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

Does supercharging with cross-face nerve graft enhance smile in non-flaccid facial paralysis patients undergoing selective neurectomy?

BACKGROUND

Cross face nerve grafting (CFNG) is a well-established nerve transfer technique in facial reanimation; however, no study has assessed outcome of supercharging the smile with CFNG in patients with synkinesis. The goal of this study was to examine the smile outcome in non-flaccid facial paralysis (NFFP) patients after supercharging with CFNG during selective neurectomy.

METHODS

NFFP patients who underwent CFNG with end-to-side coaptation to a smile branch on the paralyzed side during selective neurectomy were retrospectively identified and their charts were reviewed. Pre-operative and post-operative facial function was assessed with the electronic clinician-graded facial function tool (eFACE), and an automated computer-aided facial assessment tool (Emotrics). Smile metrics were compared pre-operatively, in early post-operative time (EPO, <6 months), and late post-operative time (LPO, >9 months) when CFNG contribution would be expected.

RESULTS

Thirteen cases were performed between June 2019 and December 2021. No objective smile metrics improved following supercharging with CFNG. Oral commissure excursion improved by 1.23 points in eFACE (p = .812), and by 0.84 in Emotrtics (p = .187) from EPO to LPO. EFACE dynamic score was improved by 0.08 points from EPO to LPO (p = .969).

CONCLUSIONS

Using CFNG for supercharging the smile during selective neurectomy in NFFP patients may not enhance smile. Longer term results following supercharging and long term natural history of selective neurectomy should be assessed.

Improved Neurotization in High Peripheral Nerve Injury: Side to Side H-shaped Nerve Graft at the Most Distal Part of an Injured Extremity in a Rabbit Model

Background

We aimed to investigate the effects of nerve repair by setting a side-to-side (H-shaped) nerve graft on the most distal part of the damaged nerve to the adjacent intact nerve to accelerate its regeneration in the end organ.

Methods

This pure experimental study was done on the lower extremities of two groups of rabbits in Animal Laboratory Department, 15 Khordad Hospital Tehran, Iran. In both groups, the sciatic nerve at the proximal part of the extremity below the superficial femoral branch was first cut and then repaired. In the investigation group, side-to-side H-shaped nerve grafts were applied between the sciatic and superficial femoral nerves (i.e., two branches) at the most distal to the cut site of the sciatic nerve below the superficial femoral branch at the lower extremity. The sciatic nerve was conventionally repaired in the control group.

Results

None of the rabbits' feet in the control group respond to pain stimulation (were without senses) and had ulcers. They had numb legs and went lame. All had muscular atrophy and lacked nerve growth (regeneration) according to pathology. In the investigation group, 86.7% of the rabbits responded to pain stimulation and only 13.3% of them had ulcers. In addition, in pathology report, 13.3% had suffered muscular atrophy and lacked nerve regeneration. Therefore, nerve regeneration was successful in 86.7% of rabbits who underwent H-shaped nerve grafts.

Conclusion

Side-to-side H-shaped nerve graft at the most distal part of an injured nerve may cause successful recovery of high (proximal) nerve injury.

Nerve Injury and Peripheral Nerve Functional Loss From Injection and Suture Needles: An Experimental Study on Rats

BACKGROUND

During invasive procedures involving needles, there is a chance of damage to peripheral nerves. Therefore, a method for experimentally simulating these situations is needed.

OBJECTIVES

In this study we aimed to evaluate peripheral nerve lesions caused by the entry and exit of an injection needle, nerve transfixion through a suture stitch, and the injection of saline solution and lidocaine into the nerve.

METHODS

After obtaining approval from the Animal Ethics Committee, we randomly divided 36 Wistar rats, weighing approximately 250 g each, into 6 groups (control, sham, suture, needle, saline, and lidocaine groups), with 6 animals in each group. All procedures were performed on the left paws of the rats. After the procedure, walking track analysis was performed to assess the walking function of rats for 8 weeks. Four months after the procedures, we performed bilateral electrophysiological studies (measuring the latency and amplitude of the electrical impulse in the peroneal nerve). Subsequently, the rats were euthanized, and bilateral tissue samples were collected from the peroneal nerve and tibialis cranialis muscle for morphometric histological analysis.

RESULTS

In the walking track analysis, all groups showed normalization of walking functionality after 13 days. There was little histological change between the groups, and no functional loss related to the procedures was observed.

CONCLUSIONS

Procedures involving the infusion of local anesthetic or saline solution, or suture needles, are safe with regard to peripheral nerve function loss. Accidents tend not to cause nerve impairment.

