Small intestine submucosa as a growth factor attractor promotes peripheral nerve regeneration by enhancing syndecan-3/glial cell line-derived neurotrophic factor (GDNF) signalling:in vivostudy.

Peripheral nerve regeneration (PNR) following trauma requires the reconstruction of the extracellular matrix (ECM) and the proper stimulation of growth factors. Decellularised small intestine submucosa (SIS) has been extensively used as an ECM scaffold for tissue repair, but its potential to enhance the effects of exogenous growth factors on PNR is not well understood. In this study, we evaluated the effects of SIS implantation combined with glial cell-derived growth factor (GDNF) treatment on PNR in a rat neurorrhaphy model. We found that both SIS and regenerating nerve tissue expressed syndecan-3 (SDC3), one of major heparan sulphate proteoglycans in nerve tissue, and that SDC3 interacted with GDNF in the regenerating nerve tissue. Importantly, the SIS-GDNF combined treatment enhanced the recovery of neuromuscular function andß3-tubulin-positive axonal outgrowth, indicating an increase in the number of functioning motor axons connecting to the muscle after neurorrhaphy. Our findings suggest that the SIS membrane offers a new microenvironment for neural tissue and promotes neural regeneration based on SDC3-GDNF signalling, providing a potential therapeutic approach for PNR.

Targeting Chondroitin Sulphate Synthase 1 (Chsy1) Promotes Axon Growth Following Neurorrhaphy by Suppressing Versican Accumulation.

Versican is a chondroitin sulfate proteoglycan (CSPG), which deposits in perineurium as a physical barrier and prevents the growth of axons out of the fascial boundary. Several studies have indicated that the chondroitin sulfate (CS) chains on versican have several possible functions beyond the physical barrier, including the ability to stabilize versican core protein in the extracellular matrix. As chondroitin sulfate synthase 1 (Chsy1) is a crucial enzyme for CS elongation, we hypothesized that in vivo knockdown of Chsy1 at peripheral nerve lesion site may decrease CS and versican accumulation, and result in accelerating neurite regeneration. In the present study, end-to-side neurorrhaphy (ESN) in Wistar rats was used as an in vivo model of peripheral nerve injury to evaluate nerve regeneration after surgical intervention. The distribution and expression of versican and Chsy1 in regenerating axons after ESN was studied using confocal microscopy and western blotting. Chsy1 was silenced at the nerve lesion (surgical) site using in vivo siRNA transfection. The results indicated that Chsy1 was successfully silenced in nerve tissue, and its downregulation was associated with functional recovery of compound muscle action potential. Silencing of Chsy1 also decreased the accumulation of versican core protein, suggesting that transient treating of Chsy1-siRNA may be an alternative and an effective strategy to promote injured peripheral nerve regeneration.

Potential of an artificial nerve graft containing Schwann cells for the treatment of a 20-mm nerve defect in rats.

OBJECTIVE: In a previous study, the authors showed that the migration of Schwann cells (SCs) through end-to-side (ETS) neurorrhaphy promotes axonal regrowth within an acellular nerve graft. In the present study, the authors investigated whether a similar strategy using an artificial nerve (AN) would allow reconstruction of a long nerve gap (20 mm) in rats. METHODS: Forty-eight 8- to 12-week-old Sprague Dawley rats were divided into control (AN) and experimental (SC migration-induced AN [SCiAN]) groups. Prior to the experiment, the ANs used in the SCiAN group were populated in vivo with SCs over a 4-week period by ETS neurorrhaphy onto the sciatic nerve. In both groups, a 20-mm sciatic nerve defect was reconstructed in an end-to-end fashion using 20-mm ANs. Sections from the nerve graft and distal sciatic nerve in both groups underwent assessments at 4 weeks for SC migration by immunohistochemical analysis and quantitative reverse transcription-polymerase chain reaction. At 16 weeks, axonal elongation was assessed by immunohistochemical analysis, histomorphometry, and electron microscopy. The number of myelinated fibers was counted, the g-ratio was calculated, and myelin sheath thickness and axon diameter were measured. Furthermore, functional recovery was evaluated at 16 weeks using the Von Frey filament test for sensory recovery and by calculating the muscle fiber area for motor recovery. RESULTS: The area occupied by SCs at 4 weeks and by axons at 16 weeks was significantly larger in the SCiAN group than in the AN group. Histomorphometric evaluation of the distal sciatic nerve revealed a significantly greater number of axons. At 16 weeks, plantar perception in the SCiAN group was significantly better, demonstrating improvement in sensory function. However, no tibialis anterior muscle motor improvement was observed in either group. CONCLUSIONS: The induction of SC migration into an AN by ETS neurorrhaphy is a useful technique for repairing 20-mm nerve defects in rats, with better nerve regeneration and sensory recovery. No motor recovery was observed in either group; however, motor recovery might require a longer period of time than the lifespan of the AN used in this study. Future studies should investigate whether structural and material reinforcement of the AN, to lower its decomposition rate, can improve functional recovery.

