Poor results after nerve grafting in the upper extremity: Quo vadis?

Restoring Sensation through Abdominal Flap Neurotization in Breast Reconstruction

Breast sensation plays a significant role in the safety and quality of life of women who undergo mastectomy and reconstruction. In 1992, Slezak et al. introduced the concept of abdominal flap neurotization to improve sensation of the reconstructed breast. Over the next 30 years, numerous studies iterated on Slezak's technique, suggesting technical modifications and new methodologies for assessing sensory recovery. Despite evidence that reinnervation increases patient satisfaction following autologous breast reconstruction, abdominal flap neurotization remains a rarely performed procedure. In this article, we review the evolution of flap neurotization in breast reconstruction and describe our approach to facilitating sensory recovery of the breast while limiting donor site morbidity.

Treatment options for digital nerve injury: a systematic review and meta-analysis

BACKGROUND

Surgical treatment of finger nerve injury is common for hand trauma. However, there are various surgical options with different functional outcomes. The aims of this study are to compare the outcomes of various finger nerve surgeries and to identify factors associated with the postsurgical outcomes via a systematic review and meta-analysis.

METHODS

The literature related to digital nerve repairs were retrieved comprehensively by searching the online databases of PubMed from January 1, 1965, to August 31, 2021. Data extraction, assessment of bias risk and the quality evaluation were then performed. Meta-analysis was performed using the postoperative static 2-point discrimination (S2PD) value, moving 2-point discrimination (M2PD) value, and Semmes-Weinstein monofilament testing (SWMF) good rate, modified Highet classification of nerve recovery good rate. Statistical analysis was performed using the R (V.3.6.3) software. The random effects model was used for the analysis. A systematic review was also performed on the other influencing factors especially the type of injury and postoperative complications of digital nerve repair.

RESULTS

Sixty-six studies with 2446 cases were included in this study. The polyglycolic acid conduit group has the best S2PD value (6.71 mm), while the neurorrhaphy group has the best M2PD value (4.91 mm). End-to-side coaptation has the highest modified Highet's scoring (98%), and autologous nerve graft has the highest SWMF (91%). Age, the size of the gap, and the type of injury were factors that may affect recovery. The type of injury has an impact on the postoperative outcome of neurorrhaphy. Complications reported in the studies were mainly neuroma, cold sensitivity, paresthesia, postoperative infection, and pain.

CONCLUSION

Our study demonstrated that the results of surgical treatment of digital nerve injury are generally satisfactory; however, no nerve repair method has absolute advantages. When choosing a surgical approach to repair finger nerve injury, we must comprehensively consider various factors, especially the gap size of the nerve defect, and postoperative complications. Type of study/level of evidence Therapeutic IV.

Failed Acellular Nerve Allografts: A Critical Review

BACKGROUND

Acellular nerve allograft (ANA) occupies an increasingly prominent role in the treatment of peripheral nerve reconstruction. There is demonstrable efficacy; however, some grafts fail to support axonal regrowth and the reasons for this are unclear. This study examines the ANA experience in a specialized peripheral nerve surgery department to discuss the clinical and histological findings in failed cases.

METHOD

Failed ANA grafts were identified from a prospective database using Medical Research Council Classification (MRCC) S3 and M3 as thresholds for success. Cases in which ANA grafting was indicated for nerve related pain and dysesthesia but where no subjective improvement in symptoms occurred were also included. Patients requiring revision surgery after ANA grafting were also considered failures. Cases were then examined in conjunction with a literature review to identify possible mechanisms of failure, including detailed histological analysis in 2 cases.

RESULTS

Eight failed procedures were identified from a database of 99 separate allograft records on 74 patients. This included procedures for 2 tibial nerves, 2 superficial radial nerves, 2 median nerves, 1 digital nerve and a lateral cord brachial plexus injury (male/female, 5:3; age range, 24-54 years). Allograft length range 25 to 120 mm. One postoperative infection was identified. Histological findings in 2 cases included adequate vascularization of allograft material without subsequent axonal regeneration, a reduction of large myelinated fibers proximal to a tibial nerve allograft in the setting of a chronic injury, and a preference for small rather than large fiber regeneration.

CONCLUSIONS

This article reports instances of ANA graft failure in a variety of contexts, for which the primary reasons for failure remain unclear. The etiology is likely to be multifactorial with both patient, graft and surgeon factors contributing to failure. Further clinical and histological analysis of ANA failures will improve our understanding of the mechanisms of graft failure.

Reconstruction of the Rat Sciatic Nerve by Using Biodegradable and Non-Biodegradable Conduits

The aim of the study was to compare two types of conduits made of either non-resorbable Reperen or resorbable Tissucol for their effects on the regeneration of the rat sciatic nerve under conditions of stump diastasis.

