Sciatic cross-over in patients with peroneal and tibial intraneural ganglia confirmed by knee MR arthrography

Background  A predictable mechanism and stereotypic patterns of peroneal intraneural ganglia are being defined based on careful analysis of MRIs. Peroneal and tibial intraneural ganglia extending from the superior tibiofibular joint which extend to the level of the sciatic nerve have been observed leading to the hypothesis that sciatic cross-over could exist. Such a cross-over phenomenon would allow intraneural cyst from the peroneal nerve by means of its shared epineurial sheath within the sciatic nerve to cross over to involve the tibial nerve, or vice versa from a tibial intraneural cyst to the peroneal nerve. Method and Findings  One patient with a peroneal intraneural ganglion and another with a tibial intraneural ganglion each underwent a knee MR arthrogram. These studies were not only definitive in demonstrating the communication of the cyst to the superior tibiofibular joint connection but also in confirming sciatic cross-over. Contrast injected into the knee could be demonstrated tracking to the superior tibiofibular joint and then proximally into the common peroneal or tibial nerve respectively, crossing over at the sciatic nerve, and then descending down the tibial and peroneal nerves. The arthrographic findings mirrored MR images upon their retrospective review. Conclusions  This study provides direct in vivo proof of the nature of sciatic cross-over theorized by critical review of MRIs and/or experimental dye injections done in cadavers. This study is important in clarifying the potential paths of propagation of intraneural cysts at points of major bifurcation.     

Dynamic phases of peroneal and tibial intraneural ganglia formation: a new dimension added to the unifying articular theory

OBJECT: The pathogenesis of intraneural ganglia has been a controversial issue for longer than a century. Recently the authors identified a stereotypical pattern of occurrence of peroneal and tibial intraneural ganglia, and based on an understanding of their pathogenesis provided a unifying articular explanation. Atypical features, which occasionally are observed, have offered an opportunity to verify further and expand on the authors' proposed theory. METHODS: Three unusual cases are presented to exemplify the dynamic features of peroneal and tibial intraneural ganglia formation. RESULTS: Two patients with a predominant deep peroneal nerve deficit shared essential anatomical findings common to peroneal intraneural ganglia: namely, 1) joint connections to the anterior portion of the superior tibiofibular joint, and 2) dissection of the cyst along the articular branch of the peroneal nerve and proximally. Magnetic resonance (MR) images obtained in these patients demonstrated some unusual findings, including the presence of a cyst within the tibial and sural nerves in the popliteal fossa region, and spontaneous regression of the cysts, which was observed on serial images obtained weeks apart. The authors identified a clinical outlier, a case that could not be understood within the context of their previously reported theory of intraneural ganglion cyst formation. Described 32 years ago, this patient had a tibial neuropathy and was found at surgery to have tibial, peroneal, and sciatic intraneural cysts without a joint connection. The authors' hypothesis about this case, based on their unified theory, was twofold: 1) the lesion was a primary tibial intraneural ganglion with proximal extension followed by sciatic cross-over and distal descent; and 2) a joint connection to the posterior aspect of the superior tibiofibular joint with a remnant cyst within the articular branch would be present, a finding that would help explain the formation of different cysts by a single mechanism. The authors proved their hypothesis by careful inspection of a recently obtained postoperative MR image. CONCLUSIONS: These three cases together with data obtained from a retrospective review of the authors' clinical material and findings reported in the literature provide firm evidence for mechanisms underlying intraneural ganglia formation. Thus, expansion of the authors' unified articular theory permits understanding and elucidation of unusual presentations of intraneural cysts. Whereas an articular connection and fluid following the path of least resistance was pivotal, the authors now incorporate dynamic aspects of cyst formation due to pressure fluxes. These basic principles explain patterns of ascent, cross-over, and descent down terminal nerve branches based on articular connections, paths of diminished resistance to fluid flow within recognized anatomical compartments, and the effects of fluctuating pressure gradients.     

