End-to-side neurorrhaphy with removal of the epineurial sheath: an experimental study in rats

Nerve transfer with functioning free muscle transplantation

In this article, the author focuses on functioning free muscle transplantation (FFMT), an advanced microneurovascular technique indicated in patients who have an advanced injury with a major brachial muscle or muscle group loss or denervation and in whom no locally available or ideal musculotendinous donor unit exists. FFMTs have been successfully applied clinically in cases involving adult brachial plexus palsy, obstetric brachial plexus palsy, facial palsy, severe Volkmann's ischemia, and severe crushing and traction injuries of the forearm or arm with major muscle loss. As the author notes, FFMT is a new challenge for the reconstructive surgeon. He outlines the eight major principles for nerve transfer with FFMT, basing his conclusions on the more than 333 patients who received FFMT between 1995 and 2005 in his hospital.

Promotion of nerve regeneration in peripheral nerve by short-course FK506 after end-to-side neurorrhaphy

BACKGROUND/AIMS

To discuss the feasibility of peripheral nerve injury treated by end-to-side neurorrhaphy in clinic and to evaluate the effect of short-course FK506 on promoting nerve regeneration after end-to-side neurorrhaphy.

METHODS

Thirty adult male Sprague Dawley rats were randomly divided into 3 groups: Group A, 10 rats received end-to-end anastomosis; Group B, 10 rats received end-to-side neurorrhaphy; Group C, 10 rats received the same operation as Group B. After operation, rats in Groups B and C received muscle injection with saline water (1 mg/kg x d(-1)) and FK506 (1 mg/kg x d(-1)), respectively, both for 4 wk. Histological and morphological examinations were performed 12 wk after the operation. In the 2nd, 4th, 6th, 8th, and 12th wk after operation, function recovery analysis was performed.

RESULTS

The results of histological and immunochemistry study (the total number of Schwann cells and the axon numbers at the distal stump of the peroneal nerve, wet weight of extensor digitorum longus muscle) suggested that there were significant differences between Group B (saline water group) and Group C (FK506 group) (P < 0.05), also between Group A (end-to-end group) and Group C (P < 0.05). There were statistically significant differences in function recovery (peroneal functional index and sciatic functional index) between Groups B and C (P < 0.05) and also between Groups A and C (P < 0.05).

CONCLUSION

End-to-side repair combined with FK506 has a potential for application in selected cases of peripheral nerve injury in clinic.

Sex-related differences in recovery of cutaneous nociception after end-to-side nerve repair in the rat

Sex-related differences in the recovery of cutaneous nociception after end-to-side nerve repair were examined in rats. Recovery of nociception in the dorsal foot was determined by skin pinch test 19 weeks after the proximal end of the distal stump of the transected peroneal nerve was sutured to the side of the adjacent intact sural nerve (end-to-side nerve coaptation). Axon sprouts in the recipient peroneal nerve were counted by light and electron microscopy. Recovery of nociception due to axon sprouting through the end-to-side coaptation was found in 87% of females and in 60% of males. The area of nociception was not significantly different (P=0.59) between females and males (13+/-8% and 11+/-9%, respectively). The number of myelinated axons in the recipient peroneal nerve (but not of unmyelinated axons) was significantly larger (P=0.028) in females (median=512, 25th and 75th percentiles: 467 and 594) than in males (median=322, 25th and 75th percentiles: 239 and 468). The majority of these axons in females and males were thin fibres, and recipient nerves in both groups were responsive to nerve pinch test. In conclusion, collateral sprouting of thin myelinated nociceptive axons into the end-to-side coapted nerve is more abundant in female than in male rats. However, recovery of cutaneous mechano-nociception due to sprouting of these axons was not different between the two sexes. Possible reasons are discussed.

RESULTS OF END-TO-SIDE NERVE COAPTATION IN SEVERE OBSTETRIC BRACHIAL PLEXUS LESIONS

OBJECTIVE

Options for nerve repair are limited in brachial plexus lesions with multiple root avulsions because an insufficient number of proximal nerve stumps are available to serve as lead-out for nerve grafts. End-to-side nerve repair might be an alternative surgical technique for repair of such severe lesions. In this technique, an epineurial window is created in a healthy nerve, and the distal stump of the injured nerve is coapted to this site. Inconsistent results of end-to-side nerve repairs in traumatic nerve lesions in adults have been reported in small series. This article evaluates the results of end-to-side nerve repair in obstetric brachial plexus lesions and reviews the literature.

METHODS

A retrospective analysis was performed of 20 end-to-side repairs in 12 infants. Evaluation of functional recovery of the target muscle was performed after at least 2 years of follow up (mean, 33 mo).

RESULTS

Five repairs failed (25%). Seven times (35%) good function (Medical Research Council at least 3) of the target muscle occurred in addition to eight partial recoveries (40%). In the majority of patients, however, the observed recovery cannot be exclusively attributed to the end-to-side repair. The reinnervation may be based on axonal outgrowth through grafted or neurolyzed adjacent nerves. It seems likely that recovery was solely based on the end-to-side repair in only two patients. No deficits occurred in donor nerve function.

CONCLUSION

This study does not convincingly show that the end-to-side nerve repair in infants with an obstetric brachial plexus lesion is effective. Its use cannot be recommended as standard therapy.

Can end-to-side neurorrhaphy bridge large defects? An experimental study in rats

This study was undertaken to evaluate collateral sprouting capability in an end-to-side repair model with long regenerative distance. Forty-five rats were used and divided into four groups, according to the reparative procedure following peroneal nerve division: (A) "double" end-to-side neurorrhaphy with a regenerative distance of 0.6 cm; (B) "double" end-to-side neurorrhaphy with a regenerative distance of 1.2 cm; (C) end-to-end neurorrhaphy; and (D) nerve stumps buried into neighboring muscles. In all animals the contralateral healthy side served as a control. Functional assessment of nerve regeneration was performed at intervals up to 5 months using the Peroneal Function Index (PFI). Evaluation 150 days after surgery included peroneal and tibial nerve histologic and morphometric examination and wet weights of the tibialis anterior muscle. Functional evaluation and axonal counting data demonstrated that there was no statistically significant difference between groups A and B, or between groups A and C. There was no functional or histologic evidence of donor nerve deterioration. In conclusion, the present study confirms that "double" end-to-side neurorrhaphy may be useful for the repair of divided human nerves with long gaps.