End-to-side neurorrhaphy in peripheral nerves: Does it work?

Acute peripheral nerve injuries are common and can cause physical disabilities with sensory and functional sequelae; they therefore require surgery. The aim of this study was to conduct a systematic review to assess the clinical applicability of end-to-side neurorrhaphy in peripheral nerve reconstruction, based on available evidence. We carried out a systematic review of the literature using MEDLINE/PubMed, EMBASE, Cochrane Library, Web of Science, Scielo and Scopus through March 16, 2021. Most of the selected studies were qualitative and employed nonrandomized groups of patients, without standardized scales for assessing outcomes, which made statistical analysis difficult. Efficacy varied from 24% to 81%. Factors for better outcome included the type of injury, type of injured nerve (sensory, motor or mixed), presence of an epineural window, topography, injury extension <1.3 cm, and intervention within 2 weeks of injury. Clinical studies so far lack scientific evidence on end-to-side neurorrhaphy in peripheral nerve lesions.

Combining reverse end-to-side neurorrhaphy with rapamycin treatment on chronically denervated muscle in rats.

This preliminary research determines whether a combination of reverse end-to-side neurorrhaphy and rapamycin treatment achieves a better functional outcome than a single application after prolonged peripheral nerve injury. We found that the tibial nerve function of the reverse end-to-side + rapamycin group recovered better, with a higher tibial function index value, higher amplitude recovery rate, and shorter latency delay rate (P < 0.05). The reverse end-to-side + rapamycin group better protected the gastrocnemius muscle with more forceful contractility, tetanic tension, and a higher myofibril cross-sectional area (P < 0.05). Combining reverse end-to-side neurorrhaphy with rapamycin treatment is a practical approach to promoting the recovery of chronically denervated muscle atrophy after peripheral nerve injury.

Syndecan-3 contributes to the regulation of the microenvironment at the node of Ranvier following end-to­side neurorrhaphy: sodium image analysis.

Syndecan-3 (SDC3) and Syndecan-4 (SDC4) are distributed throughout the nervous system (NS) and are favourable factors in motor neuron development. They are also essential for regulation of neurite outgrowth in the CNS. However, their roles in the reconstruction of the nodes of Ranvier after peripheral nerve injury (PNI) are still unclear. Present study used an in vivo model of end-to-side neurorrhaphy (ESN) for 1-3 months. The recovery of neuromuscular function was evaluated by grooming test. Expression and co-localization of SDC3, SDC4, and Nav1.6 channel (Nav1.6) at regenerating axons were detected by proximity ligation assay and confocal microscopy after ESN. Time-of-flight secondary ion mass spectrometry was used for imaging ions distribution on tissue. Our data showed that the re-clustering of sodium and Nav1.6 at nodal regions of the regenerating nerve corresponded to the distribution of SDC3 after ESN. Furthermore, the re-establishment of sodium and Nav1.6 correlated with the recovery of muscle power 3 months after ESN. This study suggested syndecans may involve in stabilizing Nav1.6 and further modulate the distribution of sodium at nodal regions after remyelination. The efficiency of sodium re-clustering was improved by the assistance of anionic syndecan, resulting in a better functional repair of PNI.