Effects of Adipose-Derived Mesenchymal Stem Cells and Human Amniotic Membrane on Sciatic Nerve Repair in Rats

Background: Peripheral nerve injuries remain a great challenge for microsurgery despite the significant progress in recent decades. The current gold standard is autogenous nerve grafting with a success rate as low as 50% in long gaps. Current studies have focused on finding alternative methods for bridging nerve defects. Previous data have demonstrated the role of human amniotic membrane in stimulating neural regeneration. On the other hand, adipose-derived mesenchymal stem cells can differentiate into all three germ layers and could support nerve repair. The purpose of this study was to compare the role of the human amniotic membrane with and without adipose tissue stem cells in sciatic nerve injury with gap in rats. Objectives: We aimed to evaluate the effectiveness of the human amniotic membrane with and without adipose-derived mesenchymal stem cells in sciatic nerve injury with gap in rats. Methods: Twenty-four male Wistar rats in four random groups were used in our study. In the first group, the nerve gap was repaired using the inverse resected nerve segment (Control group), the second group was repaired with a human amniotic membrane (AM group), the third group was repaired with an amnion sheet with seeded adipose-derived mesenchymal stem cells (AM/ADMSCs group), and the last group was not repaired, and both stumps were sutured to muscles. Results: All the animals underwent the procedures and survived without complication. The sciatic function index and hot plate test results were significantly improved in the AM and AM/ADMSCs groups compared to the Control group (as a gold standard of care) (P>0.05). Based on histopathology findings, regenerative nerve fibers were seen in the implanted area of both AM and AM/ADMSCs groups; however, nerve fibers were surrounded by significant fibrosis (scar formation) in the AM/ADMSCs group. The axon count in the Control group was significantly higher than both experimental groups (P < 0.01). Conclusions: Our study showed the role of amniotic membrane in the promotion of nerve regeneration in sciatic nerve injury with a gap, but adding adipose-derived mesenchymal stem cells not only has no extra benefits, but also causes more tissue scar.

Evidence-Based Approach to Timing of Nerve Surgery: A Review

ABSTRACT

Events causing acute stress to the health care system, such as the COVID-19 pandemic, place clinical decisions under increased scrutiny. The priority and timing of surgical procedures are critically evaluated under these conditions, yet the optimal timing of procedures is a key consideration in any clinical setting. There is currently no single article consolidating a large body of current evidence on timing of nerve surgery. MEDLINE and EMBASE databases were systematically reviewed for clinical data on nerve repair and reconstruction to define the current understanding of timing and other factors affecting outcomes. Special attention was given to sensory, mixed/motor, nerve compression syndromes, and nerve pain. The data presented in this review may assist surgeons in making sound, evidence-based clinical decisions regarding timing of nerve surgery.

Treatment of painful median nerve neuroma using pedicled vascularized lateral antebrachial cutaneous nerve with adipofascial flap: a cadaveric study and exploration of clinical application

The most common procedure for the treatment of painful median nerve neuroma is coverage with vascularized soft tissue following external neurolysis. However, the ideal treatment should include reconnecting the proximal and distal stumps of the damaged nerve to allow the growth of regenerating axons to their proper targets for a functional recovery. We developed a useful technique employing radial artery perforator adipofascial flap including the lateral antebrachial cutaneous nerve (LABCN) to repair the median nerve by vascularized nerve grafting and to achieve coverage of the nerve with vascularized soft tissue. In an anatomical study of 10 fresh-frozen cadaver upper extremities, LABCN was constantly bifurcated into two branches at the proximal forearm (mean: 8.2 cm distal to the elbow) and two branches that run in a parallel manner toward the wrist. The mean length of the LABCN branches between the bifurcating point and the wrist was 18.2 cm, which enabled inclusion of adequate length of the LABCN branches into the radial artery perforator adipofascial flap. The diameters of the LABCN branches (mean: 1.7 mm) were considered suitable to bridge the funiculus of the median nerve defect after microsurgical internal neurolysis. In all cadaver upper extremities, the 3-cm median nerve defect at the wrist level could be repaired using the LABCN branches and covered with the radial artery perforator adipofascial flap. On the basis of this anatomical study, the median nerve neuroma was successfully treated with radial artery perforator adipofascial flap including vascularized LABCN branches.

