The effects of experimental neurolysis on ectopic firing in a rat chronic constriction nerve injury model

PURPOSE: We studied the effects of experimental neurolysis on ectopic firing in a rat chronic constriction nerve injury (CCI) model. METHODS: Sixteen Wistar rats were used as CCI models; 8 in a neurolysis group and 8 in a sham operation group. Eight additional Wistar rats were used in a normal control group. The CCI model was created by loosely ligating the sciatic nerve with 4-0 chromic gut sutures. Seven days after surgery the same portion of the sciatic nerve, now embedded in scar tissue, was exposed. For the neurolysis group all sutures and scar tissue around the nerve were removed, and for the sham operation group only exposure of the sciatic nerve embedded in scar tissue was performed. Fourteen days after the first surgery the spinal cords of all animals in the 3 groups were transeated at the most rostral level of the spinal cord and ectopic firing was recorded antidromically from the sural nerve. The spontaneous ectopic firing frequency and the firing pattern at rest and the ectopic firing frequency under a hypoxic condition were analyzed. RESULTS: The ectopic firing frequency in the neurolysis group was significantly lower than that of the sham operation group but higher than that of the normal control group. Also the appearance rate of an on-off pattern was 0% in the neurolysis and normal control groups and 38% in the sham operation group. Finally the accumulated number of ectopic firings under a hypoxic condition was significantly smaller in the neurolysis and normal control groups than that of the sham operation group. CONCLUSIONS: Experimental neurolysis significantly improved the abnormal ectopic firing frequency and on-off firing pattern in the injured nerve of the CCI model. These findings may explain the efficacy of neurolysis on sensory symptoms such as numbness or spontaneous pain in chronic compression neuropathy.     

Experimental study on the repair of peripheral nerve lesions--subacute compression neuropathy and neurolysis

Neurolysis has been a widely accepted treatment for entrapment neuropathy and other nerve injuries in continuity. The purpose of this experimental study is to clarify the effects of neurolysis on the recovery from subacute compression neuropathy. The sciatic nerves of 49 mongrel dogs were used. In order to make the model of subacute compression neuropathy, the apparatus designed by Horiuchi to compress the nerve with constant force was applied to each nerve for three weeks. The pressure of compression was 55 mmHg when the thickness of the nerve was 2 mm. According to the degree of injury of the motor nerve in the peroneal funiculus of the sciatic nerve, 18 nerves were classified as first-degree injury ( Sunderland ) and 31 as second-degree injury. After removing the compressing apparatus, either external neurolysis (E.N.) or internal neurolysis (I.N.) was performed on these neuropathies under magnification. After the operation, each nerve was electrophysiologically followed up to 24 weeks; at one-week interval in the early stage and at four-week interval in the late stage. The macroscopic and histological observations were made on the fifth, eighth and 24th week. Electrophysiological findings: In the first-degree injuries, conduction block at the compressed site had already disappeared at the first week and motor nerve conduction velocity (M.N.C.V.) recovered rapidly with no apparent difference among the removal group (removal of apparatus only) and the neurolysis groups. In the second-degree injuries, evoked muscle action potential in the anterior tibial muscle appeared at the sixth week, about one week earlier in the I.N. group than in the removal group. M.N.C.V. of the removal group recovered gradually without exception, but that of the neurolysis groups inconstantly in the early stage. In the late stage, M.N.C.V. of all groups reached about 60 m/sec gradually and exponentially and never exceeded the average value (75.3 m/sec) of normal M.N.C.V. Macroscopic findings: The swelling of the portion adjacent to the compressed site ( pseudoneuroma ), which had been observed until the eighth week, disappeared at the 24th week. A scar around the nerve existed even at 24 weeks post-operatively, but it became loose and appeared like a mesoneurium and its vessels communicated with epineurial nerve vessels.(ABSTRACT TRUNCATED AT 400 WORDS)     

