Potential Donor Nerves Research Articles

Chapter 10 - Sciatic and tibial neuropathies

The sciatic nerve is the body's largest peripheral nerve. Along with their two terminal divisions (tibial and fibular), their anatomic location makes them particularly vulnerable to trauma and iatrogenic injuries. A thorough understanding of the functional anatomy is required to adequately localize lesions in this lengthy neural pathway. Proximal disorders of the nerve can be challenging to precisely localize among a range of possibilities including lumbosacral pathology, radiculopathy, or piriformis syndrome. A correct diagnosis is based upon a thorough history and physical examination, which will then appropriately direct adjunctive investigations such as imaging and electrodiagnostic testing. Disorders of the sciatic nerve and its terminal branches are disabling for patients, and expert assessment by rehabilitation professionals is important in limiting their impact. Applying techniques established in the upper extremity, surgical reconstruction of lower extremity nerve dysfunction is rapidly improving and evolving. These new techniques, such as nerve transfers, require electrodiagnostic assessment of both the injured nerve(s) as well as healthy, potential donor nerves as part of a complete neurophysiological examination.

End-to-Side vs. Free Graft Nerve Reconstruction-Experimental Study on Rats.

The long history of regeneration nerve research indicates many clinical problems with surgical reconstruction to be resolved. One of the promising surgical techniques in specific clinical conditions is end-to-side neurorrhaphy (ETS), described and then repeated with different efficiency in the 1990s of the twentieth century. There are no reliable data on the quality of recipient nerve regeneration, possible donor nerve damage, and epineural window technique necessary to be performed. This research attempts to evaluate the possible regeneration after end-to-side neurorrhaphy, its quality, potential donor nerve damage, and the influence of epineural windows on regeneration efficiency. Forty-five female Wistar rats were divided into three equal groups, and various surgical technics were applied: A-ETS without epineural window, B-ETS with epineural window, and C-free graft reconstruction. The right peroneal nerve was operated on, and the tibial nerve was selected as a donor. After 24 weeks, the regeneration was evaluated by (1) footprint analysis every two weeks with PFI (peroneal nerve function index), TFI (tibial nerve function index), and SFI (sciatic nerve function index) calculations; (2) the amplitude and latency measurements of motor evoked potentials parameters recorded on both sides of the peroneal and tibial nerves when electroneurography with direct sciatic nerve electrical stimulation and indirect magnetic stimulation were applied; (3) histomorphometry with digital conversion of a transverse semithin nerve section, with axon count, fibers diameter, and calculation of axon area with a semiautomated method were performed. There was no statistically significant difference between the groups investigated in all the parameters. The functional indexes stabilized after eight weeks (PFI) and six weeks (TFI and SFI) and were positively time related. The lower amplitude of tibial nerve potential in groups A and B was proven compared to the non-operated side. Neurophysiological parameters of the peroneal nerve did not differ significantly. Histomorphometry revealed significantly lower diameter and area of axons in operated peroneal nerves compared to non-operated nerves. The axon count was at a normal level in every group. Tibial nerve parameters did not differ from non-operated values. Regeneration of the peroneal nerve after ETS was ascertained to be at the same level as in the case of free graft reconstruction. Peroneal nerves after ETS and free graft reconstruction were ascertained to have a lower diameter and area than non-operated ones. The technique of an epineural window does not influence the regeneration result of the peroneal nerve. The tibial nerve motor evoked potentials were characterized by lower amplitudes in ETS groups, which could indicate axonal impairment.

