The reasons for end-to-side coaptation: how does lateral axon sprouting work?

End-to-side neurorrhaphy of the sural nerve to the superficial fibular nerve: An anatomically feasible technique for restoring sensation following sural nerve harvest

The sural nerve is commonly used as an autologous nerve graft. Its harvest results in a sensory deficit in the corresponding distribution area. End-to-side neurorrhaphy of the distal sural nerve stump to the superficial fibular nerve could address the problem of sensory loss in the dorsolateral foot without altering the donor nerve. The purpose of our study is to elaborate on a technique for sural nerve-to-superficial fibular nerve end-to-side neurorrhaphy. Fourteen legs from seven formaldehyde-preserved cadavers were dissected. The sural nerve was transected two centimeters above the distal tip of the lateral malleolus (LM) and mobilised to reach the intermediate dorsal cutaneous nerve (IDCN) and the medial dorsal cutaneous nerve (MDCN). The measurements were taken to localise the coaptation points with the nerves. The distal stump of the sural nerve had to be mobilised 18.0 (8.6-24.9) mm distally in relation to the distal tip of LM in order to reach the IDCN. The coaptation point with the IDCN was 18.9 (15.3-22.8) mm above the distal tip of the LM on the anterior margin of the LM. Mobilisation of 33.7 (25.5-38.8) mm was required for reaching the MDCN. The coaptation point with the MDCN was 19.9 (15.8-27.0) mm above the distal tip of the LM, overlaying the lateral margin of the extensor digitorum longus muscle. The end-to-side neurorrhaphy of the sural nerve to the superficial fibular nerve is anatomically feasible and can be performed on both IDCN and MDCN. We recommend using the MDCN due to its larger diameter.

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.

Treatment options for digital nerve injury: a systematic review and meta-analysis

BACKGROUND

Surgical treatment of finger nerve injury is common for hand trauma. However, there are various surgical options with different functional outcomes. The aims of this study are to compare the outcomes of various finger nerve surgeries and to identify factors associated with the postsurgical outcomes via a systematic review and meta-analysis.

METHODS

The literature related to digital nerve repairs were retrieved comprehensively by searching the online databases of PubMed from January 1, 1965, to August 31, 2021. Data extraction, assessment of bias risk and the quality evaluation were then performed. Meta-analysis was performed using the postoperative static 2-point discrimination (S2PD) value, moving 2-point discrimination (M2PD) value, and Semmes-Weinstein monofilament testing (SWMF) good rate, modified Highet classification of nerve recovery good rate. Statistical analysis was performed using the R (V.3.6.3) software. The random effects model was used for the analysis. A systematic review was also performed on the other influencing factors especially the type of injury and postoperative complications of digital nerve repair.

RESULTS

Sixty-six studies with 2446 cases were included in this study. The polyglycolic acid conduit group has the best S2PD value (6.71 mm), while the neurorrhaphy group has the best M2PD value (4.91 mm). End-to-side coaptation has the highest modified Highet's scoring (98%), and autologous nerve graft has the highest SWMF (91%). Age, the size of the gap, and the type of injury were factors that may affect recovery. The type of injury has an impact on the postoperative outcome of neurorrhaphy. Complications reported in the studies were mainly neuroma, cold sensitivity, paresthesia, postoperative infection, and pain.

CONCLUSION

Our study demonstrated that the results of surgical treatment of digital nerve injury are generally satisfactory; however, no nerve repair method has absolute advantages. When choosing a surgical approach to repair finger nerve injury, we must comprehensively consider various factors, especially the gap size of the nerve defect, and postoperative complications. Type of study/level of evidence Therapeutic IV.

