Peripheral Nerve Surgery Research Articles

Technique and Expected Benefit of Intraoperative Perfusion Imaging of Peripheral Nerves.

Peripheral nerve surgery, particularly in cases of nerve compression syndrome (NCS), necessitates a comprehensive evaluation of intraneural blood flow, as localized reductions in nerve perfusion are integral to the etiopathogenesis of such conditions. Although nerve perfusion is currently guided by morphologic characteristics, this assessment is subjective and prone to bias. Intraoperative fluorescence-assisted perfusion imaging with indocyanine green (ICG) is an established tool in flap and lymphatic surgery to objectively assess perfusion intraoperatively. However, only a few unspecific applications of ICG in peripheral nerve surgery have been published so far. In this study, we performed intraoperative perfusion imaging using ICG in 16 consecutive operations within the peripheral nervous system, including microsurgical reconstructions after obstetric brachial plexus injury, decompression for NCS, and vascularized ulnar nerve interposition transfers. Our findings show the utility of ICG in delineating healthy perfusion borders at proximal and distal stump levels after neuroma resection, and we demonstrate a correlation between histological findings and these clinically observed perfusion patterns. In NCS cases, we demonstrate that ICG imaging is effective in highlighting reduced perfusion predecompression and improved perfusion postdecompression. Additionally, ICG proved valuable for assessing perfusion of free vascularized nerve grafts. Intraoperative ICG perfusion imaging is a valuable tool during surgery of the peripheral nervous system, providing insights into the etiopathogenesis of NCS and aiding in the visualization of perfusion. This study underscores the potential of ICG in nerve surgery and its applicability for improving surgical outcomes and advancing our understanding of peripheral nerve pathologies.

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.

Electrophysiological Signal Validation of Regenerative Peripheral Nerve Interface at Nerve Ending: A Preliminary Rat Model Experiment.

As the number of extremity amputations continues to rise, so does the demand for prosthetics. Emphasizing the importance of a nerve interface that effectively amplifies and transmits physiological signals through peripheral nerve surgery is crucial for achieving intuitive control. The regenerative peripheral nerve interface (RPNI) is recognized for its potential to provide this technical support. Through animal experiment, we aimed to confirm the actual occurrence of signal amplification. Rats were divided into three experimental groups: control, common peroneal nerve transection, and RPNI. Nerve surgeries were performed for each group, and electromyography (EMG) and nerve conduction studies (NCS) were conducted at the initial surgery, as well as at 2, 4, and 8 weeks postoperatively. All implemented RPNIs exhibited viability and displayed adequate vascularity with the proper color. Clear differences in latency and amplitude were observed before and after 8 weeks of surgery in all groups (p < 0.05). Notably, the RPNI group demonstrated a significantly increased amplitude compared with the control group after 8 weeks (p = 0.031). Latency increased in all groups 8 weeks after surgery. The RPNI group exhibited relatively clear signs of denervation with abnormal spontaneous activities (ASAs) during EMG. This study is one of few preclinical studies that demonstrate the electrophysiological effects of RPNI and validate the neural signals. It serves as a foundational step for future research in human-machine interaction and nerve interfaces.

Early Postoperative Pain Course following Primary and Secondary Targeted Muscle Reinnervation: A Temporal Description of Pain Outcomes.