Muscle in vein conduits: our experience

Muscle in vein (MIV ) conduits have gradually been employed in the last 20 years as a valuable technique in bridging peripheral nerve gaps after nerve lesions who cannot undergo a direct tension-free coaptation. The advantages of this procedure comparing to the actual benchmark (autograft) is the sparing of the donor site, and the huge availability of both components (i.e. muscle and veins). Here we present a case serie of four MIV performed at our hospital from 2018 to 2019. The results we obtained in our experi-ence confirmed its effectiveness both in nerve regeneration (as sensibility recovery) and in neuropathic pain eradication. Our positive outcomes encourage its use in selected cases of residual nerve gaps up to 30 mm.

Flap Neurotization in Breast Reconstruction with Nerve Allografts: 1-year Clinical Outcomes

Autologous breast reconstruction is widely regarded as the gold standard approach following mastectomy. However, the lack of sensation continues to present a reconstructive challenge. In this study, clinical outcomes following abdominal flap neurotization with processed human nerve allograft were investigated.

A Multicenter Matched Cohort Study of Processed Nerve Allograft and Conduit in Digital Nerve Reconstruction

PURPOSE

Biomaterials used to restore digital nerve continuity after injury associated with a defect may influence ultimate outcomes. An evaluation of matched cohorts undergoing digital nerve gap reconstruction was conducted to compare processed nerve allograft (PNA) and conduits. Based on scientific evidence and historical controls, we hypothesized that outcomes of PNA would be better than for conduit reconstruction.

METHODS

We identified matched cohorts based on patient characteristics, medical history, mechanism of injury, and time to repair for digital nerve injuries with gaps up to 25 mm. Data were stratified into 2 gap length groups: short gaps of 14 mm or less and long gaps of 15 to 25 mm. Meaningful sensory recovery was defined as a Medical Research Council scale of S3 or greater. Comparisons of meaningful recovery were made by repair method between and across the gap length groups.

RESULTS

Eight institutions contributed matched data sets for 110 subjects with 162 injuries. Outcomes data were available in 113 PNA and 49 conduit repairs. Meaningful recovery was reported in 61% of the conduit group, compared with 88% in the PNA group. In the group with a 14-mm or less gap, conduit and PNA outcomes were 67% and 92% meaningful recovery, respectively. In the 15- to 25-mm gap length group, conduit and PNA outcomes were 45% and 85% meaningful recovery, respectively. There were no reported adverse events in either treatment group.

CONCLUSIONS

Outcomes of digital nerve reconstruction in this study using PNA were consistent and significantly better than those of conduits across all groups. As gap lengths increased, the proportion of patients in the conduit group with meaningful recovery decreased. This study supports the use of PNA for nerve gap reconstruction in digital nerve reconstructions up to 25 mm.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic III.

An update on the management of nerve gaps

No abstract required

Peripheral nerve repair throughout the body with processed nerve allografts: Results from a large multicenter study

BACKGROUND

Peripheral nerve damage resulting in pain, loss of sensation, or motor function may necessitate a reconstruction with a bridging material. The RANGER® Registry was designed to evaluate outcomes following nerve repair with processed nerve allograft (Avance® Nerve Graft; Axogen; Alachua, FL). Here we report on the results from the largest peripheral nerve registry to-date.

METHODS

This multicenter IRB-approved registry study collected data from patients repaired with processed nerve allograft (PNA). Sites followed their own standard of care for patient treatment and follow-up. Data were assessed for meaningful recovery, defined as ≥S3/M3 to remain consistent with previously published results, and comparisons were made to reference literature.

RESULTS

The study included 385 subjects and 624 nerve repairs. Overall, 82% meaningful recovery (MR) was achieved across sensory, mixed, and motor nerve repairs up to gaps of 70 mm. No related adverse events were reported. There were no significant differences in MR across the nerve type, age, time-to-repair, and smoking status subgroups in the upper extremity (p > .05). Significant differences were noted by the mechanism of injury subgroups between complex injures (74%) as compared to lacerations (85%) or neuroma resections (94%) (p = .03) and by gap length between the <15 mm and 50-70 mm gap subgroups, 91 and 69% MR, respectively (p = .01). Results were comparable to historical literature for nerve autograft and exceed that of conduit.

CONCLUSIONS

These findings provide clinical evidence to support the continued use of PNA up to 70 mm in sensory, mixed and motor nerve repair throughout the body and across a broad patient population.

Neuroma

Neuroma formation occurs because of some degree of nerve injury followed by improper intrinsic nerve repair. The cause of neuroma pain is incompletely understood, but appears to be multifactorial in nature, including local and system changes. A comprehensive understanding of nerve anatomy, injury, and repair techniques should be used when dealing with neuroma formation and its physical manifestations. Diagnosis of neuroma is clinically characterized by pain associated with scar, altered sensation within the given nerve distribution, and a Tinel sign. The pathophysiology of neuroma formation is reviewed.

