR.

The timing of nerve blocks for amputation surgery with immediate targeted muscle reinnervation (TMR) has been disputed. Traditional practices often defer nerve blocks until post-amputation, fearing interference with motor nerve target identification for TMR. Here, we present a case series demonstrating that pre-amputation regional nerve blocks do not prevent the identification of motor nerve targets. Retrospective data from 26 patients undergoing amputation with TMR and pre-operative nerve blocks were analyzed. The results in Tables 1 and 2 showcase successful TMR transfers across various amputation types, with preserved nerve stimulation for TMR despite preoperative regional anesthesia. The findings are supported by existing literature on regional anesthesia's differential blockage mechanism, emphasizing its compatibility with TMR. Moreover, pre-operative nerve blocks have shown efficacy in pain reduction and postoperative complication mitigation, possibly enhancing overall surgical outcomes. This study underscores the feasibility and benefits of integrating pre-amputation nerve blocks with TMR, offering a comprehensive approach to pain management in limb amputation. This technique optimizes both short- and long-term pain control.

Electrical stimulation of injured nerves promotes recovery in animals and humans.

The frequent poor functional outcomes after delayed surgical repair of injured human peripheral nerves results in progressive downregulation of growth-associated genes in parallel with reduced neuronal regenerative capacity under each of the experimental conditions of chronic axotomy of neurones that remain without target contact, chronic distal nerve stump denervation, and chronic muscle denervation. Brief (1h) low-frequency (20Hz) electrical stimulation (ES) accelerates the outgrowth of regenerating axons across the surgical site of microsurgical repair of a transected nerve. Exercise programmes also promote nerve regeneration with the combination of ES and exercise being the most effective. An ES conditioning lesion of intact nerve (CES) accelerates both axonal outgrowth and regeneration rate after the surgical repair of a more distal injury to the nerve, in contrast to ES of a repaired injury nerve that accelerates only the axon outgrowth. A CES accelerates both axonal outgrowth and regeneration rate after the surgical repair of a more distal injury to the nerve, in contrast to ES of a repaired injury nerve that accelerates only the axon outgrowth. The loss of contractility of permanently denervated muscles in cauda equinae-injured patients with accompanying severe loss of muscle mass, disarray of thick and thin contractile filaments, and disorganization of the sarcoplasmic reticulum that controls calcium delivery to the filaments, is alleviated by a 2-year programme of daily ES of the quadriceps muscle. These findings hold promise for recovery and rehabilitation in patients who suffer injury to the neuromuscular system. KEY POINTS: Poor functional outcomes after delayed surgical repair of injured human peripheral nerves are replicated by chronic neuronal axotomy, Schwann cell denervation in a nerve autograft, and muscle denervation. Exponential decline in expression of growth-associated genes accompanies the same decline in regenerative capacity. Brief (1h) low-frequency (20Hz) electrical stimulation (ES) that generates action potential conduction to the neuronal soma accelerates the outgrowth of regenerating axons across the surgical repair site of the transected nerve, even after delayed surgery. The same ES regimen accelerates muscle reinnervation in patients with chronic nerve injury who undergo carpal tunnel syndrome release surgery. A 2-year programme of daily ES of permanently denervated quadriceps muscles in cauda equinae-injured patients reinstated their contractility and organization.

Diagnosis and Management of Neuropathic Breast Pain

Summary: Chronic postoperative pain after breast surgery is a significant concern, with studies indicating varying rates depending on the type of surgical procedure. The risk of developing neuropathic pain is notably increased with axillary lymph node dissection due to potential nerve injuries. Additionally, the method of breast reconstruction may influence postsurgical pain rates, with conflicting findings on the impact of reconstruction type. Recent advancements in techniques such as targeted muscle reinnervation, among others, show promise in addressing postoperative pain in these patients. As the prevalence of these procedures rises, future research is likely to focus on assessing and managing pain in this patient population. The development of patient-reported outcome measures specific to breast surgery pain can aid in clinical assessment and treatment planning. This review emphasizes the importance of gaining a deeper understanding of risk factors, nerve anatomy, and treatment options to enhance outcomes and quality of life for individuals undergoing breast surgery.

