Anatomical study of sciatic nerve and common peroneal nerve compression

BACKGROUND： Many diseases of the common peroneal nerve are a result of sciatic nerve injury. The present study addresses whether anatomical positioning of the sciatic nerve is responsible for these injuries. OBJECTIVE： To analyze anatomical causes of sciatic nerve and common peroneal nerve injury by studying the relationship between the sciatic nerve and piriformis. DESIGN, TIME AND SETTING： Observe and measure repeatedly. The experiment was conducted in the Department of Anatomy, Tianjin Medical College between January and June 2005. MATERIALS： Fifty-two adult cadavers 33 males and 19 females, with a total of 104 hemispheres, and fixed with formaldehyde, were provided by Tianjin Medical College and Tianjin Medical University. METHODS： A posterior cut was made from the lumbosacral region to the upper leg, fully exposing the piriformis and path of the sciatic nerve. MAIN OUTCOME MEASURES： （1） Anatomical characteristics of the tibial nerve and common peroneal nerve. （2） According to different areas where the sciatic nerve crosses the piriformis, the study was divided into two types-normal and abnormal. Normal is considered to be when the sciatic nerve passes through the infrapiriform foramen. Remaining pathways are considered to be abnormal. （3） Observe the relationship between the suprapiriform foramen, infrapiriform foramen, as well as the superior and inferior space of piriformis. RESULTS： （1） The nerve tract inside the common peroneal nerve is smaller and thinner, with less connective tissue than the tibial nerve. When pathological changes or variations of the piriformis, or over-abduction of the hip joint, occur, injury to the common peroneal nerve often arises due to blockage and compression. （2） A total of 76 hemispheres （73.08%） were normal, 28 were abnormal （26.92%）. The piriformis can be injured, and the sciatic nerve can become compressed, when the hip joint undergoes intorsion, extorsion, or abduction. （3） The structures between the infrapiriform and suprapi     

七叶皂甙钠对坐骨神经结扎术后大鼠热痛觉及脊髓神经细胞凋亡的影响

目的探讨七叶皂甙钠对坐骨神经结扎术后大鼠热痛觉及脊髓神经细胞凋亡的影响。方法90只SD大鼠随机分为正常对照组、坐骨神经慢性压迫损伤(CCI)模型组(CCI组)和药物治疗组(药物组),每组30只大鼠。采用坐骨神经中段结扎法制作大鼠CCI模型。药物组大鼠术后给予腹腔注射0.1%七叶皂甙钠5 mg/(kg.d)治疗,CCI组给予等量生理盐水替代。各组于术前1 d取5只大鼠测定热痛觉,于术后8h、1 d、3 d、7 d、14 d及21 d时分别取5只大鼠测定热痛觉后处死。分别应用TUNEL法及免疫组化染色法检测大鼠相应损伤段脊髓组织中凋亡神经细胞数及肿瘤坏死因子-α(TNF-α)的表达。结果各组大鼠术前1 d时热痛觉的比较差异无统计学意义。CCI组及药物组大鼠术后热痛觉均较正常对照组更敏感(均P<0.05);药物组大鼠术后热痛觉较CCI组迟钝(均P<0.05)。CCI组及药物组大鼠术后各时间点脊髓组织中凋亡细胞数均明显多于正常对照组(均P<0.05);药物组大鼠术后各时间点脊髓组织中凋亡细胞数均明显少于CCI组(均P<0.05)。CCI组大鼠术后8 h～14 d,药物组术后8 h～7 d脊髓组织TNF-α的表达均明显高于正常对照组(均P<0.05);两组TNF-α的表达均于术后8 h起逐渐增高,至术后3 d时达最高,其后逐渐减少(均P<0.05);并分别于术后21 d及14 d时降至正常对照组水平。结论结扎大鼠坐骨神经可产生神经病理性疼痛,并可诱发脊髓神经细胞凋亡。七叶皂甙钠能缓解坐骨神经结扎术后大鼠热痛觉增敏,这可能与其降低TNF-α在脊髓后角的表达及抑制神经细胞的凋亡有关。     

Peripheral axonopathy in sciatic nerve of adult Wistar rats following exposure to vanadium