Melatonin Promotes Nerve Regeneration Following End-to-Side Neurorrhaphy by Accelerating Cytoskeletal Remodeling via the Melatonin Receptor-dependent Pathway.

Acceleration of cytoskeletal remodeling in regenerated axons is crucial for a fully functional recovery following peripheral nerve injury (PNI). Melatonin plays important roles in cell differentiation and protection of cytoskeleton stability, thus, the present study aimed to investigate whether melatonin can enhance neurite outgrowth and promote cytoskeletal remodeling in a PNI animal model and in differentiated neurons. End-to-side neurorrhaphy (ESN) rat model was used for assessing cytoskeletal rearrangement in regenerated axon. Subject rats received 1 mg/kg/day melatonin injection for one month. The amplitude of compound muscle action potentials and the number of re-innervated motor end plates on target muscles were assessed to represent the functional recovery after ESN. Melatonin treatment enhanced functional recovery after ESN, compared to the saline treated group. Additionally, in spinal cord and peripheral nerve tissue, animals receiving melatonin displayed enhanced expression of GAP43 and ß3-tubulin one month after ESN, and an increased number of re-innervated motor end plates on their target muscle. In vitro analysis revealed that melatonin treatment significantly promoted neurite outgrowth, and increased expression of melatonin receptors as well as ß3-tubulin in mouse neuroblastoma Neuro-2a (N2a) cells. Treatment with a melatonin receptor antagonist, luzindole, significantly suppressed melatonin receptors and ß3-tubulin expression. Importantly, we found that melatonin treatment suppressed activation of calmodulin-dependent protein kinase II (CaMKII) in vitro and in vivo, suggesting that the ß3-tubulin remodeling may occur via CaMKII-mediated Ca2+ signaling. These results suggested that melatonin may promote functional recovery after PNI by accelerating cytoskeletal remodeling through the melatonin receptor-dependent pathway.

End-to-side innervated sensate radial forearm flap in the hand: A 5-year follow-up.

Optimal functional reconstruction of the palmar surface of the hand requires good sensibility especially for the thumb and the radial side of the fingers. We report the long-term results of a distally based radial forearm flap (RFF) used for soft tissue coverage in the palm, index and middle finger and an end-to-side neurorrhaphy between the lateral antebrachial cutaneous nerve (LACN) and the proper palmar digital nerve of the middle finger to restore sensation. At 5 years' follow-up, the patient's sensory recovery was assessed through static and moving two-point discrimination, light touch sensation, pain perception, hot and cold temperature perception, an electrophysiological study and sweat test. An S3+ sensory recovery on the British Medical Research Council scale, as modified by Mackinnon and Dellon, was noted together with a good perception in the palm compared to decreased perception in the volar surface of the proximal phalanx. These findings prove that the RFF can provide good functional coverage of the palm together with good sensitivity by end-to-side reinnervation.

Current concepts in peripheral nerve surgery.

The injuries of the peripheral nerves are relatively frequent. Some of them may lead to defects which cannot be repaired with direct end-to-end repair without tension. These injuries may cause function loss to the patient, and they consist a challenge for the treating microsurgeon. Autologous nerve grafts remain the gold standard for bridging the peripheral nerve defects. Nevertheless, there are selected cases where alternative types of nerve reconstruction can be performed in order to cover the peripheral nerve defects. In all these types of reconstruction, the basic principles of microsurgery are necessary and the surgeon should be aware of them in order to achieve a successful reconstruction. The purpose of the present review was to present the most current data concerning the surgical options available for bridging such defects.

A rat study of the use of end-to-side peripheral nerve repair as a "babysitting" technique to reduce the deleterious effect of chronic denervation.