Axonal regeneration stimulated by erythropoietin: An experimental study in rats

The aim of the present study is to evaluate the effects of erythropoietin to the collateral sprouting by using systemically delivered erythropoietin in an end-to-side nerve repair model. Forty-five rats were evaluated in four groups: (A) end-to-side neurorrhaphy only, (B) end-to-side neurorrhaphy and erythropoietin administration, (C) end-to-end neurorrhaphy and (D) nerve stumps buried into neighboring muscles. In all animals, the contralateral healthy side served as control. Functional assessment of nerve regeneration was performed at intervals up to 5 months using the Peroneal Function Index. Evaluation 150 days after surgery included peroneal and tibial nerve morphometric examination, and wet weights of the tibialis anterior muscle. During the first three weeks after surgery, when erythropoietin was regularly administered, functional evaluation showed that erythropoietin may facilitate peripheral nerve regeneration. However, there was rapid deterioration in the functional recovery when erythropoietin's administration was discontinued. As a consequence, at the end of this study, erythropoietin failed to maintain its initial stimulating effect in axonal regeneration. The results of wet muscle weights revealed statistically significant differences between Groups A and C, and Group B. Furthermore, data on axonal counting showed significant difference between Groups A and C, and Group B. Erythropoietin appears to facilitate peripheral nerve regeneration at the initial phase of its administration. Further investigation will be necessary to optimise the conditions (dose, mode of administration) in order to maintain its effects.

Motor neuron regeneration through end-to-side repairs is a function of donor nerve axotomy

BACKGROUND

Over the past decade, a growing body of literature has emerged supporting the use of end-to-side (terminolateral) neurorrhaphy for the treatment of selected peripheral nerve injuries. It remains unclear, however, whether injury to the donor nerve is necessary to achieve significant regeneration through such repairs.

METHODS

End-to-side repair was studied in a rodent model in which the terminal limb of a transected peroneal nerve was sutured to the lateral aspect of the tibial nerve. Twenty-eight Lewis rats were randomized to four groups of seven animals each corresponding to incrementally greater donor nerve injuries as follows: group 1, conventional end-to-side neurorrhaphy; group 2, end-to-side neurorrhaphy with proximal crush injury; group 3, end-to-side neurorrhaphy with neurotomy; and group 4, end-to-end repair of transected peroneal nerve (positive control).

RESULTS

At 12 weeks, retrograde labeling of cell bodies of the ventral horn demonstrated significant differences between experimental groups, with mean counts in group 4 (1237 +/- 171) > group 3 (522 +/- 204) > group 2 (210 +/- 132) > or = group 1 (126 +/- 146). This association between nerve injury and motor neuron counts was closely mirrored in quantitative assessments of peripheral nerve regeneration and normalized wet muscle masses.

CONCLUSIONS

These data support the hypothesis that donor nerve injury is a prerequisite for significant motor neuronal regeneration across end-to-side repairs. Motor neuron regeneration through end-to-side repairs is optimized by deliberate transection of donor nerve axons.

Hyperbaric oxygenation in peripheral nerve repair and regeneration

Peripheral nerves are essential connections between the central nervous system and muscles, autonomic structures and sensory organs. Their injury is one of the major causes for severe and longstanding impairment in limb function. Acute peripheral nerve lesion has an important inflammatory component and is considered as ischemia-reperfusion (IR) injury. Surgical repair has been the standard of care in peripheral nerve lesion. It has reached optimal technical development but the end results still remain unpredictable and complete functional recovery is rare. Nevertheless, nerve repair is not primarily a mechanical problem and microsurgery is not the only key to success. Lately, there have been efforts to develop alternatives to nerve graft. Work has been carried out in basal lamina scaffolds, biologic and non-biologic structures in combination with neurotrophic factors and/or Schwann cells, tissues, immunosuppressive agents, growth factors, cell transplantation, principles of artificial sensory function, gene technology, gangliosides, implantation of microchips, hormones, electromagnetic fields and hyperbaric oxygenation (HBO). HBO appears to be a beneficial adjunctive treatment for surgical repair in the acute peripheral nerve lesion, when used at lower pressures and in a timely fashion (<6 hours).

Maximum Number of Collaterals Developed by One Axon during Peripheral Nerve Regeneration and the Influence of That Number on Reinnervation Effects

This study investigated the maximum number of collaterals that can be maintained by 1 axon during regeneration of rat peripheral nerve. The tibial nerve was transected, the proximal residual, with its variable number of axons, was fixed to the distal stump and served as the donor nerve. The number of myelinated axons was calculated after 12 weeks. An increasing ratio of distal stump axon numbers to proximal donor nerve axon numbers of 1.0, 1.83, 3.64 and 7.97 yielded ratios of regenerative myelinated axon numbers to proximal donor axon numbers of 0.98, 1.51, 2.39, 2.89, respectively, with an estimated maximum value of approximately 3.3 using the Hill function. The tibial function indexes and nerve conduction velocities of the regenerated tibial nerve were -44.1 +/- 5.1 and 43.2 +/- 5.3 m/s, -57.5 +/- 4.7 and 18.6 +/- 4.3 m/s, -80.2 +/- 7.1 and 12.7 +/- 3.7 m/s, and -85.4 +/- 5.7 and 10.5 +/- 3.9 m/s, respectively. It has been suggested that 1 axon can regenerate and maintain up to 3 or 4 collaterals in regenerated rat peripheral nerve.

End-to-Side Nerve Repair in Peripheral Nerve Injury

In peripheral nerve injury, end-to-side neurorrhaphy has been reported as an alternative in cases that the proximal nerve stump is not accessible. Several hypotheses have been proposed to explain peripheral nerve regeneration after end-to-side neurorrhaphy. Recent evidence suggests that nerve regeneration occurs by collateral sprouting. Although a great number of humoral factors have been identified, molecular mechanism of nerve regeneration after end-to-side neurorrhaphy has not been completely clarified yet. The goal of this technique is to provide satisfactory functional recovery for the recipient nerve, without any deterioration of the donor nerve function. End-to-side technique has been investigated in detail in both experimental and clinical studies. Only a limited number of reported cases in clinical practice, until today, can reveal that end-to-side technique may become a viable means of repairing peripheral nerves in certain clinical situations.

Direct repair (nerve grafting), neurotization, and end-to-side neurorrhaphy in the treatment of brachial plexus injury

Object

The authors present the long-term results of nerve grafting and neurotization procedures in their group of patients with brachial plexus injuries and compare the results of “classic” methods of nerve repair with those of end-to-side neurorrhaphy.

