Results of termino-lateral neurorrhaphy to original and adjacent nerves

Stem cells in end-to-side neurorrhaphy. Experimental study in rats

Purpose:

To evaluate the influence of mesenchymal stem cells from adipose tissue in the end-to-side neurorrhaphy, focusing in the nerve regeneration and the muscle reinnervation in acute trauma.

Methods:

140 animals were randomly divided in seven groups: control, denervated, end-to-side neurorrhaphy between distal stump of common peroneal nerve and tibial nerve (ESN), ESN wrapped in fascia, ESN wrapped in fascia and platelet gel, ESN wrapped in platelet gel, ESN wrapped in fascia and platelet gel within stem cells (without culture) removed from the adipose tissue. Mass measurements of the animal and of cranial tibial muscles, electromyography, walking track analysis tests and histological examinations of the nerves and muscles after 180 days was performed.

Results:

In the groups where the ESN was performed, the results were always better when compared to the denervated group, showing reinnervation in all ESN groups. The most sensitive methods were walking track and histological analysis. Only the group with stem cells showed values similar to the control group, as well as the functional indices of peroneal nerve and the number of nerve fibers in the peroneal nerve.

Conclusions:

Stem cells were effective in ESN according with the functional index of the peroneal nerve, evaluated by walking track analysis and the number of nerve fibers in the peroneal nerve.

Clinical Experience with End-to-Side Nerve Transfer

A retrospective study was undertaken to determine the effectiveness of end-to-side nerve transfer. Twenty patients with peripheral nerve lesions of varying aetiology underwent 23 end-to-side nerve transfers over a 15-month period. The mean patient age was 30 years and 18 were male. The mean delay in presentation was 2.4 months. All underwent end-to-side nerve repairs and were reviewed in outpatients at regular intervals. Ten patients were lost to follow-up before 12 months and were therefore excluded from the study. The remaining ten patients, who had undergone 13 end-to-side procedures, had a mean follow-up period of 16 months. None demonstrated objective evidence of motor recovery at the end of the study period. Four patients had modest recovery of deep protective sensation, and two patients suffered a subtle degree of ”donor“ nerve morbidity. We have abandoned this technique in our centre in preference for standard nerve grafting techniques.

Morphometric and Functional Analysis of Axonal Regeneration after End-to-end and End-to-side Neurorrhaphy in Rats

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Background:

End-to-side neurorrhaphy is controversial in the literature and has sparked debate over its degree of recovery. In this study, nerve regeneration was assessed in rats after end-to-side neurorrhaphy by morphometric analysis, electromyography, electron microscopy, and retrograde horseradish peroxidase (HRP) and Fluoro-Gold (FG; Fluorochrome Inc., Denver, Colo.) transport and then compared to end-to-end neurorrhaphy and sham operation.

Methods:

Thirty-seven animals were operated on and divided randomly into 4 groups: group 1, sham; group 2, end-to-end neurorrhaphy; group 3, end-to-side neurorrhaphy with an epineural window; and group 4, end-to-side neurorrhaphy without an epineural window. Three months after surgery, HRP was injected into the peroneal muscles. After 48 hours, nerve segments and lumbar spine segments were collected. Electromyography data were compared between groups, and FG uptake was compared in 20 other animals. Analysis of variance with Tukey-Kramer correction was used for group comparison.

Results:

The fiber count after end-to-end neurorrhaphy was higher than after end-to-side neurorrhaphy with an epineural window (q = 5.243 and P < 0.01) or without an epineural window (q = 4.951 and P < 0.01). HRP labeling showed a difference between group 2 and end-to-side neurorrhaphy with an epineural window (q = 5.291 and P < 0.01) and without an epineural window (q = 5.617 and P < 0.01). There was also a difference in mean area labeled with FG. Furthermore, the amplitudes of the action potentials were significantly higher in groups 1 and 2.

Conclusions:

There was nerve regeneration in all groups studied. However, the end-to-end neurorrhaphy group had better reinnervation than the end-to-side neurorrhaphy groups.

Contribution of the proximal nerve stump in end-to-side nerve repair: in a rat model

Background

The aim of this study was to evaluate the contribution of the proximal nerve stump, in end-to-side nerve repair, to functional recovery, by modifying the classic end-to-side neurorrhaphy and suturing the proximal nerve stump to a donor nerve in a rat model of a severed median nerve.

Methods

Three experimental groups were studied: a modified end-to-side neurorrhaphy with suturing of the proximal nerve stump (double end-to-side neurorrhaphy, Group I), a classic end-to-side neurorrhaphy (Group II) and a control group without neurorrhaphy (Group III). Twenty weeks after surgery, grasping testing, muscle contractility testing, and histological studies were performed.

