Ipsilateral and cross-over elongation of the motor nerve by nerve grafting: an experimental study in sheep

In difficult reconstructions, ipsilateral or cross-over nerve grafting is sometimes necessary to achieve reinnervation and motor function. This experimental study in sheep was to answer the question of limitation of elongation of a motor nerve by grafting, the question of the optimal time for suturing the nerve graft to the muscle nerve, and the question of the successful application of this surgical technique in extremities. In 18 sheep, the vastus nerve was elongated by a saphenous nerve graft as long as possible up to 30 cm (step 1). In 10 animals the nerve graft was applied ipsilaterally, and in 8 animals it was used as a cross-over nerve graft to the contralateral limb. The time between nerve grafting and connection of the distal end of the nerve graft to the freshly cut rectus nerve supplying the rectus femoris muscle (step 2) was variable: 0, 3, 6, 9, and 12 months. In all animals, the final experiments (step 3) were performed 6 months after the last operation (step 2). Muscle force measurements in the rectus femoris muscle and quantitative analysis of the number and diameter of myelinated nerve fibers in cross sections of the nerve biopsies at different levels showed that elongation of a motor nerve by nerve grafting is principally not limited. The functional results were rather inhomogeneous and therefore unpredictable (ipsilateral group: maximum tetanic tension = 27 to 172 N; cross-over group: 0 to 227.5 N). Nevertheless, crossover nerve grafting is recommended for selected cases even in extremities. There was no correlation between the time interval between the two operations and the functional or morphologic results, although better functional results were obtained when the distal nerve suture (step 2) was performed some months after nerve grafting (step 1). A clear correlation was found only between the number of regenerated axons in the rectus nerve behind the second suture line and the muscle function.     

Experimental studies in animals on the use of a fibrin glue from the human plasma fraction Cohn I in nerve reconstruction

In order to compare the effects of suture and glue direct nerve connections and nerve transplantations in the sciatic nerve in rats were performed. 4, 6 and 12 weeks later, the nerve anastomosis were histologically studied. In the direct nerve connections, despite a single holding suture, dehiscences were frequently detected with the penetration of the adhesive between the nerve ends. Due to the exact adaptation with the aid of inserted nerve grafts, the anastomoses could be repaired sutureless successfully using a fibrin glue cuff. Since histologically, in comparison to suture, no foreign body granulomas were found, the findings in the literature could be confirmed. No cicatricial contractions of the anastomoses could be found. In the interfascicular nerve transplantation, comparatively good results may be obtained using the two-component adhesive on the Cohn I-fraction basis.     

Neurohistological characteristics of regeneration of the ends of the injured nerve under measured traction]

A resection of sciatic nerve in 25 dogs was performed out and the ends of cut nerve were connected by sutures with special apparatus for quantified traction of nerve stumps. 5 days after resection traction was stented at the rate of 0.25 mm twice a day. A histological analysis performed in 5, 12, 19, 26, 33 days after resection an 2-12 months after nerve suture has shown that stress strain effects on intercalation of nerve structures (Ilizarov's effect). Newly formed Schwann chains free of products of axonal and myelin disruption have got a perfect longitudinal orientation and that's why can be considered as an optimum substratum for axonal regeneration.     

When should nerve gaps be grafted? An experimental study in rats

In conclusion, animal experiments have shown the following: (1) extensive elevation (mobilization) of a nerve from its bed does not interfere with its capacity to regenerate as long as the longitudinal epineural vessels are preserved, (2) suturing nerve ends under tension has a deleterious effect on the final results, (3) when a segment of nerve has been resected, the remaining nerve and the site of repair can lengthen to accommodate joint extension (within limitations), (4) if there is a segmental loss of nerve and if the nerve ends can be approximated with 10-0 epineural sutures, even if the joints must be fully flexed, the result is better than using a nerve graft, and (5) when a graft is required, it is important to avoid reversing the nerve graft. We believe direct nerve repair is preferred when flexion of the joints and mobilization of the nerve ends permits approximation with 10-0 epineural suture.     