Nerve lengthening and subsequent end-to-end repair yield more favourable outcomes compared with autograft repair of rat sciatic nerve defects

Outcomes of end-to-end nerve repairs are more successful compared with outcomes of repairs bridged by nerve grafts. However, end-to-end repairs are not always possible for large nerve gaps, as excessive tension may cause catastrophic failure. In this study, we built on previous nerve-lengthening studies to test the hypotheses that gradual lengthening of the proximal stump across a large nerve gap enables an end-to-end repair and such a repair results in more favourable regenerative outcomes than autografts, which represent the gold standard in bridging nerve gaps. To test these, we compared structural and functional outcomes in Lewis rats after repair of sciatic nerve gaps using either autografts or a novel compact internal fixator device, which was used to lengthen proximal nerve stumps towards the distal stump over 2 weeks, prior to end-to-end repair. Twelve weeks after the initial injury, outcomes following nerve lengthening/end-to-end repair were either comparable or superior in every measure compared with repair by autografting. The sciatic functional index was not significantly different between groups at 12 weeks. However, we observed a reduced rate of contracture and corresponding significant increase in paw length in the lengthening group. This functional improvement was consistent with structural regeneration; axonal growth distal to the injury was denser and more evenly distributed compared with the autograft group, suggesting substantial regeneration into both tibial and peroneal branches of the sciatic nerve. Our findings show that end-to-end repairs following nerve lengthening are possible for large gaps and that this strategy may be superior to graft-based repairs.

Spatiotemporal Differences in Gene Expression Between Motor and Sensory Autografts and Their Effect on Femoral Nerve Regeneration in the Rat

To improve the outcome after autologous nerve grafting in the clinic, it is important to understand the limiting variables such as distinct phenotypes of motor and sensory Schwann cells. This study investigated the properties of phenotypically different autografts in a 6 mm femoral nerve defect model in the rat, where the respective femoral branches distally of the inguinal bifurcation served as homotopic, or heterotopic autografts. Axonal regeneration and target reinnervation was analyzed by gait analysis, electrophysiology, and wet muscle mass analysis. We evaluated regeneration-associated gene expression between 5 days and 10 weeks after repair, in the autografts as well as the proximal, and distal segments of the femoral nerve using qRT-PCR. Furthermore we investigated expression patterns of phenotypically pure ventral and dorsal roots. We identified highly significant differences in gene expression of a variety of regeneration-associated genes along the central – peripheral axis in healthy femoral nerves. Phenotypically mismatched grafting resulted in altered spatiotemporal expression of neurotrophic factor BDNF, GDNF receptor GFRα1, cell adhesion molecules Cadm3, Cadm4, L1CAM, and proliferation associated Ki67. Although significantly higher quadriceps muscle mass following homotopic nerve grafting was measured, we did not observe differences in gait analysis, and electrophysiological parameters between treatment paradigms. Our study provides evidence for phenotypic commitment of autologous nerve grafts after injury and gives a conclusive overview of temporal expression of several important regeneration-associated genes after repair with sensory or motor graft.

Reinnervation of spinal cord anterior horn cells after median nerve repair using transposition with other nerves

Our previous studies have confirmed that during nerve transposition repair to injured peripheral nerves, the regenerated nerve fibers of motor neurons in the anterior horn of the spinal cord can effectively repair distal nerve and target muscle tissue and restore muscle motor function. To observe the effect of nerve regeneration and motor function recovery after several types of nerve transposition for median nerve defect (2 mm), 30 Sprague-Dawley rats were randomly divided into sham operation group, epineurial neurorrhaphy group, musculocutaneous nerve transposition group, medial pectoral nerve transposition group, and radial nerve muscular branch transposition group. Three months after nerve repair, the wrist flexion test was used to evaluate the recovery of wrist flexion after regeneration of median nerve in the affected limbs of rats. The number of myelinated nerve fibers, the thickness of myelin sheath, the diameter of axons and the cross-sectional area of axons in the proximal and distal segments of the repaired nerves were measured by osmic acid staining. The ratio of newly produced distal myelinated nerve fibers to the number of proximal myelinated nerve fibers was calculated. Wet weights of the flexor digitorum superficialis muscles were measured. Muscle fiber morphology was detected using hematoxylin-eosin staining. The cross-sectional area of muscle fibers was calculated to assess the recovery of muscles. Results showed that wrist flexion function was restored, and the nerve grew into the distal effector in all three nerve transposition groups and the epineurial neurorrhaphy group. There were differences in the number of myelinated nerve fibers in each group. The magnification of proximal to distal nerves was 1.80, 3.00, 2.50, and 3.12 in epineurial neurorrhaphy group, musculocutaneous nerve transposition group, medial pectoral nerve transposition group, and radial nerve muscular branch transposition group, respectively. Nevertheless, axon diameters of new nerve fibers, cross-sectional areas of axons, thicknesses of myelin sheath, wet weights of flexor digitorum superficialis muscle and cross-sectional areas of muscle fibers of all three groups of donor nerves from different anterior horn motor neurons after nerve transposition were similar to those in the epineurial neurorrhaphy group. Our findings indicate that donor nerve translocation from different anterior horn motor neurons can effectively repair the target organs innervated by the median nerve. The corresponding spinal anterior horn motor neurons obtain functional reinnervation and achieve some degree of motor function in the affected limbs.