Vascular endothelial growth factor‐loaded poly(lactic‐co‐glycolic acid) microspheres‐induced lateral axonal sprouting into the vein graft bridging two healthy nerves: Nerve graft prefabrication using controlled release system

The most commonly used surgical technique for repairing segmental nerve defects is autogenous nerve grafting; however, this method causes donor site morbidity. In this study, we sought to produce prefabricated nerve grafts that can serve as a conduit instead of autologous nerve using a controlled release system created with vascular endothelial growth factor (VEGF)‐loaded poly(lactic‐co‐glycolic acid) (PLGA) microspheres. The study was performed in vitro and in vivo. For the in vitro studies, VEGF‐loaded PLGA microspheres were prepared. Thirty rats were used for the in vivo studies. Vein grafts were sutured between the tibial and peroneal nerves in all animals. Three groups were created, and an epineural window, partial incision, and microsphere application were performed, respectively. Walking track analysis, morphologic, and electron microscopic assessment were performed at the end of the eight weeks. Microspheres were produced in spherical shapes as required. Controlled release of VEGF was achieved during a 30‐days period. Although signs of nerve injury occurred initially in the partial incision groups according to the indexes of peroneal and tibial function, it improved gradually. The index values were not affected in the other groups. There were many myelinated fibers with large diameters in the partial incision and controlled release groups, while a few myelinated fibers that passed through vein graft in the epineural window group. Thereby, prefabrication was carried out for the second and third groups. It was demonstrated that nerve graft can be prefabricated by the controlled delivery of VEGF. © 2012 Wiley Periodicals, Inc. Microsurgery, 2012.     

Intraneural Ganglion of the Superficial Peroneal Nerve: A Case Report

Ganglia affecting the peripheral nerves of the foot and ankle are rare. The most frequent location of occurrence is the common peroneal nerve at the level of the fibular neck. We report the case of an intraneural ganglion of the superficial peroneal nerve and its branches. Although there have been many previous reports of intraneural ganglion involvement with the common peroneal nerve, deep peroneal nerve, sural nerve, and the posterior tibial nerve, to our knowledge, this is the first reported occurrence of an intraneural ganglion distinctly localized to the superficial peroneal nerve and its branches. The presumptive diagnosis was made preoperatively using magnetic resonance imaging, and then confirmed postoperatively by pathologic examination. Despite the use of operative magnification, it was impossible to remove all of the cyst elements within the nerve trunk, because the nerve fascicles were intimately intertwined. Therefore, complete resection of the common trunk of the superficial peroneal nerve and its terminal branches was performed, and the proximal stump was buried in a hole in the distal fibula. Two years after the surgery, the patient was pain free and asymptomatic except for cutaneous anesthesia in the distribution of the superficial peroneal nerve.     

Evaluation of spectrum of peripheral neuropathy in predialysis patients with chronic kidney disease

Abstract

Introduction: Neurological complications secondary to the uremic state, contribute largely to the morbidity and mortality in patients with renal failure. The prevalence of peripheral neuropathy remains high in advanced renal dysfunction. Materials and methods: The present cross-sectional study was conducted on 100 adult patients of chronic kidney disease between 18 and 75 years of age with serum creatinine greater than 2?mg/dL. Apart from routine examination and baseline investigations, detailed history was elicited pertaining to patients’ neurological symptoms, and scored according to the Neurological Symptom Score. Motor nerve conduction velocity was measured from right median, ulnar, peroneal, and tibial nerves. Results: It was observed that neurological symptoms increased steadily with raise in serum creatinine. The mean nerve conduction velocities (NCVs) of right median nerve, ulnar nerve, peroneal nerve, and tibial nerve were 51.34?±?6.07, 53.04?±?5.91, 44.72?±?6.14, and 44.20?±?5.17, respectively. The NCVs of all the tested nerves decreased significantly with increase in serum creatinine levels (p?<?0.01): 70% of the patients had uremic polyneuropathy; 6% had asymptomatic neuropathy, 51% had symptomatic non-disabling neuropathy, while disabling neuropathy was seen in 13% of the patients. Conclusion: Our data suggests that NCV testing when complimented with meticulous neurological assessment can provide invaluable input. These tests apart from helping us detect neuropathy in advanced renal dysfunction; can also detect the disease in largely asymptomatic patients which avoids the necessity to order for detailed neurophysiological investigation     

Ciliary neurotrophic factor for acceleration of peripheral nerve regeneration: an experimental study