End-to-Side vs. Free Graft Nerve Reconstruction-Experimental Study on Rats

The long history of regeneration nerve research indicates many clinical problems with surgical reconstruction to be resolved. One of the promising surgical techniques in specific clinical conditions is end-to-side neurorrhaphy (ETS), described and then repeated with different efficiency in the 1990s of the twentieth century. There are no reliable data on the quality of recipient nerve regeneration, possible donor nerve damage, and epineural window technique necessary to be performed. This research attempts to evaluate the possible regeneration after end-to-side neurorrhaphy, its quality, potential donor nerve damage, and the influence of epineural windows on regeneration efficiency. Forty-five female Wistar rats were divided into three equal groups, and various surgical technics were applied: A-ETS without epineural window, B-ETS with epineural window, and C-free graft reconstruction. The right peroneal nerve was operated on, and the tibial nerve was selected as a donor. After 24 weeks, the regeneration was evaluated by (1) footprint analysis every two weeks with PFI (peroneal nerve function index), TFI (tibial nerve function index), and SFI (sciatic nerve function index) calculations; (2) the amplitude and latency measurements of motor evoked potentials parameters recorded on both sides of the peroneal and tibial nerves when electroneurography with direct sciatic nerve electrical stimulation and indirect magnetic stimulation were applied; (3) histomorphometry with digital conversion of a transverse semithin nerve section, with axon count, fibers diameter, and calculation of axon area with a semiautomated method were performed. There was no statistically significant difference between the groups investigated in all the parameters. The functional indexes stabilized after eight weeks (PFI) and six weeks (TFI and SFI) and were positively time related. The lower amplitude of tibial nerve potential in groups A and B was proven compared to the non-operated side. Neurophysiological parameters of the peroneal nerve did not differ significantly. Histomorphometry revealed significantly lower diameter and area of axons in operated peroneal nerves compared to non-operated nerves. The axon count was at a normal level in every group. Tibial nerve parameters did not differ from non-operated values. Regeneration of the peroneal nerve after ETS was ascertained to be at the same level as in the case of free graft reconstruction. Peroneal nerves after ETS and free graft reconstruction were ascertained to have a lower diameter and area than non-operated ones. The technique of an epineural window does not influence the regeneration result of the peroneal nerve. The tibial nerve motor evoked potentials were characterized by lower amplitudes in ETS groups, which could indicate axonal impairment.

Molecular Basis of Surgical Coaptation Techniques in Peripheral Nerve Injuries

Peripheral nerve injuries requiring surgical repair affect over 100,000 individuals in the US annually. Three accepted methods of peripheral repair include end-to-end, end-to-side, and side-to-side neurorrhaphy, each with its own set of indications. While it remains important to understand the specific circumstances in which each method is employed, a deeper understanding of the molecular mechanisms underlying the repair can add to the surgeon's decision-making algorithm when considering each technique, as well as help decide nuances in technique such as the need for making epineurial versus perineurial windows, length and dept of the nerve window, and distance from target muscle. In addition, a thorough knowledge of individual factors that are active in a particular repair can help guide research into adjunct therapies. This paper serves to summarize the similarities and divergences of the three commonly used nerve repair strategies and the scope of molecular mechanisms and signal transduction pathways in nerve regeneration as well as to identify the gaps in knowledge that should be addressed if we are to improve clinical outcomes in our patients.

Tissue-engineered grafts exploit axon-facilitated axon regeneration and pathway protection to enable recovery after 5-cm nerve defects in pigs

Functional restoration following major peripheral nerve injury (PNI) is challenging, given slow axon growth rates and eventual regenerative pathway degradation in the absence of axons. We are developing tissue-engineered nerve grafts (TENGs) to simultaneously "bridge" missing nerve segments and "babysit" regenerative capacity by providing living axons to guide host axons and maintain the distal pathway. TENGs were biofabricated using porcine neurons and "stretch-grown" axon tracts. TENG neurons survived and elicited axon-facilitated axon regeneration to accelerate regrowth across both short (1 cm) and long (5 cm) segmental nerve defects in pigs. TENG axons also closely interacted with host Schwann cells to maintain proregenerative capacity. TENGs drove regeneration across 5-cm defects in both motor and mixed motor-sensory nerves, resulting in dense axon regeneration and electrophysiological recovery at levels similar to autograft repairs. This approach of accelerating axon regeneration while maintaining the pathway for long-distance regeneration may achieve recovery after currently unrepairable PNIs.

