Heterologous fibrin biopolymer as an emerging approach to peripheral nerve repair: a scoping review

Nerve injuries present a substantial challenge within the medical domain due to their prevalent occurrence and significant impact. In nerve injuries, a range of physiopathological and metabolic responses come into play to stabilize and repair the resulting damage. A critical concern arises from the disruption of connections at neuromuscular junctions, leading to profound degeneration and substantial loss of muscle function, thereby hampering motor tasks. While end-to-end neurorrhaphy serves as the established technique for treating peripheral nerve injuries, achieving comprehensive morphofunctional recovery remains a formidable challenge. In pursuit of enhancing the repair process, alternative and supportive methods are being explored. A promising candidate is the utilization of heterologous fibrin biopolymer, a sealant devoid of human blood components. Notably, this biopolymer has showcased its prowess in establishing a stable and protective microenvironment at the site of use in multiple scenarios of regenerative medicine. Hence, this scoping review is directed towards assessing the effects of associating heterologous fibrin biopolymer with neurorrhaphy to treat nerve injuries, drawing upon findings from prior studies disseminated through PubMed/MEDLINE, Scopus, and Web of Science databases. Further discourse delves into the intricacies of the biology of neuromuscular junctions, nerve injury pathophysiology, and the broader utilization of fibrin sealants in conjunction with sutures for nerve reconstruction procedures. The association of the heterologous fibrin biopolymer with neurorrhaphy emerges as a potential avenue for surmounting the limitations associated with traditional sealants while also mitigating degeneration in nerves, muscles, and NMJs post-injury, thereby fostering a more conducive environment for subsequent regeneration. Indeed, queries arise regarding the long-term regenerative potential of this approach and its applicability in reconstructive surgeries for human nerve injuries.

Advances of Direct Peripheral Nerve Repair Techniques: Do We Already Have Enough Scientific Evidence?

Purpose

To systematically review the evidence of direct peripheral nerve repair techniques and to determine any differences in outcomes that would guide rational treatment. Additionally, we compare the results and outcomes of these studies and find future directions for peripheral nerve repair techniques.

Methods

We searched PubMed, Virtual Health Library, and Embase databases to identify articles involving direct peripheral nerve techniques. We analyzed and compared the results and outcomes of these techniques. We also aimed to look for the differences in outcomes that would guide the current and future treatments.

Results

We identified 1390 articles, and 19 met our criteria with evidence ranging from level I to level IV. The nerve repair techniques included direct repair, epineural repair, fascicular repair, and group fascicular repair. These nerve techniques are based on the surgeons' personal experience. The results and the outcome of these studies were based on prognostic factors and not on surgical techniques. Few studies compared the surgical techniques and found no significant difference in nerve repair techniques.

Conclusions

Analyzing all direct peripheral nerve techniques and literature of all levels of evidence, our data show no significant difference between different suturing techniques. Currently, there is a lack of scientific evidence on the best direct peripheral nerve repair techniques. Therefore, we need more research to understand the rational treatment methods for peripheral nerve injuries.

Level of evidence

IV.

The efficacy of wrapping the neurorrhaphy site utilizing dura substitute: A case series

BACKGROUND

Different procedures have been developed to improve the surgical outcome of peripheral nerve injuries. The purpose of this study was to evaluate the efficacy of wrapping the neurorrhaphy site utilizing dura substitute graft as an alternative conduit in the management of peripheral nerve injury.

METHODS

This retrospective clinical case series included 42 patients with a single peripheral nerve injury. The mean age was 26.8 ± 11 years, and the mean duration of symptoms was 3 ± 1.8 months. The visual analogue score (VAS) for pain and the Medical Research Council's (MRC) grading for motor power were used to evaluate the functional outcome among our patients. All patients were operated on for primary microscopic end-to-end repair, followed by wrapping the neurorrhaphy site with dura substitute graft as a conduit. Patients were followed in the outpatient clinic with regular visits for average of 6 months.

RESULTS

Thirty-seven patients (83%), showed functional improvement in all aspects, the VAS for pain and the MRC for motor power, as well as the functional state. One patient (2.3%) developed a postoperative hematoma collection, which needed immediate evacuation. Superficial wound infection, reported in two patients (4.7%), was treated conservatively. No postoperative neuroma was observed among our patients during the follow-up period.

CONCLUSION

Wrapping the neurorrhaphy site utilizing dura substitute as conduit appears to be safe and might prove effective in managing peripheral nerve injury.