Quantitative studies on the regeneration of myelinated nerve fibers. II. Variations of the number and size of regenerating nerve fibers after localized crushing or total section]

1. The number and size of myelinated nerve fibers have been determined at standard levels, in the nerve to medial head of right and left gastrocnemius muscles of 112 rats in which the left sciatic nerve had suffered an experimental lesion according one of the following four modalities: localized crushing, total section followed or not by suture and resection of a nervous segment of about 1 cm. 2. In the nerve to medial head of right gastrocnemius muscle (contralateral nerve used as control), the number of myelinated fibers decreased in average to 10% after crushing, 5% or 4% after section followed or not by suture. However, an increase of 6% was observed after resection. The mean values of the mean diameters showed a decrease of 8% after crushing and 5% after section without suture. This value did not seem to be affected by section followed by immediate suture and after resection, it increased of 11%. On the whole, male rats appeared to be more sensitive than female to the effects of the operation. 3. The nerves of 12 rats have been observed from 15 to 334 days after resection of about 1 cm of sciatic nerve. The 20% of the regenerating myelinated nerve fibers which have succeeded to cross over such a distance had a distribution which remained unimodal; the diameter of the large fibres did not exceed 8 micronm. 4. 34 rats have been sacrificed from 15 to 715 days after sciatic nerve section which was not followed by suture. The number of myelinated nerve fibers became normal again during the 4th month and reached afterwards a mean value of 130%, with very marked variations. The nerve fibre distribution was most frequently unimodal, but may came bimodal one year after the operation in certain nerves. Their mean diameter never exceeded 60% of the normal. 5. The nerves of 34 rats have been examined from 15 to 720 days after section and immediate suture. The number of myelinated nerve fibers returned to normal during the second month and increased afterwards to an average of 150% with very important variations. The nerve fiber distribution was generally unimodal, but may become bimodal 7 months after the operation. Their mean diameter reached only 50 to 55% of the normal. 6. 32 rats have been sacrificed from 10 to 720 rats after a localized crushing. The number of myelinated nerve fibers come back to normal during the 4th week and later increased up to a mean of 115%. Their distribution became early bimodal from the 97th day onwards. Although, their mean diameter nerver exceeded 80% of the normal, the histograms of the regenerating nerve and of the control nerve could be almost superposed during the second year.     

Sural nerve oxygen tension in diabetes.

Peripheral nerve oxygen tensions were assessed in vivo by using microelectrodes to measure endoneurial oxygen tension in exposed sural nerve. In 11 diabetic patients with chronic sensorimotor neuropathy the mean endoneurial oxygen tension was 39.7 (SD 10.2) mm Hg. In all but one patient compared with none of four non-neuropathic subjects the mean nerve oxygen tensions were below dorsal foot vein values. This unphysiological state may have a role in the aetiology of diabetic neuropathy.     

Use new PLGL-RGD-NGF nerve conduits for promoting peripheral nerve regeneration

ABSTRACT: BACKGROUND: Nerve conduits provide a promising strategy for peripheral nerve injury repair. However, the efficiency of nerve conduits to enhance nerve regeneration and functional recovery is often inferior to that of autografts. Nerve conduits require additional factors such as cell adhesion molecules and neurotrophic factors to provide a more conducive microenvironment for nerve regeneration. METHODS: In the present study, poly{(lactic acid)-co-[(glycolic acid)-alt-(L-lysine)]} (PLGL) was modified by grafting Gly-Arg-Gly-Asp-Gly (RGD peptide) and nerve growth factor (NGF) for fabricating new PLGL-RGD-NGF nerve conduits to promote nerve regeneration and functional recovery. PLGL-RGD-NGF nerve conduits were tested in the rat sciatic nerve transection model. Rat sciatic nerves were cut off to form a 10 mm defect and repaired with the nerve conduits. All of the 32 Wistar rats were randomly divided into 4 groups: group PLGL-RGD-NGF, group PLGL-RGD, group PLGL and group autograft. At 3 months after surgery, the regenerated rat sciatic nerve was evaluated by footprint analysis, electrophysiology, and histologic assessment. Experimental data were processed using the statistical software SPSS 10.0. RESULTS: The sciatic function index value of groups PLGL-RGD-NGF and autograft was significantly higher than those of groups PLGL-RGD and PLGL. The nerve conduction velocities of groups PLGL-RGD-NGF and autograft were significantly faster than those of groups PLGL-RGD and PLGL. The regenerated nerves of groups PLGL-RGD-NGF and autograft were more mature than those of groups PLGL-RGD and PLGL. There was no significant difference between groups PLGL-RGD-NGF and autograft. CONCLUSIONS: PLGL-RGD-NGF nerve conduits are more effective in regenerating nerves than both PLGL-RGD nerve conduits and PLGL nerve conduits. The effect is as good as that of an autograft. This work established the platform for further development of the use of PLGL-RGD-NGF nerve conduits for clinical nerve repair.     

