End-to-end versus end-to-side motor and sensory neurorrhaphy in the repair of the acute muscle denervation

The temporal and spatial effects of reconstructive surgery on the atrophy of hindlimb muscles in anterior cruciate ligament transected rats

After anterior cruciate ligament (ACL) injury, a decrease in muscle strength associated with muscle atrophy is frequently observed. The temporal and spatial effects of reconstructive surgery on muscle atrophy have not been examined in detail. This study aimed to 1) reveal the short and mid-term effects of reconstructive surgery on muscle atrophy, and 2) investigate the differences in the degree of atrophy after ACL reconstruction in the hindlimb muscles. ACL transection with or without reconstructive surgery was performed unilaterally on the knees of rats. Untreated rats were used as controls. At one or four weeks post-surgery, the relative muscle wet weights (wet weight/body weight) of the hindlimb muscles were calculated to assess atrophy. At one week post-surgery, muscle atrophy was induced by ACL transection and further aggravated by reconstructive surgery. Reconstructive surgery facilitated recovery from muscle atrophy in some muscles compared with those without reconstructive surgery (ACL transection alone) at four weeks post-surgery. Muscle atrophy after ACL reconstruction was greater in the rectus femoris and plantar flexors than in the semitendinosus and plantar extensors at one week post-surgery. These results indicate that reconstructive surgery exacerbates muscle atrophy in the first week post-surgery, while facilitating recovery between the first and fourth week post-surgery. After reconstructive surgery, muscle atrophy was observed not only in the quadriceps and hamstrings, but also in the lower leg muscles, suggesting the need for muscle strengthening interventions for the lower leg muscles as well as the quadriceps and hamstrings.

Peroneal Nerve Repair with Cross-Bridge Ladder Technique: Parallel End-to-Side Neurorrhaphies

Background  Multiple nerve transfer techniques are used to treat patients with nerve injuries when a primary repair is not possible. These techniques are categorized to end-to-end, end-to-side, and side-to-side neurorrhaphy. Our study aims to explore the utility of the cross-bridge ladder technique (H-shaped), which has shown promising results in animal models and probably underutilized clinically. Methods  Four patients with significant loss of ankle dorsiflexion were seen in the clinic and underwent evaluation, including electrodiagnostic studies. A cross-bridge ladder repair technique was used between the tibial nerve as the donor and the common peroneal nerve as the recipient via one or two nerve grafts coapted in parallel with end-to-side neurorrhaphies. Dorsiflexion strength was measured preoperatively using the Medical Research Council (MRC) grading system and at each postoperative follow-up appointment. Results  All four patients had suffered persistent and severe foot drop (MRC of 0) following trauma that had occurred between 6 and 15 months preoperatively. Three of the four patients improved to an MRC of 2 several months postoperatively. The last patient had an immediate improvement to an MRC of 2 by his first month and had a complete recovery of ankle dorsiflexion within 4 months from surgery. Conclusion  We demonstrate the utility and clinical outcomes of the cross-bridge ladder technique in patients with persistent and prolonged foot drop following trauma. Both early and late recovery were seen while all patients regained motor function, with some patients continuing to improve up to the most recent follow-up. IRB Approval: Obtained 2013-1411-CP005.

Sensory nerve regeneration and reinnervation in muscle following peripheral nerve injury

Sensory afferent fibers are an important component of motor nerves and compose the majority of axons in many nerves traditionally thought of as "pure" motor nerves. These sensory afferent fibers innervate special sensory end organs in muscle, including muscle spindles that respond to changes in muscle length and Golgi tendons that detect muscle tension. Both play a major role in proprioception, sensorimotor extremity control feedback, and force regulation. After peripheral nerve injury, there is histological and electrophysiological evidence that sensory afferents can reinnervate muscle, including muscle that was not the nerve's original target. Reinnervation can occur after different nerve injury and muscle models, including muscle graft, crush, and transection injuries, and occurs in a nonspecific manner, allowing for cross-innervation to occur. Evidence of cross-innervation includes the following: muscle spindle and Golgi tendon afferent-receptor mismatch, vagal sensory fiber reinnervation of muscle, and cutaneous afferent reinnervation of muscle spindle or Golgi tendons. There are several notable clinical applications of sensory reinnervation and cross-reinnervation of muscle, including restoration of optimal motor control after peripheral nerve repair, flap sensation, sensory protection of denervated muscle, neuroma treatment and prevention, and facilitation of prosthetic sensorimotor control. This review focuses on sensory nerve regeneration and reinnervation in muscle, and the clinical applications of this phenomena. Understanding the physiology and limitations of sensory nerve regeneration and reinnervation in muscle may ultimately facilitate improvement of its clinical applications.