周围神经卡压松解后病理生理变化的实验研究

目的 应用神经特殊染色技术及电生理学方法,探讨周围神经卡压松解后神经纤维的再生修复和神经传导功能的变化。方法 在大鼠坐骨神经卡压模型基础上,将６０只ＳＤ成年雄性大鼠随机分为四组。Ａ组：仅去除卡压;Ｂ组：去除卡压后切开神经外膜;Ｃ组：去除卡压后神经外膜下周围注射利美达松（０．５ｍｇ／ｋｇ）;Ｄ组：去除卡压后切开神经外膜,在神经周围注射利美达松（０．５ｍｇ／ｋｇ）。于去除卡压后１、２、３、４和５周行运     

An experimental study on compression neuropathy--the effect of neurolysis on the blood-nerve barrier]

The effects of neurolysis on the sciatic nerves of normal controls and in dogs with compression neuropathy were evaluated by macroscopic and electrophysiological studies. The function of the blood-nerve barrier (BNB) was also assessed by Evans blue albumin. Studies on normal sciatic nerves (normal controls): In the epineurectomy group, neither scars nor denervation potentials were recognized. Moreover, the motor nerve conduction velocity (MNCV) and BNB were found to remain normal. In the perineurotomy group, on the other hand, scar formation at the surrounding tissue and denervation potentials were evident. BNB function was impaired and persisted for at least eight weeks. Studies on the compression neuropathy model: MNCV was increased in both the external neurolysis group and the epineurectomy group, and BNB function required six weeks to recover. MNCV was increased in the perineurotomy group, adhesion was severe, and denervation potentials and impairment of the BNB continued. In conclusion, both external neurolysis and epineurectomy restore the function of compressed nerves. There is no significant difference between these methods. Perineurotomy is not considered an appropriate technique for managing compression neuropathy.     

Topical application of mitomycin C prevents epineural scar formation in rats

The role of topically applied mitomycin C in preventing postoperative perineural fibrosis was examined by gross anatomical dissection and histological analysis in rats. The sciatic nerve was exposed bilaterally in 24 Wistar adult male rats, and an abrasion injury was produced on the exposed surface of the biceps femoris muscle in all animals. In the experimental group, cotton pads soaked with mitomycin C (0.5 mg/ml) were placed around the nerves for 5 min, whereas cotton pads soaked with saline were applied to the control group. Four weeks after surgery, the neurolysis sites were evaluated by blinded surgical dissection. Perineural adhesions were graded using a numerical grading scheme. The scar tissue formation index was also calculated, and a grading was made according to the number of fibroblasts/fibrocytes counted around the epineurium in histological evaluation. Mitomycin C-treated nerves showed significantly less perineural adhesions than controls. Quantification of the dense connective tissue surrounding the nerves revealed a statistically significant reduction around nerves treated with mitomycin C, and the number of fibroblast/fibrocytes was also significantly reduced. Application of topical mitomycin C might be effective in preventing epineural scar formation after neurolysis of peripheral nerves.     

Application of free temporoparietal fascial flap for recurrent neural adhesion of superficial radial nerve—A case report

Because of its anatomical location, the superficial radial nerve is vulnerable to trauma as well as injury during various surgical procedures. Once the nerve adheres to surrounding scar tissue, radiating pain often occurs due to nerve traction caused by loss of smooth gliding. Since it has been reported that the success rate with neurolysis only is lower, additional preventive procedures for recurrent neural readhesion are recommended. In the current report, we describe our experience performing neurolysis followed by nerve coverage using a free temporoparietal fascial flap for recurrent neural adhesion of the superficial radial nerve. A 45‐year‐old male complained of motion pain of the left wrist and thumb joints caused by recurrent neural adhesion of the superficial radial nerve after a chain saw trauma and following multiple reconstructive procedures. The radiating pain completely disappeared after neurolysis performed by a previous surgeon; however, it recurred 4 weeks later. Four months after the previous neurolysis the patient underwent external neurolysis and covering of the nerve with a free temporoparietal fascial flap to prevent neural readhesion because local soft tissue could not be used due to the massive scar tissues on the forearm. One year after the secondary neurolysis, the symptoms of radiating pain during wrist and thumb motion were drastically improved. A free adipofascial flap such as a temporoparietal flap may be an option for prevention of neural readhesion after neurolysis of the superficial radial nerve in cases where a local flap cannot be used on the forearm. © 2015 Wiley Periodicals, Inc. Microsurgery 35:489–493, 2015.     

