Axonal supercharging technique using reverse end-to-side neurorrhaphy in peripheral nerve repair: an experimental study in the rat model

OBJECT: In an attempt to improve peripheral nerve repair, the influence of the addition of reverse end-to-side neurorrhaphy for an injured peripheral nerve was investigated in the rat sciatic nerve transection model. METHODS: Twelve Sprague-Dawley rats were divided into two groups (six rats in each group). In Group I, the right sciatic nerve was cut at a point distal to the gluteal notch and repaired using end-to-end neurorrhaphy with four 10-0 nylon epineurial sutures. In Group II, after performing the same procedure as in Group I, the left sciatic nerve was cut distally and passed through a subcutaneous tunnel to the right side. The proximal stump of the left sciatic nerve was coapted to the epineurial window of the right sciatic nerve distal to the injured point in an end-to-side fashion using 10-0 nylon epineurial sutures. The effects were evaluated using analgesimeter recordings for the hind paw, electrophysiological tests, measurement of the muscle contraction force, a double-labeling technique, weight measurement and histological examination of the gastrocnemius muscle, histological examination of the bilateral sciatic nerves, and immunofluorescent staining. RESULTS: Results from the many tests used to evaluate the reverse end-to-side neurorrhaphy technique indicated that functional recovery of the denervated target organs was promoted by axonal augmentation. CONCLUSIONS: The reverse end-to-side neurorrhaphy technique could be useful in peripheral nerve repair.     

Modified end-to-side neurorrhaphy enhances axonal sprouting: a motor functional and morphological study

This study evaluated the effect of modified end-to-side neurorrhaphy on functional recovery by modulating the epineurial window and contact areas, with a donor nerve, using a rat median nerve and finger flexors. Grasping testing, muscle contractility testing, and a histological study were performed 20 weeks after surgery. The modified end-to-side repair can enhance axonal sprouting from an intact nerve, and improve the functional recovery. Either the epineurial window surface area, or the contact configuration with the donor nerve is an important factors in an end-to-side coaptation model.     

端侧缝合与神经移位修复臂丛损伤的比较研究

目的 为临床提供端侧缝合与神经移位修复臂丛损伤疗效优劣的实验依据。方法 Wistar大鼠36只,按术后取材时间分为1、2、3个月组,每组12只。按手术方法分为2组。(1)端侧缝合组(前肢右侧):于臂丛内侧束远端外侧外膜上开窗,将桡神经远断端和内侧束开窗处作外膜端侧缝合。(2)神经移位组(前肢左侧):在正中神经远端切断神经,将其近端和桡神经远断端作端端缝合。术后两组各时间组行电生理、肌湿重、肌纤维截面积、运动终板面积及抗神经丝(neurofilament,NF)免疫组化和神经超微结构观察。结果 端侧缝合组的运动神经传导速度,诱发电位潜伏期,NF阳性表达强度均劣于神经移位组(P<0.01);肌湿重、肌纤维截面积及运动终板面积两组差异无显著意义(P>0.01)。结论 端侧缝合组术后远端神经虽可再生但疗效明显差于神经移位组,故临床上是否可用其来修复臂丛神经损伤尚需进一步研究。     

End-to-side neurorrhaphy: an experimental study in rabbits

The concept of end-to-side nerve repair was recently introduced; however, most authors have reported conflicting results with this technique. This study was conducted to assess the effectiveness of end-to-side nerve repair in both fresh and predegenerated specimens by histological evaluation in an animal study in rabbits. Thirty male rabbits were divided into three groups. In group 1 (n = 14), the peroneal nerve was divided and sutured end-to-side to the tibial nerve via an epineurial window. In group 2 (n = 13), the peroneal nerve was divided and sutured end-to-side to the tibial nerve after a 1-week "predegeneration period." In group 3 (n = 3), which was considered the control group, the peroneal nerve was divided and sutured to the adjacent soft tissues. After 3 months, specimens were harvested for histological evaluation. Nerve fiber count, in normal peroneal nerves, averaged 532/cross section. In groups 1 and 2, average nerve fiber count in implanted peroneal nerves was 6.24 and 7.00/cross section, respectively. No significant statistical difference was observed between fresh and "predegenerated" groups (P = 0.90). These data suggest that collateral sprouting of donor nerves is possible after end-to-side neurorrhaphy through an epineurial window, but the number of nerve fibers in recipient nerves is too low to result in any functional recovery in the target organ.     