OBJECTIVE: Functional recovery is disappointing after surgical repair of nerves that are injured far from their target organs and/or after delayed repair. In the former case, a nerve transfer that transects a distal nerve fascicle to innervate denervated targets is one strategy to promote nerve regeneration and functional recovery. An alternate strategy tested in this study is to perform an end-to-side neurorrhaphy to "babysit" (protect) the denervated distal nerve stump at the time of nerve repair and reduce the deleterious effect of chronic denervation on nerve regeneration. METHODS: In the hindlimbs of Sprague-Dawley rats, the common peroneal (CP) nerve was transected unilaterally and the distal CP nerve stump inserted through a perineurial window into the intact tibial (TIB) nerve, i.e., CP-TIB end-to-side neurorrhaphy. In the first experiment, TIB nerve motoneurons that had regenerated and/or sprouted axons into the CP nerve within 3 months were stimulated to elicit contractions, and thereafter, identified with retrograde dyes for counting. In the second experiment, the intact TIB nerve was transected and cross-sutured to a 3-month chronically denervated distal CP nerve stump that had either been "protected" by ingrown TIB nerves after CP-TIB neurorrhaphy or remained chronically denervated. Thereafter, the number of retrogradely labeled TIB nerve motoneurons that had regenerated their nerves within 3 months were counted and reinnervated tibialis anterior (TA) muscles weighed. RESULTS: A mean (± SE) of 231 ± 83 TIB nerve motoneurons grew into the end-to-side CP distal nerve stump with corresponding ankle flexion; 32% regenerated their axons and 24% sprouted axons from the intact TIB nerve, eliciting ankle flexor-extensor co-contraction. In the second experiment, after a 3-month period of TIB nerve regeneration, significantly more TIB motoneurons regenerated their axons into "protected" than "unprotected" CP distal nerve stumps within 3 months (mean 332 ± 43.6 vs 235 ± 39.3 motoneurons) with corresponding and significantly higher numbers of regenerated nerve fibers, resulting in significantly better recovery of reinnervated TA muscle weight. CONCLUSIONS: These experiments in rats demonstrated that delayed nerve repair is more effective when the deleterious effects of chronic denervation of the distal nerve stump are reduced by protecting the nerve stump with ingrowing nerve fibers across an end-to-side insertion of the distal nerve stump into a neighboring intact nerve. Such an end-to-side neurorrhaphy may be invaluable as a means of preventing the atrophy of distal nerve stumps and target organs after chronic denervation, which allows for effective reinnervation of the protected distal nerve stumps and target organs over distance and time.

Comparison of 4 Different Methods for Direct Hypoglossal-Facial Nerve Anastomosis in Rats.

BACKGROUND: Classic hypoglossal-facial nerve anastomosis inevitably causes hemitongue atrophy and dysfunction. Thus, many variants have been developed to reduce tongue-related morbidities. A comparative study concerning these techniques was conducted in rats to systematically evaluate long-term functional and histologic outcomes of the recipient and donor systems. METHODS: Rats (8 per group) were treated by end-to-end neurorrhaphy (EEN), EEN using the hemisectioned and longitudinally split donor nerve (EEN-Hemi), end-to-side neurorrhaphy through a perineurial window (ESN-PW), or 30% to 40% partial neurotomy (ESN-PN). Four additional rats were left intact. At 8 months postoperatively, behavioral, electrophysiologic, and morphologic studies were carried out to compare the groups. RESULTS: All techniques resulted in partial functional recovery, but complete restoration was not obtained. There were no significant differences between the experimental groups in axon diameter or myelin thickness. The facial nerve fiber count after ESN-PN, but not after EEN-Hemi or ESN-PW, was comparable with that after EEN, which agreed with the behavioral and electrophysiologic results. The hypoglossal nerve fiber count after ESN-PN was slightly less than that after ESN-PW, but markedly more than that after EEN-Hemi, corresponding to the electrophysiologic examination. Quantitative measures of muscle fiber cross-sectional area and connective tissue area density of the tongue demonstrated severe muscle atrophy on the operated side after EEN and EEN-Hemi when compared with ESN-PW and ESN-PN. CONCLUSIONS: ESN with 30% to 40% partial donor neurotomy offers the best balance between motor reinnervation and donor deficits. The method of nerve split for provision of hemihypoglossal nerve stump may not effectively preserve the tongue function.