The effect of low-dose external beam radiation on extraneural scarring after peripheral nerve surgery in rats

OBJECTIVE: Scar tissue is an inevitable result of peripheral nerve surgery. A variety of substances have been used to prevent epineurial scarring. In this study, the effect of low-dose radiation therapy on epineurial scarring was investigated. METHODS: Seventy-eight male Sprague-Dawley rats were studied. A total of 60 rats were subjected to one of three types of surgical procedure on the sciatic nerve, as follows: Procedure 1, external neurolysis (n = 20); Procedure 2, abrasive injury (n = 20); and Procedure 3, anastomosis (n = 20). On the left sciatic nerves, 700 cGy external beam radiation was administered 24 hours after surgery, and the right sciatic nerves served as a control group (surgery only). Eighteen animals without surgical intervention were used to establish the fibrotic effect of radiotherapy on normal nerves. A neurological examination was performed weekly. Six weeks after surgery, the extent of extraneural scarring was examined by gross microdissection by means of a numerical grading scheme and histological analysis. Cellular density and surface measurements of scar tissue were also evaluated. RESULTS: The dissection around the nerve was easier in rats treated with low-dose radiation compared with the control group. Furthermore, grading scores in both nerve adherence and nerve separability were significantly lower in treated nerves than in the control group (P < or = 0.05). Low-dose radiotherapy decreased the scores of cellular density and surface measurement of scar tissue (P < or = 0.05). In normal nerves, radiotherapy did not produce any fibrotic effects and the density of fibroblasts/fibrocytes was also very low. CONCLUSION: In the case of surgery or local trauma to peripheral nerve, the use of low-dose radiation therapy may be a safe method of limiting postoperative epineurial scar formation.     

神经营养素3基因修饰的神经干细胞对周围神经再生修复的影响

目的 探讨神经营养素3基因修饰的神经干细胞对周围神经再生的影响。方法 54只SD大鼠随机分为3组，造成坐骨神经切断损伤模型，神经外膜端端缝合，于小腿三头肌每周分别注射生理盐水、未被神经营养素3基因修饰的神经干细胞、及神经营养素3基因修饰的神经干细胞。术后3、6、9周动态观察坐骨神经功能指数(SFI)以了解后肢功能恢复情况、组织学切片观察、肌湿重恢复率测定、9周后吻合口神经干的电镜观察。结果 神经营养素3基因修饰的神经干细胞组动物的有髓神经纤维密度、神经组织面积、髓鞘厚度、肌湿重以及坐骨神经功能指数均显著优于未被神经营养素3基因修饰的神经干细胞组和生理盐水组，9周时差异有统计学意义。单纯神经干细胞组各项指标优于生理盐水组。结论 将神经营养素3基因修饰的神经干细胞移植于修复的周围神经，使局部释放的NT-3加快轴突再生速度以促进周围神经再生，减缓失神经支配肌肉的萎缩。     