Evaluating the Efficacy of Targeted Muscle Reinnervation (TMR) in Extremities Amputations of Pedis Squamous Cell Carcinoma: A Comprehensive Systematic Review, Meta-Analysis, and Meta-regression of Functional and Pain Outcomes

Introduction Targeted Muscle Reinnervation (TMR) is an innovative surgical procedure initially designed for upper-limb amputations, which has shown growing potential for improving functional outcomes in below-knee amputees. TMR involves redirecting severed nerves from the amputated limb to nearby residual muscles, allowing these muscles to act as amplifiers for nerve signals, thereby improving prosthetic control. Recent advancements in TMR for below-knee amputations have highlighted its ability to reduce post-amputation complications, such as neuroma pain and phantom limb pain, while offering enhanced control over prosthetic limbs, thus improving mobility and quality of life. Methods Following PRISMA guidelines, a systematic review was conducted, sourcing studies up to May 2024 from PubMed, Cochrane Library, Scopus, Springer, and Epistemonikos. The analysis included randomized controlled trials (RCTs) and clinical trials. A meta-analysis was performed to assess phantom limb pain reduction, while study quality was evaluated using RoB 2.0, ROBINS-I, and ROBINS-E. Meta-regression examined the influence of variables such as age and sex on pain outcomes. Results Seven studies, including 363 patients, were analyzed. The meta-analysis showed that TMR significantly reduced phantom limb pain (MD: -1.74; 95% CI: -2.46 to -1.02; P&lt;0.00001; I2=0%). However, the pooled risk ratio for phantom pain incidence (RR: 1.58; 95% CI: 0.61 to 4.11; P=0.35; I2=93%) indicated variable outcomes. Conclusion TMR significantly reduces phantom limb pain and improves prosthetic control, particularly for patients with SCC of the foot, ultimately enhancing their quality of life.

Quality, Reliability, and Readability of Peripheral Nerve Intervention Websites for Patients.

This study aims to evaluate the readability, quality, and reliability of online resources about peripheral nerve surgeries to determine if they meet recommended literacy standards. We analyzed a total of 137 peripheral nerve surgery website by performing a Google search using the search terms "nerve transfer," "nerve repair," "nerve graft," "nerve decompression," "neurolysis," "targeted muscle reinnervation," "regenerative peripheral nerve interface," and "vascularized denervated muscle target." The reading level of the website text was assessed using Simple Measures of Gobbledygook, Flesch-Kincaid, and Gunning Fog. Quality was evaluated using the DISCERN Instrument. Reliability was determined using the Journal of American Medical Association Benchmark Criteria. All the websites exceeded the sixth-grade reading level, with median readability scores corresponding to a high school reading level or above. Conceptually harder peripheral nerve surgeries such as targeted muscle reinnervation and regenerative peripheral nerve interface websites were generally written at a significantly higher reading level than conceptually easier surgeries such as nerve repair and nerve graft. The median quality of the websites was rated as poor, and the median reliability of the websites was rated as low. The findings indicate that the current peripheral nerve surgery websites texts do not adhere to recommended reading levels and are constructed with poor quality and low reliability. This potentially hinders patients understanding and utilization of peripheral nerve surgeries, suggesting a need for standardized guidelines to enhance the accessibility of medical information online.

GABA and glycine synaptic release on axotomized motoneuron cell bodies promotes motor axon regeneration.

Motor axon regeneration after traumatic nerve injuries is a slow process that adversely influences patient outcomes because muscle reinnervation delays result in irreversible muscle atrophy and suboptimal axon regeneration. This advocates for investigating methods to accelerate motor axon growth. Electrical nerve stimulation and exercise both enhance motor axon regeneration in rodents and patients, but these interventions cannot always be easily implemented. A roadblock to uncover novel therapeutic approaches based on the effects of activity is the lack of understanding of the synaptic drives responsible for activity-mediated facilitation of axon regeneration. We hypothesized that the relevant excitatory inputs facilitating axon regrowth originate in GABA/glycine synapses which become depolarizing after downregulation of the potassium chloride cotransporter 2 in motoneurons following axotomy. To test this, we injected tetanus toxin (TeTx) in the tibialis anterior (TA) muscle of mice to block the release of GABA/glycine specifically on TA motoneurons. Thereafter, we axotomized all sciatic motoneurons by nerve crush and analyzed the time-courses of muscle reinnervation in TeTx- treated (TA) and untreated (lateral gastrocnemius, LG) motoneurons. Muscle reinnervation was slower in TA motoneurons with blocked GABA/glycine synapses, as measured by recovery of M- responses and anatomical reinnervation of neuromuscular junctions. Post-hoc immunohistochemistry confirmed the removal of the vesicular associated membrane proteins 1 and 2 by TeTx activity, specifically from inhibitory synapses. These proteins are necessary for exocytotic release of neurotransmitters. Therefore, we conclude that GABA/glycine neurotransmission on regenerating motoneurons facilitates axon growth and muscle reinnervation and discuss possible interventions to modulate these inputs on regenerating motoneurons.