Clinical Application of Saphenous Nerve Transfer for Sensory Reconstruction of the Sole After Sciatic Nerve Injury: A Case Series

Sole sensation is essential for standing and walking. Moreover, lack of protective sensation of sole increases the risk of fall-related injuries. In the light of recent developments in nerve transfer, reconstruction of sole sensation can be achieved even in sciatic nerve injuries. Few researchers have addressed the problem of lack of potential donor nerve in proximal sciatic nerve injuries. The saphenous nerve has sufficient sensory fibers and is anatomically feasible to be used as a donor nerve to reconstruct sensation. To outline a new approach to restore the sensation of the sole using terminal branches of the saphenous nerve. In an attempt to restore sole sensation, 4 patients underwent saphenous nerve transfer to medial plantar and calcaneal branches. Highet-Zachary system scoring was used to evaluate sensory recovery in target regions (heel, metatarsal heads, and big toe). Of the study population, heel sensation recovered up to S3 in 1 case, S2 in 2 cases, and S1 in 1 case. Partial recovery of the metatarsal heads and the big toe was achieved in 2 cases. The findings of this study indicate that the saphenous nerve is a suitable and available donor to restore sole sensation in sciatic or posterior tibial nerve injuries.

Nerve to the Zygomaticus Major Muscle for Facial Reanimation Surgery: A Cadaveric Study for Branching Patterns and Axonal Count.

Background:In facial reanimation surgery, higher donor facial nerve axonal load yields a superior outcome. Nerves supplying the zygomaticus major muscle are primary donors for the grafting procedure; however, their topography has not been studied in detail. This study identified potential donor nerves by quantifying axon loads of the zygomaticus major muscle through histological analysis of cadaveric specimens.Materials and Methods:Forty-three hemifaces from 26 fresh human cadavers were studied. Branching patterns of nerves were classified according to their shapes. All branches of interest were sectioned and stained for an axon count. The potential donors were mapped into each tributary of nerves supplying the zygomaticus major.Results:Branching patterns were categorized into five types: Y-type (28%), X-type (28%), H-type (19%), E-type (14%), and F-type (11%). The mean number of axons in the most superiorly and proximally located main branches was 1387.33 ± 406.59 in Y-type, 1021.42 ± 187.79 in X-type, 1222.75 ± 193.82 in H-type, 1496.17 ± 364.567 in E-type, and 1353.40 ± 256.07 in F-type (P > 0.05). A topographic relation between facial nerves supplying the zygomaticus major muscle and their mean axonal load was illustrated. The zygomatic/buccal branches were found within 5 mm from Zuker's point in 100% of X-, Y-, H-, and E-type and 75% of F-type specimens.Conclusions:Most proximal facial nerve branches supplying the zygomaticus major, arising at the anterior border of a parotid gland, contained over 900 axons in all five branching types. The primary subbranches may be used in selected cases if donor weakness is a concern. Further, our study provides evidence that demonstrates the precision of Zuker's point.

The derivation of C7 nerve root as a potential donor nerve: a historical note.

The derivation of C7 nerve root as a potential donor nerve: a historical note.

An Anatomical Feasibility Study on the Use of the Hypoglossal and Hemi–Hypoglossal Nerve as a Donor Motor Nerve for Free Functioning Muscle Transfer in Upper Extremity Reconstruction

Objective/Hypothesis: Reconstruction of adult brachial plexus injuries remains a clinical challenge. The advent of nerve transfers and free functioning muscle transfers has increased the available reconstructive options in particular when there have been root avulsions. The accessory, intercostals, and phrenic nerves have been the most common donor nerves used to reanimate free muscle transfers. However, it is not uncommon for these patients to have sustained multiple rib fractures or a phrenic nerve avulsion precluding the use of either nerve as a donor. The paucity of currently available donor motor nerves for transfer led us to investigate the hypoglossal and hemi–hypoglossal nerve as a potential donor nerve for a free functioning muscle transfer. The hypoglossal and hemi–hypoglossal nerve have been used successfully as a nerve transfer for the facial nerve and with some success as a nerve transfer with nerve grafts to the musculocutaneous nerve in obstetrical brachial plexus palsy. We postulated that the hypoglossal and hemi–hypoglossal nerve could be used for nerve transfer without nerve grafts for innervation of a gracilis or latissimus dorsi muscle for elbow flexion in upper extremity reconstruction. To our knowledge, this has not been studied before. Materials and Methods: In 12 formalin-embalmed cadavers (6 males and 6 females), the hypoglossal, thoracodorsal, and obturator nerve branch to gracilis was dissected bilaterally and their respective lengths from their origin to the muscle measured. The distance from the lowest point of the hypoglossal nerve in the neck to the lateral third of the clavicle was measured. Results: The average distance from the lowest point of the hypoglossal to the lateral clavicle was 8.4 ± 1.3 cm in males and 7.7 ± 0.8 cm in females. When the hypoglossal was transected distally and brought down, the average distance to the clavicle was 4.5 ± 1.6 cm in males and 3.8 ± 1.5 cm in females. The average length of the nerve to the gracilis was 13.1 ± 1.6 cm in males and 12.4 ± 11 cm in females and of the thoracodorsal nerve 14.9 ± 1.5 cm in males and 14.0 ± 1.0 cm in females. Conclusion: This cadaveric study demonstrates that the hypoglossal and hemi–hypoglossal nerves may be used as potential motor donor nerves by direct nerve transfer without the need for nerve grafting to innervate a free functioning gracilis or latissimus dorsi muscle for upper extremity reconstruction.