腰椎手术后硬膜外腔瘢痕预防的实验研究

目的比较腰椎手术后硬膜外放置明胶海绵、几丁糖和高分子量的透明质酸钠 (sodium hyaluronate,HA)对术后硬膜外瘢痕形成的预防作用。方法 96只 Wistar大鼠被随机分成四组,每组 24只。一组为对照组,其它三组分别于单侧半椎板切除术和椎间盘破坏术关闭切口前在硬膜外腔放置明胶海绵、几丁糖和高分子量 HA。分别在术后第 2、 4、 8、 12周时,每组各取 6只大鼠进行大体标本、组织切片 (HE、 VG和免疫组化染色 )和透射电镜观察。对术后硬膜外瘢痕的多少和椎管的大小进行计算机图像分析和统计学处理。检测对照组和高分子量 HA组大鼠脑脊液中的 HA浓度。结果几丁糖和高分子量 HA组的硬膜外瘢痕比其它各组显著减少 (P< 0.05);椎管的大小在各组各时段差异没有显著性意义;在各组各时段均可见到纤维环的环状纤维未能修复椎间盘手术带来的连续性中断。所有脑脊液标本中 HA浓度最高的 2例在 2周时的 HA组。结论几丁糖和高分子量 HA能减少后路腰椎间盘术后的硬膜外瘢痕的形成;评价材料对硬膜外瘢痕影响的同时,也要考虑到其对椎间盘破口愈合的影响;在硬膜外腔放置各种材料时应考虑到其对中枢神经系统的潜在影响。     

神经牵拉延长器修复神经缺损的实验研究

探讨神经牵拉延长器修复神经缺损,为临床应用提供依据。方法：健康家兔３０只,分３组,右侧坐骨神经造成１．０ｃｍ缺损,Ａ组：自制神经牵拉延长器延长,二期端－端缝合;Ｂ组：神经原位移植;Ｃ组：直接拉扰缝合。术后不同时期分别进行电生理、组织学、神经纤维计数等检查。     

聚-DL-乳酸可吸收医用膜防止周围神经粘连的实验研究

目的研究聚-DL-乳酸(PDLLA)可吸收医用膜防止周围神经损伤修复后粘连形成的作用。方法SD大鼠60只,随机分成两组,即单纯缝合 PDDLA组(实验组)和单纯缝合组(对照组),每组各30只。坐骨神经切断后显微缝合,实验组缝合口局部用PDLLA膜包裹,对照组未做处理。术后2、4、8、12、16周行大体观察和组织学检查,术后12、16周行神经电生理检查,术后16周行计算机图像分析。结果实验组神经缝合口局部瘢痕增生和粘连程度较对照组明显减轻,再生神经纤维较直,排列结构较整齐。电生理检查和计算机图像分析结果显示实验组的效果明显优于对照组。结论PDLLA可吸收医用膜能有效地防止周围神经修复后局部瘢痕组织增生和粘连的形成,提高神经功能恢复的效果。     

周围神经卡压松解的实验研究

周围神经卡压是常见病，多以手术松解来治疗。但各术式的优劣尚未见临床或实验报告。为解决此问题，进行了实验研究。方法：在Ｍａｃｋｉｎｎｏｎ［１，３］所设计的大鼠坐骨神经卡压模型的基础上，研究了神经卡压松解四种不同方法的优劣。实验分组，Ａ组，仅去除卡压：Ｂ组，去除卡压后用手术刀切开神经外膜；Ｃ组，去除卡压后，神经外膜内注射确炎舒松－Ａ：Ｄ组，去除卡压后再用手术刀切开神经外膜，然后在神经周围置确炎舒松－Ａ。术后不同时间（１～４周）进行电生理、组织学检测。结果：神经卡压物去除后，神经外膜内注射确炎舒松－Ａ，或切开神经外膜，周围再置确炎舒松－Ａ，这两种方法为较理想的神经卡压松解术式。     

ADVERSE EFFECTS OF SALINE NEUROLYSIS ON A CHRONICALLY COMPRESSED RAT SCIATIC NERVE

We have evaluated the effect of saline neurolysis compared with a simple decompression procedure on chronically compressed sciatic nerves in rats. Eight months after the initiation of nerve compression within a silicone tube, rats were divided into three groups of 35. In group I, saline was injected subepineurially at the compressed segment of the nerve after removal of the tube (decompression plus saline neurolysis). The nerves in group II were treated by removal of the tube only (simple decompression). In group III the tubes were left in place. Adding saline neurolysis to decompression provided no histological, morphometric, electrophysiological, or vascular advantages up to four months, and even gave worse results than simple decompression. We conclude that saline neurolysis has no beneficial effect on a chronically compressed nerve and it is not recommended for clinical use.     