Targeted muscle reinnervation (TMR) is an effective surgical treatment of neuropathic pain for amputees. However, limited data exist regarding the early postoperative pain course for patients who undergo either primary (<14 days since amputation) or secondary (≥14 days) TMR. This study aims to outline the postoperative pain course for primary and secondary TMR during the first 6 postoperative months to aid in patient education and expectation management. Patients were eligible if they underwent TMR surgery between 2017 and 2023. Prospectively collected patient-reported outcome measures of pain scores, Pain Interference, and Pain Intensity were analyzed. Multilevel mixed-effects models were utilized to visualize and compare pain courses between primary and secondary TMR patients. A total of 203 amputees were included, with 40.9% being primary and 59.1% being secondary TMR patients. Primary TMR patients reported significantly lower pain scores over the full 6-month postoperative trajectory (p < 0.001) compared with secondary TMR patients, with a difference of Δ -1.0 at the day of TMR (primary = 4.5, secondary = 5.5), and a difference of Δ -1.4 at the 6-month mark (primary = 3.6, secondary = 5.0). Primary TMR patients also reported significantly lower Pain Interference (p < 0.001) and Pain Intensity scores (p < 0.001) over the complete trajectory of their care. Primary TMR patients report lower pain during the first 6 months postoperatively compared with secondary TMR patients. This may reflect how pre-existing neuropathic pain is more challenging to mitigate through peripheral nerve surgery. The current trends may assist in both understanding the postoperative pain course and managing patient expectations following TMR. Therapeutic - IV.

Technical Strategies and Learning Curve in Robotic-assisted Peripheral Nerve Surgery.

Robotic-assisted peripheral nerve surgery (RASPN) has emerged as a promising advancement in microsurgery, offering enhanced precision and tremor reduction for nerve coaptations. This study investigated the largest published patient collective in RASPN and provided specific technical aspects, operative setups, and a learning curve. Data collection involved creating a prospective database that recorded surgical details such as surgery type, duration, nerve coaptation time, and number of stitches. The experienced surgeon first underwent a 12-hour training program utilizing the Symani robot system in combination with optical magnification tools before using the system clinically. The study included 19 patients who underwent robot-assisted peripheral nerve reconstruction. The cohort included six men (31.6%) and 13 women (68.4%), with an average age of 53.8 ± 18.4 years. The procedures included nerve transfers, targeted muscle reinnervation, neurotized free flaps, and autologous nerve grafts. Learning curve analysis revealed no significant reduction in time per stitch over the initial nine coaptations (4.9 ± 0.5 min) compared with the last 10 coaptations (5.5 ± 1.5 min). The learning curve for RASPN was compared with early experiences with other surgical robots, emphasizing the importance of surgical proficiency and assistant training. Obstacles such as instrument grip strength and blood clot formation were highlighted, and suggestions for future advancements were proposed. RASPN presents an exciting opportunity to enhance precision; however, ongoing research and optimization are necessary to fully harness its benefits.

Advances in Modern Microsurgery.

Background/Objectives: Microsurgery employs techniques requiring optical magnification and specialized instruments to operate on small anatomical structures, including small vessels. These methods are integral to plastic surgery, enabling procedures such as free tissue transfer, nerve reconstruction, replantation, and lymphatic surgery. This paper explores the historical development, advancements, and current applications of microsurgery in plastic surgery. Methods: The databases MEDLINE (via PubMed) and Web of Science were selectively searched with the term "(((microsurgery) OR (advances)) OR (robotic)) OR (AI)) AND (((lymphatic surgery) OR (peripheral nerve surgery)) OR (allotransplantation))" and manually checked for relevance. Additionally, a supplementary search among the references of all publications included was performed. Articles were included that were published in English or German up to June 2024. Results: Modern microsurgical techniques have revolutionized plastic surgery, enabling precise tissue transfers, improved nerve reconstruction, and effective lymphedema treatments. The evolution of robotic-assisted surgery, with systems like da Vinci and MUSA, has enhanced precision and reduced operative times. Innovations in imaging, such as magnetic resonance (MR) lymphography and near-infrared fluorescence, have significantly improved surgical planning and outcomes. Conclusions: The continuous advancements in microsurgery, including supermicrosurgical techniques and robotic assistance, have significantly enhanced the capabilities and outcomes of plastic surgery. Future developments in AI and robotics promise further improvements in precision and efficiency, while new imaging modalities and surgical techniques expand the scope and success of microsurgical interventions.

Optimal Technique for Cutting Peripheral Nerves in Nerve Transfer Surgery: A Survey of Peripheral Nerve Surgeons.