Reconstruction of bladder function and prevention of renal deterioration by means of end-to-side neurorrhaphy in rats with neurogenic bladder.

AIMS: To investigate the feasibility of restoring bladder function and prevention of renal deterioration by neurorrhaphy in rats with neurogenic bladder (NB). METHODS: Forty-two rats were assigned to the end-to-side nerve coaptation group (ECG, n = 16), no nerve coaptation group (NCG, n = 16), and control group (CG, n = 10). In the ECG, the left ventral root (VR) and dorsal root (DR) of L6 and S1 were transected, and the distal stump of L6VR was sutured to the lateral face of L4VR. In the NCG, the left VR and DR of L6 and S1 were transected, but coaptation was not performed. In the CG, no operation was performed. Nerve regeneration, bladder function, and renal function were evaluated by FluoroGold (FG) retrograde tract tracing, cystometry, electrical stimulation, MRI, histology and biochemical assays. RESULTS: In the ECG, FG-labeled neurons were observed in the left ventral horn of L4 spinal cord. There was a significant increase in intravesical pressure upon stimulation of the left L4VR proximal to the coaptation. Maximum cystometric capacity, post-void residual urine, bladder compliance and weight, serum creatinine, blood urea nitrogen, and fibrotic area of bladder and kidney were lower in the ECG than in the NCG, but higher than the CG. Hydronephrosis was noticed in ECG and NCG rats. Maximum detrusor voiding pressure was higher in the ECG and CG than in the NCG. CONCLUSIONS: End-to-side neurorrhaphy is a useful method for restoring bladder function and preventing renal injury in rats with NB.

Morphofunctional evaluation of end-to-side neurorrhaphy through video system magnification.

BACKGROUND: The surgical microscope is an essential tool for microsurgery. Nonetheless, several promising alternatives are being developed, including endoscopes and laparoscopes with video systems. However, these alternatives have only been used for arterial anastomoses so far. The aim of this study was to evaluate the use of a low-cost video-assisted magnification system in end-to-side neurorrhaphy in rats. MATERIALS AND METHODS: Forty rats were randomly divided into four matched groups: (1) normality (sciatic nerve was exposed but was kept intact); (2) denervation (fibular nerve was sectioned, and the proximal and distal stumps were sutured-transection without repair); (3) microscope; and (4) video system (fibular nerve was sectioned; the proximal stump was buried inside the adjacent musculature, and the distal stump was sutured to the tibial nerve). Microsurgical procedures were performed with guidance from a microscope or video system. We analyzed weight, nerve caliber, number of stitches, times required to perform the neurorrhaphy, muscle mass, peroneal functional indices, latency and amplitude, and numbers of axons. RESULTS: There were no significant differences in weight, nerve caliber, number of stitches, muscle mass, peroneal functional indices, or latency between microscope and video system groups. Neurorrhaphy took longer using the video system (P < 0.05). The amplitude was higher in the microscope group than in the video group. CONCLUSIONS: It is possible to perform an end-to-side neurorrhaphy in rats through video system magnification. The success rate is satisfactory and comparable with that of procedures performed under surgical microscopes.

The effects of FK1706 on nerve regeneration and bladder function recovery following an end-to-side neurorrhaphy in rats.