Cavernous nerve reconstruction to preserve erectile function following non-nerve-sparing radical retropubic prostatectomy: a prospective study

Erectile dysfunction following radical prostatectomy for treatment of clinically localized prostate cancer remains a problem that deters many men from seeking surgical treatment. Sparing the cavernous nerves has been popularized as a method of preserving potency, but men with locally advanced disease may be at increased risk for positive margins with this technique. In this study, sural nerve grafting of the cavernous nerve bundles, to preserve postoperative potency while potentially maximizing cancer control, was examined. Thirty men were enrolled in this prospective phase I study and underwent non-nerve-sparing radical prostatectomy performed by one of two protocol surgeons. Preoperative erectile function was assessed both objectively, using a RigiScan (Timm Medical Technologies, Inc., Eden Prairie, Minn.), and subjectively. The cavernous nerves were identified and resected during the operation with the use of an intraoperative mapping device (CaverMap; Alliant Medical Technologies, Norwood, Mass.). Bilateral autologous sural nerve grafting to the cavernous nerve stumps was performed by one of two protocol plastic surgeons. Postoperative erectile dysfunction therapy, using intracorporeal injection, a vacuum pump, and/or oral sildenafil therapy, was instituted 6 weeks after the operation. Spontaneous erectile activity was subjectively and objectively measured every 3 months after the operation. Follow-up periods ranged from 13 to 33 months (mean, 23 months). Overall, 18 of 30 patients (60 percent) demonstrated both objective and subjective evidence of spontaneous erectile activity. Of those 18 men, 13 (72 percent) were able to have intercourse (seven unassisted and six with the aid of sildenafil). No disease or biochemical recurrences have been noted in this group of patients with locally advanced disease. In conclusion, autologous sural nerve grafting after non-nerve-sparing radical prostatectomy is an effective means of preserving spontaneous erectile activity after the operation while maximizing cancer control potential.     

Neuromuscular rehabilitation by treadmill running or electrical stimulation after peripheral nerve injury and repair.

Numerous studies have been devoted to the regeneration of the motor pathway toward a denervated muscle after nerve injury. However, the regeneration of sensory muscle endings after repair by self-anastomosis are little studied. In previous electrophysiological studies, our laboratory showed that the functional characteristics of tibialis anterior muscle afferents are differentially affected after injury and repair of the peroneal nerve with and without chronic electrostimulation. The present study focuses on the axonal regeneration of mechano- (fibers I and II) and metabosensitive (fibers III and IV) muscle afferents by evaluating the recovery of their response to different test agents after nerve injury and repair by self-anastomosis during 10 wk of treadmill running (LSR). Data were compared with control animals (C), animals with nerve lesion and suture (LS), and animals with lesion, suture, and chronic muscle rehabilitation by electrostimulation (LSE) with a biphasic current modulated in pulse duration and frequency, eliciting a pattern mimicking the activity delivered by the nerve to the muscle. Compared with the C group, results indicated that 1) muscle weight was smaller in LS and LSR groups, 2) the fatigue index was greater in the LS group and smaller in the LSE group, 3) metabosensibility remained altered in the LS and LSE groups, and 4) mechanosensitivity presented a large increase of the activation pattern in the LS and LSE groups. Our data indicated that chronic muscle electrostimulation partially favors the recovery of muscle properties (i.e., muscle weight and twitch response were close to the C group) and that rehabilitation by treadmill running also efficiently induced a better functional muscle afferent recovery (i.e., the discharge pattern was similar to the C group). The effectiveness of the chronic electromyostimulation and the treadmill exercise on afferent recovery is discussed with regard to parameters listed above.     

The peripheral nerve allograft in the primate immunosuppressed with Cyclosporin A: II. Functional evaluation of reinnervated muscle.