Predictive Value of Preoperative Pain Sketches in Lower Extremity Amputees Undergoing Secondary Targeted Muscle Reinnervation for Treatment of Neuropathic Pain.

Targeted Muscle Reinnervation (TMR) is an effective surgical treatment for neuropathic pain in amputees. Qualitative descriptions of pain, depicted by pain sketches, could enhance the understanding of symptomatic improvement following surgery. Our aim is to assess whether pre-operative pain sketches, drawn by lower extremity (LE) amputees, can predict surgical outcomes following Secondary TMR surgery. Eligible patients were LE amputees who underwent Secondary TMR surgery between 2017 and 2023. Pain sketches and pain scores were prospectively collected both before and after surgery. The pain trajectory, as categorized by pre-operative pain sketches, was analyzed and assessed for improvement, defined as reaching the Minimal Clinically Important Difference (MCID). The transition into different pain sketches and the occurrence of phantom drawings were evaluated for their association with improvement. Fifty-eight patients were included, of which 18 (31.1%) depicted diffuse pain (DP), 26 (44.8%) depicted focal pain (FP), and 18 (24.1%) depicted radiating pain (RP) in their pre-operative sketch. FP sketches were associated with the lowest pre- and post-operative pain scores and most frequently developed into sketches indicating "no pain". RP sketches were associated with the least pain improvement, the lowest likelihood of achieving the MCID, and were more prevalent in patients with diabetes or depression. RP sketches were associated with phantom drawings; no other sketch types developed into RP sketches at the final follow-up. In LE amputees who underwent Secondary TMR, pre-operative pain sketches could serve as a helpful tool in predicting pain outcomes. RP sketches seemed to be associated with worse outcomes, and FP sketches with the most improvement.

Early and Late Intrinsic Hand Muscle Reinnervation After End-to-Side AIN to Ulnar Motor Nerve Transfer.

The "supercharge" end-to-side (SETS) anterior-interosseous-nerve (AIN) to ulnar-motor nerve transfer is used to improve intrinsic muscle recovery in cases of severe ulnar nerve compression or proximal axonotmetic injuries. Previous work has found differing intrinsic muscle recovery after this transfer. The objectives of this study were to examine the patterns of recovery in first dorsal interossei (FDI) and abductor digiti minimi (ADM) and the impact of AIN transfer to a specific fascicular location on the ulnar-motor nerve. A retrospective review of one fellowship-trained surgeon's consecutive patients at a single center from December 2019 to September 2021 was conducted. Patients who had an AIN to ulnar-motor nerve transfer for any indication were included and were excluded if they had less than 9 months follow-up. Seventeen patients were included (88% male, mean age 55 ± 14 years). At early follow-up, compound muscle action potential amplitudes for ADM and FDI did not increase. Compound muscle action potential amplitude for ADM significantly increased at late follow-up (P < .01). Average British Medical Research Council (BMRC) strength increased at early follow-up for FDI (P < .05), but not ADM. The proportion of patients with BMRC ≥ 3 increased for FDI (P < .01) and ADM (P < .05) at late follow-up. Volar-ulnar AIN insertion position did not have a clear effect on outcomes. The SETS AIN to ulnar-motor nerve transfer demonstrates clinical and electrophysiologic evidence of intrinsic muscle recovery and reinnervation, with differing recovery of outcomes. The role of specific fascicular targeting is still unclear and required further examination as does the mechanism behind differing intrinsic recovering.

Surgical Treatments for Facial Aberrant Reinnervation Syndrome: A Systematic Review.

Background: Facial aberrant reinnervation syndrome is characterized by aberrant facial muscle reinnervation after facial nerve injury producing facial synkinesis, hypertonicity, and muscle spasm. Objective: To systematically review the surgical treatments for facial aberrant reinnervation syndrome and assess their effectiveness as measured by patient-reported outcomes, physician-graded outcomes, or computer-automated grading systems. Methods: We conducted a systematic review using PubMed, Embase, and Cochrane CENTRAL in accordance with PRISMA guidelines. Texts reporting outcomes of any surgical treatment for facial aberrant reinnervation syndrome from 2003 to 2023 were included. Results: After screening, 25 studies with 731 patients were included. Surgical procedures included selective neurectomy (SN), selective myectomy (SM), cross-facial nerve graft, masseter nerve transfer, and gracilis muscle transfer. All surgical techniques and combinations showed significant improvement in at least one clinical outcome measure from baseline (p < 0.05), although one study found no significant improvement. Thirty different outcome measures were used, the most common being the FaCE and eFACE scales (seven studies each). Conclusions: All surgical procedures in this review yield improved clinical outcome measures for facial aberrant reinnervation syndrome, with SN and SM being the dominant surgical treatments. Standardized outcome assessment and more nuanced patient evaluation are necessary to determine the most effective surgical treatments.