BACKGROUND: Immunophilin ligands are neuroregenerative agents binding to FK506 binding proteins, by which stimulate recovery of neurons in a variety of injury nerves. FK1706 is a novel immunophilin ligand which has neuroprotective and neuroregenerative effects but without immunosuppressive activity. At present, most reports about FK1706 in ameliorating nerve injury and functional recovery are limited to cavernous nerve injury and erectile function recovery. This study aimed to demonstrate the effects of FK1706 on nerve regeneration and bladder function recovery following an end-to-side neurorrhaphy in rat models. METHOD: The numbers of regenerated myelinated axons of the pelvic parasympathetic nerve (PPN) in the three groups' rats (FK1706 + ETS, ETS and control groups) were evaluated. Their intravesical pressure (IVP), S100ß and growth associated protein 43 (GAP43) expressions were also compared. RESULTS: In FK1706 + ETS group, 90% the rats showed that the frequency of FG labeled neurons was larger than the 3.5 cutoff value, 100% the rats showed that the frequency of FG-FB double-labeled neurons was larger than the 5.5 cutoff value. The average maximum of IVP in FK1706 + ETS group reached 76.3% of the value in control group. Their average number of myelinated axons of regenerated PPN reached 80% of the amount in control group. The nerve regeneration-associated markers data indicated that the expression level of S100ß and GAP43 in FK1706 + ETS group was approximately 2-fold higher than that of ETS group (P < 0.05). CONCLUSIONS: After end-to-side neurorrhaphy, FK1706 effectively enhanced the nerve regeneration and bladder function recovery.

End-to-side neurorrhaphy repairs peripheral nerve injury: sensory nerve induces motor nerve regeneration.

End-to-side neurorrhaphy is an option in the treatment of the long segment defects of a nerve. It involves suturing the distal stump of the disconnected nerve (recipient nerve) to the side of the intimate adjacent nerve (donor nerve). However, the motor-sensory specificity after end-to-side neurorrhaphy remains unclear. This study sought to evaluate whether cutaneous sensory nerve regeneration induces motor nerves after end-to-side neurorrhaphy. Thirty rats were randomized into three groups: (1) end-to-side neurorrhaphy using the ulnar nerve (mixed sensory and motor) as the donor nerve and the cutaneous antebrachii medialis nerve as the recipient nerve; (2) the sham group: ulnar nerve and cutaneous antebrachii medialis nerve were just exposed; and (3) the transected nerve group: cutaneous antebrachii medialis nerve was transected and the stumps were turned over and tied. At 5 months, acetylcholinesterase staining results showed that 34% ± 16% of the myelinated axons were stained in the end-to-side group, and none of the myelinated axons were stained in either the sham or transected nerve groups. Retrograde fluorescent tracing of spinal motor neurons and dorsal root ganglion showed the proportion of motor neurons from the cutaneous antebrachii medialis nerve of the end-to-side group was 21% ± 5%. In contrast, no motor neurons from the cutaneous antebrachii medialis nerve of the sham group and transected nerve group were found in the spinal cord segment. These results confirmed that motor neuron regeneration occurred after cutaneous nerve end-to-side neurorrhaphy.

Long-term follow-up of treatment of erectile dysfunction after radical prostatectomy using nerve grafts and end-to-side somatic-autonomic neurorraphy: a new technique.

OBJECTIVE: To study a novel penile reinnervation technique using four sural nerve grafts and end-to-side neurorraphies connecting bilaterally the femoral nerve and the cavernous corpus and the femoral nerve and the dorsal penile nerves. PATIENTS AND METHODS: Ten patients (mean [± sd; range] age 60.3 [± 4.8; 54-68] years), who had undergone radical prostatectomy (RP) at least 2 years previously, underwent penile reinnervation in the present study. Four patients had undergone radiotherapy after RP. All patients reported satisfactory sexual activity prior to RP. The surgery involved bridging of the femoral nerve to the dorsal nerve of the penis and the inner part of the corpus cavernosum with sural nerve grafts and end-to-side neurorraphies. Patients were evaluated using the International Index of Erectile Function (IIEF) questionnaire and pharmaco-penile Doppler ultrasonography (PPDU) preoperatively and at 6, 12 and 18 months postoperatively, and using a Clinical Evolution of Erectile Function (CEEF) questionnaire, administered after 36 months. RESULTS: The IIEF scores showed improvements with regard to erectile dysfunction (ED), satisfaction with intercourse and general satisfaction. Evaluation of PPDU velocities did not reveal any difference between the right and left sides or among the different time points. The introduction of nerve grafts neither caused fibrosis of the corpus cavernosum, nor reduced penile vascular flow. CEEF results showed that sexual intercourse began after a mean of 13.7 months with frequency of sexual intercourse varying from once daily to once monthly. Acute complications were minimal. The study was limited by the small number of cases. CONCLUSIONS: A total of 60% of patients were able to achieve full penetration, on average, 13 months after reinnervation surgery. Patients previously submitted to radiotherapy had slower return of erectile function. We conclude that penile reinnervation surgery is a viable technique, with effective results, and could offer a new treatment method for ED after RP.