Isometric contractile function was evaluated in primates receiving peripheral nerve allografts and autografts. Twelve adult male cynomolgus monkeys received both sural nerve allografts and autografts to the ulnar nerve in opposite forearms. Half the animals received Cyclosporin A (CsA) immunosuppression (25 mg/kg per day); the remaining animals received placebo. One year following nerve engraftment, isometric contractile muscle function was evaluated in reinnervated abductor digiti quinti and intact abductor pollicis brevis muscles. Maximal twitch tension (Pt), tetanic tension (P(o)), time to peak tension (tpt), rate of rise of twitch tension (DP/dt), and muscle fatigue were evaluated at optimal muscle length (L(o)). All reinnervated muscles distal to nerve autografts and allografts in both Cyclosporin A-immunosuppressed and placebo-treated animals generated equivalent maximal twitch tension, tetanic tension, and time to peak tension, with no significant difference between groups (p > 0.05 by ANOVA). There was a tendency toward increased muscle fatiguability in Cyclosporin A-treated animals (p > 0.05). However, the rate of rise of twitch tension was significantly faster in the reinnervated and intact muscles of Cyclosporin A-treated primates (p < 0.05). Evidence of excellent functional reinnervation across nerve allografts and autografts similar to that seen in histologic and electrophysiologic studies was noted. Cyclosporin A immunosuppression did not significantly enhance recovery of muscle function distal to nerve allografts in this model.     

Effect of weight bearing on recovery from nerve injury in skeletal muscle.

We examined the effect of weight bearing (WB) on muscle recovery after nerve injury. Rats were housed in individual cages for 2 wk under WB or hindlimb suspension (HS) after being subjected to sciatic nerve compression for 1 wk. Sham operated on rats served as controls (sham group). We used 31P- and 19F-nuclear magnetic resonance spectroscopy combined with histochemical, physiological, and biochemical techniques to assess the outcome in the three groups. Creatine kinase-BB (CK-BB) mRNA levels expression, CK activity, and type I fiber density in the WB group were elevated compared with those in the HS group. In addition, sciatic functional index, tetanic tension, energy state, and local circulation dynamics of the WB group were greater than those of the HS group. These results suggested that WB plays an important role in muscle regeneration, inhibits the reduction of CK activity, and facilitates the activation of neural recovery, energy state, and local circulation dynamics.     

The effects of cisplatinum and vincristine on peripheral nerve regeneration

Current treatment modalities for extremity sarcoma often include tumor extirpation plus neoadjuvant therapy. Limb-sparing surgery may require reconstruction of critical nerve defects. Neurotoxic side effects from adjuvant chemotherapy have been reported and raise concerns regarding the effects of chemotherapy on nerve regeneration. In an attempt to define the effects of adjuvant chemotherapy on peripheral nerve regeneration, cisplatin and vincristine were administered to rats following isografting of the posterior tibial nerve. Parameters used to assess peripheral nerve regeneration included walking track analysis and histomorphology. Sixty 250-g Sprague-Dawley rats were randomly allocated into one of three treatment groups. Each animal underwent a 15-mm reversed interposition nerve isograft from 30 donor rats into the right posterior tibial nerve. Ten animals served as control. The remaining animals were divided into two groups of 25 animals each. One group received cisplatin (75 mg/m2) and the other group received vincristine (1 mg/m2). Chemotherapy was administered at 4-week cycles for a total of six cycles (24 weeks). Walking track analysis was performed monthly. Nerve specimens were harvested from the grafted segment and the distal posterior tibial nerve for histomorphology. Walking track analysis demonstrated no statistical difference in print length between the control and chemotherapeutic groups at the conclusion of the study. The number of axons per square millimeter and nerve fiber density were not statistically different between control and chemotherapeutic groups. In the rodent posterior tibial nerve model, postoperative adjuvant therapy does not significantly alter functional outcome in peripheral nerve regeneration. The practice of immediate nerve grafting after tumor extirpation, despite planned postoperative chemotherapy, is supported.     

Defensin NP-1 in restoration of the injured nerve trunk functions

The effect of Defensin NP-1 on early phase of injured sciatic nerve regeneration was studied in rats. Using the technique of AP compound recording performed within 21 days after the nerve trunk cutting with subsequent microsurgical nerve suture, the rate of fibres growth was shown to increase by 30% following Defensin treatment: the distance to which the nerve impulse conductivity through injured nerve fibres was restored has extended from 7.22 +/- 1.2 mm (control) to 10.5 +/- 0.8 mm (Defensin treatment) from the suture site (p < 0.05). Moreover, the conducting capacity of the regenerating nerve fibres has risen by 20% as compared with control values. The findings suggest a positive effect of Defensin on restoration of injured peripheral nerve in rats.     