Neuroma prevention by end-to-side neurorraphy: an experimental study in rats

PURPOSE: The successful treatment of painful neuromas remains a difficult goal to attain. In this report we explore the feasibility of neuroma prevention by insertion of the proximal end of a nerve through an end-to-side neurorraphy into an adjacent mixed nerve to provide a pathway and target for axons deprived of their end organ. METHODS: Experiments were performed on a total of twenty 250-g Sprague-Dawley rats. Two groups of 10 animals were prepared. Group A served as an anatomic control. In group B the right saphenous nerve was transected and implanted end-to-side through an epineurial window into the tibial nerve distal to the trifurcation of the sciatic nerve. After 12 weeks the corresponding sensory neurons were identified by retrograde labeling techniques and histomorphometric analysis of the proximal and distal tibial nerve segments, and regular histology of the end-to-side site were performed. RESULTS: The results of the retrograde labeling of the corresponding sensory neuron pool of the saphenus nerve showed extensive labelling of the L1 to L3 spinal ganglions after intracutaneous tracer application of the planta pedis. The morphology of the end-to-side coaptation site and histomorphologic analysis prove that sensory neurons penetrate the perineurial sheath and axons regenerate along the tibial Schwann cell tubes toward their targets. CONCLUSIONS: Axons of a severed peripheral nerve that are provided with a pathway and target through an end-to-side coaptation will either be pruned or establish some type of end-organ contact so that a neuroma can be prevented. Whether these axons will lead to disturbing sensations such as paresthesia or dysesthesia in the newly found environment or remain silent codwellers, this experiment cannot answer. Long-term results of future clinical work will have to decide whether the prevention of the neuroma through end-to-side coaptation will be an appropriate therapy for this difficult problem.     

Reverse end-to-side neurotization

The authors describe a reverse end-to-side neurorrhaphy model in which the proximal end of a donor nerve is sutured to an epineurial window in the side of a recipient nerve. If effective, this technique would have useful applications in nerve reconstructive surgery. Female Sprague-Dawley rats were divided into three groups (n = 9). In Group A, the peroneal nerve was transected and directly repaired in standard end-to-end fashion. In Group B, the tibial nerve was transected and the proximal end was sutured to the side of the intact peroneal nerve through an epineurial window. In Group C, the tibial nerve was also transected and the proximal end sutured to the side of the intact peroneal nerve, but the peroneal nerve was then cut proximally. After 12 weeks, contractile forces of the extensor digitorum communis (EDC) were measured, following stimulation of the proximal sciatic nerve on all experimental (and normal) hind limbs. For Group B, the peroneal nerve was transected proximal to the repair site just prior to stimulation. Group B animals did not demonstrate any measurable contractions. No statistically significant differences were found between Groups A and C. This demonstrated the successful neurotization of a denervated muscle using a reverse end-to-side neurorrhaphy model.     

A modified end-to-side method for peripheral nerve repair: large epineurial window helicoid technique versus small epineurial window standard end-to-side technique

This study evaluated 2 end-to-side nerve repair techniques for ability to induce nerve sprouting and muscular recovery. Twenty-four rats underwent identical surgeries. The helicoid method of neurorrhaphy was used on the left (large epineurial window) side and the standard end-to-side (small epineurial window) repair on the right side of each rat to repair the peroneal nerve. The helicoid configuration markedly increases the area from which axons can sprout into the recipient nerve. At 11 months after surgery, axons were counted in donor and recipient nerves, and muscle moist weight of the extensor digitorum longus (EDL) and tetanic force were measured. Muscle volume, tetanic force, and moist weight of EDL muscles were significantly higher on the left side (helicoid) than on the right (end-to-side). Histologic analysis and nerve axon counting of the recipient peroneal nerve showed significantly more regenerative nerves on the left than on the right. There were no significant differences between sites above and below the repair site in the donor tibial nerve in regard to mean number of nerve fibers. Helicoid nerve repair can entice more nerve fiber sprouts from the intact donor nerve, improve muscular recovery, and maintain donor nerve health.     