The objective of this study was to investigate the effect of topically administrated ciliary neurotrophic factor (CNTF) on peripheral nerve regeneration. Sixty-eight Sprague Dawley rats underwent a unilateral sciatic nerve transection and silicon tubulization, with a 10-mm gap between the proximal and distal nerve stumps. Recombinant human CNTF (1 mg/kg) was injected into the rats of the experimental group, while normal saline was injected into the control group animals. Electrophysiologic and histologic studies, including nerve morphometry and electron microscopic observation, were performed at 1, 3, and 4 months postoperatively. HRP tracing was carried out at 3 months postoperatively to label spinal-cord, ventral-horn, and dorsal-root ganglia. The results revealed that CNTF-treated animals showed a higher motor nerve conduction velocity of the sciatic nerve and a higher muscle action potential amplitude of the anterior tibial muscle, compared to the controls ( p < 0.01). Nerves repaired with CNTF had larger axon diameter, greater number of axons, and more advanced myelination ( p < 0.05). More HRP-labeled motor neurons were also found in the ventral horns of CNTF-treated animals. These results indicate that topical application of CNTF to the injury site potentiates motor nerve axonal regrowth and axon maturation during peripheral nerve regeneration.     

Functional indices for sciatic,peroneal, and posterior tibial nerve lesions in the mouse

The sciatic functional index previously described in rats has proven to be a reliable index of functional recovery following sciatic nerve injury and repair. A similar functional assay of sciatic, peroneal, and posterior tibial nerve lesions was developed in a mouse model. Forty-eight C57/BL6 mice were randomly divided into 4 groups: sham surgery, sciatic nerve transection, peroneal nerve transection, and posterior tibial nerve transection. Preoperative and postoperative (48 hours) walking tracks were obtained. The pawprints were analyzed in a blinded fashion for measurements of print length (PL), toe spread (TS), intermediate toe spread (IT), and the orthogonal distance from the toe of one paw to the hind pad of the opposite paw (TOF). Multiple linear regression analysis was performed using these measurements to determine their significance and appropriate weighted contribution to the index formula for each nerve lesion. For the sciatic functional index, changes in the PL (P = 0.0092) and TS (P = 0.0008) were significant, resulting in an R² value of 0.88. For the peroneal functional index, only TS (P < 0.0001) was significant with R² = 0.83. For the posterior tibial index, only PL (P < 0.0001) was significant with R² = 0.89. Formulas for a sciatic, peroneal, and posterior tibial functional index were created based on the coefficients derived from the multiple linear regression analysis. The indices that were developed will allow investigators to assess functional recovery following specific nerve lesions in mice. © 1998 Wiley-Liss, Inc. MICROSURGERY 18:119-124 1998     

Minimally invasive peripheral nerve surgery: peroneal nerve neurolysis

Background: Both patients and surgeons recognize the value of procedures that minimize scarring and tissue dissection. No previous reports have described a minimally invasive technique for peroneal nerve neurolysis, or evaluated its safety. Methods: The senior author's technique for a minimally invasive approach to neurolysis of the common, superficial, and deep peroneal nerves is presented. Safety of the technique was determined by review of records of all patients undergoing this procedure from 2003–2011, looking for major complications. Results: Using the minimally invasive approach to peroneal nerve neurolysis, average skin incision size is 3.5 cm for the common peroneal nerve, 4 cm for the superficial peroneal nerve, and 2.5 cm for the deep peroneal nerve. In 400 patients undergoing 679 total procedures, there were no nerve injuries, postoperative neuromas, or adjacent structures harmed. Conclusions: Peroneal nerve neurolysis can be accomplished safely and effectively via a minimal skin incision, improving aesthetic results and decreasing possible scar‐related complications. © 2011 Wiley Periodicals, Inc. Microsurgery, 2012.     

Targeted mesenchymal stem cell and vascular endothelial growth factor strategies for repair of nerve defects with nerve tissue implanted autogenous vein graft conduits