The Neurotrophic Effects and Mechanism of Action for FK1706 in Neurorrhaphy Rat Models and SH-SY5Y Cells

FK1706 is a novel non-immunosuppressive immunophilin ligand with neurotrophic activity and exerts its neurotrophic effect through NGF. The present study aimed to elaborate on the neurotrophic activity and the mechanism of action of FK1706 in end-to-side neurorrhaphy rats and SH-SY5Y cells. In the regenerating nerves of neurorrhaphy rats, FK1706 increased the thickness of myelin sheath and the level of nerve regeneration-related proteins. The mechanism of action of FK1706 on neurite regrowth was elucidated in vitro by incubating SH-SY5Y cells in different conditions (Control, NGF, FK1706, NGF + FK1706, NGF + FK1706 + geldanamycin). Under the conditions where NGF was used, the phosphorylation level of major proteins (Raf-1 and ERK) in the Ras/Raf/MAPK/ERK signaling pathway related to SH-SY5Y cell proliferation was significantly enhanced following the application of FK1706. The number of viable cells, cell viability and neurite length of SH-SY5Y cells was maximal when NGF and FK1706 were used simultaneously. The binding level of HSP90 and Raf-1 in FK1706 group was the highest. These results indicated that FK1706 could significantly promote nerve regeneration after neurorrhaphy. The putative mechanism of action stated that FK1706 could promote the binding of HSP90 and Raf-1, make Raf-1 continue to be activated, thereby affecting key proteins in the Ras/Raf/MAPK/ERK signaling pathway related to the neurotrophic effects of NGF to promote the proliferation and neurite regrowth of nerve cells.

Effect of Nimodipine and Botulinum Toxin A on Peripheral Nerve Regeneration in Rats: A Pilot Study

BACKGROUND

Peripheral nerve damage is a frequent problem, with an estimated 2.8%-5.0% of trauma admissions involving peripheral nerve injury. End-to-end, tension-free microsurgical repair (neurorrhaphy) is the current gold standard treatment for complete transection (neurotmesis). While neurorrhaphy reapproximates the nerve, it does not address the complex molecular regenerative process. Evidence suggests that botulinum toxin A (BTX) and nimodipine (NDP) may improve functional recovery, but mechanisms of action remain unknown.

METHODS

This research investigates BTX and NDP for their novel capacity to improve neural regeneration in the setting of neurorrhaphy using a Lewis rat tibial nerve neurotmesis model. In a triple-masked, placebo-controlled, randomized study design, we compared functional (rotarod, horizontal ladder walk), electrophysiological (conduction velocity, duration), and stereological (axon count, density) outcomes of rats treated with: NDP+saline injection, BTX+NDP, Saline+placebo, and BTX+placebo. Additional controls included sham surgery +/- BTX.

RESULTS

NDP+saline outperformed other treatment groups in the ladder walk. This group had the fewest deep slips (15.07% versus 30.77% in BTX+NDP, P = 0.122), and the most correct steps (70.53% versus 55.58% in BTX+NDP, P = 0.149) in functional testing. NDP+saline also had the fastest nerve conduction velocity (0.811m/s versus 0.598m/s in BTX+NDP, P = 0.126) among treatment groups. BTX+NDP had the highest axon count (10,012.36 versus 7,738.18 in NDP+Saline, P = 0.009).

CONCLUSION

This study is the first to test NDP with BTX in a multimodal assessment of nerve recovery following neurotmesis and neurorrhaphy. NDP outperformed BTX+NDP functionally. Future work will focus on nimodipine in an effort to improve nerve recovery in trauma patients.

Is Decorin a Promising New Agent for Facial Nerve Regeneration? An Experimental Study

OBJECTIVE

The aim of this study was to investigate the effects of systemic administration of decorin (DC) on facial nerve (FN) regeneration.

METHODS

A total of 32 female albino Wistar rats were divided into 4 groups: control (C) group: no bilateral FN neurorrhaphy (B-FNN), no DC application, sham-operated group: B-FNN without DC application, DC group: DC application without B-FNN, and B-FNN + DC group: B-FNN and DC application. Nerve conduction studies were performed before and after skin incisions at 1st, 3rd, 5th, and 7th weeks in all groups. The amplitude and latency of compound muscle action potentials were recorded. FN samples were obtained and were investigated under light microscopy and immunohistochemical staining. The nerve and axon diameter, number of axons, H score, Schwann cell proliferation, and myelin and axonal degeneration were recorded quantitatively.