Enhancement of nerve regeneration and orientation across a gap with a nerve graft within a vein conduit graft: a functional, stereological, and electrophysiological study

In this study, the right sciatic nerves of 40 rats were used to determine whether a nerve graft within a vein graft might accelerate and facilitate axonal regeneration, compared with a nerve graft alone. The animals were separated into four groups, as follows: group 1, sham control; group 2 (control), segmental nerve resection and no repair; group 3, segmental nerve resection and nerve grafting; group 4, segmental nerve resection and reconstruction with a nerve graft within a vein conduit graft. For all groups, sciatic functional indices were calculated before the operation and on postoperative days 7 and 90. On postoperative day 90, the sciatic nerves were reexposed and nerve conduction velocities were recorded. The sciatic nerves were harvested from all groups for counting of the myelinated axons with a stereological method. No statistically significant differences with respect to return of gait function, axon count, or nerve conduction were noted between groups 3 and 4 (p > 0.05). However, functional recovery in group 4 on postoperative day 90 was significant, compared with group 2 (p < 0.05); the recovery difference between groups 2 and 3 was not significant (p > 0.05). This study was not able to demonstrate any functional benefits with the use of a nerve graft within a vein graft, compared with standard nerve grafting.     

Autogenous vein graft repair of digital nerve defects in the finger: a retrospective clinical study

Twenty-two digital nerve repairs were performed in the finger using autogenous vein grafts. Eighty-two percent of the repairs were available for follow-up. Results of sensibility return were assessed using moving two-point discrimination, Semmes-Weinstein monofilaments, and vibratory testing. Two-point discrimination averaged 4.6 mm for 11 acute digital nerve repairs using vein conduits 1 to 3 cm in length. Delayed digital nerve repair with vein conduits yielded poor results. Semmes-Weinstein values demonstrated comparable levels of return of slowly adapting fiber/receptors to the quickly adapting fiber/receptors, as evidenced by moving two-point discrimination tests. Vibratory sensibility was present in all. A review of previous experiences with end-to-end digital neurorrhaphies and digital nerve grafting suggests that repair of 1- to 3-cm gaps in digital nerves with segments of autologous vein grafts appears to give comparable results to nerve grafting. Further laboratory and clinical research is necessary to better define the role of interpositional vein conduits for repair of peripheral nerves.     

A prospective clinical evaluation of autogenous vein grafts used as a nerve conduit for distal sensory nerve defects of 3 cm or less

The purpose of this study was to determine the efficacy of autogenous vein grafts as nerve grafts (AVNC) for bridging of small peripheral sensory nerve gaps as compared with direct repair and with conventional nerve grafting techniques (ANG). Patients with painful neuroma or segmental nerve injury of 3 cm were chosen as the test group. Those amenable to direct repair were classified as controls. Between 1982 to 1988, a total of 22 patients were enrolled in this study. A total of 34 nerves were repaired, 15 with a venous nerve conduit, 4 with a sural nerve graft, and 15 with direct repair. Significant symptom relief and satisfactory sensory function return were uniformly observed. The two-point discrimination measurements indicated superiority of direct repair and probably of conventional nerve grafting. However, the universally favorable patient acceptance and the return of measurable two-point discrimination indicates the effectiveness of autogenous vein grafts as nerve conduits when selectively applied to bridge a small nerve gap (less than or equal to 3 cm) on nonessential peripheral sensory nerves.     

Quantitative studies on the motor root of the mouse facial nerve. An electron-microscopic study.

Fiber count analysis was performed with the electron microscope on the motor root of the facial nerve in six mice. On an average, 3,433 (84.9%) of the total nerve fibers (4,046) were myelinated and 592 (14.6%) unmyelinated. The motor root consisted mostly of large myelinated fibers (large fiber group), but a part of the root consisted of small myelinated and unmyelinated fibers (small fiber group). The nerve fibers of the small fiber group appear to correspond with those of the intermediate nerve, and to pass through the motor root and enter the intermediate nerve near the geniculate ganglion.     