Effect of End-to-side Repair of Proximal Nerve Stumps of Transected Peripheral Nerves on the Development of Neuroma (Experimental Study)

Objective Neuroma is a psychologically and physically disabling problematic condition without any current standard therapy. For that reason, we investigated whether end-to-side anastomosis of the proximal end of the transected nerve into the adjacent nerve will prevent the development of neuroma in different types of nerve injuries. Study design In this study, hind legs of 18 Sprague–Dawley female rats were used. Six groups were formed. In group I, peroneal nerves were transected and its proximal end was attached end-to-side through the epineural window to the adjacent tibial nerve. In group II, contrary to group I, an epineural window was created in the tibial nerve and the same number of sutures were employed. In group III, tibial nerve was transected proximal to the end-to-side repair site, whereas in group IV, distal segment of the nerve was cut, and an end-to-end repair procedure was repeated. In group V, unlike group I, an approximately 1-cm segment was resected and removed distal (from tibial nerve) to the end-to-side repair site. In group VI, an epineural window was created in the tibial nerve and the same number of sutures were used, and also a 1-cm distal nerve segment was resected. The rats were followed for 2 months, and then all of the groups were evaluated histopathologically, and weights of the posterior muscle groups of hind legs were evaluated. Findings and Conclusions No neuroma formation was observed in the proximal stumps of peroneal nerve segments in end-to-side repair sites in groups I, III, IV, and V, and proximal stumps of the tibial nerve in group V. In group VI, neuroma formation was observed in the proximal end of the tibial nerve. When weights of the posterior muscle groups of hind legs in groups I and II were comparatively assessed, statistically significant difference was not detected. In conclusion, based on histological data obtained for proximal nerve ends and segments distal to the end-to-side repair sites, we think that end to side neurorrhaphy of the proximal end of the damaged nerve to adjacent nerve will prevent the development of neuroma without injuring the intact nerve segment.     

End-to-side neurorrhaphy as a salvage procedure for irreparable nerve injuries. Technical note

After a few reports on end-to-side nerve repair at the beginning of the last century, the technique was put aside until its recent reintroduction. The authors present their results in three patients with median nerve defects that were between 15 and 22 cm long and treated using end-to-side median-to-ulnar neurorrhaphy through an epineurial window. The follow-up times were between 32 and 38 months. Sensory evaluation involved superficial touch, pinprick, and two-point discrimination tests. Motor evaluation was completed by assessing the presence of opposition and by palpating the abductor pollicis brevis muscle. Sensory recovery was observed in all patients in the median nerve dermatome, and motor recovery was absent, except in Case 1. End-to-side nerve repair can be a viable alternative to nerve grafting in patients with long gaps between the ends of the injured nerve.     

不同端侧缝合方法对周围神经再生的影响

目的比较各种不同的端侧缝合方法治疗周围神经损伤后神经再生的优劣。方法ＳＤ大鼠９０只，随机分成５组。前４组右侧腓总神经作端侧缝合，左侧切除长１．５ｃｍ的腓总神经作为对照。Ａ组：右侧远断端与近段行侧端吻合，外膜不开窗。Ｂ组：方法同Ａ组，但束、外膜开窗。Ｃ组：右侧近断端与远段行端侧吻合，外膜不开窗。Ｄ组：方法同Ｃ组，但束、外膜开窗。Ｅ组：右侧以４５度角、左侧以９０度角作侧端缝合。各组分别于术后１、２、３个月取材，作肌电图、组织学及肌湿重检查。结果Ａ与Ｂ，Ｃ与Ｄ组比较，运动神经诱发电位潜伏期、波幅及有髓纤维计数，后者优于前者（Ｐ＜０．０５）。肌湿重及肌纤维截面积，两者无明显差异（Ｐ＞０．０５）。４５度与９０度角比较，前者神经再生质量明显优于后者（Ｐ＜０．０５）。结论周围神经可通过端侧吻合而再生，以束、外膜开窗及４５度角的缝合方法为佳     

Motor functional and morphological findings following end-to-side neurorrhaphy in the rat model.