RESULTS

In the sham group, the 3rd and 5th postoperative week, amplitude values were significantly lower than those of the B-FNN + DC group (p < 0.05). Nerve diameters were found to be significantly larger in the sham, DC, and B-FNN + DC groups than in the C group (p < 0.05). The number of axons, the axon diameter, and the H scores were found to be significantly higher in the B-FNN + DC group than in the sham group (p < 0.05). The Schwann cell proliferation, myelin degeneration, and axonal degeneration scores were significantly lower in the B-FNN + DC group than in the sham group (p < 0.05).

CONCLUSION

Electrophysiological and histopathological evaluation revealed the potential benefits provided by DC. This agent may increase FN regeneration.

Microsurgery training: A combined educational program

A proposed microsurgical training program is presented that includes all the existing training methods, such as simulation in nonliving models, virtual reality simulation system and exercise in living models. Our experience in microsurgery training over the last decades indicates the need of evolution in training programs. This can be achieved with the introduction of new technologies into education and training. The first primary results of the described training program are promising, however this system needs to be assessed by training greater number of microsurgeons. Furthermore, more complex scenarios (such as whole operations) should be inserted into the virtual reality simulation system to create a more interactive experience.

Syndecan-3 contributes to the regulation of the microenvironment at the node of Ranvier following end-to‑side neurorrhaphy: sodium image analysis

Syndecan-3 (SDC3) and Syndecan-4 (SDC4) are distributed throughout the nervous system (NS) and are favourable factors in motor neuron development. They are also essential for regulation of neurite outgrowth in the CNS. However, their roles in the reconstruction of the nodes of Ranvier after peripheral nerve injury (PNI) are still unclear. Present study used an in vivo model of end-to-side neurorrhaphy (ESN) for 1-3 months. The recovery of neuromuscular function was evaluated by grooming test. Expression and co-localization of SDC3, SDC4, and Nav1.6 channel (Nav1.6) at regenerating axons were detected by proximity ligation assay and confocal microscopy after ESN. Time-of-flight secondary ion mass spectrometry was used for imaging ions distribution on tissue. Our data showed that the re-clustering of sodium and Nav1.6 at nodal regions of the regenerating nerve corresponded to the distribution of SDC3 after ESN. Furthermore, the re-establishment of sodium and Nav1.6 correlated with the recovery of muscle power 3 months after ESN. This study suggested syndecans may involve in stabilizing Nav1.6 and further modulate the distribution of sodium at nodal regions after remyelination. The efficiency of sodium re-clustering was improved by the assistance of anionic syndecan, resulting in a better functional repair of PNI.

Masseteric-zygomatic nerve transfer for the management of eye closure-smile excursion synkinesis

OBJECTIVE

The purpose of this study is to illustrate the efficacy of masseteric-to-zygomatic nerve transfer to address eye closure-smile excursion synkinesis after facial nerve paralysis.

BACKGROUND

Synkinesis after facial nerve paralysis represents a wide range of facial movement disability. One manifestation is involuntary smiling with eye closure and a concomitant reduction of oral commissure movement with attempted smile ("frozen smile") - arising as a result of aberrant fibers populating the zygomatic branch-muscle complex. This is a particularly difficult area to treat with conservative management. We propose a single-stage procedure to sever the dysfunctional zygomatic nerve and perform a masseteric-zygomatic nerve coaptation to recover a voluntary smile.

METHODS

We present a case series of eight patients with eye closure/smile excursion synkinesis who underwent single-stage masseteric-zygomatic nerve transfer by a single surgeon. The surgical technique and indications for surgery were reviewed. Patients underwent facial movement analysis using Emotrics.

RESULTS

We analyzed the pre- and post- surgical photographic images of 8 patients with synkinesis (7 female, 1 male). Masseteric-facial nerve transfer was performed from 18 months to 22 years after the initial facial paralysis. Eyelid and brow positioning were more symmetric after surgery, with discrepancy between affected and unaffected side decreasing from 2.1 to 1.0 mm (p < .05) and 1.74 to 1.29 mm (p < .05), respectively. Symmetry of smile excursion postoperatively was also improved with commissure excursion discrepancy decreasing from 8.8 to 3.78 mm (p < .05). Discrepancy in the smile angle when comparing affected to unaffected side improved postoperatively from 10.3 to 5.2 degrees (p < .05). Improvement in oral commissure height was noted, but not statistically significant.