Methods

Between 1994 and 2006, direct repair (nerve grafting), neurotization, and end-to-side neurorrhaphy were performed in 168 patients, 95 of whom were followed up for at least 2 years after surgery. Successful results were achieved in 79% of cases after direct repair and in 56% of cases after end-to-end neurotization. The results of neurotization depended on the type of the donor nerve used. In patients who underwent neurotization of the axillary and the musculocutaneous nerves, the use of intraplexal nerves (motor branches of the brachial plexus) as donors of motor fibers was associated with a significantly higher success rate than the use of extraplexal nerves (81% compared with 49%, respectively, p = 0.003). Because of poor functional results of axillary nerve neurotization using extraplexal nerves (success rate 47.4%), the authors used end-to-side neurorrhaphy in 14 cases of incomplete avulsion. The success rate for end-to-side neurorrhaphy using the axillary nerve as a recipient was 64.3%, similar to that for neurotization using intraplexal nerves (68.4%) and better than that achieved using extraplexal nerves (47.4%, p = 0.19).

Conclusions

End-to-side neurorrhaphy offers an advantage over classic neurotization in not requiring sacrifice of any of the surrounding nerves or the fascicles of the ulnar nerve. Typical synkinesis of muscle contraction innervated by the recipient nerve with contraction of muscles innervated by the donor was observed in patients after end-to-side neurorrhaphy.

Origin and history of end-to-side neurorrhaphy

This historical note offers a perspective concerning the origin of the employment of end-to-side (termino-lateral) anastomosis for nerve repair and summarizes the works that have been published on this surgical technique through the first part of the 20th Century. While the origin of end-to-side neurorrhaphy is usually dated to the beginning of the 20th Century, some works referring to this technique were published earlier, the first of which dates as far back as 1873. A number of interesting clinical and experimental studies have been carried out on end-to-side nerve anastomosis during the first years of the twentieth century. However, this literature is not easily detectable through current online scientific databases. In this paper we will give an overview of these early works. This history contributes interesting information to the debate surrounding this surgical concept and adds perspective to the use of a technique that has attracted a great deal of attention over the last 15 years.

Using an end-to-side interposed sural nerve graft for facial nerve reinforcement after vestibular schwannoma resection

✓ Increasing rates of facial and cochlear nerve preservation after vestibular schwannoma surgery have been achieved in the last 30 years. However, the management of a partially or completely damaged facial nerve remains an important issue. In such a case, several immediate or delayed repair techniques have been used.

On the basis of recent studies of successful end-to-side neurorrhaphy, the authors applied this technique in a patient with an anatomically preserved but partially injured facial nerve during vestibular schwannoma surgery. The authors interposed a sural nerve graft to reinforce the facial nerve whose partial anatomical continuity had been preserved. On follow-up examinations 18 months after surgery, satisfactory cosmetic results for facial nerve function were observed.

The end-to-side interposed nerve graft appears to be a reasonable alternative in cases of partial facial nerve injury, and might be a future therapeutic option for other cranial nerve injuries.

Concepts of nerve regeneration and repair applied to brachial plexus reconstruction

Brachial plexus injury is a serious condition that usually affects young adults. Progress in brachial plexus repair is intimately related to peripheral nerve surgery, and depends on clinical and experimental studies. We review the rat brachial plexus as an experimental model, together with its behavioral evaluation. Techniques to repair nerves, such as neurolysis, nerve coaptation, nerve grafting, nerve transfer, fascicular transfer, direct muscle neurotization, and end-to-side neurorraphy, are discussed in light of the authors' experimental studies. Intradural repair of the brachial plexus by graft implants into the spinal cord and motor rootlet transfer offer new possibilities in brachial plexus reconstruction. The clinical experience of intradural repair is presented. Surgical planning in root rupture or avulsion is proposed. In total avulsion, the authors are in favor of the reconstruction of thoraco-brachial and abdomino-antebrachial grasping, and on the transfer of the brachialis muscle to the wrist extensors if it is reinnervated. Surgical treatment of painful conditions and new drugs are also discussed.

End-to-side (terminolateral) nerve regeneration: a challenge for neuroscientists coming from an intriguing nerve repair concept

The last 15 years have seen a growing interest regarding a technique for nerve repair named end-to-side (terminolateral) neurorrhaphy. This technique is based on the concept that nerve fiber regeneration along the distal stump of a transected nerve, the proximal stump of which was lost, can be obtained by just suturing the proximal end of its distal stump to the epinerium of a neighbor healthy and undamaged donor nerve. A large body of experimental studies have shown that end-to-side neurorrhaphy, in fact, is able to induce collateral sprouting from donor nerve's axons which is at the basis of the massive repopulation of the distal nerve stump. The regenerating nerve fibers eventually reinnervate the periphery of the severed nerve leading to a recovery of the lost function the degree of which varies depending on factors that still have to be elucidated. Surprisingly, this puzzling concept of nerve regeneration has attracted very little attention from basic neuroscientists so far and, thus, the present paper is intended to call for more biological research on it by overviewing the relevant literature and indicating the several unanswered questions that this concept asks to the neuroscience community.

Influence of Aging on Regeneration in End-to-Side Neurorrhaphy

Aging profoundly affects the structural and functional characteristics of the peripheral nervous system. Although several experiments have investigated the effect of aging on nerve regeneration after crush and transection nerve injuries, little is known about the influence of age on end-to-side nerve repairs. It was hypothesized that decreased terminal and collateral sprouting in older animals would be associated with less robust regeneration through end-to-side nerve repairs. In this study, 27 Lewis rats underwent end-to-side repair at ages 2 weeks, 3 months, or 1 year. Histomorphometric assessments at 12 weeks demonstrated increased fiber width, percent neural tissue, and neural density in animals undergoing nerve reconstruction at the age of 2 weeks (P < 0.05). A trend toward further decline in regeneration was noted at ages 1 year versus 3 months. After end-to-side nerve repair, younger animals exhibit a more robust regenerative response, consistent with prior experience in other nerve injury models.

Use of an intact sensory nerve to bridge a motor nerve defect: an experimental study

Object

End-to-side neurorrhaphy has recently became popular for peripheral nerve repair. Although this method is mainly indicated in nerve defects in which there is an absent proximal nerve stump, bridging a motor nerve defect by coapting the proximal and distal ends of the defect to a neighboring mixed nerve in an end-to-side fashion has been another experimental use of this method. In this situation, however, the source of the regenerating axons is unclear because the axons in both the proximal end of the defect and the bridging intact nerve have the capacity for regeneration. The goal of this study was to identify the source of the regenerating axons.

Methods

In this experimental study, the authors used a sensory nerve to bridge a motor nerve defect so that they could elucidate the source of the regenerating motor axons in the distal part of the motor nerve. One advantage of using a sensory nerve was that it eradicated the risk of damaging another motor nerve. Tests used in the analysis included gait evaluation, electrophysiological tests, and histological assessment.

Conclusions

Results of this study showed that, in the rat model, a sensory nerve can be used to bridge a motor nerve defect, thereby eliminating the need for nerve grafting.