Nerve repair cannot always be achieved by the conventional end-to-end technique. This study evaluated the functional recovery of nerves repaired with end-to-side neurorrhaphy in a rat model. The right peroneal nerves of 80 female rats were transected and divided into four groups. In group A, the nerve ends were separated and remained unrepaired; in group B, the distal peroneal ends were directly sutured to the epineurium of the tibial nerves in end-to-side fashion; in group C, the distal ends were sutured through an epineurial window at the repair site in end-to-side fashion; and in group D, the nerve ends were reconnected by the traditional end-to-end technique. Evaluation included gait analysis by calculation of a peroneal functional index, measurement of contractile function of the extensor digitorum longus muscle, wet weight of the extensor digitorum longus, and histological examination. The findings of this study suggested the following: (a) end-to-side neurorrhaphy allows effective motor functional recovery, demonstrated by earlier improvement of the peroneal functional index, stronger muscle contractile function, greater muscle weight, and higher density of regenerated axons compared with unrepaired nerves; (b) removal of the epineurium of the donor nerve at the nerve coaptation site increases the effectiveness of end-to-side neurorrhaphy, but the epineurium appears to be a partial barrier to axonal regeneration; (c) removal of the epineurium does not affect the structure and function of the donor nerve; and (d) end-to-end repair achieved the best functional recovery among the four groups; therefore, end-to-side repair should be considered as a potential alternative only when no proximal nerve is available.     

Choline acetyltransferase activity in collateral sprouting of peripheral nerve after surgical intervention: experimental study in rats.

The purpose of this study was to establish an assay of choline acetyltransferase (ChAT) activity to investigate the regeneration of injured peripheral nerve, repaired by end-to-end or end-to-side neurorrhaphy. Murine sciatic and peroneal nerves were exposed, and the peroneal nerve was transected at a site 5 mm from its ramification. For end-to-side neurorrhaphy, an epineurotomy producing a 5-x5-mm window was carried out on the tibial nerve, just above the level of gastrocnemius muscle ramification. The peroneal nerve stump was then sutured end-to-side to the tibial nerve window. For end-to-end neurorrhaphy, the peroneal stump was directly sutured end-to-end. ChAT activity was measured at a site distal to the peroneal stump at 1 to 3 months postoperatively, and the results were compared among four groups: 1) end-to-end neurorrhaphy group; 2) end-to-side neurorrhaphy group; 3) unrepaired group; and 4) positive controls. ChAT activity in the end-to-side neurorrhaphy yielded approximately two-thirds the value of the end-to-end neurorrhaphy, and more than half the value of positive controls at 3 months postoperatively. Histologic sections of the end-to-side and end-to-end sutured peroneal nerve demonstrated large numbers of myelinated axons and Schwann cells at the third postoperative month. All the results demonstrated that end-to-side neurorrhaphy is comparable to well-performed end-to-end neurorrhaphy, thus providing another option for surgical treatment of avulsion nerve injury and massive nerve defect.     

End-to-side neurorrhaphy for defects of palmar sensory digital nerves.

Ten traumatic nerve defects at the palm or digit level were treated by end-to-side (ETS) neurorrhaphy. The technique included removal of an epineurial window on the donor nerve and coaptation of the sharply cut distal end of the injured nerve by epineurial stitches under microscopic magnification. At final follow-up, the static two-point discrimination test (2 pd) scored at an average of 9.1 mm (range, 6-12 mm) on the repaired nerve, compared to an average of 4.6 mm (range, 4-6 mm) on the contralateral uninjured control side. Moving 2 pd scored at an average of 7 mm (range, 4-9 mm) on the repaired nerve compared to an average of 2.6 mm (range, 2-4 mm) on the control side. This short series showed that ETS neurorrhaphies are effective and give comparable results with those of nerve grafts or vein conduits.     

Our experience about ten end-to-side sensitive nerve sutures at the hand

Ten traumatic nerve defects at the palm or digit level were treated by end-to-side (ETS) neurorrhaphy. The technique included removal of an epineurial window on the donor nerve and coaptation of the sharply cut distal end of the injured nerve by epineurial stitches under microscope magnification. At final follow-up, the static two-point discrimination test scored at an average of 9.1 (range, 6-12) mm on the repaired nerve, compared to an average of 4.6 (range, 4-6) mm on the contralateral uninjured control side. The moving two-point discrimination test scored at an average of 7 (range, 4-10) mm on the repaired nerve compared to an average of 2.6 (range, 2-4) mm on the control side. This short series showed ETS neurorrhaphies are effective and give comparable results with those of nerve grafts or vein conduits, but worse than direct repairs.     

