A comparison of stimulation patterns in axillary block: part 2

BACKGROUND AND OBJECTIVES: Radial plus musculocutaneous nerve stimulation may have a predominant role in the success of an axillary block, producing more extensive anesthesia of the upper limb than median plus musculocutaneous nerve stimulation. However, no comparison has been made with ulnar plus musculocutaneous nerve stimulation. We compared the extent of both sensory and motor block after ulnar plus musculocutaneous nerve stimulation or radial plus musculocutaneous nerve stimulation. METHODS: Sixty patients were randomly assigned to receive an axillary block using either radial plus musculocutaneous or ulnar plus musculocutaneous nerve stimulation with 40 mL plain 1.5% mepivacaine. Patients were assessed for sensory block by the pinprick method at 5 and 20 minutes. RESULTS: No statistically significant differences were found in the rates of anesthesia at 20 minutes in the cutaneous nerve distributions of the upper limb between radial plus musculocutaneous and ulnar plus musculocutaneous nerve stimulation except for the following nerves: radial (90% and 63.3%, respectively), medial cutaneous of the forearm (83.3% and 100%, respectively), and medial cutaneous of the arm (73.3% and 93.3%, respectively). Global sensory score (minimum: 0; maximum: 12 points) at 20 minutes was significantly higher after radial plus musculocutaneous than after ulnar plus musculocutaneous nerve stimulation: 12 (11-13) and 11 (10-12), respectively. The rates of median nerve blockade were 50% and 53%, respectively. CONCLUSIONS: Radial plus musculocutaneous nerve stimulation produced more extensive anesthesia of the upper limb than did ulnar plus musculocutaneous nerve stimulation. However, there is not an optimal combination of 2 responses in axillary brachial plexus block.     

Transfer of the medial pectoral nerve: myth or reality?

OBJECTIVE: Transfer of the medial pectoral nerve is one of the most controversial procedures used to reinnervate the paralyzed upper arm because of brachial plexus spinal nerve root avulsion or directly irreparable proximal lesions of spinal nerves. The purpose of this study was to determine the value of this type of nerve transfer to the musculocutaneous and axillary nerves. METHODS: The 25 patients included in the study comprised 14 patients who had nerve transfer to the musculocutaneous nerve and 11 who underwent nerve transfer to the axillary nerve. These patients' functional recovery and the time course of their recovery were analyzed according to the type of transfer of one donor nerve or the donor nerve in combination with other donors. RESULTS: Useful functional recovery was achieved in 85.7% of patients who had nerve transfer to the musculocutaneous nerve and in 81.8% of patients who underwent nerve transfer to the axillary nerve. There was no significant difference in results with regard to the type of nerve transfer and which recipient nerves were involved. A strong trend toward better results after procedures involving the use of a donor nerve combined with other donors was observed, however. CONCLUSION: Our surgical results suggest that the transfer of the medial pectoral nerve to the musculocutaneous nerve and also to the axillary nerve may be a reliable and effective procedure.     

膈神经移位术后肱肌及肱肌肌支恢复的实验研究

目的 观察两种膈神经移位术后肱肌及肱肌肌支功能恢复的情况,探讨修复后肱肌及肱肌肌支再利用的可能性.方法 取SD大鼠48只,体质量150～200 g,随机分为两组,膈神经通过移植神经移位至上干前股组(上干组),膈神经通过移植神经移位至肌皮神经组(移植组).分别于术后1、2、3个月取材进行大体观察、神经电生理学及组织学检测.结果 上干组于术后17～20 d出现与呼吸同步的屈肘运动,移植组于术后20～25 d出现与呼吸同步的屈肘运动.术后3个月切断肱肌肌支对两组大鼠的屈肘动作均无明显影响.两组肱肌复合肌肉运动电位最大波幅恢复率、肌湿重恢复率、肌纤维截面积恢复率于术后3个月差异均无统计学意义(P>0.05),肱肌肌支再生有髓神经纤维通过率于术后3个月差异有统计学意义(P<0.05),上干组优于移植组.结论 两种膈神经移位术均可使肱肌及肱肌肌支得到恢复,肱肌的远期恢复程度在两组间差异无统计学意义,肱肌肌支的远期恢复上干组优于移植组.     