Depletion of myelin and neurobehavioural deficits are indications that vanadium crosses the blood‐brain barrier and such neurotoxic effects of vanadium on the brain of Wistar rats have been elucidated. The effect however on the peripheral nerves, is yet to be reported. Thus, this work was designed to evaluate the axonal and myelin integrity of sciatic nerves in Wistar rats following exposure to vanadium. Ten male Wistar rats were exposed to 3 mg/kg body weight of sodium metavanadate for 7 days, subjected to rearing and forelimb grip behavioural tests, and sciatic nerves processed for histology (haematoxylin and eosin, cresyl violet, and luxol fast blue). Dystrophic axons with vesiculated myelin, thinned myelin sheath, and demyelinated axons were observed in the vanadium exposed rats, suggestive of axonopathy, classified as fourth‐degree nerve injury. Lower behavioural scores were recorded for vanadium‐dosed rats; thus, corroborating histological pictures observed of the sciatic nerves. Authors posit that vanadium crossed the “blood‐nerve” barrier and caused the observed axonal pathologies and myelin depletion in the sciatic nerves of these rodents with resultant motor deficits. The present paper discusses possible motor deficits and the likely public health importance in regions with crude oil pollution and gas flaring rich in vanadium products.     

Reinnervation of muscles after transection of the sciatic nerve in adult rats

Functional recovery after transection of the sciatic nerve in adult rats is poor, probably because of abnormalities in reinnervation. Denervation and reinnervation patterns were studied morphologically in the lateral gastrocnemius (LGC), tibialis anterior (TA), and soleus (SOL) muscles for 21 weeks after nerve transection (motor endplates by acetylcholinesterase staining; nerves by silver impregnation). Motor endplates in the TA showed improving morphology with age, and, at 21 weeks, three-quarters of these were normal. Poorest recovery was observed in the SOL, as, at 21 weeks, only one-third of the motor endplates had a normal morphology. Polyneuronal innervation initially was more pronounced in the SOL, but, at 21 weeks, 10% of the motor endplates in all three muscles were still polyneuronally innervated. Our results indicate important differences in the reinnervation of these three hindleg muscles, and, even at 5 months, abnormalities were still present. These factors may in part explain the abnormal locomotion in rats as well as the limited recovery of function observed clinically in humans after nerve transection.     

PEMF fails to enhance nerve regeneration after sciatic nerve crush lesion

Abstract The use of electromagnetic fields has been reported to enhance peripheral nerve regeneration. This study aimed to identify the effects of a prolonged protocol of low‐frequency pulsed electromagnetic field (PEMF) on peripheral nerve regeneration. Thirty‐four male Swiss mice (Mus musculus) were divided into PEMF (n = 17) and control (n = 17) groups. All animals underwent a unilateral sciatic‐crush lesion, and the PEMF group was exposed to a 72‐Hz, 2‐G electromagnetic field for 30 min, five days a week, for three weeks. Functional analysis was carried out weekly. After three weeks, the animals were euthanized, and histological, morphometric, oxidative stress, and TGF‐β1 analyses were performed. Functional analysis showed no differences between the groups. Histological appearance was similar between PEMF and control nerves. Morphometric assessment showed that the PEMF nerves trended toward decreased regeneration. The levels of free radicals were more pronounced in PEMF nerves, but were not associated with an increase in the content of the TGF‐β1/Smad signaling pathway. Prolonged PEMF regimen leads to delayed histological peripheral nerve regeneration and increased oxidative stress but no loss of function recovery.     

Immunological rejection of acellular heterogeneous nerve transplant for bridging the sciatic nerve in rats