A Technique to Reconstruct a Nerve Injured at Its Bifurcation Site Using Autograft and End-to-Side Neurorrhaphy

Peripheral nerves injuries are relatively frequent after high-energy trauma in both upper and lower limb. This case report describes the reconstruction of a 5-cm nerve defect involving the superficial peroneal nerve (SPN) where it divides into its two terminal branches. A 5-cm nerve graft was harvested from the proximal part of the medial dorsal cutaneous nerve (MDN) and interposed to fill the gap between the distal stump of the SPN and the intermediate dorsal cutaneous nerve (IDN). The stump of the MDN was then sutured with an end-to-side (ETS) technique to the IDN, distally to the nerve graft, by opening a window in the epineurium of IDN. The sensory restoration of the dorsal area of the foot after 8 months was evaluated satisfactory from the authors. Tenderness and Tinel’s sign at the lesion site were not present. The patient’s satisfaction was excellent. The results of this case may suggest that a nerve defect involving a bifurcation point can be treated with satisfactory results using one distal stump as donor nerve for a nerve autograft to bridge the nerve gap followed by an ETS neurorrhaphy of donor one on the other stump. In this way, it is possible to reconstruct a bifurcation point by creating a new division point with the same Y-shape in a more distal position, without adding morbidity due to the harvesting of a nerve graft from another area of the body.

Stimulation of Neurite Outgrowth Using Autologous NGF Bound at the Surface of a Fibrous Substrate

Peripheral nerve injury still remains a major clinical challenge, since the available solutions lead to dysfunctional nerve regeneration. Even though autologous nerve grafts are the gold standard, tissue engineered nerve guidance grafts are valid alternatives. Nerve growth factor (NGF) is the most potent neurotrophic factor. The development of a nerve guidance graft able to locally potentiate the interaction between injured neurons and autologous NGF would be a safer and more effective alternative to grafts that just release NGF. Herein, a biofunctional electrospun fibrous mesh (eFM) was developed through the selective retrieval of NGF from rat blood plasma. The neurite outgrowth induced by the eFM-NGF systems was assessed by culturing rat pheochromocytoma (PC12) cells for 7 days, without medium supplementation. The biological results showed that this NGF delivery system stimulates neuronal differentiation, enhancing the neurite growth more than the control condition.

Facial reanimation with interposition nerve graft or masseter nerve transfer: a comparative retrospective study

Both interposition nerve grafts and masseter nerve transfers have been successfully used for facial reanimation after irreversible injuries to the cranial portion of the facial nerve. However, no comparative study of these two procedures has yet been reported. In this two-site, two-arm, retrospective case review study, 32 patients were included. Of these, 17 patients (eight men and nine women, mean age 42.1 years) underwent interposition nerve graft after tumor extirpation or trauma between 2003 and 2006 in the Ear Institute, School of Medicine, Shanghai Jiao Tong University, China, and 15 patients (six men and nine women, mean age 40.6 years) underwent masseter-to-facial nerve transfer after tumor extirpation or trauma between November 2010 and February 2016 in Shanghai Ninth People's Hospital, China. More patients achieved House-Brackmann III recovery after masseter nerve repair than interposition nerve graft repair (15/15 vs. 12/17). The mean oral commissure excursion ratio was also higher in patients who underwent masseter nerve transfer than in patients subjected to an interposition nerve graft. These findings suggest that masseter nerve transfer results in strong oral commissure excursion, avoiding obvious synkinesis, while an interposition nerve graft provides better resting symmetry. This study was approved by the Institutional Ethics Committee, Shanghai Ninth People's Hospital, China (approval No. SH9H-2019-T332-1) on December 12, 2019.