膈神经移位术后肱肌及肱肌肌支恢复的实验研究

目的 观察两种膈神经移位术后肱肌及肱肌肌支功能恢复的情况,探讨修复后肱肌及肱肌肌支再利用的可能性.方法 取SD大鼠48只,体质量150～200 g,随机分为两组,膈神经通过移植神经移位至上干前股组(上干组),膈神经通过移植神经移位至肌皮神经组(移植组).分别于术后1、2、3个月取材进行大体观察、神经电生理学及组织学检测.结果 上干组于术后17～20 d出现与呼吸同步的屈肘运动,移植组于术后20～25 d出现与呼吸同步的屈肘运动.术后3个月切断肱肌肌支对两组大鼠的屈肘动作均无明显影响.两组肱肌复合肌肉运动电位最大波幅恢复率、肌湿重恢复率、肌纤维截面积恢复率于术后3个月差异均无统计学意义(P>0.05),肱肌肌支再生有髓神经纤维通过率于术后3个月差异有统计学意义(P<0.05),上干组优于移植组.结论 两种膈神经移位术均可使肱肌及肱肌肌支得到恢复,肱肌的远期恢复程度在两组间差异无统计学意义,肱肌肌支的远期恢复上干组优于移植组.     

膈神经移位术后肱肌及肱肌肌支恢复的实验研究

目的 观察两种膈神经移位术后肱肌及肱肌肌支功能恢复的情况,探讨修复后肱肌及肱肌肌支再利用的可能性.方法 取SD大鼠48只,体质量150～200 g,随机分为两组,膈神经通过移植神经移位至上干前股组(上干组),膈神经通过移植神经移位至肌皮神经组(移植组).分别于术后1、2、3个月取材进行大体观察、神经电生理学及组织学检测.结果 上干组于术后17～20 d出现与呼吸同步的屈肘运动,移植组于术后20～25 d出现与呼吸同步的屈肘运动.术后3个月切断肱肌肌支对两组大鼠的屈肘动作均无明显影响.两组肱肌复合肌肉运动电位最大波幅恢复率、肌湿重恢复率、肌纤维截面积恢复率于术后3个月差异均无统计学意义(P>0.05),肱肌肌支再生有髓神经纤维通过率于术后3个月差异有统计学意义(P<0.05),上干组优于移植组.结论 两种膈神经移位术均可使肱肌及肱肌肌支得到恢复,肱肌的远期恢复程度在两组间差异无统计学意义,肱肌肌支的远期恢复上干组优于移植组.     

The sensory-motor bridge neurorraphy: an anatomic study of feasibility between sensory branch of the musculocutaneous nerve and deep branch of the radial nerve

Introduction: Restoring elbow flexion remains the first step in the management of total palsy of the brachial plexus. Non avulsed upper roots may be grafted on the musculocutaneous nerve. When this nerve is entirely grafted, some motor fibres regenerate within the sensory fibres quota. Aiming potential utilization of these lost motor fibres, we attempted suturing the sensory branch of the musculocutaneous nerve onto the deep branch of the radial nerve. The objective of our study was to assess the anatomic feasibility of such direct suturing of the terminal sensory branch of the musculocutaneous nerve onto the deep branch of the radial nerve. Methods: The study was carried out with 10 upper limbs from fresh cadavers. The sensory branch of the musculocutaneous muscle was dissected right to its division. The motor branch of the radial nerve was identified and dissected as proximally as possible into the radial nerve. Then, the distance separating the two nerves was measured so as to assess whether direct neurorraphy of the two branches was feasible. Results: The excessive distance between the two branches averaged 6 mm (1–13 mm). Thus, direct neurorraphy of the sensory branch of the musculocutaneous nerve and the deep branch of the radial nerve was possible. Conclusions: When the whole musculocutaneous nerve is grafted, some of its motor fibres are lost amongst the sensory fibres (cutaneous lateral antebrachial nerve). By suturing this sensory branch onto the deep branch of the radial nerve, “lost” fibres may be retrieved, resulting in restoration of digital extension. © 2011 Wiley‐Liss, Inc. Microsurgery, 2011.     