Adverse effects of saline neurolysis on a chronically compressed rat sciatic nerve.

We have evaluated the effect of saline neurolysis compared with a simple decompression procedure on chronically compressed sciatic nerves in rats. Eight months after the initiation of nerve compression within a silicone tube, rats were divided into three groups of 35. In group I, saline was injected subepineurially at the compressed segment of the nerve after removal of the tube (decompression plus saline neurolysis). The nerves in group II were treated by removal of the tube only (simple decompression). In group III the tubes were left in place. Adding saline neurolysis to decompression provided no histological, morphometric, electrophysiological, or vascular advantages up to four months, and even gave worse results than simple decompression. We conclude that saline neurolysis has no beneficial effect on a chronically compressed nerve and it is not recommended for clinical use.     

异体神经段皮下包埋对坐骨神经再生影响的研究

目的　探讨异体周围神经段皮下包埋对坐骨神经再生的影响。　方法　 Wistar大鼠 30只 ,雄性。 6只为供体 (C组 ) ,余随机分为两组。实验组 (A组 ) 12只 ,于右大腿后侧皮下行异体坐骨神经 (15 mm)包埋 ,2周后取出 ,修整为 10 mm的片段移植于左侧新鲜的坐骨神经缺损处 (10 m m)。对照组 (B组 ) 12只 ,于右腿相应部位皮肤切口直接缝合 ,左侧新鲜坐骨神经 (10 mm)原位吻合。术后 2、4、8和 14周行组织学观察 ,14周作电生理测定和电镜观察。　结果　术后 2周 ,A组炎性反应稍重于 B组 ;至 4周时两组的炎性反应程度相似 ,近端少许胶原纤维增生 ;8周时两组的炎性反应基本停止 ,胶原纤维增生稍明显 ;14周时两组神经外膜构成完整 ,束膜、内膜结构无明显差异。再生大量的有髓神经纤维及少量的无髓神经纤维。髓鞘结构完整。再生轴突数目、面积差异无统计学意义 ,束膜厚度、分布及范围相似。运动神经传导速度、峰值及潜伏期差异无统计学意义 (P>0 .0 5 )。　结论　皮下包埋的异体周围神经段虽有一定的炎性反应 ,但仍具有与自体神经移植相似的神经再生引导作用。     

神经内松解术对周围神经卡压作用的实验研究

评估神经内松解术对周围神经卡压的效果。方法：将大鼠坐骨神经卡压１２周后，分别采用单纯减压、神经内松解、神经内松解加地塞米松等３种方法手术。于术后第４、８、１２周作神经电生理检测，组织形态学观察。结果显示：内松解术组的电生理指标，神经纤维的直径、数目，髓鞘的厚度及纤维结缔组织减少的程度均优于同期的单纯减压     

Novel Polysaccharide‐derived hydrogel prevents perineural adhesions in a rat model of sciatic nerve adhesion

We investigated the effects of a novel carboxymethylcellulose (CMC)‐derived hydrogel, in which phosphatidylethanolamine (PE) was introduced into the carboxyl groups of CMC, for preventing perineural adhesion after extensive internal neurolysis of rat sciatic nerve. Sciatic nerves were randomly assigned to one of the following groups: the Control group, operated but no treatment; the HA group, operated and treated with 1% hyaluronan; the CMC–PE(L) group, operated and treated with low‐viscosity CMC–PE hydrogel; and the CMC–PE(H) group, operated and treated with high‐viscosity CMC–PE hydrogel. Perineural adhesions were evaluated at 6 weeks. Nerves were also subjected to biomechanical testing to assess ultimate breaking strength. Electrophysiological and wet muscle weight measurements were performed. Breaking strengths were significantly lower for the CMC–PE(L) group than for the Control and HA groups. Latency was significantly longer for the Control group than for the CMC–PE(L) group at 20 days. The mean percentage of wet muscle weight to body weight was significantly lower for the Control group than for the CMC–PE(L) group at 6 weeks. Low‐viscosity CMC–PE hydrogel appears to prevent perineural adhesions and allow early restoration of nerve function. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 28:284–288, 2010     