Free flap reconstruction of the sole of the foot with or without sensory nerve coaptation

The authors present a retrospective study on major plantar foot reconstruction to evaluate the role of the free fasciocutaneous flap and the importance of sensory nerve reconstruction in improving long-term results. Between 1995 and 1999, 20 patients with major defects of the sole of the foot underwent free forearm flap reconstruction performed by the senior author (F.S.). Sensory nerve reconstruction was added to this technique in 1997. The age and sex of the patients and the cause, location, and dimensions of their defects were recorded. The patients were clinically and neurophysiologically evaluated at 3, 6, and 12 months after the procedure for the following parameters: flap contour, flap stability, load capacity, walking ability, touch sensation, pain sensation, static two-point discrimination, and thermal sensibility. Dermatomic somatosensory-evoked potentials were also tested at 12 months. Follow-up ranged from 1 to 5 years. Patients were divided into two groups according to sensory nerve reconstruction. Group A consisted of 11 patients with nerve repair, and group B consisted of nine patients without nerve repair. One patient from group A who had an idiopathic neuropathy was excluded from the study because of interference with the reinnervation process. Five more patients (three from group A and two from group B) were lost at follow-up and excluded from the study. The final sample size in each group was seven. Data from both groups were compared and statistically analyzed with the Mann-Whitney test and the Fisher exact test. Long-term results confirmed in all reconstructions long-lasting stability. During the first postoperative year, patients with sensory nerve reconstruction showed better sensibility. The statistical analyses confirmed significant differences between the two groups to be dependent upon surgical technique at 3 and 6 months. Two-point discrimination and dermatomic somatosensory-evoked potentials were recorded. After 12 months, flaps without surgical nerve repair showed progressive improvement of sensitive thresholds, achieving a good protective sensibility, similar to that of the other group, but these flaps never regained two-point discrimination or dermatomic somatosensory-evoked potentials.     

Increased occurrence of PGP 9.5-immunoreactive epidermal Langerhans cells in rat plantar skin after sciatic nerve injury

This study examines the occurrence and distribution of epidermal dendritic cells (DCs) in cryostate sections from plantar skin in normal rats and in rats with a crush injury or neurotomy and suture of the sciatic nerve. The dendritic cells were visualized with antibodies against protein-gene product 9.5 (PGP 9.5). Counts under the fluorescence microscope showed that the occurrence of dendritic cells is increased and that the proportion of dendritic cells in the basal layer is elevated 3 months after sciatic neurotomy and suture but not after a crush lesion. The countings also revealed that the number of cells is elevated as soon as 1 week after neurotomy and suture. Labelling with specific antibodies showed that the dendritic cells examined represent Langerhans cells (LCs). These observations show that there is a neural influence on the occurrence and distribution of PGP 9.5-immunoreactive epidermal Langerhans cells. Whether this influence is direct or indirect remains to be ascertained.     

Reconstruction of the Abdominal Vagus Nerve Using Sural Nerve Grafts in Canine Models

Background

Recently, vagus nerve preservation or reconstruction of vagus has received increasing attention. The present study aimed to investigate the feasibility of reconstructing the severed vagal trunk using an autologous sural nerve graft.

Methods

Ten adult Beagle dogs were randomly assigned to two groups of five, the nerve grafting group (TG) and the vagal resection group (VG). The gastric secretion and emptying functions in both groups were assessed using Hollander insulin and acetaminophen tests before surgery and three months after surgery. All dogs underwent laparotomy under general anesthesia. In TG group, latency and conduction velocity of the action potential in a vagal trunk were measured, and then nerves of 4 cm long were cut from the abdominal anterior and posterior vagal trunks. Two segments of autologous sural nerve were collected for performing end-to-end anastomoses with the cut ends of vagal trunk (8–0 nylon suture, 3 sutures for each anastomosis). Dogs in VG group only underwent partial resections of the anterior and posterior vagal trunks. Laparotomy was performed in dogs of TG group, and latency and conduction velocity of the action potential in their vagal trunks were measured. The grafted nerve segment was removed, and stained with anti-neurofilament protein and toluidine blue.

Results

Latency of the action potential in the vagal trunk was longer after surgery than before surgery in TG group, while the conduction velocity was lower after surgery. The gastric secretion and emptying functions were weaker after surgery in dogs of both groups, but in TG group they were significantly better than in VG group. Anti-neurofilament protein staining and toluidine blue staining showed there were nerve fibers crossing the anastomosis of the vagus and sural nerves in dogs of TG group.

Conclusion

Reconstruction of the vagus nerve using the sural nerve is technically feasible.