BACKGROUND:Artificial materials composed of acellular heterogeneous nerves can resolve donor shortage problems for the repair of peripheral nerve defects.However,it remains unclear whether artificial materials can overcome immunological rejection of heterogeneous nerve grafts and obtain similar effects as allogeneic nerve grafts.OBJECTIVE:To analyze regeneration and immunological rejection of defective sciatic nerves in rats through the use of acellular heterogeneous nerve grafts.DESIGN,TIME AND SETTING:A randomized,controlled study was performed at the Department of Anatomy,China Medical University and the Experimental Center,First Affiliated Hospital,China Medical University between January and December 2008.MATERIALS:TritonX-100 (Sigma,USA) and deoxycholate (Pierce,USA) were used.METHODS:Bilateral sciatic nerves were collected from adult rabbits and treated with TritonX-100 and sodium deoxycholate to prepare acellular sciatic nerves,which were used to bridge 1 -cm defective sciatic nerves in adult rats.MAIN OUTCOME MEASURES:The lymphocyte percentage in leukocytes was quantified following hemocyte staining.Neural regeneration and the recovery of motor end plates in the gastrocnemius muscle were observed under optical and electronic microscopy following toluidine blue staining,as well as acetylcholinesterase and succinate dehydrogenase histochemical staining.RESULTS:There was no significant difference in the lymphocyte percentage in leucocytes between transplanted and normal rats (P > 0.05).At 3 months after surgery,the rat toes on the operated side were separated and the rats could walk.In addition,the footplates exhibited an escape response when acupunctured.A large number of regenerated nerve fibers were observed in the transplant group,and acetylcholinesterase-positive motor end plates were visible in fibers of the gastrocnemius muscle.CONCLUSION:Acellular heterogeneous nerve transplants for the repair of defective sciatic nerves in rats promote neural regeneration without significant immunological rejection.     

维拉帕米与神经生长因子促进大鼠坐骨神经再生的协同作用

背景：实验证明周围神经损伤时,轴突的变性与神经元凋亡都与Ca2+的超载有着极其密切的关系。 目的：利用大鼠坐骨神经损伤模型观察L型钙离子通道阻滞剂维拉帕米联合神经生长因子促进周围神经再生的协同作用。 设计、时间及地点：随机对照动物实验,于2007-04/2008-11在辽宁医学院手外科实验室完成。 材料：同系健康雄性SD大鼠32只,体质量220~260 g;维拉帕米为辽宁卫星制药厂产品,国药准字H21022847;神经生长因子为sigma公司产品。 方法：同系SD大鼠32只随机分为4组,每组8只,分别在右侧梨状肌下缘5 mm切断坐骨神经后立即原位缝合造成坐骨神经损伤模型。①维拉帕米+神经生长因子组：腹腔注射维拉帕米4 mg/(kg•d),术侧腓肠肌肉注射神经生长因子0.6 μg/d。②维拉帕米组：腹腔注射维拉帕米4 mg/(kg•d),术侧腓肠肌注射等量生理盐水。③神经生长因子组：术侧腓肠肌注神经生长因子0.6 μg/d,并腹腔注射等量生理盐水。④空白对照组：分别腹腔,肌注等量生理盐水。以左侧坐骨神经为正常对照。 主要观察指标：术后12周对各组再生神经进行大体观察,神经电生理测定,组织学观察及有髓神经纤维计数。 结果：术后12周,维拉帕米+神经生长因子组足部溃疡的出现与愈合以及展抓反射出现的时间均早于其他各组。神经传导速度恢复率和有髓神经纤维计数恢复率分析表明：维拉帕米+神经生长因子组>维拉帕米组>神经生长因子组>空白对照组。光镜和电镜下可见：维拉帕米+神经生长因子组再生的神经纤维最多,轴突较为粗大。有髓神经纤维多,髓鞘完整,优于其他3组。神经纤维直径恢复率分析表明：维拉帕米+神经生长因子组>神经生长因子组>维拉帕米组>空白对照组。 结论：维拉帕米与神经生长因子对促进周围神经形态结构和功能的恢复均具有明显的协同作用。     

Variation in rat sciatic nerve anatomy: implications for a rat model of neuropathic pain

We discovered a variation of rat sciatic nerve anatomy as an incidental finding during the anatomical exploration of the nerve lesion site in a rat neuropathic pain model. To confirm the composition and distribution of rat sciatic nerve, macroscopic anatomical investigation was performed in both left and right sides in 24 adult Sprague-Dawley rats. In all rats, the L4 and L5 spinal nerves were fused tightly to form the sciatic nerve. However, the L6 spinal nerve did not fuse with this nerve completely as a part of the sciatic nerve, but rather sent a thin branch to it in 13 rats (54%), whereas in the remaining 11 rats (46%), L6 ran separately along with the sciatic nerve. Also, the L3 spinal nerve sent a thin branch to the L4 spinal nerve or sciatic nerve in 6 rats (25%). We conclude that the components of sciatic nerve in Sprague-Dawley rats vary from L3 to L6; however, the major components are L4 and L5 macroscopically. This finding is in contrast to the standard textbooks of rat anatomy which describe the sciatic nerve as having major contributions from L4, L5, and L6.     