A nanofibrous polycaprolactone/collagen neural guidance channel filled with sciatic allogeneic schwann cells and platelet-rich plasma for sciatic nerve repair.

Sciatic nerve damage, a common condition affecting approximately 2.8% of the US population, can lead to significant disability due to impaired nerve signal transmission, resulting in loss of sensation and motor function in the lower extremities. In this study, a neural guidance channel was developed by rolling a nanofibrous scaffold produced via electrospinning. The scaffold's microstructure, biocompatibility, biodegradation rate, porosity, mechanical properties, and hemocompatibility were evaluated. Platelet-rich plasma (PRP) activated with 30,000 allogeneic Schwann cells (SCs) was injected into the lumen of the channels following implantation into a rat model of sciatic nerve injury. Recovery of motor function, sensory function, and muscle re-innervation was assessed using the sciatic function index (SFI), hot plate latency time, and gastrocnemius muscle wet weight loss. Results showed mean hot plate latency times of Autograft: 7.03, PCL/collagen scaffolds loaded with PRP and SCs (PCLCOLPRPSCs): 8.34, polymer-only scaffolds (PCLCOL): 10.66, and untreated animals (Negative Control): 12.00. The mean SFI values at week eight were Autograft: -49.30, PCLCOLPRPSCs: -64.29, PCLCOL: -75.62, and Negative Control: -77.14. The PCLCOLPRPSCs group showed a more negative SFI compared to the Autograft group but performed better than both the PCLCOL and Negative Control groups. These findings suggest that the developed strategy enhanced sensory and functional recovery compared to the negative control and polymer-only scaffold groups.

Pain Remission Following Delayed Targeted Muscle Reinnervation in Amputees.

Targeted muscle reinnervation (TMR) has demonstrated efficacy for treatment of neuropathic pain. This study aims to identify patients for whom delayed TMR may be most effective and to identify associated factors for favorable pain outcomes in this patient population. An analysis was conducted on prospectively enrolled amputee patients who underwent delayed TMR at a tertiary care center from 2017 to 2024. Data on demographics, comorbidities, surgical details, and pain outcomes were collected. Patient reported pain severity on a 0-10 scale was prospectively collected. The main pain outcome was pain remission (achieving the minimally clinically important difference (MCID)). Additionally, sustained mild pain (pain score ≤ 3/10 for ≥ 3 months), and pain disappearance (pain score 0/10 for ≥ 3 months) were assessed. Multivariable regression analyses identified factors influencing pain outcomes. Out of 101 patients included in this study, 64 patients (63.4%) achieved pain remission within a two-year post-operative period, and 37 patients (36.6%) did not. Sustained mild pain, which could be achieved in addition to pain remission, was achieved by 45.8% of patients, with 17.8% of these achieving complete pain disappearance. Patients achieving pain remission demonstrated lower pain over the entire post-operative trajectory (p < 0.001). Lower pre-operative pain scores, absence of depression, no pre-operative opioid use, lower Elixhauser Comorbidity Index, and distal amputation levels were correlated with favorable outcomes following delayed TMR (p < 0.05). Pre-operative pain severity, psychiatric comorbidities, and opioid use significantly influenced pain outcomes, emphasizing the need for comprehensive patient assessment. These findings will help with patient stratification and pre-operative counseling to support patients who are best suitable for delayed TMR surgery.