Peripheral nerve gaps exceeding 1 cm require a bridging repair strategy. Clinical feasibility of autogenous nerve grafting is limited by donor site comorbidity. In this study we investigated neuroregenerative efficacy of autogenous vein grafts implanted with tissue fragments from distal nerve in combination with vascular endothelial growth factor (VEGF) or mesenchymal stem cells (MSCs) in repair of rat peripheral nerve defects. Six‐groups of Sprague‐Dawley rats (n = 8 each) were evaluated in the autogenous setting using a 1.6 cm long peroneal nerve defect: Empty vein graft (group 1), Nerve graft (group 2), Vein graft and nerve fragments (group 3), Vein graft and nerve fragments and blank microspheres (group 4), Vein graft and nerve fragments and VEGF microspheres (group 5), Vein graft and nerve fragments and MSCs (group 6). Nerve fragments were derived from distal segment. Walking track analysis, electrophysiology and nerve histomorphometry were performed for assessment. Peroneal function indices (PFI), electrophysiology (amplitude) and axon count results for group 2 were ?9.12 ± 3.07, 12.81 ± 2.46 mV, and 1697.88 ± 166.18, whereas the results for group 5 were ?9.35 ± 2.55, 12.68 ± 1.78, and 1566 ± 131.44, respectively. The assessment results did not reveal statistical difference between groups 2 and 5 (P > 0.05). The best outcomes were seen in group 2 and 5 followed by group 6. Compared to other groups, poorest outcomes were seen in group 1 (P ≤ 0.05). PFI, electrophysiology (amplitude) and axon count results for group 1 were ?208.82 ± 110.69, 0.86 ± 0.52, and 444.50 ± 274.03, respectively. Vein conduits implanted with distal nerve‐derived nerve fragments improved axonal regeneration. VEGF was superior to MSCs in facilitating nerve regeneration. © 2015 Wiley Periodicals, Inc. Microsurgery 36:578–585, 2016.     

不同年龄大鼠神经再生趋化性差异的研究

目的 比较不同年龄大鼠坐骨神经切断后，其神经再生趋化性在组织持异性和解剖特异性水平上的差异。方法 大鼠按年龄分幼年和成年组各40只，分别建立组织特异性(幼、成年组各20只)和解剖特异性(幼、成年组各20只)模型，术后3、6周分别采用神经电图、组织学检测神经再生。结果 术后3、6N，幼年组在神经传导速度恢复率、神经纤维再生准确率、胫腓神经传导速度比值和波幅比值、远端胫神经侧与腓总神经侧有髓轴索数的比值方面均低于成年组；但复合肌肉动作电位波幅恢复率两组无显著差异。结论 幼年大鼠周围神经再生趋化性的组织和解剖特异性较成年差，提示幼年大鼠较易发生主动肌与拮抗肌同步收缩的主要原因在于周围神经的错向生长。     

The blood supply of the common peroneal nerve in the popliteal fossa

We investigated the blood supply of the common peroneal nerve. Dissection of 19 lower limbs, including six with intra-vascular injection of latex, allowed gross and microscopic measurements to be made of the blood supply of the common peroneal nerve in the popliteal fossa. This showed that a long segment of the nerve in the vicinity of the fibular neck contained only a few intraneural vessels of fine calibre. By contrast, the tibial nerve received an abundant supply from a constant series of vessels arising directly from the popliteal and posterior tibial arteries. The susceptibility of the common peroneal nerve to injury from a variety of causes and its lack of response to operative treatment may be explained by the tenuous nature of its intrinsic blood supply.     

Changes of the donor nerve in end‐to‐side neurorrhaphies with epineurial window and partial neurectomy: A long‐term evaluation in the rat model

End‐to‐side (ETS) neurorrhaphy has been applied in the repair of peripheral nerve injuries and in babysitter procedures. However, the long‐term changes of donor nerve and muscle after ETS remain unknown. This study was designed to investigate long‐term changes in donor nerve and muscle in a rat model. Sixty Lewis rats were equally allocated into three groups of 20 rats. The peroneal nerve was divided. In Group A, end‐to‐end (ETE) neurorrhaphy was performed. In Group B, ETS was performed to an epineurial window on the tibial nerve. In Group C, ETS was performed to the tibial nerve with 40% partial neurectomy. The following data were obtained at 6, 12, 18, and 24 weeks postoperatively: latency delaying rate (LDR), amplitude recovery rate (ARR), myelinated fiber counts, muscle force and weight, and cross‐sectional area of gastrocnemius muscle fibers. The results showed no significant changes of the donor nerve and muscle in Group B. Nerve regeneration was found in the peroneal nerve, and myelinated fiber number was significantly decreased when compared to the nerve with ETE. In Group C, the myelinated axon number in the peroneal nerve was equivalent to the level in ETE repair. However, function and structure of the donor nerve and muscle were significantly impaired in the early postoperative period. Nonetheless, full recovery was observed 24 weeks after surgery. Both ETS with epineurial window and 40% donor nerve neurectomy showed reinnervation of the recipient nerve without structural and functional changes of the donor system in a long‐term follow‐up. Partial neurectomy may promote recipient nerve regeneration, but at the cost of donor neuromuscular compromises in the early postoperative period. This study provides long‐term evidence for further investigation of ETS in peripheral nerve repair and in babysitter procedures. © 2013 Wiley Periodicals, Inc. Microsurgery 34:136–144, 2014.     