The use of the phrenic nerve communicating branch to the fifth cervical root for nerve transfer to the suprascapular nerve in infants with obstetric brachial plexus palsy.

Traditionally, suprascapular nerve reconstruction in obstetric brachial plexus palsy is done using either the proximal C5 root stump or the spinal accessory nerve. This paper introduces another potential donor nerve for neurotizing the suprascapular nerve: the phrenic nerve communicating branch to the C5 root. The prevalence of this communicating branch ranges from 23% to 62% in various anatomical dissections. Over the last two decades, the phrenic communicating branch was used to reconstruct the suprascapular nerve in 15 infants. Another 15 infants in whom the accessory nerve was used to reconstruct the suprascapular nerve were selected to match the former 15 cases with regard to age at the time of surgery, type of palsy, and number of avulsed roots. The results showed that there is no significant difference between the two groups with regard to recovery of external rotation of the shoulder. It was concluded that the phrenic nerve communicating branch may be considered as another option to neurotize the suprascapular nerve.

Imaging and electrodiagnostic work-up of acute adult brachial plexus injuries

Imaging and electrodiagnostic studies form an essential part of the evaluation of the patient with traumatic brachial plexopathy, enabling clarification of surgical options, prognostication of outcome and formulation of postoperative management. The primary objective of imaging is to identify pre-ganglionic injury indicative of nerve root avulsion. The presence of one or more nerve root avulsion injuries is a critical factor in surgical decision-making and the prognosis of surgical reconstruction. CT myelography is the current imaging modality of choice for this purpose. Initial electrodiagnostic (EDX) testing is ideally performed no sooner than 4 weeks following injury unless otherwise clinically indicated. Follow-up testing can be helpful at approximately 6 week intervals. The sensory nerve amplitudes are the most important component of nerve conduction testing in distinguishing between pre- and post-ganglionic injuries. Electromyographic studies will also assist in the determination of a pre- from post-ganglionic injury, the level of plexus involvement and identify potential donor nerves that may be suitable for use as transfers.

Contralateral spinal accessory nerve for ipsilateral neurotization of branches of the brachial plexus: a cadaveric feasibility study

Additional nerve transfer options are important to the peripheral nerve surgeon to maximize patient outcomes following nerve injuries. Potential regional donors may also be injured or involved in the primary disease. Therefore, potential contralateral donor nerves would be desirable. To the authors' knowledge, use of the contralateral spinal accessory nerve (SAN) has not been explored for ipsilateral neurotization procedures. In the current study, therefore, the authors aimed to evaluate the SAN as a potential donor nerve for contralateral nerve injuries by using a novel technique. In 10 cadavers, the SAN was harvested using a posterior approach, and tunneled subcutaneously to the contralateral side for neurotization to various branches of the brachial plexus. Measurements were made of the SAN available for transfer and of its diameter. The authors found an SAN length of approximately 20 cm (from transition of upper and middle fibers of the trapezius muscle to approximately 2-4 cm superior to the insertion of the trapezius muscle onto the spinous process of T-12) available for nerve transposition. The average diameter was 2.5 mm. Based on these findings, the contralateral SAN may be considered for ipsilateral neurotization to the suprascapular and axillary nerves.