膈神经移位至肌皮神经两种术式肌电随访结果的比较分析

目的　对两种术式的膈神经移位至肌皮神经后的肌电随访结果进行统计学分析,总结两者的各自规律,为临床选择术式和判断疗效提供肌电检测依据。方法　回顾性地对行两种术式病例的长期肌电随访资料进行统计学分析。有有效随访资料者49例,其中膈神经加移植神经移位至肌皮神经主干21例;膈神经移位至上干前股肌皮神经束28例。总结两者的肌电恢复有效率;用Kaplan-Meier法估计最早出现有效再生电位的平均时间。结果　膈神经加移植神经移位至肌皮神经主干组的有效率为90.5%;最早出现有效再生电位的时间为术后［(360.00±48.97)d,     

Morphometric study of the upper intercostal nerves: practical application for neurotizations in traumatic brachial plexus palsies

The aim of the study was a morphometric evaluation of the intercostal nerves at different levels along their course in order to determine their adequacy in neurotizing the recipient nerves. The intercostal nerves were harvested from 5 cadavers. A biopsy of the nerve was obtained at 2 levels for each nerve in the parasternal region and at the level of the mid-axillary line. The musculocutaneous nerve was isolated at its origin from the lateral cord. Each harvested specimen was embedded in paraffin and sections were made using a microtome. These sections were then stained histochemically using HPS (Hematein, Phloxine, Safran). Real-time digitalisation of the video image under the microscope was performed. The sum of the different fascicular zones is the effective sensorimotor surface of the nerve at the level being studied. RESULTS: Direct suture of the upper three intercostal nerves to the musculocutaneous nerve is always possible upto the axillary fossa. The sixth intercostal nerve can be delivered upto this level in only 50% of cases without dissection of the musculocutaneous nerve upto its entry into the coracobrachialis. The musculocutaneous nerve presents a mean surface area of 2.64 mm2 while the nerve to the biceps has a mean surface area of 0.34 mm2 i.e. a ration of 1/8. The mean surface area of the intercostal nerves at the parasternal level is 0.23 mm2 while that at the axillary level is 0.34 mm2. Thus a loss of 33% in surface area occurs between the axillary and the parasternal levels. Our study confirms the insufficiency between the surface area of the intercostal nerves and the different nerve trunks to be neurotized. The relationship between the surface area of the musculocutaneous nerve and the three intercostal nerves is 26.72% with a minimum of 17.2%. If a fourth intercostal nerve is added, this ratio nerves appears to be a superior technique. We were able to deliver the sixth intercostal nerve for a direct suture to the musculocutaneous nerve in only half the cases.     

膈神经移位接上干前股的解剖与临床研究

目的 通过对肌皮神经肱二头肌肌支的解剖学研究,为臂丛损伤后设计应用膈神经移接手臂丛上干前肌恢复屈肘功能的新术式。方法 对１０具２０侧尸体上肢的肱二头肌肌支作逆行解剖,观察其在上干前肌内的定位。对２１例臂丛损伤患者,将膈神经移接于上干前肌,并观察其疗效。结果 解剖学研究：肱二头肌肌支位于上干前股前外侧及前正中束组,其横截面积占上干前股横截面积的３４％ＲＲ。２１例患者屈肘功能恢复的总有效率达８０．９５     

Restoration of elbow flexion in adult traumatic brachial plexus injury – a quantitative analysis of results of single versus double nerve transfer

BackgroundRestoration of elbow flexion is one of the key components of adult brachial plexus surgery. Nerve transfers are routinely used to attain elbow flexion.PurposeThis study aims to quantify the recovery of elbow flexion power and to compare the outcome following single nerve transfer and double nerve transfer to branches of the musculocutaneous nerve in adult traumatic brachial plexus injury.MethodWe conducted a retrospective cohort study of patients with traumatic upper brachial plexus injury who underwent nerve transfer of the musculocutaneous nerve with either Ulnar nerve fascicles (SN) or both Ulnar and Median nerve fascicles (DN) for restoring elbow flexion. Patients with a minimum follow up of 18 months after surgery were included in this study. Elbow flexion strength was quantified using a force transducer and software module and the results were compared between the two groups.ResultThe median strength of elbow flexion was 14.3 Newton meter. In the SN group, the mean strength of elbow flexion was 5.4 ± 5 Nm, and for DN group it was 20.4 ± 9.9 Nm. Elbow flexion strength following DN procedure was significantly better when compared with SN.ConclusionThe additional nerve transfer of median nerve fascicles with musculocutaneous nerve branch to the brachialis muscle does not add clinically obvious morbidity to the patient but has definite benefit as observed in this study. We advocate double fascicular nerve transfer for elbow flexion in upper brachial plexus injuries if the median and ulnar nerve functions are normal.     