Nerve transfer procedures are performed in patients with proximal nerve injuries to optimize their potential for functional recovery. The study aimed to determine the preferred surgical technique and tool used by peripheral nerve surgeons to transect nerves in nerve transfers. All current members of the American Society of Peripheral Nerve were invited to complete a cross-sectional 10-question survey. Data on practice demographics, nerve-cutting instruments/techniques used, and their belief on whether this impacted patient outcomes were collected. A total of 49 American Society of Peripheral Nerve members participated in the study, the majority of whom were over 10 years into practice (n = 30/49; 61%). The most common response was a scalpel blade (n = 26/49; 53%), with the remaining 47% using iris scissors, micro-serrated scissors, a razor blade, specialized nerve microscissors, or a specialized nerve-cutting device. The number of years in practice (P = 0.0271) and the percentage of practice that involves treating patients with peripheral nerve injuries (P = 0.0054) is significantly associated with the belief that crushing the donor nerves during transection may result in worse outcomes following nerve transfer. Only the latter is significantly associated with this belief in recipient nerves (P = 0.0214). Our findings demonstrate that peripheral nerve surgeons believe that the technique used to transect nerves before coaptation influences outcomes after nerve transfer. Further ex vivo studies are necessary to investigate how different cutting techniques influence nerve morphology and scarring at the coaptation site to optimize outcomes after peripheral nerve surgery.

Outcome measures used in peripheral nerve surgery for symptomatic neuroma in upper extremity amputations: A scoping review.

Novel surgical treatments for painful neuromas are increasingly used, but determining which provides the greatest benefit has been difficult due to the inconsistent use of outcome measures. We mapped the current literature of outcome measures used to evaluate peripheral nerve surgery for the management of symptomatic neuromas in patients who underwent an adult-acquired upper extremity amputation (UEA). Medline, Embase, Cochrane, and CINAHL were searched for primary research written in the English language from inception to February 2023. The search yielded 1137 articles, of which 35 were included for final analysis. Studies varied in their assessment of pain, health-related quality of life (HRQOL), neurotrophic measures, psychological and sensorimotor function, highlighting a consensus on crucial domains but also revealing significant heterogeneity in the use and application of outcome measures among primary studies. Our findings highlight the need to establish common standards that reflect the best evidence and unique needs of the UEA population. This includes developing a core outcome set, utilizing multi-center trials, and maintaining flexibility to adapt to ongoing advancements in patient-reported outcome measures (PROMs) research.

SCOPING: A Pilot Study Exploring the Role of A Series of Clinical Observational Parameters as Indicators of Nerve Regeneration.

Following the repair of a mixed peripheral nerve, functional recovery requires successful nerve regeneration across the repair site and, eventually, reinnervation of distal targets. Reliably determining a failing nerve repair so that revision may be performed before irreversible muscle atrophy remains a challenge in peripheral nerve surgery. This study aimed to ascertain whether any commonly used clinical examination tests during surveillance after nerve repair can detect a failing repair and prompt earlier salvage intervention. A prospective observational cohort study was performed to evaluate commonly used clinical determinants of neuron regeneration that may provide early surrogate recovery measures. Sequential cutaneous thermography was used to identify temperature differences between denervated and normal skin in the hand operated on, with the contralateral hand as a control. Six out of nine patients completed between 6 and 18 months of follow-up. Tinel sign progression was observed in all subjects. Tinel progression rate was associated with motor and sensory Medical Research Council grade. The delta temperature was calculated to document the size and direction of any temperature differentials in the hand detected by thermography, but we did not have sufficient data to calculate any correlations with motor and sensory Medical Research Council grade. Specifically, the progression of Tinel sign is associated with recovery measured by progression of the British Medical Research Council motor and sensory grades. The use of thermographic imaging demonstrates that there is a difference in temperature between an injured and noninjured nerve. Future studies could investigate to what extent thermographic imaging predicts final nerve repair outcomes.