Promoting effect of percutaneous electrical stimulation on nerve regeneration after end-to-side neurorrhaphy in rats / 中国比较医学杂志

Objective To observe and explore the effect and clinical value of percutaneous electrical stimulation on nerve regeneration after end-to-side neurorrhaphy in rats. Methods Thirty-two SPF male S-D rats were randomly divided into four groups ( n = 8 ): group A, the normal control group; group B, with end to end neurorrhaphy of musculocutaneous nerve injury matched to the ulnar nerve; group C, with end to side neurorrhaphy of musculocutaneous nerve injury matched to the ulnar group; and group D, with end to side neurorrhaphy of musculocutaneous nerve injury matched to the ulnar nerve plus postoperative transcutaneous electrical stimulation ( 30 min per day for 6 weeks ) . Electromyography, postoperational nerve conduction velocity, the histological and ultrastructural changes of the nerve fibers were examined, and NF-200 expression in frozen sections was observed using imunohistological staining, to assess the recovery of muscle strength of the diseased side limb and the neuroregeneration in the rats after treatment. Results The amplitude and conduction velocity of the groups C and D were lower than that of the group A, the latency was higher than that of the group A, while the amplitude and conduction velocity of the group D were lower than that of the group C,and the latency was higher than that of the group C. The wet weight ratio of the biceps brachii muscle and the cross-sectional area of muscle fibers in the groups B, C and D were lower than those in the group A, and the recovery of muscle in the group C was the worst. The expression of NF-200 in the rats of groups B, C and D was significantly lower than that in the group A, and the expression of NF-200 in the group D was significantly higher than that in the group C, but still significantly less than that in the group B ( P < 0. 05 ) . Electron microscopy showed mature myelinated fibers in the group B, whereas unmyelinated fibers were the main component and the myelin sheath was poorly developed in the group C. The myelin regeneration in the group D was better than that in the group C, but still some unmyelinated nerve fibers were seen. Conclusions The percutaneous electrical stimulation can effectively promote nerve axonal regeneration and can delay the atrophy of the target muscle after end-to-side neurorrhaphy. Though there is difference compared with the end-to-end neurorrhaphy, the end-to-side neurorrhaphy is still an effective method in clinical repair of peripheral nerve injury.

Redistribution of Cav2.1 channels and calcium ions in nerve terminals following end-to-side neurorrhaphy: ionic imaging analysis by TOF-SIMS.

The P/Q-type voltage-dependent calcium channel (Cav2.1) in the presynaptic membranes of motor nerve terminals plays an important role in regulating Ca2+ transport, resulting in transmitter release within the nervous system. The recovery of Ca2+-dependent signal transduction on motor end plates (MEPs) and innervated muscle may directly reflect nerve regeneration following peripheral nerve injury. Although the functional significance of calcium channels and the levels of Ca2+ signalling in nerve regeneration are well documented, little is known about calcium channel expression and its relation with the dynamic Ca2+ ion distribution at regenerating MEPs. In the present study, end-to-side neurorrhaphy (ESN) was performed as an in vivo model of peripheral nerve injury. The distribution of Ca2+ at regenerating MEPs following ESN was first detected by time-of-flight secondary ion mass spectrometry, and the specific localization and expression of Cav2.1 channels were examined by confocal microscopy and western blotting. Compared with other fundamental ions, such as Na+ and K+, dramatic changes in the Ca2+ distribution were detected along with the progression of MEP regeneration. The re-establishment of Ca2+ distribution and intensity were correlated with the functional recovery of muscle in ESN rats. Furthermore, the re-clustering of Cav2.1 channels after ESN at the nerve terminals corresponded with changes in the Ca2+ distribution. These results indicated that renewal of the Cav2.1 distribution within the presynaptic nerve terminals may be necessary for initiating a proper Ca2+ influx and shortening the latency of muscle contraction during nerve regeneration.