CONCLUSIONS

The masseteric-zygomatic nerve transfer is a useful technique for the treatment of eye closure/smile excursion synkinesis after failure of chemodenervation and/or physical therapy.

Side-to-End Hypoglossal-Facial Neurorrhaphy for Treatment of Complete and Irreversible Facial Paralysis after Vestibular Schwannoma Removal by Means of a Retrosigmoid Approach: A Clinical and Anatomic Study

BACKGROUND

Facial paralysis secondary to a complete and irreversible anatomic or functional lesion of the facial nerve (FN) causes severe functional and psychological disorders for the patient. A large number of surgical techniques have therefore been developed for FN repair. Our objective was to propose a surgical FN reanimation protocol for patients with irreversible anatomic or functional postsurgical injury of the FN in the cerebellopontine angle after vestibular schwannoma resection.

METHODS

The clinical study included a total of 16 patients undergoing side-to-end hypoglossal-facial neurorrhaphy (SEHFN) since 2010, in which the FN injury was always secondary to vestibular schwannoma surgery in the cerebellopontine angle using a retrosigmoid approach. All patients had complete clinical facial paralysis at the time of the SEHFN. The anatomic study was conducted using 3 heads and necks (6 SEHFN).

RESULTS

Twelve months after surgery, FN function assessment with the House and Brackmann scale showed 2 patients with grade II, 13 patients with grade III, and only 1 patient with grade IV, and after 2 years, 4 patients had grade II, 11 patients had grade III, and 1 patient had grade IV. The average length of the anastomotic translocation portion of the FN in the anatomic study was 34.76 mm.

CONCLUSIONS

Side-to-end epineural suture of the FN, mobilizing its mastoid segment on the hypoglossal nerve with partial section of the dorsal aspect of the hypoglossal nerve, is a safe anatomic surgical technique for FN reanimation with outstanding clinical results.

Neurorrhaphy for Facial Reanimation with Interpositional Graft: Outcome in 23 Patients and the Impact of Timing on the Outcome

OBJECTIVE

Neurorrhaphy with interpositional graft is a practical technique to achieve facial reanimation when the continuity of the facial nerve is interrupted and a large gap between the proximal and distal stump exists. The aim of this study was to report long-term outcomes of neurorrhaphy for facial reanimation with interpositional graft. The roles of some variable factors in the outcome of neurorrhaphy with interpositional graft were also evaluated and compared.

METHODS

A retrospective case series from a single tertiary referral center comprised 23 patients with facial nerve interruptions who underwent neurorrhaphy with interpositional graft using either end-to-end anastomosis or end-to-side hypoglossal-facial technique. Preoperative data (age, sex, primary lesion, interval from paralysis to surgery, facial nerve function), intraoperative data (surgical approach, graft and type of neurorrhaphy), and postoperative data (facial nerve function) were collected and analyzed.

RESULTS

Mean follow-up time was 26.6 ± 11.9 months. Patients who underwent neurorrhaphy for facial reanimation within 1 year after onset of facial paralysis were more likely to achieve House-Brackmann grade ≤3 compared with patients who underwent neurorrhaphy >1 year after onset of facial paralysis (odds ratio = 23.85, P = 0.04). No other factors were associated with improved outcomes.

CONCLUSIONS

Early neurorrhaphy with interpositional graft (≤1 year) for facial reanimation resulted in better final facial nerve function outcomes compared with a delayed procedure.

The role of peripheral nerve surgery in a tissue reinnervation

In modern neuroscience, the most relevant is the study of the problem of reinnervation of tissues after severe injuries. Complete restoration of lost physiological functions is still impossible with lesions of peripheral nerves with the formation of extensive diastasis between their proximal and distal sites. In this case, the standard neurorrhaphy cannot be carried out because of the eruption of the filaments during tension and convergence of the ends. To solve this problem, a technique was developed for autotransplantation of the nerve sections, which is still the gold standard for the reconstruction of extensive nerve defects. However, the presence of significant shortcomings led to the development of the doctrine of the direction of regeneration with the help of conduits. Currently, the use of nerve channels is the most promising technology for peripheral nerve repair after trauma. The most actively developing now is the direction of reinnervation, such as neurotization. Neurotization, in some way, combined all the methods of restoring nerves. The overall goal of all these methods-the restoration of extensive nerve defects-allows them to be combined into a new industry: reinnervating neurosurgery.