Results

The grasping strength, muscle contraction force and nerve fiber count were significantly higher in group I than in group II, and there was no evidence of nerve recovery in group III.

Conclusions

The contribution from the proximal nerve stump in double end-to-side nerve repair might improve axonal sprouting from the donor nerve and help achieve a better functional recovery in an end-to-side coaptation model.

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.

Quantitative Characterization of Regenerating Axons after End-to-Side and End-to-End Coaptation in a Rat Brachial Plexus Model: A Retrograde Tracer Study

The efficacy of end-to-side repair as a method of nerve reconstruction has been questioned, and most studies that characterize the mode of re-innervation are marred by inappropriate experimental design and lack quantitative analysis. This makes characterization of re-innervating neurons confusing and consequently controversy remains as to the extent and source of reinnervating axons. In an experimental brachial plexus rat model, we transected the musculocutaneous nerve, labeled its neuron pool with Fast-Blue and joined the distal stump to the side of the intact ulnar nerve, or to the proximal stump of the divided ulnar nerve, to characterize neurons that reinnervate the recipient nerve. Tetramethyl-rhodamine dextran (TMRD) or fluoro-gold was used to map the reinnervating motor and sensory neurons at 12 weeks post-transection. No neurons originally labeled from musculocutaneous nerve were subsequently labeled with TMRD or fluoro-gold, showing that this original neuron pool does not contribute to re-innervation of the distal musculocutaneous nerve, but that reinnervation occurs solely by ulnar nerve motor and sensory axons. In the end-to-side group, 16.4% of the motor and 7% of the sensory donor ulnar nerve neurons re-innervated the musculocutaneous nerve exclusively, and a further 10% motor and 11.6% sensory innervated the musculocutaneous nerve by collateral sprouting of their axons. This compared to re-innervation by 62.6% of motor and 70.4% of ulnar nerve sensory neurons in the positive control that underwent end-to-end repair. Our results confirm the concept of collateral sprouting and support the use of end-to-side repair.

End-to-side nerve coaptation: a qualitative and quantitative assessment in the primate

There are several reasons why end-to-side nerve coaptation has not been widely adopted clinically. Among these are the putative damage inflicted on the donor nerve and the variable quality of the regeneration in the recipient nerve. So far experiments on end-to-side nerve repair have been short term and mostly carried out on rats. This long-term study of end-to-side nerve repair of ulnar to median and median to ulnar nerve was performed using adult nonhuman primates. Eleven nerve repairs were studied at different time points. Eighteen, 22, 33 and 57 months after surgery a qualitative and quantitative analysis of the donor nerve and regenerating nerve revealed variable levels of percentage axonal regeneration compared with matched controls (1.4%-136%). Morphological evidence of donor nerve damage was identified distal to the coaptation site in four of the 11 cases, and in these cases the best axonal regeneration in the corresponding recipient nerves was observed. This donor nerve damage could neither be demonstrated in terms of a decrease in axon counts distal to the coaptation nor as donor target organ denervation. Recipient target organ regeneration like the axonal regeneration varied, with evidence of motor regeneration in eight out of 11 cases and sensory regeneration, as measured by percentage innervation density compared with matched controls, varied from 12.5% to 49%. Results from the present study demonstrate that the end-to-side coaptation technique in the nonhuman primate does not give predictable results. In general the motor recovery appeared better than the sensory and in those cases where donor nerve damage was observed there was better motor and sensory regeneration overall than in the remaining cases.

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.

Anatomic bases of graciloplasty using end-to-side nerve pudendal anastomosis

The objective of this study was to evaluate the possibilities of reinnervation of the gracilis muscle, transposed around the anus, by the pudendal nerve using an end-to-side nerve anastomosis. This study was carried out in 14 cases (7 adult human cadavers bilaterally). The gracilis muscle and its vascular-nervous bundle have been dissected and the nerve innervating the gracilis muscle has been cut at its origin. The gracilis muscle, accompanied by its nerve, has then been transposed around the anus. The pudendal nerve has been dissected from its extrapelvic part. The reinnervation using an end-to-side nerve anastomosis has been considered as feasible when the proximal ending of the nerve of the gracilis was put into a tension-free contact with the extrapelvic part of the pudendal nerve. The extrapelvic part of the pudendal nerve has a common trunk in 12 cases. The width of the extrapelvic part of the pudendal nerve was 2.6+/-0.7 mm, range 1-3.5. The width of the proximal endings of the nerve innervating the gracilis muscle was 2.3+/-0.5 mm, range 2-3. The reinnervation of the gracilis muscle by the pudendal nerve has been possible in 14 cases. An average supplementary length of 17.4+/-15.4 mm was available (range 5-52). These results suggest an eventual practical aspect of this technique for the reconstruction of a functional sphincter using the gracilis muscle transposed around the anus.