Redistribution of nerve strain enables end-to-end repair under tension without inhibiting nerve regeneration

End-to-end repair under no or low tension leads to improved outcomes for transected nerves with short gaps, compared to repairs with a graft. However, grafts are typically used to enable a tension-free repair for moderate to large gaps, as excessive tension can cause repairs to fail and catastrophically impede recovery. In this study, we tested the hypothesis that unloading the repair interface by redistributing tension away from the site of repair is a safe and feasible strategy for end-to-end repair of larger nerve gaps. Further, we tested the hypothesis that such an approach does not adversely affect structural and functional regeneration. In this study, we used a rat sciatic nerve injury model to compare the integrity of repair and several regenerative outcomes following end-to-end repairs of nerve gaps of increasing size. In addition, we proposed the use of a novel implantable device to safely repair end-to-end repair of larger nerve gaps by redistributing tension away from the repair interface. Our data suggest that redistriubution of tension away from the site of repair enables safe end-to-end repair of larger gap sizes. In addition, structural and functional measures of regeneration were equal or enhanced in nerves repaired under tension – with or without a tension redistribution device – compared to tension-free repairs. Provided that repair integrity is maintained, end-to-end repairs under tension should be considered as a reasonable surgical strategy. All animal experiments were performed under the approval of the Institutional Animal Care and Use Committee of University of California, San Diego (Protocol S11274).

Anatomical Considerations to Optimize Sensory Recovery in Breast Neurotization with Allograft

Background:

Breast numbness is a recognized problem following mastectomy and subsequent reconstruction. Contemporary literature acknowledges the positive role of breast neurotization, but it is characterized by a variety of technical approaches and substantial heterogeneity with respect to the degree of recovered sensibility that remains suboptimal in comparison with other sensory nerve reconstructions. This study’s purpose was to provide an anatomical basis for observed inconsistencies and therein provide a principle that can be used to develop a technical approach that will optimize sensory recovery.

Methods:

Anatomical dissections on 6 fresh cadavers, that is, 12 hemi-abdominal flaps and 12 hemi-chest dissections, were performed. The technical aspects of harvesting the abdominal flap with a nerve target, that is, inclusion of a sensory nerve branch only, recipient nerves in the chest, and the applications of allograft for acquired nerve gap reconstruction were investigated.

Results:

Abdominal flaps that include sensory-only intercostal nerve 10–12 segments and identification of recipient chest wall intercostal nerves 2–4 could be consistently performed. The dissection and extraction of the donor sensory nerve target allowed preservation of the motor rectus innervation. The acquired nerve gap was easily bridged by an interposing allograft, allowing free arch of rotation for flap inset, suitable for either single or dual neurotization.

Conclusions:

We provide a likely anatomical explanation for suboptimal sensory recovery after deep inferior epigastric perforator (DIEP) flap breast neurotization, as mixed intercostal autograft is prohibitive to maximal sensory recovery. Breast neurotization with allograft that bridges sensory donor intercostal nerves to sensory recipient intercostal nerves should anatomically optimize restoration of breast sensibility.

Reconstruction of a long defect of the ulnar artery and nerve with an arterialized neurovenous free flap in a teenager: A case report and literature review

There is evidence that nerve flaps are superior to nerve grafts for bridging long nerve defects. Moreover, arterialized neurovenous flaps (ANVFs) have multiple potential advantages over traditional nerve flaps in this context. This paper describes a case of reconstruction of a long defect of the ulnar artery and nerve with an arterialized neurovenous free flap and presents a literature review on this subject. A 16‐year‐old boy sustained a stab wound injury to the medial aspect of the distal third of his right forearm. The patient was initially observed and treated at another institution where the patient was diagnosed with a flexor carpis ulnaris muscle and an ulnar artery section. The artery was ligated and the muscle was sutured. Four months later, the patient was referred to our institution with complaints of ulnar nerve damage, as well as hand pain and cold intolerance. Physical examination and ancillary tests supported the diagnosis of ulnar artery and nerve complete section. Surgery revealed an 8 cm hiatus of the ulnar artery and a 5 cm defect of the ulnar nerve. These gaps were bridged with a flow through ANVF containing the sural nerve and the lesser saphenous vein. The postoperative course was uneventful. Two years postoperatively, the patient had regained normal trophism and M5 strength in all previously paralyzed muscles according to the Medical Research Council Scale. Thermography revealed good perfusion in the right ulnar angiosome. The ANVF may be an expedite, safe and efficient option to reconstruct a long ulnar nerve and artery defect.