Effect of Hyaluronic Acid-Carboxymethylcellulose Solution on Perineural Scar Formation after Sciatic Nerve Repair in Rats

Background

Scar tissue formation is the major cause of failure in peripheral nerve surgery. Use of a hyaluronic acid-carboxymethylcellulose (HA-CMC) membrane (Seprafilm) as a solid anti-adhesion barrier agent is one of the therapeutic approaches to reduce postoperative scar tissue formation. However, a solid membrane may not be suitable for repair of a weak peripheral nerve site. This study examined the effect of HA-CMC solution on perineural scar formation after peripheral nerve repair in rats.

Methods

The sciatic nerves of 40 rats were transected and then immediately repaired using 10-0 nylon. The nerves were divided randomly into two groups. Saline and HA-CMC solution were applied topically to the nerve repair sites in the control and experimental groups, respectively. Reoperation was performed at 3, 6, 9, and 12 weeks to assess scar tissue formation. The assessment included the quality of wound healing, presence of perinueral adhesion, cellular components of the scar tissue, thickness of the scar tissue and histomorphological organization of the repair site.

Results

Topical application of the HA-CMC solution significantly decreased the macroscopic nerve adherence score and the numbers of the cellular components such as fibroblasts and inflammatory cells (p < 0.05, Mann-Whitney U-test). The scar tissue formation index was significantly lower in the experimental group at 12 weeks than that in the control group (p < 0.05, Mann-Whitney U-test). The grading scores of the histomorphological axonal organization at the repair site were significantly higher in the experimental group than those in the control group at 12 weeks (p < 0.05, Mann-Whitney U-test). No evidence of wound dehiscence or inflammatory reactions against the HA-CMC solution was noted.

Conclusions

Topical application of a HA-CMC solution is effective in reducing the perineural scar formation and adhesion after sciatic nerve repair in rats, and is effective in promoting peripheral nerve regeneration at the repair site.     

Effects of hyaluronic acid-carboxymethylcellulose membrane on extraneural adhesion formation and peripheral nerve regeneration

The goal of nerve repair in the peripheral nervous system is to increase the number of axons passing from proximal to distal stump, and to enable the regenerated axons to reach the end organ as soon as possible. In the present study, the effect of the membrane formed by a mixture of hyaluronic acid and carboxymethylcellulose (HA-CMC) on nerve regeneration and perineurial scar formation was investigated. Eighteen New Zealand rabbits were allocated into control (n = 9) and experimental groups (n = 9). In the control group, conventional nerve repair was carried out following the transection of the sciatic nerve, while in the experimental group, following repair of the nerve, the repair line was covered by HA-CMC membrane extending 1 cm beyond the distal and proximal ends. Nerve regeneration and extraneurial adhesion formation were compared between the two groups 3 months later. It was observed that adhesion in the surrounding tissues was significantly less in the experimental group than in the control group. Furthermore, morphometric analysis of specimens obtained from the distal parts of nerves showed that the number of axons with myelin was higher in the experimental group than in the control group, with a statistically significant difference. Histologic sections obtained from the nerve repair line demonstrated that extraneural and intraneural fibrosis was significantly lower in the experimental group. It was concluded that HA-CMC membrane had a favorable effect on nerve regeneration, as well as extraneural scar formation, encouraging the clinical application of HA-CMC following nerve injuries.