Gastrodin modified polyurethane conduit promotes nerve repair via optimizing Schwann cells function

Peripheral nerve regeneration and functional recovery remain a major clinical challenge. Nerve guidance conduit (NGC) that can regulate biological behavior of Schwann cells (SCs) and facilitate axonal regeneration through microenvironmental remodeling is beneficial for nerve regeneration and functional recovery. Gastrodin, a main constituent of a Chinese traditional herbal medicine, has been known to display several biological and pharmacological properties, especially antioxidative, anti‐inflammatory and nerve regeneration. Herein, polyurethane (PU) NGCs modified by different weight ratio of Gastrodin (0, 1 and 5 wt%) were designed for sequential and sustainable drug release, that created a favorable microenvironment for nerve regeneration. The scaffold showed suitable pore structure and biocompatibility in vitro, and evidently promoted morphological and functional recovery of regenerated sciatic nerves in vivo. Compared to the PU and 1%Gastrodin/PU scaffolds, the 5%Gastrodin/PU significantly enhanced the proliferation, migration and myelination of SCs and up-regulated expression of neurotrophic factors, as well as induction of the differentiation of PC12 cells. Interestingly, the obvious anti-inflammatory response was observed in 5%Gastrodin/PU by reduced expression of TNF-α and iNOS, which also evidenced by the few fibrous capsule formation in the subcutaneous implantation. Such a construct presented a similarity to autograft in vivo repairing a 10 mm sciatic nerve defects. It was able to not only boost the regenerated area of nerve and microvascular network, but also facilitate functional axons growth and remyelination, leading to highly improved functional restoration. These findings demonstrate that the 5%Gastrodin/PU NGC efficiently promotes nerve regeneration, indicating their potential for use in peripheral nerve regeneration applications.

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NGC with a sustained release of Gastrodin creates a favorable microenvironment. .

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Gastrodin/PU has superior anti-inflammatory effects.

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SCs-mediated tissue engineering strategies effectively drive myelination.

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5Gastrodin/PU boosts nerve regeneration and functional restoration in vivo.

Corneal neurotization for neurotrophic keratopathy: Review of surgical techniques and outcomes

Neurotrophic keratopathy is a degenerative disease in which damage to the corneal nerves leads to corneal hypoesthesia. Injuries to neurotrophic corneas are notoriously difficult to treat and have traditionally been approached with supportive management. However, recent progress in the field of corneal neurotization has given new direction for addressing nerve loss directly by stimulating new nerve growth onto the cornea from nearby sensory nerves transferred to the perilimbal region. Herein, we review the surgical techniques utilized in corneal neurotization, including direct transfers and the use of nerve grafts. Considerations in surgical approach, as well as factors that influence prognosis and outcomes of the surgical intervention are also discussed.

Overview of the short- and long-term quantitative outcomes following end-to-side neurorrhaphy in a rat model

The time course of events following end-to-side nerve coaptation remains unclear. Re-innervation and effects on the donor nerve were assessed following short- and long-term end-to-side neurorrhaphy were investigated in a rat model. One hundred and our Sprague-Dawley female rats were randomized to fresh and pre degenerated repair groups with or without perineurotomy. The right peroneal nerve was sutured to the tibial nerve in an end-to-side manner. Histological and electro-physiological assessment of re-innervation and of the donor nerve was performed at two-three months and at nine-twelve months, post-operatively. The results demonstrated that end-to-side neurorrhaphy could attract axonal sprouts and successfully re-innervate the target muscles. The influence on donor nerve was minimal in late stages, although it did have early negative effect. Double labeling provided evidence that one of the mechanisms of this procedure is probably by collateral sprouting.

Side-to-End Hypoglossal-Facial Neurorrhaphy for Treatment of Complete and Irreversible Facial Paralysis after Vestibular Schwannoma Removal by Means of a Retrosigmoid Approach: A Clinical and Anatomic Study

BACKGROUND

Facial paralysis secondary to a complete and irreversible anatomic or functional lesion of the facial nerve (FN) causes severe functional and psychological disorders for the patient. A large number of surgical techniques have therefore been developed for FN repair. Our objective was to propose a surgical FN reanimation protocol for patients with irreversible anatomic or functional postsurgical injury of the FN in the cerebellopontine angle after vestibular schwannoma resection.