Painful pediatric traumatic neuroma: surgical management and clinical outcomes

PURPOSE

Painful neuromas can limit function and decrease quality of life. Although management of traumatic neuromas in adults is well represented in the literature, traumatic neuromas are seen less frequently in children and adolescents, and their management is underrepresented in the literature. We present a sample of our clinical experience with painful pediatric neuromas and describe the surgical management and clinical outcomes of these cases.

METHODS

A retrospective case review was conducted on patients treated at our pediatric tertiary care center. The same surgeon was responsible for management and follow-up of all patients.

RESULTS

The sample of five patients was 60 % female and had a mean age of 12.2 (3-16) years. Each case was managed using a different surgical technique. All the patients had acceptable outcomes with a mean post-operative pain score of 0.4 (0-2) out of 10 and no residual functional outcomes.

CONCLUSIONS

It is important for clinicians to recognize that pediatric patients develop painful neuromas following nerve trauma and to understand the neurophysiologic basis for their management. Our report demonstrates that many of the techniques that we use for neuroma repair in adults are applicable in the pediatric population.

A Multicenter, Prospective, Randomized, Pilot Study of Outcomes for Digital Nerve Repair in the Hand Using Hollow Conduit Compared With Processed Allograft Nerve

BACKGROUND

Current repair options for peripheral nerve injuries where tension-free gap closure is not possible include allograft, processed nerve allograft, and hollow tube conduit. Here we report on the outcomes from a multicenter prospective, randomized, patient- and evaluator-blinded, pilot study comparing processed nerve allograft and hollow conduit for digital nerve reconstructions in the hand.

METHODS

Across 4 centers, consented participants meeting inclusion criteria while not meeting exclusion criteria were randomized intraoperatively to either processed nerve allograft or hollow conduit. Standard sensory and safety assessments were conducted at baseline, 1, 3, 6, 9, and 12 months after reconstruction. The primary outcome was static 2-point discrimination (s2PD) testing. Participants and assessors were blinded to treatment. The contralateral digit served as the control.

RESULTS

We randomized 23 participants with 31 digital nerve injuries. Sixteen participants with 20 repairs had at least 6 months of follow-up while 12-month follow-up was available for 15 repairs. There were no significant differences in participant and baseline characteristics between treatment groups. The predominant nerve injury was laceration/sharp transection. The mean ± SD length of the nerve gap prior to repair was 12 ± 4 mm (5-20 mm) for both groups. The average s2PD for processed allograft was 5 ± 1 mm (n = 6) compared with 8 ± 5 mm (n = 9) for hollow conduits. The average moving 2PD for processed allograft was 5 ± 1 mm compared with 7 ± 5 mm for hollow conduits. All injuries randomized to processed nerve allograft returned some degree of s2PD as compared with 75% of the repairs in the conduit group. Two hollow conduits and one allograft were lost due to infection during the study.

CONCLUSIONS

In this pilot study, patients whose digital nerve reconstructions were performed with processed nerve allografts had significantly improved and more consistent functional sensory outcomes compared with hollow conduits.

Nerve Repair and Nerve Grafting

Direct repair and nerve autografting are primary options in the treatment of upper extremity peripheral nerve injuries. Deciding between these surgical options depends on the mechanism of injury, time since injury, and length of repair defect. Principles of direct repair and nerve autografting are reviewed. Finally, a literature-based review of the outcomes of upper extremity peripheral nerve repair and autografting is provided. Taken together, this article provides relevant and recent data for surgeons regarding patient selection, technique selection, surgical technique, surgical outcomes, and prognostic factors that will aid surgeons treating patients with upper extremity peripheral nerve injuries.

Autograft Substitutes: Conduits and Processed Nerve Allografts

Manufactured conduits and allografts are viable alternatives to direct suture repair and nerve autograft. Manufactured tubes should have gaps less than 10 mm, and ideally should be considered as an aid to the coaptation. Processed nerve allograft has utility as a substitute for either conduit or autograft in sensory nerve repairs. There is also a growing body of evidence supporting their utility in major peripheral nerve repairs, gap repairs up to 70 mm in length, as an alternative source of tissue to bolster the diameter of a cable graft, and for the management of neuromas in non-reconstructable injuries.