Differential effects of pro-BDNF on sensory neurons after sciatic nerve transection in neonatal rats

Brain-derived neurotrophic factor (BDNF) plays a critical role in the development of the central and peripheral nervous systems, and also in neuronal survival after injury. The actions of BDNF are mediated by its high-affinity receptors TrkB and p75NTR. Recent studies have shown that proneurotrophins bind p75NTR and sortilin with high affinity, and trigger apoptosis of neurons in vitro . As proneurotrophins are a dominant form of gene products in developing and adult animals, it is imperative to understand their physiological functions in animals. Here, we showed differential roles of proBDNF in injured and uninjured sensory neurons. proBDNF, p75NTR and sortilin are highly expressed in dorsal root ganglia (DRG) neurons. Recombinant proBDNF induced a dose-dependent death of PC12 cells and the death activity was completely abolished in the presence of antibodies against the prodomain of BDNF. The exogenous proBDNF enhanced the death of axotomized sensory neurons and the neutralizing antibodies to the prodomain or exogenous sortilin-extracellular domain-Fc fusion molecule reduced the death of axotomized sensory neurons. Interestingly, the treatment of neutralizing antibody in vivo increased the number of sensory neurons in the contralateral DRG. We conclude that proBDNF may induce the death of axotomized sensory neurons and suppress neuronal addition in the intact DRG in neonatal rats, and the suppression of endogenous proBDNF may protect neurons after neurotrauma.     

Effect of the combination of high-frequency repetitive magnetic stimulation and neurotropin on injured sciatic nerve regeneration in rats

Repetitive magnetic stimulation is effective for treating posttraumatic neuropathies following spinal or axonal injury.Neurotropin is a potential treatment for nerve injuries like demyelinating diseases.This study sought to observe the effects of high-frequency repetitive magnetic stimulation,neurotropin and their combined use in the treatment of peripheral nerve injury in 32 adult male Sprague-Dawley rats.To create a sciatic nerve injury model,a 10 mm-nerve segment of the left sciatic nerve was cut and rotated through 180°and each end restored continuously with interrupted sutures.The rats were randomly divided into four groups.The control group received only a reversed autograft in the left sciatic nerve with no treatment.In the high-frequency repetitive magnetic stimulation group,peripheral high-frequency repetitive magnetic stimulation treatment(20 Hz,20 min/d)was delivered for 10 consecutive days after auto-grafting.In the neurotropin group,neurotropin therapy(0.96 NU/kg per day)was administrated for 10 consecutive days after surgery.In the combined group,the combination of peripheral high-frequency repetitive magnetic stimulation(20 Hz,20 min/d)and neurotropin(0.96 NU/kg per day)was given for 10 consecutive days after the operation.The Basso-Beattie-Bresnahan locomotor rating scale was used to assess the behavioral recovery of the injured nerve.The sciatic functional index was used to evaluate the recovery of motor functions.Toluidine blue staining was performed to determine the number of myelinated fibers in the distal and proximal grafts.Immunohistochemistry staining was used to detect the length of axons marked by neurofilament 200.Our results reveal that the Basso-Beattie-Bresnahan locomotor rating scale scores,sciatic functional index,the number of myelinated fibers in distal and proximal grafts were higher and axon lengths were longer in the high-frequency repetitive magnetic stimulation,neurotropin and combined groups compared with the control group.These measures were not significantly different among the high-frequency repetitive magnetic stimulation,neurotropin and combined groups.Therefore,our results suggest that peripheral high-frequency repetitive magnetic stimulation or neurotropin can promote the repair of injured sciatic nerves,but their combined use seems to offer no significant advantage.This study was approved by the Animal Ethics Committee of the Affiliated Changzhou No.2 People’s Hospital of Nanjing Medical University,China on December 23,2014(approval No.2014keyan002-01).