Regenerating Axons Emerge Far Proximal to the Coaptation Site in End-to-Side Nerve Coaptation without a Perineurial Window Using a T-Shaped Chamber

BACKGROUND

Considerable controversy exists concerning the mechanism of axonal regeneration in end-to-side neurorrhaphy. The authors studied the mode of axonal regeneration in end-to-side neurorrhaphy without a perineurial window using a rat sciatic nerve model.

METHODS

Twenty-seven rats were used. A 10-mm segment of peroneal nerve was harvested and coapted to the ipsilateral tibial nerve in end-to-side fashion using a T-shaped silicone chamber to minimize the tibial nerve damaged by surgery. To explain the role of nerve damage on axonal regeneration in end-to-side neurorrhaphy, we also used an isogenic nerve transplantation model in which the peroneal nerve remained intact. The mode of axonal regeneration was studied with electron microscopy, morphometric analysis, immunofluorescence, and immunohistochemistry.

RESULTS

Both morphometric analysis and immunolabeling of neurofilaments demonstrated that regenerating axons emerge at sites far proximal to the coaptation site, travel within the tibial nerve, traverse the perineurium circumferentially around the coaptation site, and then invade into the peroneal nerve. Electron microscopy and a double-labeled immunofluorescence study with antibodies against neurofilament and tenascin-C confirmed large-scale axonal penetration into the perineurium around the coaptation site. Immunofluorescence with antibody against NG2, a marker of axonal regeneration, prevented the possibility of collateral sprouting at the coaptation site. In addition, an end-to-side neurorrhaphy model with an isogenic peroneal nerve clearly demonstrated that nerve damage is a prerequisite for axonal regeneration through end-to-side neurorrhaphy.

CONCLUSIONS

The authors could not locate the site of axonal sprouting in end-to-side neurorrhaphy without a perineurial window; however, this study cast doubts on current hypothesis on the mode of axonal regeneration in end-to-side neurorrhaphy.

Shoulder function following partial spinal accessory nerve transfer for brachial plexus birth injury

Over a 5-year-period, 26 infants underwent a partial transfer of the spinal accessory nerve into the suprascapular nerve using a nerve graft, as part of the repair of a brachial plexus birth injury. At a minimum follow-up of 2.5 years, all children had shoulder function of Grade 4 or better using a modified Gilbert Scale. Average lateral rotation was measured at 53 degrees.

Functional upgrading of partially recovered facial palsy by cross-face nerve grafting with distal end-to-side neurorrhaphy

BACKGROUND

Cross-face nerve grafting combined with functional muscle transplantation has become the standard in reconstructing an emotionally controlled smile in complete irreversible facial palsy. A special problem exists in incomplete or partially recovered facial palsies, when the little existing function should be preserved but the existing function alone is clinically insufficient.

METHODS

In this situation, cross-face nerve grafting performed by means of end-to-end coaptation to a zygomatic branch of the healthy side and by end-to-side neurorrhaphy to a corresponding branch of the incompletely paralyzed side is proposed to upgrade smile function on the latter side and contribute to more static and dynamic overall symmetry. The interposition nerve graft is set in overlength to preserve the possibility of a later muscle transplantation in case of unsatisfying functional result through the additional neuronal input. The authors have used this concept in seven patients with irreversible partial facial palsy. Three cases have a sufficiently long follow-up to be presented here. Outcome was objectively quantified with three-dimensional video analysis of facial movements.

RESULTS

In all three cases, functional improvement and a positive effect on the static and dynamic symmetry of the face could be measured. None of the patients was disappointed by the smile function achieved or wanted to undergo additional muscle transplantation.

CONCLUSION

On the basis of these first clinical experiences, the authors recommend cross-face nerve grafting with overlength and a distal end-to-side neurorrhaphy in patients with irreversible incomplete facial palsy affecting the smile.

Repair of the main nerve trunk of the upper limb with end-to-side neurorrhaphy: An experimental study in rabbits

The aim of this study was to assess the effectiveness of reinnervation using end-to-side neurorrhaphy in the upper extremity of the rabbit. The cut right ulnar nerve was repaired and sutured to the side of the median nerve about 3 cm above the elbow joint. The extent of reinnervation was quantitatively evaluated, as well as the integrity of the intact donor nerve in 36 rabbits randomly treated with fresh or delayed nerve repair with or without perineurotomy. Evaluations included nerve conduction velocity (NCV) of both the ulnar and medial nerves, dry muscle weight, and histologic examination (neurofilament stain and morphometric assessment) at 3 and 6 months postoperatively. NCV recovery rates were 79% and 87% for the ulnar nerve, and 89% and 94% for the median nerve compared to contralateral intact nerves, at 3 and 6 months, respectively. Flexor carpi ulnaris muscle mass measurements revealed a recovery in dry muscle weight of about 81% and 88% at 3 and 6 months, respectively, compared to the intact contralateral flexor carpi ulnaris. Histologic studies with neurofilament staining reveal numerous axonal sprouts at the distal end of the median nerve, indicative of myelinated axonal regeneration. Morphometric analysis demonstrated no difference between fresh and delayed repairs. These results indicate that in the upper extremity of rabbits, end-to-side neurorrhaphy permits axonal regeneration from the intact donor nerve, and is associated with satisfactory recovery. The effect of the procedure on the donor nerve was negligible.

Simultaneous end-to-side coaptations of two severed nerves to a single healthy nerve in rats

Object

This experimental study was designed to evaluate functional and sensory outcomes and morphological features observed after simultaneous end-to-side coaptations of distal stumps of two nerves to a single neighboring nerve. Studies were performed using both parallel and end-to-side coaptation (PEC) and serial end-to-side coaptation (SEC) methods in a rat model.

Methods

In the PEC group, distal stumps of the sural and common fibular nerves were coapted to the intact tibial nerve 1 cm apart from each other in an end-to-side fashion. In the SEC group, identical surgical procedures apart from the coaptation method were conducted. For the coaptation method in this group, the distal stump of the common fibular nerve was first coapted to the side of the intact tibial nerve, and then the distal stump of the sural nerve was coapted to the side of the common fibular nerve 1 cm apart from the first coaptation site.

Nonoperated contralateral sides were used as controls. Nerve regeneration in both groups was evaluated functionally, electrophysiologically, and histomorphometrically.

Conclusions

When there is a need for two end-to-side coaptations of two severed nerves, PEC is the recommended method of choice to obtain better axonal regeneration into both nerves.

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.