A complex cyst characterized into its individual components: a shared pathogenesis from the superior tibiofibular joint

In a patient with a peroneal neuropathy, magnetic resonance imaging (MRI) allowed characterization of a complex para-articular cyst into three different types of cysts, all derived from the superior tibiofibular joint: 1) an intraneural cyst extending along the articular branch to the common peroneal nerve; an interconnected intraneural component extending within the extensor digitorum muscle neural branch, penetrating the fascia of the anterior compartment, and reaching the subcutaneous tissues; 2) an intraosseous cyst isolated to the fibular head and neck, and 3) an extraneural cyst heading toward the tibial nerve and vessels. Joint resection and articular branch disconnection led to excellent functional recovery; an MRI confirmed no cyst recurrence. This case illustrates that different types of cysts can derive from a single joint of origin and extend in various locations and that the articular (synovial) theory is versatile for demonstrating a joint connection, even in unusual appearing combinations of cysts.     

Intraneural Lipoma of the Tibial Nerve: A Case Report

Intraneural lipomas, neurofibrolipomas, lipofibromatous hamartomas, and perineural lipomas are subsets of hamartomas that typically present as fibroadipose, soft tissue masses within the epineurium of a nerve. Several cases involving intraneural lipomas of the median nerve in the upper extremity have been reported; however, owing to the lesion's rare incidence in the foot and ankle, only a select few cases involving the superficial peroneal nerve have been reported. We present the first case of a tibial nerve intraneural lipoma in a 42-year-old female with a follow-up period of 2 years. We discuss the clinical presentation, distinguishing features, surgical procedures, and short-term outcome regarding this unique tumor.     

Tibial Intraneural Ganglia in the Tarsal Tunnel: Is There a Joint Connection?

Intraneural ganglia are rare entities, and, as such, their pathogenesis has been extremely controversial. Recent evidence from intraneural ganglia occurring at more proximal sites-the peroneal nerve at the fibular neck (the most common site) and the tibial nerve at the knee-has suggested an articular origin rather than de novo formation. To our knowledge, of the 10 previous reports of tibial intraneural ganglia within the tarsal tunnel by others, a joint connection to the ankle joint was only identified in 2 cases. To support a hypothesis that tibial intraneural ganglia occurring within the tarsal tunnel region arise from neighboring joints, we analyzed 3 patients retrospectively, all of whom had magnetic resonance (MR) imaging and operative intervention. One of these patients was treated by a peripheral nerve surgeon specializing in foot and ankle surgery. The other 2 patients were the only ones previously published in the literature who had MR images available for reinterpretation. In none of these cases was a joint communication appreciated by radiologists interpreting the MR images preoperatively or by surgeons intraoperatively. Our review of these same cases demonstrated radiographic evidence of joint communications with the subtalar joints. Based on our findings in this article and our knowledge of intraneural ganglia occurring at more proximal sites, we believe that tibial intraneural ganglia within the tarsal tunnel originate from neighboring joints and that their connections to the joints (pedicles) are through articular branches. The importance of these connections is 2-fold: first, for their role in the pathogenesis of this entity, and second, for their potential therapeutic implications. As is highlighted by the clinical and radiographic follow-up in the 1 patient in this article and in many previously reported at other sites, intraneural cyst recurrence can occur if surgeons do not specifically address the articular connection.     