终末器官对端侧神经吻合后轴突再生影响的实验研究

目的　探讨受神经远端终末器官对端侧吻合后神经再生的影响。方法　SD雌性大鼠 1 0只 ,动物随机分为A、B2组。A组 :在近端切断腓总神经 ,其远断端与胫神经外膜开窗处进行端侧吻合 ;B组 :同A组两神经端侧吻合后 ,在距吻合口 1 .5cm处切断其与终末器官的联系 ,并将连接肌肉的腓总神经远端反折固定在邻近的肌肉组织。术后 1 2周取吻合口处的神经标本 ,甲苯胺蓝和抗神经微丝抗体免疫组化染色、光镜检查及图像分析。结果　甲苯胺蓝染色及神经微丝免疫组化染色结果说明A、B2组再生神经纤维数目、髓鞘厚度、纤维结缔组织含量及神经纤维丝排列 ,均有明显差异。结论　终末器官对促进端侧神经吻合后神经再生具有重要作用     

Specificity of muscle reinnervation following repair of the transected sciatic nerve. A comparative study of different repair techniques in the rat.

Specificity of muscle reinnervation and the recovery of muscle contractility were studied after repair of the transected rat sciatic nerve. Six different techniques were compared: epineurial suture, perineural suture, whole nerve graft, interfascicular grafts, skeletal muscle bridge and tubulization. Muscle tetanic force and specificity of reinnervation were evaluated 12 weeks after nerve repair. Recovery of tetanic force was superior after repair with epineurial sutures. There was no statistical significance between the other methods in respect of tetanic force. The specificity of muscle reinnervation was best after tubulization, repair with interfascicular grafts and perineurial suture.     

Recovery of cutaneous pain sensitivity after end-to-side nerve repair in the rat.

OBJECT: The hypothesis that collaterally sprouting axons from an uninjured donor nerve may provide recovery of pain sensitivity in the skin after end-to-side nerve repair was investigated in rats. In addition, the effect of this technique on the donor nerve was examined. METHODS: The distal stump of the transected peroneal nerve was sutured end to side to the intact sural nerve. No epineurial window or perineurial slit was made in the sural nerve at the site of coaptation. Other nerves in the leg were transected and ligated. Eighteen weeks later, the sural nerve was transected at a site distal from the coaptation site. The residual pain sensitivity in the peroneal innervation field in the instep was documented using the skin pinch test in three of 11 animals. The area of sensitivity encompassed 19 to 40% of the maximum nociceptive innervation area of the normal peroneal nerve. The nerve pinch test revealed functional sensory axons in all communicating peroneal nerves, in which 277+/-119 myelinated axons (mean +/- standard deviation) were found by histological investigation. CONCLUSIONS: The authors conclude that at least partial recovery of sensory function due to collateral sprouting of axons after end-to-side nerve repair is possible in principle. However, the presence of functional sensory axons in the peroneal nerve stumps did not guarantee the recovery of skin sensitivity to pain in all animals. No functional or morphological evidence of an untoward effect of collateral sprouting into the end-to-side communicating nerve was detected in the axons of the donor nerve itself.     

Impact of epineurial excision of the distal recipient nerve in terminolateral neurorrhaphy

Different surgical modifications were studied to improve success in terminolateral neurorrhaphy. The authors evaluated the efficacy of distal epineurial excision of the recipient nerve stump. Forty male Wistar rats were evaluated in four groups. The right hind limbs of the animals were used as experimental limbs and the left hind limbs as control limbs. The peroneal nerve was transected at a level 1 cm above the bifurcation of the tibial nerve. The proximal stump of the peroneal nerve was covered with gluteus maximus muscle fibers in all groups. In Group 1, the distal peroneal nerve was not processed and was left in the operative field. In Group 2, the distal peroneal nerve stump was sutured to an epineurial window on the tibial nerve by epineurial neurorrhaphy. In Group 3, the distal stump of the peroneal nerve was buried in the tibial nerve without epineurial resection, and in Group 4 with a 1-mm epineurial excision. Walking track analyses, electromyographic studies, and histomorphometric analyses were performed after a 3-month follow-up period. Statistical analysis was done with ANOVA and Tukey tests. No important donor-nerve injury was detected. Axonal regeneration and functional results were better in Group 4 compared to Groups 2 and 3. An increased donor and recipient nerve contact surface area with the excision of the epineurium from the distal peroneal nerve stump (Group 4) might provide superior results with longer follow-up periods.