La réparation nerveuse périphérique : 30 siècles de recherche

INTRODUCTION

Nerve injury compromises sensory and motor functions. Techniques of peripheral nerve repair are based on our knowledge regarding regeneration. Microsurgical techniques introduced in the late 1950s and widely developed for the past 20 years have improved repairs. However, functional recovery following a peripheral mixed nerve injury is still incomplete.

STATE OF ART

Good motor and sensory function after nerve injury depends on the reinnervation of the motor end plates and sensory receptors. Nerve regeneration does not begin if the cell body has not survived the initial injury or if it is unable to initiate regeneration. The regenerated axons must reach and reinnervate the appropriate target end-organs in a timely fashion. Recovery of motor function requires a critical number of motor axons reinnervating the muscle fibers. Sensory recovery is possible if the delay in reinnervation is short. Many additional factors influence the success of nerve repair or reconstruction. The timing of the repair, the level of injury, the extent of the zone of injury, the technical skill of the surgeon, and the method of repair and reconstruction contribute to the functional outcome after nerve injury.

CONCLUSION

This review presents the recent advances in understanding of neural regeneration and their application to the management of primary repairs and nerve gaps.

End-to-Side Nerve Coaptation

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.

Functional Remobilization Evaluation of the Paralyzed Vocal Cord by End-to-Side Neurorrhaphy in Rats

OBJECTIVE

To investigate the value of end-to-side neurorrhaphy to treat vocal cord paralysis.

STUDY DESIGN

A prospective study evaluating the effects of end-to-side neurorrhaphy to treat vocal cord paralysis by means of fiberoptic laryngoscopy and nerve electromyography.

METHODS

Thirty Sprague-Dawley rats were divided into experimental group 1, experimental group 2, and a control group randomly. Right recurrent laryngeal nerve (RLN) was incised, and the distal end of the RLN was anastomosed to the right phrenic nerve by end-to-side neurorrhaphy in experimental group 1 or by end-to-end nerve anastomosis in experimental group 2, respectively. The adductor nerve branch of the right RLN was incised and anastomosed to the proximal end of the right ansa cervicalis nerve by end-to-end nerve anastomosis. Fiberoptic laryngoscopy and nerve electromyography were used to examine the vocal cord movement and nerve regeneration.

RESULTS

Three months after operation, this effect of end-to-side neurorrhaphy created a significant difference compared with the end-to-end nerve anastomosis (P < .05). The end-to-side neurorrhaphy did not lead to vocal cord movement compared with end-to-end nerve anastomosis.

CONCLUSION

Vocal cord paralysis cannot be treated by this microsurgical technique.

Repair of brachial plexus lesions by end-to-side side-to-side grafting neurorrhaphy: experience based on 11 cases

Eleven brachial plexus lesions were repaired using end-to-side side-to-side grafting neurorrhaphy in root ruptures, in phrenic and spinal accessory nerve neurotizations, in contralateral C7 neurotization, and in neurotization using intact interplexus roots or cords. The main aim was to approximate donor and recipient nerves and promote regeneration through them. Another indication was to augment the recipient nerve, when it had been neurotized or grafted to donors of dubious integrity, when it was not completely denervated, when it had been neurotized to a nerve with a suboptimal number of fibers, when it had been neurotized to distant donors delaying its regeneration, and when it had been neurotized to a donor supplying many recipients. In interplexus neurotization, the main indication was to preserve the integrity of the interplexus donors, as they were not sacrificeable. The principles of end-to-side neurorrhaphy were followed. The epineurium was removed. Axonal sprouting was induced by longitudinally slitting and partially transecting the donor and recipient nerves, by increasing the contact area between both of them and the nerve grafts, and by embedding the grafts into the split predegenerated injured nerve segments. Agonistic donors were used for root ruptures and for phrenic and spinal accessory neurotization, but not for contralateral C7 or interplexus neurotization. Single-donor single-recipient neurotization was successfully followed in phrenic neurotization of the suprascapular (3 cases) and axillary (1 case) nerves, spinal accessory neurotization of the suprascapular nerve (1 case), and dorsal part of contralateral C7 neurotization of the axillary nerve (2 cases). Apart from this, recipient augmentation necessitated many donor to single-recipient neurotizations. This was successfully performed using phrenic-interplexus root to suprascapular transfers (2 cases), phrenic-contralateral C7 to suprascapular transfer (1 case), and spinal accessory-interplexus root to musculocutaneous transfer (1 case). Both recipient augmentation and increasing the contact area between grafts and recipients necessitated single or multiple donor to many recipient neurotizations. This was applied in root ruptures (3 cases), with results comparable to those obtained in classical nerve-grafting techniques. It was also applied in ventral C7 transfer to the lateral or medial cords (3 cases) with functional recovery occurring in the biceps and pronator teres muscles, but not in dorsal C7 transfer to the axillary and radial nerves (3 cases) with functional recovery occurring in the deltoid and triceps muscles, and in whole C7 transfer to C5, 6, 7, 8T1 roots with functional recovery occurring in the deltoid (M4), biceps (M4), pronator teres (M4), and triceps (M3) (3 cases), and less so in the flexor carpi ulnaris and FDP (M3) (1 case) and the extensor digitorum longus (M3) (1 case). Contralateral C7 transfer to the lateral and posterior cords (4 cases) was followed by cocontractions that took 1 year to improve and that involved the rotator cuff, deltoid, biceps, and pronator teres (all agonists). Functional recovery in the triceps muscle was less than in the above muscles. Contralateral C7 transfer to C5-7 (1 case) was followed by cocontractions that took 1 year to resolve and that occurred between the deltoid, biceps, and flexor digitorum profundus. Interplexus root neurotization was done only in conjunction with other neurotization techniques, and so its role is difficult to judge. Though the same applies to regenerated lateral cord transfer to the posterior cord (2 cases), the successful results obtained from medial cord neurotization to the axillary, musculocutaneous, and radial nerves (1 case), and from ulnar and median nerve neurotization to the radial nerve (1 case), show that neurotization at the interplexus cord level may play a role in brachial plexus regeneration and may even be used to neurotize nerves and muscles distal to the elbow. The timing of repair was within 6 months after injury, except for 2 cases. In the first case, contralateral C7 transfer was successfully performed more than 1 year after injury. The second case was an obstetric palsy operated upon at age 8. Deterioration in motor power of the donor muscles that improved in 6 months was observed in 2 cases of interplexus neurotization at the cord level, because of looping the sural nerve grafts tightly around the donor nerves. Deterioration in donor-muscle motor power as a consequence of end-to-side neurorrhaphy was noted in the obstetric palsy case, when the flexor carpi radialis (donor) became grade 3 instead of grade 4. This was associated with cocontractions between it and the extensors. It took nearly 1 year to improve.