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 neurorrhaphy for defects of palmar sensory digital nerves

Ten traumatic nerve defects at the palm or digit level were treated by end-to-side (ETS) neurorrhaphy. The technique included removal of an epineurial window on the donor nerve and coaptation of the sharply cut distal end of the injured nerve by epineurial stitches under microscopic magnification. At final follow-up, the static two-point discrimination test (2 pd) scored at an average of 9.1 mm (range, 6-12 mm) on the repaired nerve, compared to an average of 4.6 mm (range, 4-6 mm) on the contralateral uninjured control side. Moving 2 pd scored at an average of 7 mm (range, 4-9 mm) on the repaired nerve compared to an average of 2.6 mm (range, 2-4 mm) on the control side. This short series showed that ETS neurorrhaphies are effective and give comparable results with those of nerve grafts or vein conduits.

End-to-side neurorrhaphy

End-to-side neurorrhaphy, a possible strategy for treating nerve lesions without useable proximal nerve stumps, has been experimentally and clinically investigated. In end-to-side neurorrhaphy, three main elements should be considered: 1) the induction of axonal collateral sprouting in the donor nerve; 2) the ability of the collateral axons to pierce the different conjunctival layers, including the ability the donor nerve basal laminae, to reinnervate the recipient nerve; and 3) the functional plasticity and behavioral readjustment of single motoneurons that have eventually adopted new motor units. This article reviews the following areas of research and clinical investigation: animal models, axonal collateral sprouting from end-to-side neurorrhaphy, effect of epineurotomy and perineurotomy on axon regeneration, motor reinnervation, and clinical trials.

Hemihypoglossal nerve transfer in brachial plexus repair: technique and results

OBJECTIVE

In multiple avulsions of the brachial plexus, the search for extraplexal donor nerves in the hope of achieving motor neurotization is a major goal. We explored the possibility of using the hypoglossal nerve as a transfer point to reanimate muscles in the upper limb.

METHODS

The hypoglossal nerve was used as a donor nerve for neurotization in seven patients with avulsive injuries of the brachial plexus. The surgical technique--an end-to-side microsuture using approximately half of the nerve fascicles--is basically the same as that used in the hypoglossal nerve-facial nerve jump graft, which is a well-known technique in facial nerve reanimation. The recipient nerves were the suprascapular (two patients), the musculocutaneous (one patient), the posterior division of the upper trunk (two patients), and the medial contribution to the median nerve (two patients).

RESULTS

In spite of a connection documented by electromyography and selective activation in three of seven patients, the functional results in our patients were extremely disappointing: no patient had an outcome better than M1 in the reinnervated muscles.

CONCLUSION

This technique was of no help to the patients and thus has been abandoned at our institution.

Physiologic and morphologic aspects of nerve regeneration after end-to-end or end-to-side coaptation in a rat model of brachial plexus injury

The results of repairing a transected rat musculocutaneous nerve by suturing the distal stump, end to side or end to end, to the ipsilateral ulnar nerve were assessed at 3 months by retrograde labeling and morphologic and physiologic analysis. Unlike most other models of end-to-side repair in which the injured recipient and donor reinnervating nerves have overlapping neuron pools in the spinal cord, in this model the neurons of the injured musculocutaneous and the reinnervating ulnar nerves are located in mutually exclusive segments of the spinal cord. Using retrograde labeling we show that the reinnervating fibers are derived solely from the ulnar nerve pool. Both end-to-side and end-to-end coaptation resulted in reinnervation of the distal musculocutaneous nerve and significant functional reinnervation of its dependent biceps brachii muscle. Although end-to-end coaptation resulted in better axon morphology and muscle function, it resulted in total loss of donor nerve function. By contrast, end-to-side coaptation resulted in good recovery with only minimal donor nerve deficit. These results show that significant functional reinnervation of biceps brachii muscle can occur solely on the basis of collateral sprouting of intact axons from the adjacent ulnar nerve.

[Terminal-lateral nerve anastomoses. Preliminary clinical report of two cases]

Nerve regeneration is based on three phenomenons of critical importance: neurotropism, nerve guidance and neurotrophis. These principles allow understanding the mechanisms of nerve suture and grafting, but also the newly described end-to-side nerve anastomoses. In this procedure, the distal stump of a severed nerve is anastomosed on the lateral side of an intact nerve, with or without removal of the perineurium. Authors report their beginning experience with this procedure (ten cases) and discuss the early results. End-to-side anastomosis seems to be a useful and reliable technique for clinical nerve repair. Even if nerve grafting remains the gold standard to bridge nerve defects, one has nothing to loose if a few minutes, anastomosing the severed nerve on the lateral side of an intact nerve, rather than doing nothing.