大鼠神经端侧缝合的实验研究

目的：为进一步了解神经端侧缝合后再生的可能性。方法：用大鼠进行研究，实验分五组：Ａ组，将切断的腓神经远端与正常胫神经干行端侧缝合，保留缝合部胫神经外膜；Ｂ组，同Ａ组，缝合部胫神经外膜予以去除（“开窗”）；Ｃ组，将一神经移植段的两端分别与正常胫神经干和切断的腓神经远端神经干行“开窗”的端侧缝合；Ｄ组，将胫神经切断，近端与切断的腓神经远端神经干行“开窗”的端侧缝合。Ｅ组对照：仅切断腓神经。术后不同时期分别行电生理、组织学、神经纤维计数等检查。结果：鼠神经端侧缝合后腓神经远端有不同数量的有髓神经纤维再生。结论：动物鼠类神经端侧缝合能够再生     

Correlation between Evoked Motor Response of the Sciatic Nerve and Sensory Blockade

Background: Incomplete sensory blockade of the foot after sciatic nerve block in the popliteal fossa may be related to the motor response that was elicited when the block was performed. We investigated the appropriate motor response when a nerve stimulator is used in sciatic nerve block at the popliteal fossa.

Methods: Six volunteers classified as American Society of Anesthesiologists' physical status I underwent 24 sciatic nerve blocks. Each volunteer had four sciatic nerve blocks. During each block, the needle was placed to evoke one of the following motor responses of the foot: eversion, inversion, plantar flexion, or dorsiflexion. Forty milliliters 1.5% lidocaine was injected after the motor response was elicited at < 1 mA intensity. Sensory blockade of the areas of the foot innervated by the posterior tibial, deep peroneal, superficial peroneal, and sural nerves was checked in a blinded manner. Motor blockade was graded on a three-point scale. The width of the sciatic nerve and the orientation of the tibial and common peroneal nerves were also examined in 10 cadavers.

Results: A significantly greater number of posterior tibial, deep peroneal, superficial peroneal, and sural nerves were blocked when inversion or dorsiflexion was seen before injection than after eversion or plantar flexion (P < 0.05). Motor blockade of the foot was significantly greater after inversion. Anatomically, the tibial and common peroneal nerves may be separate from each other throughout their course. The sciatic nerve ranged from 0.9-1.5 cm in width and was divided into the tibial and common peroneal nerves at 8 +/- 3 (range, 4-13) cm above the popliteal crease.     

New treatment for peripheral nerve defects: Reconstruction of a 2 cm,monkey median nerve gap by direct lengthening of both nerve stumps

We have developed a new treatment for peripheral nerve defects: nerve‐lengthening method, and confirmed the efficacy and safety of our method using cynomolgus monkeys. A 20‐mm defect in the median nerve of monkey's forearms was repaired through the simultaneous lengthening of both nerve stumps with original nerve‐lengthening device. To evaluate nerve regeneration after neurorrhaphy, electrophysiological, histological, and functional recovery were examined and compared to the standard autografting. Nerve conduction velocity, axon maturation, and the result of functional test were superior in the nerve‐lengthening method than in the autografting. And there were no adverse events associated with our method. We concluded that this method is practical for clinical application. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:153–161, 2012     

End-to-side nerve coaptation: is an additional proximal coaptation useful when available?

The aim of this experimental study was to evaluate the effects of end-to-side coaptation of the proximal end of a severed nerve to the same intact nerve, in addition to traditional end-to-side coaptation of the distal end, with an aim to use the intact nerve as a nerve conduit in a rat model and to compare the functional and histologic results of this modality to those obtained after nerve grafting and traditional end-to-side nerve coaptation. In group A, a peroneal nerve defect measuring 1 cm was created in the left hind limb, and a nerve graft 1 cm long was used to bridge the defect. In group B, only the distal stump of the peroneal nerve was coapted to the intact tibial nerve. In group C, both ends of the peroneal nerve defect were coapted to the intact tibial nerve in an end-to-side fashion 1.5 cm apart from each other, and in group D, the peroneal nerve defect was left unrepaired. Group E was consisted of nonoperated peroneal nerves that were used to obtain normative data. Although significantly higher myelinated axon densities were observed in groups B and C compared with group A and group E, total number of the myelinated axons was significantly higher only in group C. Peroneal functional index assessments demonstrated that nerve recovery in the peroneal nerve was similar in groups A and C, and both were better than those observed in groups B and D. Collectively, these results suggest that end-to-side coaptation of both ends of a severed nerve to an intact nerve, in case of a nerve defect in this length, may serve as an alternative for nerve grafting.     

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.