End-to-side nerve repair in the upper extremity of rat

The end-to-side nerve-repair technique, i.e., when the distal end of an injured nerve is attached end-to-side to an intact nerve trunk in an attempt to attract nerve fibers by collateral sprouting, has been used clinically. The technique has, however, been questioned. The aim of the present study was to investigate end-to-side repair in the upper extremity of rats with emphasis on functional recovery, source, type, and extent of regenerating fibers. End-to-side repair was used in the upper limb, and the radial or both median/ulnar nerves were attached end-to-side to the musculocutaneous nerve. Pawprints and tetanic muscle force were used to evaluate functional recovery during a 6-month recovery period, and double retrograde labeling was used to detect the source of the regenerated nerve fibers. The pawprints showed that, in end-to-side repair of either one or two recipient nerves, there was a recovery of toe spreading to 60-72% of the preoperative value (lowest value around 47%). Electrical stimulation of the end-to-side attached radial or median/ulnar nerves 6 months after repair resulted in contraction of muscles in the forearm innervated by these nerves (median tetanic muscle force up to 70% of the contralateral side). Retrograde labeling showed that both myelinated (morphometry) sensory and motor axons were recruited to the end-to-side attached nerve and that these axons emerged from the motor and sensory neuronal pool of the brachial plexus. Double retrograde labeling indicated that collateral sprouting was one mechanism by which regeneration occurred. We also found that two recipient nerves could be supported from a single donor nerve. Our results suggest that end-to-side repair may be one alternative to reconstruct a brachial plexus injury when no proximal nerve end is available.

Nerve transfers in adult brachial plexus injuries: my methods

The reconstructive strategies for avulsion in-juries vary from patient to patient and over time,continue to evolve depending on the surgeon's philosophy, available facilities and therapy, the elapsed time from injury to intervention, the severity of injury, and patient age and motivation. The author's results show that nerve transfer can obtain an average of 60 degrees (range, 20 degrees - 180 degrees) of shoulder elevation without shoulder arthrodesis, M3 to M4 muscle strength of elbow flexion, M2 to M4 elbow extension, and M3 finger flexion and sensation. Intrinsic hand function was obtained with help of dynamic splinting for interphalangeal joint extension and arthrodesis of thumb joints asa post for opposition.

Effect of genetically modified Schwann cells with increased motility in end-to-side nerve grafting

Taking into account that Schwann-cell (SC) motility is a prerequisite for myelination during peripheral nerve regeneration, the present study was designed with the intention to increase SC motility in vitro and to evaluate the effect of transduced SC on nerve regeneration in vivo, through silicone tubes after end-to-side nerve repair. Our in vitro study demonstrated that SC transduction with the pREV-HW3 retrovirus, encoding for sialyl-transferase-X (STX), significantly increased their motility compared to the control. In the in vivo study, 45 Wistar rats were randomized into three groups of 15 each. In all animals, the left peroneal nerve was severed, and a 10-mm segment was removed. The distal stump of the peroneal nerve was connected end-to-side to a perineurial window in the ipsilateral tibial nerve with either a silicone tube lined with SC (group A) or a silicone tube lined with STX-transduced SC (groups B and C). Fluorescence and light microscopy in group C showed that SCs were viable the first critical 15 postoperative days. After 90 days, light microscopy in group B demonstrated that STX-transduced SCs with increased motility ensured nerve regeneration, through silicone tubes, in all cases. Furthermore, STX-transduced SCs increased significantly fiber diameter and myelin thickness, and most importantly enhanced significantly the functional outcome compared to non-transduced SCs.

End-to-side nerve grafting of the tibial nerve to bridge a neuroma-in-continuity

Standard treatment for a neuroma-in-continuity with partial retained function is neurolysis with or without grafting. The present study tests the outcome of a novel partial nerve lesion bypassed with an end-to-side bridge graft, intended to increase the number of axons crossing the defect while not disturbing intact axons. An 8-mm portion of tibial nerve was resected in 20 rats. Three weeks later, half had the defect repaired with an end-to-side bridge allograft and perineurial windows; controls had only neurolysis. Recovery was evaluated using walking-track analysis, allodynia testing, muscle weight ratios, and histology at 8 weeks. No significant differences in motor or sensory functional recovery were noted between the two groups. Histology showed good axonal regeneration through the defect in all specimens. The experimental group also had regenerated axons in the bridge graft, but their maturity was less advanced, presumably due to delays in regeneration.

Low-power laser biostimulation enhances nerve repair after end-to-side neurorrhaphy: a double-blind randomized study in the rat median nerve model

Previous studies have shown that low-power laser biostimulation (lasertherapy) promotes posttraumatic nerve regeneration. The objective of the present study was to investigate the effects of postoperative lasertherapy on nerve regeneration after end-to-side neurorrhaphy, an innovative technique for peripheral nerve repair. After complete transection, the left median nerve was repaired by end-to-side neurorrhaphy on the ulnar "donor" nerve. The animals were then divided into four groups: one placebo group, and three laser-treated groups that received lasertherapy three times a week for 3 weeks starting from postoperative day 1. Three different types of laser emission were used: continuous (808 nm), pulsed (905 nm), and a combination of the two. Functional testing was carried out every 2 weeks after surgery by means of the grasping test. At the time of withdrawal 16 weeks postoperatively, muscle mass recovery was assessed by weighing the muscles innervated by the median nerve. Finally, the repaired nerves were withdrawn, embedded in resin and analyzed by light and electron microscopy. Results showed that laser biostimulation induces: (1) a statistically significant faster recovery of the lesioned function; (2) a statistically significant faster recovery of muscle mass; (3) a statistically significant faster myelination of the regenerated nerve fibers. From comparison of the three different types of laser emissions, it turned out that the best functional outcome was obtained by means of pulsed-continuous-combined laser biostimulation. Taken together, the results of the present study confirm previous experimental data on the effectiveness of lasertherapy for the promotion of peripheral nerve regeneration and suggest that early postoperative lasertherapy should be considered as a very promising physiotherapeutic tool for rehabilitation after end-to-side neurorrhaphy.