Oncologic reconstruction: General principles and techniques

Halsted's principle of radical mastectomy influenced cancer treatment for decades. Randomized controlled trials resulted in a paradigm shift to less radical surgery and the use of adjuvant therapies. Oncologic reconstruction performed by plastic surgeons has evolved, ranging from skin grafts and local flaps for smaller defects to pedicled flaps and free flaps for larger and more complex defects. Immediate reconstruction facilitates resection is oncologically safe and contributes to meaningful improvements in quality of life. J. Surg. Oncol. 2016;113:852-864. © 2016 Wiley Periodicals, Inc.

Comparison of short- with long-term regeneration results after digital nerve reconstruction with muscle-in-vein conduits

Muscle-in-vein conduits are used alternatively to nerve grafts for bridging nerve defects. The purpose of this study was to examine short- and long-term regeneration results after digital nerve reconstruction with muscle-in-vein conduits. Static and moving two-point discriminations and Semmes-Weinstein Monofilaments were used to evaluate sensory recovery 6–12 months and 14–35 months after repair of digital nerves with muscle-in-vein in 7 cases. Both follow-ups were performed after clinical signs of progressing regeneration disappeared. In 4 of 7 cases, a further recovery of both two-point discriminations and in another case of only the static two-point discrimination of 1–3 mm could be found between the short-term and long-term follow-up examination. Moreover, a late recovery of both two-point discriminations was demonstrated in another case. Four of 7 cases showed a sensory improvement by one Semmes-Weinstein Monofilaments. This pilot study suggests that sensory recovery still takes place even when clinical signs of progressing regeneration disappear.

Comparison of results between chitosan hollow tube and autologous nerve graft in reconstruction of peripheral nerve defect: An experimental study

OBJECT

This study evaluated a chitosan tube for regeneration of the injured peripheral nerve in a rodent transected sciatic nerve model in comparison to autologous nerve graft repair.

METHODS

Chitosan hollow tube was used to bridge a 10-mm gap between the proximal and distal ends in 11 rats. In the control group, an end-to-end coaptation of 10-mm long autologous nerve graft was performed in 10 rats for nerve reconstruction.

RESULTS

SFI showed an insignificant advantage to the autologous group both at 30 days (P = 0.177) and at 90 days post procedure (P = 0.486). Somato-sensory evoked potentials (SSEP) and compound muscle action potentials (CMAP) tests showed similar results between chitosan tube (group 1) and autologous (group 2) groups with no statistically significant differences. Both groups presented the same pattern of recovery with 45% in group 1 and 44% in group 2 (P = 0.96) showing SSEP activity at 30 days. At 90 days most rats showed SSEP activity (91% vs.80% respectively, P = 0.46). The CMAP also demonstrated no statistically significant differences in latency (1.39 ms in group 1 vs. 1.63 ms in group 2; P = 0.48) and amplitude (6.28 mv vs. 6.43 mv respectively; P = 0.8). Ultrasonography demonstrated tissue growth inside the chitosan tube. Gastrocnemius muscle weight showed no statistically significant difference. Histomorphometry of the distal sciatic nerve, 90 days post reconstructive procedure, showed similar number of myelinated fibers and size parameters in both groups (P ≥ 0.05).

CONCLUSIONS

Chitosan hollow tube used for peripheral nerve reconstruction of rat sciatic nerve showed similar results in comparison to autologous nerve grafting. © 2015 Wiley Periodicals, Inc. Microsurgery 36:664-671, 2016.

Brain-derived neurotrophic factor expression in dorsal root ganglion neurons in response to reanastomosis of the distal stoma after nerve grafting

Studies have shown that retreatment of the distal stoma after nerve grafting can stimulate nerve regeneration. The present study attempted to verify the effects of reanastomosis of the distal stoma, after nerve grafting, on nerve regeneration by assessing brain-derived neurotrophic factor expression in 2-month-old rats. Results showed that brain-derived neurotrophic factor expression in L2-4 dorsal root ganglia began to increase 3 days after autologous nerve grafting post sciatic nerve injury, peaked at 14 days, decreased at 28 days, and reached similar levels to the sham-surgery group at 56 days. Brain-derived neurotrophic factor expression in L2-4 dorsal root ganglia began to increase 3 days after reanastomosis of the distal stoma, 59 days after autologous nerve grafting post sciatic nerve injury, significantly increased at 63 days, peaked at 70 days, and gradually decreased thereafter, but remained higher compared with the sham-surgery group up to 112 days. The results of this study indicate that reanastomosis of the distal stoma after orthotopic nerve grafting stimulated brain-derived neurotrophic factor expression in L2-4 dorsal root ganglia.