Criteria for predicting the development of recurrent peripheral nerve sheas tumors

Peripheral nerve sheaths tumors (PNST) account for about 8 % of all nervous system cancers. The relapse rate ranges from 17.3 to 26.4 %, showing an upward trend. The causes and provoking factors for the development of relapses of PNST have not been fully studied. Purpose of the study: to establish criteria for predicting recurrence of PNST. Material and Methods. The study included 122 patients who were treated at the Department of Spine and Peripheral Nerve Surgery of A.I. Polenov Russian Research Neurosurgical Institute from 2009 to 2021. Among them, there were 87 (71.3 %) patients with primary PNST and 35 (28.7 %) patients with recurrent PNST. All patients underwent MRI and ENMG both before and after surgery. An immunohistochemical study of Ki67 and SO X10 markers was performed. Results. The majority of relapses occured within 1 year after surgery. In cases with radical removal of PNST, the risk of relapse was: 28.6 % for schwannomas 28.6 %, 37.1 % for neurofibromas and 34.3 % for MP NST 34.3 % (p≥0.05). The risk of developing relapse of PNST was 2.9 times higher in patients aged ≥49 years than in patients aged ≤48 years (p&lt;0.004). The larger the initial size of the tumor, the higher the risk of relapse in the late postoperative period. The risk of developing relapse of MP NST was 8.79 times higher in patients with tumor size of greater than 11.5 cm than in patients with smaller tumor size (p&lt;0.02). The of Ki67 level above 4.85 % in schwannomas and above 5.17 % in neurofibromas can predict relapse of PNST (p&lt;0.05). Loss of SO X10 protein expression was associated with an increase in histological anaplasia of the tumor, which causes a high risk of relapse and an unfavorable clinical course of the disease. Conclusion. Despite radical (total) resection of PNST, the risk of relapse remains high. The pathological type of tumor, its size, levels of SO X10 and Ki67 markers, patient’s age, degree of preoperative neurological deficit and extent of surgery are significant criteria for predicting the development of relapse of PNST.

Phantom sensation in genital gender-affirming surgery: a narrative review.

To review findings related to phantom genital sensation, emphasizing phantom sensation in the transgender and gender diverse (TGD) population. We discuss prevalence, presentation and potential implications for sensory outcomes in genital gender-affirming surgery. There is a high prevalence of phantom genital sensations in the TGD population. The prevalence varies by body part, approaching 50% in the most frequently reported transgender phantom - the phantom penis. Unlike genital phantoms that occur after trauma or surgery which are often painful, transgender phantoms are typically neutral and often erogenous in experience. Phantom sensation in the TGD population can be an affirming experience and important part of sexual well being and embodiment. Recent studies have begun to characterize the prevalence and presentations of phantom genital sensations in TGD people, informing our evolving understanding of the sensory experiences of the transgender and gender diverse population. Targeting integration of these centrally-mediated phantom genital sensations with the peripherally generated sensation from genital stimulation may represent one potential avenue to improve sensation and embodiment following genital gender-affirming surgical procedures. Additionally, emerging techniques in modern peripheral nerve surgery targeting phantom pain may offer potential treatment options for painful phantom sensation seen after cases of genital surgery or trauma.

The role of patient-reported outcomes in peripheral nerve surgery.

Measuring the outcome of peripheral nerve surgery is challenging because of the spectrum of functional impairment is dependent on the level and severity of the lesion. There are no nerve-specific patient-reported outcome measures, and no universally accepted outcome measurement both in terms of the parameters to be assessed and the methods and timing of the assessment. Nevertheless, the use of patient-reported outcome measures is fundamental to better understand the needs and expectations of patients, to take advantage of all treatment opportunities to offer the best possible support to these patients. This paper outlines current concepts in the measurement of outcome in peripheral nerve surgery.

Intraoperative Neurophysiological Monitoring in Neurosurgery.