Nerve Conduit Enhancement with Vomeronasal Organ Improves Rat Sciatic Functional Index in a Segmental Nerve Defect Model

ABSTRACT Background Segmental nerve loss presents a challenge to the reconstructive surgeon. The best regenerative results are obtained by using autologous interpositional nerve grafts. While this method can be successful, it necessitates a second surgical step, sacrifices donor nerve function and depends upon a finite supply of potential donor nerves. Collagen nerve conduits are commercially available for reconstruction of segmental nerve defects. However, no conduit-based reconstructive strategy has been as successful as autograft reconstruction. We hypothesized that collagen nerve conduits used to bridge a sciatic nerve defect may be enhanced by grafting with vomeronasal organ (VNO), owing to the unique capacity for regeneration of this mammalian olfactory tissue. Methods 21 rats underwent resection of a 1.0 cm segment of sciatic nerve. Seven rats underwent repair of the resultant nerve defect using a commercially available collagen nerve conduit (NeuraGen, Integra Life Sciences, Plainsboro NJ, USA). Seven rats underwent immediate repair of the nerve defect using the conduit filled with freshly harvested VNO allograft. An additional Seven rats underwent resection of a 4 mm segment of sciatic nerve and direct epineural repair. At 14 weeks postoperatively, all animals underwent walking track analysis. Toe prints were analyzed morphometrically to permit calculation of sciatic functional index (SFI). At 16 weeks postoperatively, rats were sacrificed and tissues were processed for histomorphometric analysis. This analysis included quantification of the number and diameter of myelinated axons as well as calculation of the axon density. Results All animals survived treatment without any serious surgical complications. All sciatic nerves were in continuity at sacrifice. All animals showed signs of sciatic denervation (decubitus ulcers, muscle atrophy) postoperatively. At 14 weeks, the mean sciatic functional index (SFI) was significantly higher in the VNO-enhanced group (p = 0.006) and the epineural repair (ER) groups (p = 0.004) than the conduit-only (CO) group. SFI was equivalent between VNO and ER groups (p = 0.338). Axon density was greater in the VNO (p = 0.013) and ER groups (p = 0.048) than in the CO group. Axon density was equivalent between the VNO and ER groups (p = 0.306). Conclusions In a rat sciatic nerve segmental defect model, modification of collagen nerve conduits to contain the pluripotent neuroepitheilial tissue vomeronasal organ (VNO) improves functional recovery and offers increased axon density relative to reconstruction with an empty conduit (CO).

Surgical anatomy of sensory portion of superficial fibular nerve for harvesting nerve grafts from fetuses

The use of superficial fibular nerve (Sfn) as a potential donor nerve in nerve grafting has been introduced. The limited availability of donor nerves has paved the way for nerve allografting. We studied the sensory portion of Sfn in 60 limbs from 30 fetuses. Three distinct patterns of the nerve were designated as Types 1, 2, and 3 by us. Type 1 (66.67%) comprised Sfn piercing fascia cruris then branching into Mdn and Idn. Type 2 (21.67%) was a pattern where Sfn penetrated deep fascia then continued undivided over the dorsum of foot. Type 3 (11.67%) was where Mdn and Idn penetrated deep fascia independently. The study provided quantitative measurement data of the sensory portion of Sfn and its branching nerves with respect to osseous landmarks like the head of fibula and the malleoli. Such data may be of help in defining nerve segments suitable for harvesting in nerve grafts from fetuses.