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

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

Morphofunctional Improvement of the Facial Nerve and Muscles with Repair Using Heterologous Fibrin Biopolymer and Photobiomodulation

Peripheral nerve injuries impair the patient's functional capacity, including those occurring in the facial nerve, which require effective medical treatment. Thus, we investigated the use of heterologous fibrin biopolymer (HFB) in the repair of the buccal branch of the facial nerve (BBFN) associated with photobiomodulation (PBM), using a low-level laser (LLLT), analyzing the effects on axons, muscles facials, and functional recovery. This experimental study used twenty-one rats randomly divided into three groups of seven animals, using the BBFN bilaterally (the left nerve was used for LLLT): Control group-normal and laser (CGn and CGl); Denervated group-normal and laser (DGn and DGl); Experimental Repair Group-normal and laser (ERGn and ERGl). The photobiomodulation protocol began in the immediate postoperative period and continued for 5 weeks with a weekly application. After 6 weeks of the experiment, the BBFN and the perioral muscles were collected. A significant difference (p < 0.05) was observed in nerve fiber diameter (7.10 ± 0.25 µm and 8.00 ± 0.36 µm, respectively) and axon diameter (3.31 ± 0.19 µm and 4.07 ± 0.27 µm, respectively) between ERGn and ERGl. In the area of muscle fibers, ERGl was similar to GC. In the functional analysis, the ERGn and the ERGI (4.38 ± 0.10) and the ERGI (4.56 ± 0.11) showed parameters of normality. We show that HFB and PBM had positive effects on the morphological and functional stimulation of the buccal branch of the facial nerve, being an alternative and favorable for the regeneration of severe injuries.

Corneal neurotization for neurotrophic keratopathy: Review of surgical techniques and outcomes

Neurotrophic keratopathy is a degenerative disease in which damage to the corneal nerves leads to corneal hypoesthesia. Injuries to neurotrophic corneas are notoriously difficult to treat and have traditionally been approached with supportive management. However, recent progress in the field of corneal neurotization has given new direction for addressing nerve loss directly by stimulating new nerve growth onto the cornea from nearby sensory nerves transferred to the perilimbal region. Herein, we review the surgical techniques utilized in corneal neurotization, including direct transfers and the use of nerve grafts. Considerations in surgical approach, as well as factors that influence prognosis and outcomes of the surgical intervention are also discussed.

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.

Prevention of denervated muscle atrophy with accelerated nerve-regeneration by babysitter procedure in rat facial nerve paralysis model

PURPOSE

The "babysitter" procedure is a reconstruction technique for facial nerve complete paralysis and uses the movement source from the healthy facial nerve with a cross-nerve graft. First, an end-to-side neurorrhaphy is performed between the affected facial nerve trunk and hypoglossal nerve for continuously delivering stimuli to the mimetic muscles for preventing the atrophy of mimetic muscles. Despite favorable clinical results, histological and physiological mechanisms remain unknown. This study attempted to establish a model for the "babysitter" procedure and find its efficacy in rats with facial nerve complete paralysis.

MATERIALS AND METHODS

A total of 16 Lewis rats were used and divided into 2 groups; cross nerve graft (n = 8) and babysitter groups (n = 8). The facial nerve trunk was transected in both groups. Babysitter group underwent a two-stage procedure. Cross nerve graft group underwent only the transfer of nerve graft from the healthy side to affected side. The animals were assessed physiologically by compound muscle action potential (CMAP), and the regenerated nerve tissues were evaluated histopathologically at 13 weeks after surgery.

RESULTS

Facial nucleus stained with retrograde tracers proved the re-innervation of affected facial muscle by the babysitter procedure. In CMAP, the amplitude of babysitter group was significantly higher than that of the cross-facial nerve graft group (p < .05). Histological examination found a significant difference in myelin g-ratio between two groups (p < .05).

CONCLUSION

This study investigated the "babysitter" procedure for rat facial nerve palsy. Babysitter procedure shortened the denervation period without mimic muscle atrophy.

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).

Does the type of electrode affect the electromyoneurographic parameters in rats?1

Purpose

To evaluate if the type of electrode (needle vs. surface) affects the electromyoneurography parameters in rats.

Methods

Twenty male rats were anesthetized, then compound muscle action potential were recorded using a Neuropack S1 MEB- 9400^©. All animals were submitted to two electroneuromyography analysis: first with surface electrode and then by needle electrode. We evaluated the latency, amplitude, duration and area of the negative peak of the gastrocnemius and cranial tibial muscles.

Results

There were no significant differences between the groups in the mean of duration, latency, amplitude or area of the negative peak in gastrocnemius and cranial tibial muscles.

Conclusion

The type of electrode does not affect the electroneuromyography parameters.