How timing and preexisting pain affect outcomes of TMR: a systematic review

Introduction: Targeted muscle reinnervation (TMR) is increasingly common in the care of major limb amputation to limit amputation-related pain. This review aims to elucidate how chronic pain states and length of delay prior to TMR affect its success and outcomes. Methods: Manuscripts were collected from three databases. Articles were first screened and excluded based on exclusion criteria. The remaining manuscripts were independently reviewed to determine inclusion. Article and patient demographics, as well as pain outcomes, were extracted. Data were analyzed based on pain condition, amputation vs. neuroma, and time from amputation/injury to surgery. Results: The literature search yielded 723 articles, with 41 meeting the inclusion criteria. Twenty-one articles included patients with residual limb pain (RLP) and phantom limb pain (PLP), including 14 on amputation and 6 on neuroma excision. Five articles included cancer-related amputation. Complex Regional Pain Syndrome (CRPS) was discussed in 3 articles, ischemia or infection in 2 articles, and neurofibromatosis 1 in 1 article. Twenty-two articles described TMR at the time of amputation. Conclusions: TMR is effective at preventing neuroma formation and limiting pain when performed at the time of amputation. Delayed patients had a greater improvement in RLP but less of an improvement in PLP, when assessed against immediate TMR patients who were compared to non-TMR standard amputees. In the presence of chronic pain states, such as CRPS, there is also improved analgesia. However, current clinical data are limited, indicating a need for further research into the use of TMR for chronic pain management.

Robotic microsurgery for pediatric peripheral nerve surgery

The technology of microsurgical robotic systems has shown potential benefit during the last decade for a variety of microsurgical procedures, such as vascular anastomoses, lymphatic anastomoses or nerve coaptation. At the same time, peripheral nerve surgery has produced ever more sophisticated nerve transfers in which the smallest nerve structures are connected to each other. Following obstetric brachial plexus injuries, nerve reconstruction surgery is often required in the first few years of life in order to improve the function of the affected arm, including nerve transfers to denervated muscles, which enable reinnervation of target muscles. In pediatric patients, these donor-nerve structures are even smaller than in adults, which further increases the demands to the microsurgeon. In this publication, we show the possible applications, capabilities and limitations of a dedicated microsurgical robotic system for nerve transfers in pediatric patients.

Surgical Complications after Targeted Muscle Reinnervation at a Safety-Net Hospital.

Targeted muscle reinnervation (TMR) and regenerative peripheral nerve interface (RPNI) can reduce neuroma formation and phantom limb pain (PLP) after lower extremity (LE) amputation. These techniques have not been studied in safety-net hospitals. This study aims to examine the surgical complication rates after TMR and/or RPNI at an academic safety-net hospital in an urban setting. This was a retrospective review of patients older than 18 years who had prior above-knee guillotine amputation (AKA) or below-knee guillotine amputation (BKA) and underwent stump formalization with TMR and/or RPNI from 2020 to 2022. Demographics, medical history, and operative and postoperative characteristics were collected. The primary outcome was any surgical complication, defined as infection, dehiscence, hematoma, neuroma, or reoperation. Univariate analysis was conducted to identify variables associated with surgical complications and PLP. Thirty-two patients met the inclusion criteria. The median age was 52 years, and 75% were males. Indications for amputation included diabetic foot infection (71.9%), necrotizing soft tissue infection (25.0%), and malignancy (3.1%). BKA was the most common indication for formalization (93.8%). Most patients (56.3%) had formalization with TMR and RPNI, 34.4% patients had TMR only, and 9.4% had RPNI alone. The incidence of postoperative complications was 46.9%, with infection being the most common (31.3%). The median follow-up time was 107.5 days. There was no significant difference in demographics, medical history, or operative characteristics between patients who did and did not have surgical complications. However, there was a trend toward higher rates of PLP in patients who had a postoperative wound infection (p = 0.06). Overall complication rates after LE formalization with TMR and/or RPNI at our academic safety-net hospital were consistent with reported literature. Given the benefits, including reduced chronic pain and lower health care costs, we advocate for the wider adoption of these techniques at other safety-net hospitals.

Targeted Muscle Reinnervation Compared to Standard Peripheral Nerve Management Following Amputation: A Systematic Review and Meta-Analysis.

Chronic pain remains a significant challenge for individuals following limb amputation, with incidence of painful neuromas, phantom limb pain (PLP), and residual limb pain (RLP). Targeted muscle reinnervation (TMR) is a surgical technique designed to restore motor control information lost during amputation by redirecting residual nerves to new muscle targets. This systematic review and meta-analysis aims to compare patient-reported and functional outcomes following amputation with either TMR or standard neurological treatment (SNT). The study also includes an examination of primary versus secondary TMR and explores outcomes in highly comorbid patient populations. A search of central databases was performed, and meta-analysis was completed on extracted data where possible. Eleven studies were identified. Results indicate a significant reduction in PLP and RLP in patients undergoing TMR compared to SNT using various pain scores. TMR also demonstrates improved functional outcomes and decreased opioid use. Furthermore, results indicated patients who underwent TMR at the time of amputation (primary TMR) had improved pain scores compared with those who had TMR performed later (secondary TMR). The review emphasizes the benefits of TMR as a valuable surgical adjunct for amputee patients, while also highlighting the need for further research, especially in comorbid populations.