Ulnar nerve repair by end‐to‐side neurorrhaphy on the median nerve with interposition of a vein: An experimental study

Our study used a rat animal model to verify that Schwann cell migration, collateral axonal sprouting, and regeneration were not hindered by interposition of a 10-mm vein segment between the distal stump of the transected ulnar nerve and the donor median nerve in end-to-side reconstruction. Reconstructed nerves were withdrawn at 7, 14, 30, and 60 days after surgery, then analyzed by confocal laser microscopy after immunolabeling with anti-neurofilament-200 kD (an axonal marker) and anti-S100 (a glial marker) antibodies. Results are reported at 7, 14, 30, and 60 days after surgery. Our observations indicate that chemotactic factors that stimulate end-to-side nerve regeneration can exert their action at this distance. These findings suggest a possible clinical application for this surgical technique in cases when the severed nerve stump is far from the potential donor nerve.

The harvest and clinical application of the superficial peroneal sensory nerve for grafting motor and sensory nerve defects.

Potential donor nerves for autografting are finite and usually limited to cutaneous nerves of the extremities. The superficial peroneal nerve is the major lateral branch of the common peroneal nerve that innervates the peroneus longus and brevis muscles and provides sensation to the lateral aspect of the lower leg and the dorsal foot. It has generally been overlooked as a potential donor of nerve autografts. Cadaver dissections were performed on 10 fresh lower extremity specimens to investigate the anatomic characteristics of the superficial peroneal nerve and to refine a harvesting technique for the nerve. Thirty-one patients underwent nerve grafting of 39 upper and lower extremity nerves using the superficial peroneal donor. There were nine median nerves, four ulnar nerves, two radial nerves, two brachial plexus lesions, 16 digital nerves, and six lower extremity nerves grafted. The superficial peroneal nerve provided a consistently long donor, comparable in length to the sural nerve. The anatomic pattern is consistent, the patient positioning is simple, the surgical harvesting technique is straightforward, and the donor defect is acceptable. The superficial peroneal nerve provides a safe and valuable donor nerve, particularly in cases where multiple or very long nerve grafts are required.

Microanatomic analysis of the medial antebrachial nerve as a potential donor nerve in maxillofacial grafting.

Microanatomic analysis of the medial antebrachial nerve as a potential donor nerve in maxillofacial grafting.

Discussion: Microanatomic Analysis of the Medial Antebrachial Nerve as a Potential Donor Nerve in Maxillofacial Grafting

Discussion: Microanatomic Analysis of the Medial Antebrachial Nerve as a Potential Donor Nerve in Maxillofacial Grafting

Microanatomic analysis of the medial antebrachial nerve as a potential donor nerve in maxillofacial grafting

Purpose : To histologically compare the anterior branch of the medial antebrachial cutaneous nerve (MACN) with the sural nerve using biometric techniques. Patients and Methods : Twenty-centimeter segments of the right and left (MACN) and sural nerves from three cadavers were analyzed. The number of fascicles within the nerves were counted and the neural to connective tissue ratio was estimated. Results : Sural nerves consistently showed greater amounts of connective tissue between the fascicles than the MACN. Fascicle diameter varied less throughout the length of the MACN. Fascicle diameter varied less throughout the length of the MACN and it showed fewer and larger fascicles, more closely approximating the anatomy of the inferior alveolar nerve. Conclusion: These preliminary data suggest that the MACN, on anatomic grounds, is theoretically more suited for grafting to the alveolar and lingual nerves than the sural nerve.

Posterior interosseous nerve: An anatomic study of potential nerve grafts

Anatomic dissection of the posterior interosseous nerve in 26 cadaver forearms was performed to assess variability in location, diameter, and branching patterns of the nerve. The purpose of our study was to determine the anatomic reliability of the posterior interosseous nerve at the distal forearm level as a potential donor nerve graft for segmental digital nerve loss. The nerve was located in a separate fascicle sheath in the deep radial aspect at the fourth dorsal compartment in all specimens. It ranged from 1 to 5 mm in diameter with one to five fascicles present (15 of 26 specimens had a single fascicle). Ten additional specimens were dissected for assessment of potential length of nerve available for grafting, and this ranged from 5 to 10 cm. These nerves were believed to be of sufficient diameter for grafting of digital-level nerve injuries. There is minimal morbidity when a donor graft is obtained in the same limb as the recipient area, and there is no known donor deficit as a result of posterior interosseous nerve procurement at wrist level.