同侧颈7神经根移位治疗臂丛上千根性撕脱伤的实验研究

目的 实验性比较同侧C7神经根全根移位与其他3种方法治疗臂丛上千根性撕脱伤的疗效.方法 120只SD大鼠建立上千根性撕脱伤模型后随机等分为4组,每组30只.(1)A组:同侧C7移位至上千+副神经至肩胛上神经;(2)B组:Oberlin手术(尺神经一束移位至肱二头肌支)+副神经至肩胛上神经+桡神经肱三头肌长头支至腋神经前支;(3)C组:膈神经移位至上千前股+副神经至肩胛上神经+颈丛运动支至上千后股;(4)D组:膈神经移位至上千前股+副神经至肩胛上神经,不作腋神经修复.术后3、6和12周每组取10只大鼠作Ochiai评分、Barth足错步试验、Terzis梳头试验及神经再生指标的榆测.结果 术后3周,A组3项行为学检测指标与3个对照组差异无统计学意义(P>0.017),腋神经电生理指标均显著优于3个对照组,其余各项腋神经及三角肌组织学指标均显著优于C组和D组,但与B组比较差异无统计学意义.A组除肌皮神经再生有髓神经纤维通过率显著优于C组外,其余肌皮神经及肱二头肌的电牛理与组织学检测指标与3个对照组比较差异无统计学意义.12周时,A组各项行为学观察、几乎全部腋神经和三角肌的电生理与组织学检测以及部分肌皮神经和肱二头肌的电生理与组织学检测指标均已显著优于3个对照组.结论 同侧C7神经根移位对治疗臂丛上千根性撕脱伤的实验性疗效显著.     

Transfer of brachialis branch of musculocutaneous nerve for finger flexion: anatomic study and case report

Based on an anatomic study, a transfer of the brachialis muscle branch of the musculocutaneous nerve (BMBMCN) to finger flexor functional fascicles of the median nerve was designed. Preliminary results of clinical application of this new procedure are reported. Dissection of 32 cadaver upper limbs revealed that BMBMCN derives from the musculocutaneous nerve at the distal 1/3 upper arm level. Mostly it is of single-branch type, with an average dissectable length of 5.2 cm. At this level, functional fascicles of finger flexors are located at the posterior 1/3 of the median nerve. BMBMCN can be directly coapted to these finger flexion fascicles. In one case of brachial plexus lower trunk injury, this neurotization procedure was done. No impairment of elbow flexion and wrist flexion was found postoperatively. Recovery of finger and thumb flexion was seen 1 year postoperatively. This neurotization is safe and effective for treating lower trunk injuries.     

选择性颈_7神经根移位与膈神经移位术疗效比较的实验研究

目的　以大鼠为动物模型 ,比较选择性颈 7神经根移位术与膈神经移位术的疗效。　方法　 SD大鼠 12 0只 ,随机分成 2组。 A组 :肌皮神经与膈神经缝合 ;B组 :肌皮神经与同侧颈 7神经根的前股前外侧束组缝合。术后肱二头肌电生理学、组织学、肌生理功能检测评价两组疗效。　结果　术后各时间组 ,选择性颈7神经根移位与膈神经移位各检测指标相比 ,差异无显著性 (P>0 .0 5 ) ,但前者在多项指标上优于后者。　结论　选择性颈 7神经根移位术与膈神经移位术疗效无明显差异 ,在臂丛上干根性撕脱伤合并膈神经损伤时 ,前者是较为理想的可选方法。     

膈神经端侧吻合移位治疗肌皮神经损伤的实验研究

目的 研究膈神经端侧吻合移位至肌皮神经治疗臂丛神经撕脱伤的可行性.方法 取雄性SD大鼠51只,随机分成4组:A组,单侧全臂丛神经撕脱组;B组,膈神经端端吻合组;C组,膈神经端侧吻合组;D组,膈神经螺旋状端侧吻合组(B、C、D组膈神经均移植2.0 cm腓肠神经至肌皮神经).并于术后进行肢体功能、组织学和神经电生理检测.另取绿色荧光蛋白(green fluorescent protein,GFP)转基因F344大鼠9只,通过荧光显微镜观察膈神经轴突再生情况.方果 各实验组术后手术侧肢体功能逐渐恢复,术后神经电生理和组织学检测表明,术后3个月,C、D组左侧肱二头肌肌张力恢复率和肌湿重恢复率,分别为B组的76.4%和86.3%、85.6%和87.7%,即端侧吻合组肱二头肌功能达到端端吻合组的80%以上,同时保留了膈肌的功能.荧光显微镜观察发现膈神经轴突通过端侧吻合口长入移植神经.方论 膈神经端侧吻合治疗臂丛神经损伤的手术方法是有效、可行的.     