METHODS

The clinical study included a total of 16 patients undergoing side-to-end hypoglossal-facial neurorrhaphy (SEHFN) since 2010, in which the FN injury was always secondary to vestibular schwannoma surgery in the cerebellopontine angle using a retrosigmoid approach. All patients had complete clinical facial paralysis at the time of the SEHFN. The anatomic study was conducted using 3 heads and necks (6 SEHFN).

RESULTS

Twelve months after surgery, FN function assessment with the House and Brackmann scale showed 2 patients with grade II, 13 patients with grade III, and only 1 patient with grade IV, and after 2 years, 4 patients had grade II, 11 patients had grade III, and 1 patient had grade IV. The average length of the anastomotic translocation portion of the FN in the anatomic study was 34.76 mm.

CONCLUSIONS

Side-to-end epineural suture of the FN, mobilizing its mastoid segment on the hypoglossal nerve with partial section of the dorsal aspect of the hypoglossal nerve, is a safe anatomic surgical technique for FN reanimation with outstanding clinical results.

Animal models used to study direct peripheral nerve repair: a systematic review

Objective:

Peripheral nerve repair is required after traumatic injury. This common condition represents a major public health problem worldwide. Recovery after nerve repair depends on several factors, including the severity of the injury, the nerve involved, and the surgeon’s technical skills. Despite the precise microsurgical repair of nerve lesions, adequate functional recovery is not always achieved and, therefore, the regeneration process and surgical techniques are still being studied. Pre-clinical animal models are essential for this research and, for this reason, the focus of the present systematic review (according to the PRISMA statement) was to analyze the different animal models used in pre-clinical peripheral nerve repair studies.

Data sources:

Original articles, published in English from 2000 to 2018, were collected using the Web of Science, Scopus, and PubMed databases.

Data selection:

Only preclinical trials on direct nerve repair were included in this review. The articles were evaluated by the first two authors, in accordance with predefined data fields.

Outcome measures:

The primary outcomes included functional motor abilities, daily activity and regeneration rate. Secondary outcomes included coaptation technique and animal model.

Results:

This review yielded 267 articles, of which, after completion of the screening, 49 studies were analyzed. There were 1425 animals in those 49 studies, being rats, mice, guinea pigs, rabbits, cats and dogs the different pre-clinical models. The nerves used were classified into three groups: head and neck (11), forelimb (8) and hindlimb (30). The techniques used to perform the coaptation were: microsuture (46), glue (12), laser (8) and mechanical (2). The follow-up examinations were histology (43), electrophysiological analysis (24) and behavioral observation (22).

Conclusion:

The most widely used animal model in the study of peripheral nerve repair is the rat. Other animal models are also used but the cost-benefit of the rat model provides several strengths over the others. Suture techniques are currently the first option for nerve repair, but the use of glues, lasers and bioengineering materials is increasing. Hence, further research in this field is required to improve clinical practice.

Penile Reinnervation Surgery: A Comprehensive Review of the Literature

BACKGROUND

Modern approaches to erectile dysfunction (ED) often entail the use of multimodal medical therapy and surgery; however, with recent advances in microsurgery, new options may exist for patients suffering from ED. This comprehensive review of the literature serves to reevaluate anatomical and physiological principles that mediate erection to improve understanding for reconstructive surgeons hoping to offer new interventions.

METHODS

A search strategy for this review was agreed upon by all authors. Articles were divided into 2 categories - primary and secondary. Primary articles were defined as those in which the anatomy of the pelvis and/or perineum was the primary focus of the article, whereas secondary did not directly focus on anatomic considerations. Select historical texts and textbook chapters were also included to provide well established and critical anatomical evidence for this review.

RESULTS

Several approaches may be used to restore nerve function to treat neurogenic and vasculogenic ED. Somatic sensory loss can be treated by either direct neurorrhaphy or neuroplasty in the location of disruption. Microvascular techniques also exist to improve flow or to repair small vessels injured in the pelvis. Classical approaches to impotence include vein stripping to reduce venous outflow or direct vascularization to improve inflow.