Outcome of End to Side Nerve Modified Double Oberlin Procedure and End to End Dorsal Approach Spinal Accessory to Suprascapular Nerve in Partial Postganglionic BPI: A Case Report

Introduction: Brachial plexus injury (BPI) is a devastating peripheral nerve injury that mostly affecting young men, often due to motor vehicle accidents. BPIs can be classified into preganglionic and postganglionic lesions, with postganglionic injuries allowing potential nerve regeneration. The Oberlin method, aimed at reinnervating the biceps, and the Mackinnon technique, targeting both biceps and brachialis muscles, have shown promising outcomes in BPI management. Case report: A 45-year-old man presented with right hand weakness and occasional tingling in the upper arm and fingers two months after a motorcycle accident. Motor examination revealed muscle strength of 0/5 in the right trapezius, rhomboids, serratus anterior (positive winging scapula), pectoralis minor and major, latissimus dorsi, deltoid, biceps, and elbow flexion. Wrist and finger functions remained intact. Diagnosed with post-ganglionic BPI, the patient underwent two nerve transfer surgeries: the Mackinnon technique, transferring the spinal accessory nerve to the suprascapular nerve to reinnervate shoulder muscles, and the Double Oberlin procedure, transferring fascicles from the median and ulnar nerves to the musculocutaneous nerve for reinnervation of the biceps and brachialis muscles. Post-surgery, the patient engaged in an aggressive rehabilitation program focusing on strength, range of motion, and sensory re-education. Over nine months, the patient showed significant improvement in elbow flexion (MRC grade 3), wrist extension (MRC grade 5), hand grip strength (MRC grade 3) with improved sensation across the affected limb. He returned to work and daily activities with mild residual weakness and sensory deficits. Discussion: This case illustrates the effectiveness of the Mackinnon and Double Oberlin nerve transfer techniques in restoring function in a patient with total post-ganglionic BPI. The Mackinnon technique enabled shoulder muscle reinnervation, essential for abduction and stabilization, while the Double Oberlin procedure enhanced elbow flexion by reinnervating both the biceps and brachialis muscles. The combined surgical and intensive rehabilitation approach facilitated significant functional recovery. Conclusion: The successful application of the Double Oberlin and Mackinnon techniques in this case demonstrates their potential in managing total post-ganglionic BPI. Early surgical intervention and consistent rehabilitation are crucial for optimizing recovery outcomes. This case highlights the importance of a multidisciplinary approach in treating complex peripheral nerve injuries. Keywords: Double Oberlin, Mackinnon, Brachial Plexus Injury

The Use of Grayscale Muscle Ultrasound to Indicate Muscle Recovery After Peripheral Nerve Reconstruction.

This study aimed to validate the use of grayscale muscle ultrasound by measuring echo intensity to longitudinally evaluate functional muscle reinnervation in a rabbit peroneal nerve defect model. Eighteen New Zealand White rabbits underwent a 30-mm peroneal nerve reconstruction with autografts or decellularized allografts. Ultrasound measurements of tibialis anterior muscles were performed before surgery and at 4, 8, 12, 16, 20, and 24 weeks postoperatively and included cross-sectional muscle area, mean gray value (MGV), and mean gray value normalized for area (MGVA). At 24 weeks, functional motor recovery was evaluated with isometric tetanic force (ITF) and compound muscle action potential (CMAP). MGVA data was compared with ITF and CMAP measurements by calculating the Spearman correlation coefficient. Muscle area (Left/Right Ratio (L/R)) of autografts was superior to allografts at 4, 12, 16, 20 and 24 weeks (p<0.03 for all comparisons). MGVs of the operated side were significantly higher for autografts at 4, 8, and 12 weeks and at 12, 16, 20, and 24 weeks for allografts (p<0.01 for all comparisons), compared to their unoperated sides. Similar patterns were seen in both groups for MGVA (operated versus control side). MGVA (L/R) demonstrated a strong correlation with ITF (L/R) for autografts (ρ = -0.7) and allografts (ρ = -0.87), but inconsistent with CMAPs (L/R). Quantitative muscle ultrasound demonstrated a reliable, non-invasive tool for evaluating motor recovery in a rabbit peroneal nerve reconstruction model. Clinical translation could provide valuable insights into muscle health and structural changes following nerve reconstruction.