The musculocutaneous nerve: ultrasound appearance for peripheral nerve block

BACKGROUND AND OBJECTIVES: To gain complete anesthesia of the forearm, block of the musculocutaneous nerve is necessary. Variations in its course and position make localization of the musculocutaneous nerve problematic. The aim of the study is to describe the ultrasound appearance of the musculocutaneous nerve in the axilla and to suggest potential areas to target neural block. METHODS: We scanned the axillary regions of 19 volunteers and assessed the size and shape of 34 musculocutaneous nerves at entry into, exit from, and in the center of the coracobrachialis muscle. Furthermore, we measured the depth of the musculocutaneous nerve under the skin surface and its distance from the axillary artery at those 3 measurement points. RESULTS: As it travels through the coracobrachialis muscle, the musculocutaneous nerve changes in shape from oval to flat-oval to triangular. During this course, the musculocutaneous nerve also separates from the axillary artery and becomes more lateral while changing its depth from the surface. The musculocutaneous nerve increases its transverse area along this nerve path. In 2 subjects, the musculocutaneous nerve could not be visualized unilaterally within the course of the coracobrachialis muscle. CONCLUSIONS: Knowledge of its ultrasound appearance facilitates localization and successful block of the musculocutaneous nerve. Because the distance between the musculocutaneous nerve and brachial plexus varies, different locations of musculocutaneous nerve puncture during ultrasound-guided regional anesthesia can be chosen.     

Phrenic nerve neurotization of the musculocutaneous nerve with end-to-side neurorrhaphy: a short report in a rabbit model

This experimental study was performed to evaluate the efficacy of end-to-side coaptation between the musculocutaneous nerve and the phrenic nerve for brachial plexus injuries with nerve-root avulsions. In an experimental rabbit model, neurotization of the musculocutaneous nerve with the phrenic nerve was compared using end-to-end and end-to-side neurorrhaphy. Preliminary results from electrophysiologic and histologic examinations indicate that end-to-side neurotization of the musculocutaneous nerve with the phrenic nerve is an effective means for musculocutaneous nerve repair. The effectiveness of the phrenic nerve is attributed to its large number of motor axons.     

Transfer of pectoral nerves to the musculocutaneous nerve in obstetric upper brachial plexus palsy

OBJECTIVE: To investigate the results of transfer of pectoral nerves to the musculocutaneous nerve for treatment of obstetric brachial palsy. METHODS: In 25 cases of obstetric brachial palsy (20 after breech deliveries), branches of the pectoral nerve plexus were transferred directly to the musculocutaneous nerve. For all patients, the nerve transfer was part of an extended brachial plexus reconstruction. Results were tested both clinically and with the Mallet scale, at a mean follow-up time of 70 months (standard deviation, 34.3 mo). RESULTS: There were two complete failures, which were attributable to disconnection of the transferred nerve endings. The results after transfer were excellent in 17 cases and fair in 5 cases. Steindler flexorplasty improved elbow flexion for three patients. CONCLUSION: Transfer of pectoral nerves to the musculocutaneous nerve for treatment of obstetric upper brachial palsy may be effective, if the specific anatomic features of the pectoral nerve plexus are sufficiently appreciated.     

荧光逆行示踪法定位神经端侧缝合后再生来源的实验研究

目的 应用荧光逆行示踪法研究神经端.侧缝合修复臂丛神经损伤的有效性及再生神经的脊髓定位.方法 雌性SD大鼠24只,随机分为4组,造成臂丛神经上干损伤模型,分别以膈神经、同侧颈,神经根为供体神经,按照端.侧和端.端两种缝合方式修复肌皮神经.术后3个月,对大鼠肌皮神经和供体神经分别采用真蓝和双脒基黄进行逆行示踪.3、7、14 d后进行灌注固定,取颈段脊髓连续切片,荧光显微镜观察.结果 各观察点背根节及脊髓前角均出现荧光标记细胞,并逐渐增多.以同侧颈,为供体神经组,标记细胞仅出现在该节段,而以膈神经为供体神经组,标记细胞出现在颈_(3-5)节段.端一侧缝合组在相应脊髓前角或背根神经节出现,同时具有两种荧光剂的双标细胞或在同一脊髓节段同时出现分别以两种荧光剂标记的单标细胞.结论 采用不同供体神经进行端.侧缝合联合神经移植修复臂丛神经可使神经再生,荧光逆行示踪可以准确定位端.侧缝合后再生神经的来源.     