Hypoglossal-facial 'side'-to-side Neurorrhaphy Combined with Electrical Myostimulation for Facial Palsy in Rats

Introduction This study investigated the effect of combining hypoglossal-facial nerve “side”-to-side neurorrhaphy and electrical myostimulation in a rat model of facial palsy.

Methods Rats with facial nerve crush injury were subjected to control condition, monotherapy of either neurorrhaphy or electrical myostimulation, or bitherapy of the two treatments. After 1, 3, and 6 months, rats were performed the facial symmetry evaluation, electrophysiological examination and the retrograde labeling of motor neurons.

Results As early as 3 months after injury, face symmetry significantly improved in rats of the bitherapy group. At 3 or 6 months after injury, either the parameters of electrophysiological examination or the number of labeled motor neurons were significantly increased in the bitherapy group than in any other group.

Discussion The combination of neurorrhaphy and electrical myostimulation effectively promoted the functional recovery after facial nerve crush injury.

Polyethylene glycol (PEG) and other bioactive solutions with neurorrhaphy for rapid and dramatic repair of peripheral nerve lesions by PEG-fusion

BACKGROUND

Nervous system injuries in mammals often involve transection or segmental loss of peripheral nerves. Such injuries result in functional (behavioral) deficits poorly restored by naturally occurring 1-2 mm/d axonal outgrowths aided by primary repair or reconstruction. "Neurorrhaphy" or nerve repair joins severed connective tissues, but not severed cytoplasmic/plasmalemmal extensions (axons) within the tissue.

NEW METHOD

PEG-fusion consists of neurorrhaphy combined with a well-defined sequence of four pharmaceutical agents in solution, one containing polyethylene glycol (PEG), applied directly to closely apposed viable ends of severed axons.

RESULTS

PEG-fusion of rat sciatic nerves: (1) restores axonal continuity across coaptation site(s) within minutes, (2) prevents Wallerian degeneration of many distal severed axons, (3) preserves neuromuscular junctions, (4) prevents target muscle atrophy, (5) produces rapid and improved recovery of voluntary behaviors compared with neurorrhaphy alone, and (6) PEG-fused allografts are not rejected, despite no tissue-matching nor immunosuppression.

COMPARISON WITH EXISTING METHODS

If PEG-fusion protocols are not correctly executed, the results are similar to that of neurorrhaphy alone: (1) axonal continuity across coaptation site(s) is not re-established, (2) Wallerian degeneration of all distal severed axons rapidly occurs, (3) neuromuscular junctions are non-functional, (4) target muscle atrophy begins within weeks, (5) recovery of voluntary behavior occurs, if ever, after months to levels well-below that observed in unoperated animals, and (6) allografts are either rejected or not well-accepted.

CONCLUSION

PEG-fusion produces rapid and dramatic recovery of function following rat peripheral nerve injuries.

Combination of heterologous fibrin sealant and bioengineered human embryonic stem cells to improve regeneration following autogenous sciatic nerve grafting repair

Background

Peripheral nerve injury is a worldwide clinical problem, and the preferred surgical method for treating it is the end-to-end neurorrhaphy. When it is not possible due to a large nerve gap, autologous nerve grafting is used. However, these surgical techniques result in nerve regeneration at highly variable degrees. It is thus very important to seek complementary techniques to improve motor and sensory recovery. One promising approach could be cell therapy. Transplantation therapy with human embryonic stem cells (hESCs) is appealing because these cells are pluripotent and can differentiate into specialized cell types and have self-renewal ability. Therefore, the main objective of this study was to find conditions under which functional recovery is improved after sciatic nerve neurorrhaphy. We assumed that hESC, either alone or in combination with heterologous fibrin sealant scaffold, could be used to support regeneration in a mouse model of sciatic nerve injury and repair via autografting with end-to-end neurorrhaphy.

Methods

Five millimeters of the sciatic nerve of C57BL/6 J mice were transected off and rotated 180 degrees to simulate an injury, and then stumps were sutured. Next, we applied heterologous fibrin sealant and/or human embryonic stem cells genetically altered to overexpress fibroblast growth factor 2 (FGF2) at the site of the injury. The study was designed to include six experimental groups comprising neurorrhaphy (N), neurorrhaphy + heterologous fibrin sealant (N + F), neurorrhaphy + heterologous fibrin sealant + doxycycline (N + F + D), neurorrhaphy + heterologous fibrin sealant + wild-type hESC (N + F + W), neurorrhaphy + heterologous fibrin sealant + hESC off (N + F + T), and neurorrhaphy + heterologous fibrin sealant + hESC on via doxycycline (N + F + D + T). We evaluated the recovery rate using Catwalk and von Frey functional recovery tests, as well as immunohistochemistry analysis.