Functional and morphometric evaluation of end-to-side neurorrhaphy for muscle reinnervation

This study was undertaken to quantify the effect of motor collateral sprouting in an end-to-side repair model allowing end organ contact. Besides documentation of the functional outcome of muscle reinnervation by end-to-side neurorrhaphy, this experimental work was performed to determine possible downgrading effects to the donor nerve at end organ level. In 24 female New Zealand White rabbits, the motor nerve branch to the rectus femoris muscle of the right hindlimb was dissected, cut, and sutured end-to-side to the motor branch to the vastus medialis muscle after creating an epineural window. The 24 rabbits were divided into two groups of 12 each, with the second group receiving additional crush injury of the vastus branch. After a period of 8 months, maximum tetanic tension in the reinnervated rectus femoris and the vastus medialis muscles was determined. The contralateral healthy side served as control. The reinnervated rectus femoris muscle showed an average maximum tetanic force of 24.9 N (control 26.2 N, p = 0.7827), and the donor- vastus medialis muscle 11.0 N (control 7.3 N, p = 0.0223). There were no statistically significant differences between the two experimental groups (p = 0.9914). The average number of regenerated myelinated nerve fibers in the rectus femoris motor branch was 1,185 +/- 342 (control, 806 +/- 166), and the mean diameter was 4.6 +/- 0.6 microm (control, 9.4 +/- 1.0 microm). In the motor branch to the vastus medialis muscle, the mean fiber number proximal to the coaptation site was 1227 (+/-441), and decreased distal to the coaptation site to 795 (+/-270). The average difference of axon counts in the donor nerve proximal to distal regarding the repair site was 483.7 +/- 264.2. In the contralateral motor branch to the vastus medialis muscle, 540 (+/- 175) myelinated nerve fibers were counted. In nearly all cross-section specimens of the motor branch to the vastus medialis muscle, altered nerve fibers could be identified in one fascicle distal and proximal to the repair site. The results show a relevant functional reinnervation by end-to-side neurorrhaphy without functional impairment of the donor muscle. It seems to be evident that most axons in the attached segment were derived from collateral sprouts. Nonetheless, the present study confirms that end-to-side neurorrhaphy is a reliable method of reconstruction for damaged nerves, which should be applied clinically in a more extended manner.

End-to-side pudendal nerve anastomosis for the creation of a new reinforcing anal sphincter in dogs

BACKGROUND

An ideal reinforcing neo-sphincter should be innervated by the pudendal nerve to work in coordination with the external anal sphincter. The aim of this study was to create a skeletal muscle innervated by the pudendal nerve without inducing external anal sphincter morbidity.

METHODS

Seven dogs were used. On the right side of each dog, the distal end of the transected nerve innervating the biceps femoris muscle was anastomosed to the perineural window of the pudendal nerve, where the epineurium was excised over a small area without injuring the funiculus. Reinnervation was studied 5 months after the operations. The left side of the dogs was used as a control.

RESULTS

For all 7 dogs, there was no macroscopic difference detected in the external anal sphincter. For 6 dogs, the biceps femoris muscle was preserved after end-to-side pudendal nerve anastomosis. After the pudendal nerve central to the anastomosis site was electrically stimulated, the external anal sphincter contracted in all dogs. After end-to-side pudendal nerve anastomosis, the biceps femoris muscle contracted with the evoked potential in 5 dogs (71%) and demonstrated electric activity at rest in 3 dogs (43%), but there was no reflex activity after anal stimulation. The ratio of type 1 to type 2 muscle fiber in the biceps femoris muscle after end-to-side pudendal nerve anastomosis significantly changed and became the same as that in the external anal sphincter. The diameter of type 2 muscle fibers in the biceps femoris muscle significantly decreased after surgery. In addition, regenerated myelinated axons were observed in a cross section of the anastomosed nerve in 6 dogs.

CONCLUSIONS

End-to-side pudendal nerve anastomosis is a promising technique for the creation of an anal sphincter in patients who have fecal incontinence. The technique preserved the original external anal sphincter and created a skeletal muscle that was innervated by the pudendal nerve in 71% of the dogs studied. This newly innervated skeletal muscle was capable of contracting in coordination with the original external anal sphincter on electric stimulation and also demonstrated characteristics closely similar to those of the external anal sphincter.