Collateral sprouting occurs following end-to-side neurorrhaphy

Recent evidence supports the use of end-to-side neurorrhaphy for the treatment of certain peripheral nerve disorders. However, the mechanism by which nerves regenerate following this procedure is still unclear. To address this question, the authors designed a new end-to-side coaptation model in rats in which the donor nerves were uninjured. The regenerated axons at the coaptation site were observed directly using fluorescent dye as the neural tracer. The sciatic nerve from adult Wistar rats was transplanted between the left and right median nerves. Fifteen rats were divided into three groups. In group I, the donor (right median) nerve was sutured end to side to the divided grafted nerve using a noninjury technique. In group II, the aponeurosis of the spinal muscles was harvested and the sciatic and right median nerves were coapted end to side noninjuriously by wrapping them in the excised aponeurosis. In group III, a perineurial window was created and a partial neurectomy was carried out at the suture site, after which the sciatic and right median nerves were sutured end to side. Sixty days after the operation, nerve regeneration was evaluated by recording action potentials in the grafted nerve, by performing electromyography in the flexor muscles in the forearm, and by histological examination. The grafted nerves were fixed and sectioned, the number of regenerated nerve fibers was counted, and axonal diameters were measured. Fluorescent dye crystal was used, in conjunction with confocal microscopy, to observe the regenerated axons at the co-aptation site. The results showed that nerve regeneration had occurred in the animals, as determined electrophysiologically and histologically. Both the right and left flexor muscles of the forearm contracted simultaneously as a result of indirect electric stimulation of the grafted nerve, which suggests that the regenerated nerve was physiologically connected with the donor nerve. Nerve fiber counts did not show any differences among groups (p > 0.05), but axonal diameters were significantly greater in group III than in the other two groups. Fluorescent dye staining revealed the presence of regenerated nerve fibers beyond the coaptation site. In group III, the regenerating nerves were observed within the whole section of the coaptation site and collateral sprouting was found to occur even at a site distal to the suture. From these results, the authors conclude that in end-to-side neurorrhaphy, nerve regeneration occurs by collateral sprouting from the donor nerve.

The end-to-side peripheral nerve repair

Morphologic and functional recovery following an end-to-side repair was studied comparatively with conventional end-to-end repair in a model of peroneal nerve lesion in rats. Twenty-eight rats were used and divided into four groups according to the reparative procedure following nerve division: (1) nerve stumps buried into neighboring muscles (n = 8); (2) conventional end-to-end repair (n = 7); (3) end-to-side repair onto the tibial nerve (n = 8); (4) sham operation (n = 5). The sciatic functional index (SFI) was evaluated at weekly intervals for 8 weeks, the peroneal nerve being resected on the 56th day for histologic and morphometric studies. The SFI progressively improved in Groups 2 (-16.9) and 3 (-22.7), although it did not reach normal values (around -8). The average nerve fiber density increased to normal values in both Groups 2 and 3, although accompanied by a marked decrease of average minimal and maximal nerve fiber diameter, myelin sheath area and G quotient. The differences between Groups 2 and 3 or Groups 2 and 4 were not significant. We conclude that, although resulting in significant morphologic and functional recovery, end-to-side repair is not as efficient as the conventional end-to-end nerve repair. However, end-to-side repair has a potential for application in selected cases in humans.

Morphological evidence of collateral sprouting of intact afferent and motor axons of the rat ulnar nerve demonstrated by one type of tracer molecule

In our experimental paradigm we sutured the distal stump of a transected musculocutaneous nerve to an intact ulnar nerve of the rat in an end-to-side fashion. We demonstrated the formation of collateral sprouts from intact afferent and motor axons by application of one type of molecule conjugated by two different fluorophores (Fluoro-Ruby and Fluoro-Emerald). Fluoro-Ruby and Fluoro-Emerald were applied distal to end-to-side suture into fresh cut ends of the ulnar and musculocutaneous nerves, respectively. Formation of collateral sprouts was evidenced by findings of mixed (a yellow to orange color) fluorescence labeling of spinal motoneurons and dorsal root ganglia neurons. Colocalization of two different tracers retrogradely transported to the neurons was verified by the individual green and red fluorescence profiles analyzed by means of the computer-assisted image-analyzing system. Our results unequivocally demonstrate that a nerve stump attached to an intact nerve can induce collateral sprouting of both afferent and motor axons.

Effect of Perineurial Window Size on Nerve Regeneration, Blood–Nerve Barrier Integrity, and Functional Recovery

End-to-side neurorrhaphy is used clinically to reconstruct nerve injuries when the lack of a suitable proximal nerve stump precludes conventional approaches to microsurgical repair. In end-to-side neurorrhaphy, the distal stump of a transected nerve is sutured to the side of an intact nerve that serves as an axon donor. Prior studies suggest that this perineurial window is a prerequisite for effective nerve regeneration into the recipient nerve. However, the optimal size for this perineurial window remains uncertain. This study evaluated the effect of perineurial window size on collateral axonal sprouting, blood-nerve barrier architecture, and functional impairment of the donor nerve. One hundred twenty Lewis rats were randomized to 1 and 5 mm perineurial window groups and examined at serial time points. The 5 mm perineurial window group exhibited significantly greater fiber counts at the repair zone than the 1mm group within 4 weeks (p < 0.005). Marked breakdown of the blood-nerve barrier was present 2 week postoperatively and resolved by 4 weeks regardless of 1 versus 5 mm perineurial window size. Tibial function indices in both groups normalized between 4 and 6 weeks postoperatively. A large (5 mm) perineurial window induced greater collateral sprouting or regenerative response than a small (1 mm) perineurial window without increasing cross sectional nerve injury or delaying functional recovery.

End-to-side neurorrhaphy as a salvage procedure for irreparable nerve injuries. Technical note

After a few reports on end-to-side nerve repair at the beginning of the last century, the technique was put aside until its recent reintroduction. The authors present their results in three patients with median nerve defects that were between 15 and 22 cm long and treated using end-to-side median-to-ulnar neurorrhaphy through an epineurial window. The follow-up times were between 32 and 38 months. Sensory evaluation involved superficial touch, pinprick, and two-point discrimination tests. Motor evaluation was completed by assessing the presence of opposition and by palpating the abductor pollicis brevis muscle. Sensory recovery was observed in all patients in the median nerve dermatome, and motor recovery was absent, except in Case 1. End-to-side nerve repair can be a viable alternative to nerve grafting in patients with long gaps between the ends of the injured nerve.

End-to-side nerve suture in clinical practice

The phenomenon of lateral sprouting of axons into an end-to-side sutured recipient nerve is well documented. The exact nature, however, still needs further investigation. Since 1996, we have been continuously involved in primate research as well as using this end-to-side nerve suture (ETSNS) method in clinical practice. Fifty-six patients with a variety of conditions, ranging from brachial plexus avulsion to digital nerve lesions, have been operated. From our experience, it seems that the best results achieved are proximal motor re-innervation (e.g. biceps) and distal sensory re-innervation (e.g. volar skin of the hand). The discussion will cover various aspects for ETSNS in the human patient, such as indications, parameters, technique, and the importance of rehabilitation. ETSNS restores function in conditions previously difficult to operate, and may replace nerve grafting in many instances. It provides an additional method in our armamentarium in peripheral nerve surgery.