大鼠周围神经可塑性的实验研究

目的 通过建立大鼠感觉神经束(前臂内侧皮神经)近端与运动神经束(肌皮神经)远端吻合的神经再生模型,观察在靶器官改变时感觉神经的结构与功能发生的可塑性变化.方法 取健康成年SD大鼠30只,雌雄不限,体重200～250 g,随机分成3组,每组10只.每组大鼠左上肢制备实验模型,右上肢为正常对照,不作任何处理.A组:于距前臂内侧皮神经起点5 mm处切断该神经,将其近端与切断的肌皮神经远端行无张力端端吻合;B组:于距肌皮神经入肌点5 mm处切断该神经,将其远端与切断的前臂内侧皮神经近端行无张力的端端吻合;C组:切断肌皮神经和前臂内侧皮神经后不予吻合,形成肱二头肌失神经支配模型.于术后观察各组大鼠的一般情况、屈肘功能、肱二头肌湿重、肌纤维横截面积、诱发电位的潜伏期和波幅,行吻合口近端的神经乙酰胆碱酯酶(acetylcholinesterase,AchE)染色观察.结果 术后所有大鼠一般情况良好,切口无感染,均存活至24周.术后各组大鼠左侧肘关节主动屈曲功能丧失,24周时A、B组大鼠主动屈肘功能均有恢复.根据"泼水清理实验"评估,A组获4～5分肢体7例,B组5例,均较C组O例有明显恢复(P＜0.05),A、B组间差异无统计学意义(P＞0.05).在肱二头肌湿重、肌纤维横截面积方面,A、B组明显优于C组(P＜0.05),A组与B组差异无统计学意义(P＞0.05).A、B两组大鼠电生理均可测得肱二头肌的诱发电位,吻合口近端的前臂内侧皮神经在AchE染色后可见到轴突深染的有髓神经纤维(运动神经纤维),在屈肘功能的恢复情况、诱发电位的潜伏期和波幅、吻合口近端的运动神经纤维数量方面,两组差异均无统计学意义(P＞0.05).结论 当靶器官改变时感觉神经的结构及功能均发生了适应性的重塑,这种重塑可能为修复周围神经损伤提供一种新方法.     

Role of the target in end-to-side neurorrhaphy: reinnervation of a single muscle vs. multiple muscles

The authors examined the effects of end-to-side neurorrhaphy for reinnervation of the musculocutaneous nerve (Group A) which innervates the biceps muscle, compared to reinnervation of the median nerve which innervates multiple muscles in a rat model. Additionally, end-to-end neurorrhaphy to the musculocutaneous nerve using one-third of the median nerve (Group B) was investigated. End-to-end coaptation of the musculocutaneous nerve served as a control (Group C). In a grooming test, the biceps muscle function in Group A animals demonstrated a slower but nearly similar good recovery to Groups B and C. Biceps muscle contraction force investigated after 24 weeks demonstrated no statistically significant differences among all groups. In Groups A and B, no significant impairment of the donor median nerve function was found in a grasping test and the muscle contraction force of the flexor carpi radialis muscle, and histologic evaluation of the musculocutaneous nerve showed multiple regenerated axons distal to the coaptation site. Retrograde double-labeling in Group A animals showed reinnervation of the musculocutaneous nerve by median nerve axons located at the coaptation site. These results validate that end-to-side neurorrhaphy to a nerve innervating a single muscle is more efficient than to a nerve innervating multiple muscles, as demonstrated in an earlier study. The reason for this phenomenon is most likely that all sprouting axons are directed toward one target rather than toward multiple targets, with the latter situation resulting in a smaller number of axons and a variable distribution of axons per target. Since donor nerve sprouting axons were observed at the coaptation site, a relevance of the selected site for end-to-side neurorrhaphy is suggested. Both end-to-side neurorrhaphy and end-to-end neurorrhaphy, using one-third of the median nerve, led to useful functional recovery in this rat model, if an agonistic donor nerve is employed.