Intraoperative neurophysiological monitoring (IONM) is a crucial advancement in neurosurgery, enhancing procedural safety and precision. This technique involves continuous real-time assessment of neurophysiological signals, aiding surgeons in timely interventions to protect neural structures. In addition to inherent limitations, IONM necessitates a detailed anesthetic plan for accurate signal recording. Given the growing importance of IONM in neurosurgery, we conducted a narrative review including the most relevant studies about the modalities and their application in different fields of neurosurgery. In particular, this review provides insights for all physicians and healthcare professionals unfamiliar with IONM, elucidating commonly used techniques in neurosurgery. In particular, it discusses the roles of IONM in various neurosurgical settings such as tumoral brain resection, neurovascular surgery, epilepsy surgery, spinal surgery, and peripheral nerve surgery. Furthermore, it offers an overview of the anesthesiologic strategies and limitations of techniques essential for the effective implementation of IONM.

An early case of successful peripheral nerve repair in 1880: Francis L. Parker, MD.

The modern technique of epineural suture repair, along with a detailed reporting of functional restoration, came from Carl Hueter in 1873. While there is extensive information on peripheral nerve surgery throughout recorded history leading up to the 1800s, little early American scientific literature is available. While Schwann, Nissl, and Waller were publishing their work on nerve anatomy and physiology, Francis LeJau Parker was born. The South Carolina native would go on to describe one of the first American cases of peripheral nerve repair with the restoration of function. Francis Parker was born in 1836 in Abbeville, South Carolina. He gained local notoriety as one of the first American surgeons to suture a severed nerve, resulting in restored function. The case dates back to 1880, when a patient presented to his clinic with severing of the posterior interosseous nerve. The details of this case come from the archives of the South Carolina Medical Association. The authors reviewed these records in detail and provide a case description of nerve repair not previously reported in the modern literature. The history, neurological examination, and details of the case provide insight into the adroit surgical skills of Dr. Parker.

Current perspectives on peripheral nerve repair and management of the nerve gap.

From the first surgical repair of a nerve in the 6th century, progress in the field of peripheral nerve surgery has marched on; at first slowly but today at great pace. Whether performing primary neurorrhaphy or managing multiple large nerve defects, the modern nerve surgeon has an extensive range of tools, techniques and choices available to them. Continuous innovation in surgical equipment and technique has enabled the maturation of autografting as a gold standard for reconstruction and welcomed the era of nerve transfer techniques all while bioengineers have continued to add to our armamentarium with implantable devices, such as conduits and acellular allografts. We provide the reader a concise and up-to-date summary of the techniques available to them, and the evidence base for their use when managing nerve transection including current use and applicability of nerve transfer procedures.

Anatomical and Technical Considerations in Fascicular Nerve Transfers for Foot Drop.

Foot drop is the common endpoint for a diverse set of nerve injuries, affecting over 128,000 in the United States each year. The wide and oftentimes underappreciated zone of injury, finite pace of regeneration, and exponential decay in the percentage of motor end-plates reinnervated over time may explain the limited success with natural recovery and/or peripheral nerve surgery. Previously described nerve transfer techniques also suffer from incompletely balancing the foot and ankle, poor donor-target nerve synergy, and/or not effectively bypassing the zone of injury. Based on an understanding of why past nerve techniques have failed to correct foot drop, a set of surgical principles can be codified to optimize functional outcomes. Surgical technique should be versatile enough to address foot drop from any of the three common pathways of injury (lumbar spine, sciatic nerve, and common peroneal nerve). For maximal stability, one should look to balance the foot in both dorsiflexion and eversion. Detailed description and illustrations of the branching anatomy for the peroneal and tibial nerves are provided, with specific application to nerve transfer reconstruction. With increasing familiarity using this once poorly understood anatomical region, limitations with past nerve transfer techniques may be overcome.

Three Useful Tips and Tricks for Intraoperative Nerve Stimulation.