Re-innervation of M. biceps by end-to-side nerve suture

End-to-side nerve suture (ETSNS) is a viable option to re-innervate a paralysed biceps muscle. The host or donor nerve could be any of the adjacent large nerves including the brachial plexus. It is important to adhere to certain principles when performing ETSNS, e.g. epineural window only, suture line without tension, the recipient nerve should not "kink" in any way and complete immobilisation for at least three weeks. The earlier this ETSNS is done after injury the better the outcome. Patient co-operation and motivation is of the utmost importance. The post-operative rehabilitation programme is essential to "awaken" and strengthen the dormant muscle. Our results are based on five patients. Good elbow flexion, i.e. biceps contraction can be regained after ETSNS of, for example, the musculo-cutaneous nerve into an appropriate viable host nerve.

Comparison of functional results of nerve graft, vein graft, and vein filled with muscle graft in end-to-side neurorrhaphy

End-to-side neurorrhaphy is an alternative method in the situation where the proximal part of the nerve cannot be found. When the intact nerve is not close enough to perform end-to-side neurorrhaphy, it will be necessary to use a graft for transporting the regenerating axons. In this study, we tried to find out whether it is possible to use a graft in an end-to-side neurorrhaphy, and compared the nerve graft with possible alternative grafts, i.e., vein and muscle-filled vein grafts. Thirty male Sprague Dawley rats were used, with an average weight of 293 g (range, 250-350 g). All experiments were done on the right side. A 2-cm nerve graft, beginning 1 cm distal to the branching level, was sectioned from the peroneal nerve. A 1-mm epineural window was opened in the tibial nerve. In the first group, the proximal side of this graft was sutured to the tibial nerve side in an end-to-side fashion, and the distal side was sutured to the distal peroneal nerve stump in an end-to-end fashion. In the second group, the right 2-cm jugular vein was harvested, and was used to bridge the defect instead of the nerve graft used in the first group. In the third group, a 2-cm jugular vein filled with fresh skeletal muscle was used to bridge the defect. At 2, 4, 8, 12, 20, and 28 weeks, functional assessment of nerve regeneration was performed, using walking-track analysis. The numbers of myelinated fibers and fiber diameters were measured, and an electron microscopic evaluation was carried out. Based on walking-track analysis and fiber diameters, the differences of all three groups were statistically significant (P < 0.05). While the differences of myelinated fibers between the first and second groups were not significant, the differences between the rest (group 1-group 3 and group 2-group 3) were significant (P < 0.05). Our study showed that, in end-to-side neurorrhaphy, the use of a nerve graft is possible, and a vein graft is also a good alternative, but a muscle-filled vein graft is not.

The use of end-to-side nerve grafts to reinnervate the paralyzed orbicularis oculi muscle

Facial paralysis is a serious neurologic disorder, particularly when it affects the eye. Loss of the protective blink reflex may lead to corneal ulceration and, possibly, visual loss. The purpose of this study was to compare different nerve-grafting techniques to reanimate the paralyzed eyelid. Sixteen adult dogs (25 kg each) were allocated into four groups. Denervation of the left hemi-face was performed in all cases. One dog served as a control animal (group I). Group II dogs (n = 5) underwent end-to-side coaptation of the nerve graft to the intact palpebral branch and end-to-end coaptation to the denervated palpebral branch. Group III dogs (n = 5) underwent end-to-end coaptation of the nerve graft to the intact palpebral branch and end-to-end coaptation to the denervated palpebral branch. Group IV dogs (n = 5) underwent end-to-side coaptation of the nerve graft to the intact and denervated palpebral branches. The animals were monitored for 9 months after the surgical procedures, to allow adequate time for reinnervation. The dogs were postoperatively monitored with clinical observation, electrophysiologic testing, video motion analysis, and histologic assessments. Clinical observation and electrophysiologic testing demonstrated the production of an eye blink in the denervated hemi-face in all experimental groups. There was a trend toward increased speed of reinnervation for group III animals (end-to-end coaptations). It was concluded that end-to-side coaptation can produce a contralateral synchronous eye blink in a clinically relevant, large-animal model.

[Lengthening temporalis myoplasty and transfacial nerve graft (VII-V). Technical note]

Authors report the first five cases of lengthening temporalis myoplasty associated with transfacial nerve grafting. After a follow-up period of 10 months and 8 months for the 2 first cases, temporalis reinnervation by the facial nerve could be observed. Nerve growth was documented by electromyography. Three other cases have been performed using this technique and are in the nerve growth phase. Operative technique is described in detail. Transfacial nerve grafting seems to help the transposed temporalis muscle obtain more facial function and therefore, improve the quality of the spontaneous smile. The temporalis muscle become double innervated (trigeminal and facial nerve). It should be indicated in children, young adults or in patients in whom physical therapy will be difficult.

[Surgical procedures for labial reanimation in facial paralysis]

With an extensive review of the literature, the authors described the surgical approach of the labial reanimation in facial palsy. First they remind some important points about neural suture, with or without graft. After, the palliatives procedures are detailed (upper and lower lip, unilateral or bilateral). The main surgical treatments are exposed in technical notes, particularly lengthening temporalis myoplasty and free muscle transplantation.

[Indications for labial reanimation in facial paralysis]

The therapeutic approach of labial reanimation depends on several points, like the association with others abnormalities, the palsy which can be complete or partial, the age of the patient and the practice of the surgical team. Nevertheless, the authors try to propose a surgical approach of labial reanimation in facial palsy, depending on the facial nerve which can be reparable or not, and on the facial muscles which can be used or not. At least, the indications in partial labial palsy are recalled.

Nerve regeneration through a healthy peripheral nerve trunk as a nerve conduit: a preliminary study of a new concept in peripheral nerve surgery

The popularity of nerve conduits has increased recently due to the need for alternative nerve reconstruction techniques, obviating the harvest of nerve grafts. Based on ideas suggesting nerve tissue itself, which was the most physiologic environment for nerve regeneration, a study using 40 sciatic nerves of 20 rats was performed. The proximal stumps of transected peroneal nerves were sutured to the lateral wall of healthy tibial nerve trunks after removal of the epineurium. Twelve weeks later, tissue samples were taken from the anastomosis sites and from the levels above and below these sites. Configurations of fascicles were evaluated, and numbers of fibers were estimated. It was observed that the fibers of peroneal nerves regenerated into and through the tibial nerve trunk distally. This suggested that active regenerating fibers of a proximal stump of a nerve could regenerate and progress as a fascicular unit in optimum condition at the trunk of another healthy nerve. This preliminary study should stimulate further studies based on this new concept: that a nerve trunk can serve as the host for the regenerating fibers of another nerve.