Results

The experiments indicated that sensory function improved when transgenic hESCs were used. The regeneration of sensory fibers indeed led to increased reflexes, upon stimulation of the paw ipsilateral to the lesion, as seen by von-Frey evaluation, which was supported by immunohistochemistry.

Conclusions

Overall, the present data demonstrated that transgenic embryonic stem cells, engineered to overexpress FGF-2 in an inducible fashion, could be employed to support regeneration aiming at the recovery of both motor and sensory functions.

Cross-tongue procedure: a new treatment for long-standing numbness of the tongue

The lingual nerve may be injured during oral procedures, usually during extraction of lower third molars. Patients often complain of numbness of the hemitongue postoperatively. If this persists for 3 months or more, microsurgical exploration and reconstruction of the lingual nerve is required, and better outcomes are achieved after early repair. After 18-24 months the production of axoplasmic fluid through the axons of the proximal stump is reduced, and neurorrhaphy between the proximal and distal stumps is not recommended. In such cases we suggest that a portion of the opposite lingual nerve should be used as an additional nerve source.

Major peripheral nerve injuries

Major peripheral nerve injuries in the upper extremities can result in significant morbidity. Understanding the pathophysiology of these injuries aids in the assessment and planning of appropriate treatment. With limited nerve mobilization, tension-free repairs can often be performed using sutures, fibrin glue, or nerve connectors. Acellular allograft and autograft reconstruction are better for bridging any gaps greater than a few millimeters. Adherence to proper principles of nerve repair improves the chances of achieving a favorable result, although in general these injuries portend a guarded prognosis.

The incidence of symptomatic neuroma in amputation and neurorrhaphy patients

PURPOSE

The incidence of symptomatic neuroma in finger nerve injuries varies widely in the literature. In this retrospective study, we evaluated the incidence of symptomatic neuroma after repair of digital nerve injuries (neurorrhaphy) and after amputation of one or more fingers. We also determined the need for re-operation on symptomatic neuroma patients.

METHODS

In a retrospective study, we collected data from medical files. All patients who were treated for a hand trauma in the emergency department during the last 10 years were included. We gathered data on the presence of symptomatic neuroma and re-operation of the patients.

RESULTS

In our database, 583 people had a peripheral nerve injury of whom 177 people had an amputation. The incidence of digital nerve injury without amputation followed by neurorrhaphy was 1%. In digital nerve injuries with amputation the incidence was 7.8%, which is significantly higher than after digital nerve injuries without amputation.

CONCLUSIONS

People with an amputation injury have significantly more symptomatic neuroma than people who undergo neurorrhaphy. People who have a symptomatic neuroma after digital nerve injuries have been operated significantly more than people who have a non-symptomatic neuroma or no neuroma at all. This information can be of help when treating digital nerve injuries. TYPE OF STUDY/LEVEL OF EVIDENCE (LOE): Prognostic.

Digital nerve injuries: a review of predictors of sensory recovery after microsurgical digital nerve repair

BACKGROUND

Optimal surgical management of digital nerve lesions remains uncertain despite the publication of numerous studies. The purposes of this review were primarily to analyze whether there is a superior surgical technique for digital nerve repair and secondarily to statistically verify the variables to be predictors of sensory recovery.

METHODS

A literature search was performed using PubMed including citation from MEDLINE. Studies were included if they involved patients with digital nerve lacerations in whom end-to-end neurorrhaphy, nerve grafts, conduits, or end-to-side neurorrhaphy were performed. Further, the sensory outcome had to be assessed according to the modified American Society for Surgery of the Hand guidelines to stratify for two-point discrimination in millimeters. The variables age, follow-up, delay in repair, type of trauma, and gap length were extracted. The association between each predictor and response was assessed using a linear mixed model and corrected for heterogeneity between studies. Significance was considered present at p ≤ 0.05.

RESULTS

Of the 34 articles found, 14 articles were included giving appropriate individual data for 191 nerves. There was no statistically significant difference in outcome between operation techniques. Age and follow-up were verified predictors of sensory recovery.

CONCLUSION

In this review, the type of operation for digital nerve repair does not influence sensory outcome. However, we verified outcome to be influenced by the patient's age and the follow-up period. To add more scientific evidence to our results, larger cohort prospective studies need to be done with better detailed description of data.