CONCLUSIONS

Postradical prostatectomy ED has been demonstrated to improve with microsurgical interventions. In the coming years, innovation will continue and collaboration between plastic surgeons and urologists will allow us to tackle this common and difficult problem.

The role of peripheral nerve surgery in a tissue reinnervation

In modern neuroscience, the most relevant is the study of the problem of reinnervation of tissues after severe injuries. Complete restoration of lost physiological functions is still impossible with lesions of peripheral nerves with the formation of extensive diastasis between their proximal and distal sites. In this case, the standard neurorrhaphy cannot be carried out because of the eruption of the filaments during tension and convergence of the ends. To solve this problem, a technique was developed for autotransplantation of the nerve sections, which is still the gold standard for the reconstruction of extensive nerve defects. However, the presence of significant shortcomings led to the development of the doctrine of the direction of regeneration with the help of conduits. Currently, the use of nerve channels is the most promising technology for peripheral nerve repair after trauma. The most actively developing now is the direction of reinnervation, such as neurotization. Neurotization, in some way, combined all the methods of restoring nerves. The overall goal of all these methods-the restoration of extensive nerve defects-allows them to be combined into a new industry: reinnervating neurosurgery.

Reinnervation of spinal cord anterior horn cells after median nerve repair using transposition with other nerves

Our previous studies have confirmed that during nerve transposition repair to injured peripheral nerves, the regenerated nerve fibers of motor neurons in the anterior horn of the spinal cord can effectively repair distal nerve and target muscle tissue and restore muscle motor function. To observe the effect of nerve regeneration and motor function recovery after several types of nerve transposition for median nerve defect (2 mm), 30 Sprague-Dawley rats were randomly divided into sham operation group, epineurial neurorrhaphy group, musculocutaneous nerve transposition group, medial pectoral nerve transposition group, and radial nerve muscular branch transposition group. Three months after nerve repair, the wrist flexion test was used to evaluate the recovery of wrist flexion after regeneration of median nerve in the affected limbs of rats. The number of myelinated nerve fibers, the thickness of myelin sheath, the diameter of axons and the cross-sectional area of axons in the proximal and distal segments of the repaired nerves were measured by osmic acid staining. The ratio of newly produced distal myelinated nerve fibers to the number of proximal myelinated nerve fibers was calculated. Wet weights of the flexor digitorum superficialis muscles were measured. Muscle fiber morphology was detected using hematoxylin-eosin staining. The cross-sectional area of muscle fibers was calculated to assess the recovery of muscles. Results showed that wrist flexion function was restored, and the nerve grew into the distal effector in all three nerve transposition groups and the epineurial neurorrhaphy group. There were differences in the number of myelinated nerve fibers in each group. The magnification of proximal to distal nerves was 1.80, 3.00, 2.50, and 3.12 in epineurial neurorrhaphy group, musculocutaneous nerve transposition group, medial pectoral nerve transposition group, and radial nerve muscular branch transposition group, respectively. Nevertheless, axon diameters of new nerve fibers, cross-sectional areas of axons, thicknesses of myelin sheath, wet weights of flexor digitorum superficialis muscle and cross-sectional areas of muscle fibers of all three groups of donor nerves from different anterior horn motor neurons after nerve transposition were similar to those in the epineurial neurorrhaphy group. Our findings indicate that donor nerve translocation from different anterior horn motor neurons can effectively repair the target organs innervated by the median nerve. The corresponding spinal anterior horn motor neurons obtain functional reinnervation and achieve some degree of motor function in the affected limbs.