End-to-side neurorrhaphy for nerve repair and function rehabilitation.

BACKGROUND: End-to-side neurorrhaphy is a promising procedure for nerve repair in peripheral nerve injury. However, in previous studies, this technique was limited to somatic nerves. The present study was designed to investigate the feasibility of nerve regeneration after end-to-side neurorrhaphy between autonomic nerve and somatic nerve. MATERIALS AND METHODS: Thirty adult male Sprague-Dawley rats were randomly divided into the following three groups (n = 10 per group) for different treatments: (1) end-to-side neurorrhaphy group, the left L6 and S1 spinal nerves were transected in the dura, and the distal stump of L6 ventral root (L6VR) was sutured to the lateral face of L4 ventral root (L4VR) through end-to-side coaptation; (2) no repair group, the rats received the same operation as the end-to-side neurorrhaphy group but without coaptation; (3) control group, the rats received the same operation as the end-to-side neurorrhaphy group but the L6VR was preserved. After 4 month, the origin and mechanism of nerve regeneration were evaluated by retrograde nerve tracing. Morphologic and functional properties of the regenerated nerve were investigated by morphologic examination and intravesical pressure measurement. RESULTS: Retrograde nerve tracing indicated that the new neural reflex pathway was successfully established, and the main regeneration mechanism was axon collateral sprouting. Morphologic examination and intravesical pressure measurement indicated prominent axonal regeneration and good bladder functional rehabilitation in the neurorrhaphy group. Wet weight and morphology of left extensor digitorum longus muscles appeared no detrimental effect on the donor nerve. CONCLUSIONS: These results indicated that the somatic motor axons growth into autonomic nerve may be achieved through axon collateral sprouting for nerve repair and function rehabilitation after end-to-side neurorrhaphy of autonomic nerve and somatic nerve without apparent impairment of the donor somatic nerve.

End-to-side "loop" graft for total facial nerve reconstruction: Over 10 years experience.

BACKGROUND: Multiple-branch reconstruction is required in order to attain facial reanimation for extensive facial nerve defects. We previously reported that end-to-side nerve grafting, with the use of a single nerve graft for defect reconstruction, was easy to perform. We have also demonstrated the efficacy of end-to-side nerve suture of the recipient nerve to the donor graft nerve, in experimental rat models and clinical cases. The regenerating axons, which extended into the nerve graft, were "distributed" to multiple recipient nerves via end-to-side nerve-suture sites. METHODS: Thirty-two patients who underwent facial nerve reconstruction (five to 10 branches) had a single sural nerve graft coapted to the proximal stump of the facial nerve in an end-to-end manner, followed by end-to-side nerve suture of the recipient nerve stumps to the side of the nerve graft. In 19 patients who were expected to undergo postoperative radiotherapy and/or chemotherapy, the distal end of the graft was connected to the side of the hypoglossal nerve for "axonal supercharging," to enhance the recovery of the facial muscles. RESULTS: Initial facial movements were noted at 5-12 months postoperatively, and good recovery (House-Brackmann grade III/IV) was observed during long-term follow-up in most patients. CONCLUSION: End-to-side nerve suture of the recipient nerve stumps to the nerve graft requires less graft nerve material and less technical mastery to reconstruct multiple branches of the facial nerve. We also described the concept of "axonal supercharging," namely the connection of double-donor neural sources to the graft, and "axonal distribution," namely the reinnervation of multiple recipient nerve stumps connected to the graft in an end-to-side manner. This combination of axonal supercharging and distribution can be a useful option in facial nerve reconstruction.