Ulnar nerve decompression and transposition with versus without supercharged end-to-side motor nerve transfer for advanced cubital tunnel syndrome: a randomized comparison study

OBJECTIVE

The objective of this prospective randomized study was to compare ulnar nerve decompression and anterior subfascial transposition with versus without supercharged end-to-side anterior interosseous nerve-to-ulnar motor nerve transfer for advanced cubital tunnel syndrome, to describe performing the nerve transfer through a small incision, and to investigate predictive factors for poor recovery following the procedure.

METHODS

Between January 2013 and October 2016, 93 patients were randomly allocated to a study group (n = 45) and a control group (n = 48). Patients in the study group were treated with supercharged motor nerve transfer via a 5-cm incision following decompression and anterior subfascial transposition. Patients in the control group were treated with decompression and anterior subfascial transposition alone. Postoperative pinch strength and compound muscle action potential amplitude (CMAPa) were assessed. Function of the limb was assessed based on the Gabel/Amadio scale. Between-group data were compared, and significance was set at p < 0.05. Potential risk factors were collected from demographic data and disease severity indicators.

RESULTS

At the final follow-up at 2 years, the results of the study group were superior to those of the control group with regard to postoperative pinch strength (75.13% ± 7.65% vs 62.11% ± 6.97%, p < 0.05); CMAPa of the first dorsal interossei (17.17 ± 5.84 mV vs 12.20 ± 4.09 mV, p < 0.01); CMAPa of abductor digiti minimi (11.57 ± 4.04 mV vs 8.43 ± 6.11 mV, p < 0.01); and excellent to good results (0.67 for the study group vs 0.35 for the control group, p < 0.05). Multivariate analysis showed that the advanced age (OR 2.98, 95% CI 2.25-4.10; p = 0.003) in the study group was related to unsatisfactory outcome in the patients.

CONCLUSIONS

In the treatment of advanced cubital tunnel syndrome, additional supercharged end-to-side anterior interosseous nerve-to-ulnar motor nerve transfer may produce a better function of the hand. The authors also found that cases in the elderly were related to unsatisfactory postoperative results for these patients and that they could be informed of the possibility of worsening surgery results.

Ulnar Nerve Injuries (Sunderland Grade V): A Simplified Classification System and Treatment Algorithm

This study introduced a novel technical approach to the ulnar nerve injuries. The ulnar nerve was divided into 4 distinct surgical zones, each mandating a unique management strategy.

Methods

A prospective observational study was conducted to verify the hypothesized algorithm. The study included 110 patients diagnosed with ulnar nerve injury (Sunderland grade 5). We divided the patients into 4 groups depending on the site of injury. Each group of patients was managed in accordance with a particular strategy, exploiting nerve transfer techniques along with the updated knowledge of the internal topography of the ulnar nerve. The motor recovery of the small muscles of the hand was assessed after 2 years of follow-up, using the disabilities of the arm, shoulder, and hand score, and other parameters including key pinch strength, hand grip strength, and the motor power of the first dorsal interosseous muscle on the Medical Research Council scale.

Results

The mean values of the disabilities of the arm, shoulder, and hand score, key pinch strength, and hand grip strength showed a statistically significant improvement across all patient groups (P < 0.05). Of those with zone (I) injury, postoperatively, 79.9% patients attained a first dorsal interosseous muscle power grade >3 on the Medical Research Council scale, while 93.9% of patients with zone (II) damage achieved the same result. Surprisingly, 84% of patients included in both zones (III) and (IV) also recovered to the same extent.

Conclusions

This prospective observational study examined and successfully confirmed the validity of our proposed novel algorithm for the management of ulnar nerve injuries (Sunderland grade 5).

End-to-side versus end-to-end neurorrhaphy at the peroneal nerve in rats

PURPOSE

To evaluate three different kinds of neurorrhaphy of the peroneal nerve.

METHODS

Eigthy rats were divided into 5 groups. Control: nerve had no intervention. End-to-end (EE): nerve was cut and elongated with a nerve graft with two end-to-end neurorrhaphies. End-to-side (ES): nerve was cut and sutured to the graft with at the lateral side of the nerve. Side-to-end (SE): the nerve was cut and sutured to the graft with end-to-end neurorrhaphy. Denervated: nerve was cut and both endings were buried into the muscle. The evaluation was done by walking track analysis, electrophysiology, body mass, cranial tibial muscle mass, nerve and muscle fibers morphometry.