Aligned fibers enhance nerve guide conduits when bridging peripheral nerve defects focused on early repair stage

Nerve conduits enhance nerve regeneration in the repair of long-distance peripheral nerve defects. To help optimize the effectiveness of nerve conduits for nerve repair, we developed a multi-step electrospinning process for constructing nerve guide conduits with aligned nanofibers. The alignment of the nerve guide conduits was characterized by scanning electron microscopy and fast Fourier transform. The mechanical performance of the nerve guide conduits was assessed by testing for tensile strength and compression resistance. The biological performance of the aligned fibers was examined using Schwann cells, PC12 cells and dorsal root ganglia in vitro. Immunohistochemistry was performed for the Schwann cell marker S100 and for the neurofilament protein NF200 in PC12 cells and dorsal root ganglia. In the in vivo experiment, a 1.5-cm defect model of the right sciatic nerve in adult female Sprague-Dawley rats was produced and bridged with an aligned nerve guide conduit. Hematoxylin-eosin staining and immunohistochemistry were used to observe the expression of ATF3 and cleaved caspase-3 in the regenerating matrix. The recovery of motor function was evaluated using the static sciatic nerve index. The number of myelinated fibers, axon diameter, fiber diameter, and myelin thickness in the distal nerve were observed by electron microscopy. Gastrocnemius muscle mass ratio was also determined. The analyses revealed that aligned nanofiber nerve guide conduits have good mechanical properties and can induce Schwann cells, PC12 cells and dorsal root ganglia to aggregate along the length of the nanofibers, and promote the growth of longer axons in the latter two (neuronal) cell types. The aligned fiber nerve conduits increased the expression of ATF3 and cleaved caspase-3 at the middle of the regenerative matrix and at the distal nerve segment, improved sciatic nerve function, increased muscle mass of the gastrocnemius muscle, and enhanced recovery of distal nerve ultrastructure. Collectively, the results show that highly aligned nanofibers improve the performance of the nerve conduit bridge, and enhance its effectiveness in repairing peripheral nerve defects.

Supermicrosurgery: History, Applications, Training and the Future

Supermicrosurgery, a technique of dissection and anastomosis of small vessels ranging from 0.3 to 0.8 mm, has revolutionized the fields of lymphedema treatment and soft tissue reconstruction. The technique offers several distinct benefits to microsurgeons, including the ability to manipulate small vessels that were previously inaccessible, and to minimize donor-site morbidity by dissecting short pedicles in a suprafascial plane. Thus, supermicrosurgery has become increasingly popular in recent years, and its applications have greatly expanded since it was first introduced 20 years ago. While supermicrosurgery was originally developed for procedures involving salvage of the digit tip, the technique is now routinely used in a wide variety of microsurgical cases, including lymphovenous anastomoses, vascularized lymph node transfers and perforator-to-perforator anastomoses. With continued experimentation, standardization of supermicrosurgical training, and high quality studies focusing on the outcomes of these novel procedures, supermicrosurgery can become a routine and valuable component of every microsurgeon's practice.

End-to-side neurotization with the phrenic nerve in restoring the function of toe extension: an experimental study in a rat model

The phrenic nerve being transferred to the posterior division of the lower trunk with end-to-end neurorrhaphy is reported to be effective in restoring the function of digit extension in literature. However, the phrenic nerve is extremely important in respiration. We designed an animal experiment to discover whether the phrenic nerve being transferred to the posterior division of the lower trunk with end-to-side neurotization was feasible and provided the theoretical basis. A sum of 36 Sprague-Dawley rats was randomly assigned to one of two groups. In Group A, the phrenic nerve was transferred to the posterior division of the lower trunk with end-to-side neurotization. In Group B, the posterior division of the lower trunk was directly sutured. The results of behavioral assessment, electrophysiology, histology and nerve fiber count and muscle weight at 12 weeks postoperatively were recorded. In Group A, none of the rats experienced tachypnea. The motion of slight toe extension was observed. The results of electrophysiology, histology and nerve fiber count and muscle weight in Group A were not as well as those of Group B, but gradually improved with time. The phrenic nerve being transferred to the posterior division of lower trunk with end-to-side neurotization can partially restore the function of toe extension in a rat model. Whether the function of digit extension can be restored by the phrenic nerve with end-to-side neurotization in humans still needs more practice in clinic.