Disposable handheld nerve stimulators are widely used in peripheral nerve surgery. Such devices stimulate a motor nerve or the motor component of a mixed nerve by applying electrical current to the proximal region, targeting the main nerve trunk. This stimulation then travels along the motor nerve, reaching the distal end to control the corresponding muscle(s). In this study, the authors demonstrate three useful tips and tricks for handheld nerve stimulation during targeted muscle reinnervation and peripheral nerve surgery. The three tips are (1) identification of proximal muscle contraction by retrograde electrical stimulation of a distal sensory nerve; (2) graded stimulation for identifying motor nerves within fibrotic scarred tissue beds or parallel to the major motor/mixed nerve of interest; and (3) proximal stimulation for validation of adequate post-targeted muscle reinnervation coaptation(s).

Differential Diagnosis of "Foot Drop": Implications for Peripheral Nerve Surgery.

At least 128,000 patients in the United States each year suffer from foot drop. This is a debilitating condition, marked by the inability to dorsiflex and/or evert the affected ankle. Such patients are rendered to a lifetime of relying on an ankle-foot orthosis (AFO) for walking and nighttime to prevent an equinovarus contracture. This narrative review explores the differential diagnosis of foot drop, with a particular focus on clinical presentation and recovery, whether spontaneously or through surgery. Contrary to popular belief, foot drop can be caused by more than just insult to the common peroneal nerve at the fibular head (fibular tunnel). It is a common endpoint for a diverse spectrum of nerve injuries, which may explain its relatively high prevalence. From proximal to distal, these conditions include lumbar spine nerve root damage, sciatic nerve palsy at the sciatic notch, and common peroneal nerve injury at the fibular head. Each nerve condition is marked by a unique clinical presentation, frequency, likelihood for spontaneous recovery, and cadre of peripheral nerve techniques. The ideal surgical technique for treating foot drop, other than neurolysis for compression, remains elusive as traditional peripheral nerve procedures have been marred by a wide spectrum of functional results. Based on a careful understanding of why past techniques have achieved limited success, we can formulate a working set of principles to help guide surgical innovation moving forward, such as fascicular nerve transfer.

Optimizing Rehabilitation for Nerve Gap Repair: Evidence-Based Recommendations

Peripheral nerve surgeries are a complex undertaking that require a multifaceted team approach. For optimal outcomes, early involvement of therapy, planning with the surgical team, and communication with the patient are crucial. This facilitates compliance and is an integral component of the recovery process after these large procedures.

A functional tacrolimus-releasing nerve wrap for enhancing nerve regeneration following surgical nerve repair.

JOURNAL/nrgr/04.03/01300535-202501000-00036/figure1/v/2024-05-14T021156Z/r/image-tiff Axonal regeneration following surgical nerve repair is slow and often incomplete, resulting in poor functional recovery which sometimes contributes to lifelong disability. Currently, there are no FDA-approved therapies available to promote nerve regeneration. Tacrolimus accelerates axonal regeneration, but systemic side effects presently outweigh its potential benefits for peripheral nerve surgery. The authors describe herein a biodegradable polyurethane-based drug delivery system for the sustained local release of tacrolimus at the nerve repair site, with suitable properties for scalable production and clinical application, aiming to promote nerve regeneration and functional recovery with minimal systemic drug exposure. Tacrolimus is encapsulated into co-axially electrospun polycarbonate-urethane nanofibers to generate an implantable nerve wrap that releases therapeutic doses of bioactive tacrolimus over 31 days. Size and drug loading are adjustable for applications in small and large caliber nerves, and the wrap degrades within 120 days into biocompatible byproducts. Tacrolimus released from the nerve wrap promotes axon elongation in vitro and accelerates nerve regeneration and functional recovery in preclinical nerve repair models while off-target systemic drug exposure is reduced by 80% compared with systemic delivery. Given its surgical suitability and preclinical efficacy and safety, this system may provide a readily translatable approach to support axonal regeneration and recovery in patients undergoing nerve surgery.