RESULTS

The EE, ES and SE have the same potential of reinnervation.

CONCLUSION

There is no functional or histological difference between these different types of neurorrhaphy.

Morphological differences in skeletal muscle atrophy of rats with motor nerve and/or sensory nerve injury

Skeletal muscle atrophy occurs after denervation. The present study dissected the rat left ventral root and dorsal root at L_4-6 or the sciatic nerve to establish a model of simple motor nerve injury, sensory nerve injury or mixed nerve injury. Results showed that with prolonged denervation time, rats with simple motor nerve injury, sensory nerve injury or mixed nerve injury exhibited abnormal behavior, reduced wet weight of the left gastrocnemius muscle, decreased diameter and cross-sectional area and altered ultrastructure of muscle cells, as well as decreased cross-sectional area and increased gray scale of the gastrocnemius muscle motor end plate. Moreover, at the same time point, the pathological changes were most severe in mixed nerve injury, followed by simple motor nerve injury, and the changes in simple sensory nerve injury were the mildest. These findings indicate that normal skeletal muscle morphology is maintained by intact innervation. Motor nerve injury resulted in larger damage to skeletal muscle and more severe atrophy than sensory nerve injury. Thus, reconstruction of motor nerves should be considered first in the clinical treatment of skeletal muscle atrophy caused by denervation.

A gastrocnemius heterotopical transplant model with end-to-side neurorraphy

PURPOSE

To present an animal model to assess the effects of end-to-side innervation in the heterotopically transplanted model with reduced chances of neural contamination.

METHODS

The medial portion of the gastrocnemius muscle in wistar male rats was isolated and its pedicle dissected and performed a flap in the abdominal portion. To prevent neural contamination in the abdominal region, the muscle was wrapped with a Goretex(r) sheet. The specimens were divided into 2 groups (G). In G1 was performed an end-to-end suture between tibial nerve of the gastrocnemius and femoral motor nerve and between the saphenous sensory nerve and the motor nerve. In G2 was performed a end-to-side suture between the tibial nerve and the motor femoral and between the tibial nerve and saphenous motor nerve. The specimens were evaluated 60 days later to check the structure of the neurorraphy. Sections were obtained proximal and distal to the coaptation site.

RESULTS

The medial gastrocnemius muscle had the advantage of maintaining visible mass after 60 days. No disruption of the coaptation site was found. No major injury to the donor nerve was seen in group 2.

CONCLUSION

The proposed model is simple, reproduciple and prevent the neural contamination in the flap in end-to-side suture.

Muscle reinnervation in one or two stages?: experimental study in rats with end-to-side nerve graft

PURPOSE: To compare muscle reinnervation in one and two surgical stages using end-to-side neurorrhaphy (ESN) without donor nerve injury. METHODS: The experiment was performed on four groups of 20 rats. Group 1 (G1), one stage, received the graft which was sutured to the tibial nerve, with ESN, and its free stump was sutured end-to-end to the distal stump of the sectioned peroneal nerve (PN), all in the same operation. In Group 2 (G2), two stages, the nerve graft was sutured to the tibial nerve, with ESN. Two months later the PN was sectioned and its distal stump connected to the distal stump of the graft as in G1. Normal control group (Gn) received the graft only sutured to the tibial nerve, with ESN. Denervated control group (Gd), as well received the graft and had the PN sectioned and its two stumps buried in adjacent musculature, with the aim of denervating the cranial tibial muscle (CTM), the target of this study. The parameters used to evaluate CTM reinnervation were muscle mass, muscle fiber's minimum diameter and area. RESULTS: The mean CTM mass, the average of the muscular fibers areas and the average of the muscular fiber minimum diameters was higher (all p<0.0001) in G2 than in G1. Comparing the four groups, these parameters had their maximum expression in Gn and the minimum in Gd, as expected. CONCLUSION: The two stages showed better muscle reinnervation than one stage.

Recent advances and developments in neural repair and regeneration for hand surgery

End-to-end suture of nerves and autologous nerve grafts are the 'gold standard' for repair and reconstruction of peripheral nerves. However, techniques such as sutureless nerve repair with tissue glues, end-to-side nerve repair and allografts exist as alternatives. Biological and synthetic nerve conduits have had some success in early clinical studies on reconstruction of nerve defects in the hand. The effectiveness of nerve regeneration could potentially be increased by using these nerve conduits as scaffolds for delivery of Schwann cells, stem cells, neurotrophic and neurotropic factors or extracellular matrix proteins. There has been extensive in vitro and in vivo research conducted on these techniques. The clinical applicability and efficacy of these techniques needs to be investigated fully.