Evaluation of emergency nerve grafting for proper palmar digital nerve defects: a retrospective single centre study

HYPOTHESIS

Finger trauma often results in discontinuity of the proper palmar digital nerves. The goal of this study was to retrospectively evaluate the clinical outcomes of emergency nerve grafting and the resulting donor site morbidity.

MATERIAL AND METHOD

Three women and 13 men who had been operated between 2008 and 2012 were reviewed. The average patient age was 39 years (range 18-78). All were operated on an emergency basis. The average defect was 38 mm long (range 15-60). The nerves were harvested from four sites: lateral antebrachial cutaneous nerve (12 cases), banked finger (2 cases), terminal portion of posterior interosseous nerve (1 case) and anterior interosseous nerve (1 case). The evaluation consisted of patient questioning and clinical examination of the treated finger and donor site. An objective sensory exam was also performed. The results were expressed according to the British Medical Research Council (MRC) classification.

RESULTS

There was little donor site morbidity (2 cases of symptomatic hypoesthesia, 1 case of scar hypersensitivity). Sixty-nine percent of patients stated that their grafted finger did not cause them any trouble during activities of daily living. Three patients required job retraining. Pain in the grafted finger was 0.6 (range 0-5) on the VAS. Normal sensation was restored in 31% of cases based on the monofilament sensory test; 25% had a slight decrease in touch sensitivity and 25% had reduced protective sensations. Weber's two-point discrimination test found 50% normal sensibility (threshold<6mm) and 6% with mediocre sensibility (threshold of 6-10mm). On the MRC grading scale, 50% of patients were at S4, 6% at S3+, 19% at S3, 12% at S2 and 12% at S1.

CONCLUSION

There were 56% good results in this patient series (S3+/S4) and no patients at S0. Donor site morbidity was rare. Thus use of nerve grafting is still a relevant option in an emergency setting.

LEVEL OF EVIDENCE

Level IV.

Evaluation of sensory recovery after reconstruction of digital nerves of the hand using muscle-in-vein conduits in comparison to nerve suture or nerve autografting

BACKGROUND

Muscle-in-vein conduits are a good alternative solution to nerve autografts for bridging peripheral nerve defects since enough graft material is available and no loss of sensation at the harvesting area is expected. The purpose of this study was to compare regeneration results after digital nerve reconstruction with muscle-in-vein conduits, nerve autografts, or direct suture.

PATIENTS AND METHODS

46 patients with 53 digital nerve injuries of the hand subjected to direct suture (n = 22) or reconstruction of 1-6 cm long defects with either nerve autografts (n = 14) or muscle-in-vein conduits (n = 17) between 2008 and 2012, were examined using the two-point discrimination and Semmes-Weinstein Monofilaments.

RESULTS

The follow-up examinations took place 12 to 58 months after surgery. A median reduction of sensibility of 2 Semmes-Weinstein monofilaments compared with intact digits was observed after direct suture (DS) and of 2.5 and 2 Semmes-Weinstein monofilaments after reconstruction with autologous nerve grafts (ANG) and muscle-in-vein conduits (MVC), respectively. No statistically significant differences between all three groups could be found with a significance level set by a P < 0.006 (PDS-ANG = 0.24, PDS-MVC = 0.03, PANG-MVC = 0.52). After harvesting a nerve graft, reduction of sensibility at the donor site occurred in 10 of 14 cases but only in one case after harvesting a muscle-in-vein conduit.

CONCLUSIONS

Muscle-in-vein conduits may be a good alternative solution to autografts for the reconstruction of digital nerves, since no significant differences could be demonstrated between the two methods.

Median nerve injury and repair

Median nerve injuries in the forearm are reasonably common and can lead to devastating functional sequelae for the hand if they are not managed in a timely and appropriate fashion. Most nerve lacerations should be repaired soon after injury, and current widespread application of microsurgical techniques should lead to reasonable results in most individuals. Despite these advances, many patients do not have ideal outcomes from injuries to the median nerve and are often left with permanent sequelae. This article will discuss current techniques in the management of median nerve injuries, with the goal of preventing or alleviating the potential negative sequelae of these injuries.

Clinical applications of autografts, conduits, and allografts in repair of nerve defects in the hand: current guidelines

Traumatic nerve injuries are common conditions treated by hand surgeons, and the optimal treatment of a severed nerve requires providing a healthy wound bed, generous trimming to healthy nerve substance, and a minimal-tension approximation. The gold standard for repair of a critical nerve gap has been the nerve autograft. However, results are generally less favorable than direct suture. Autogenous and synthetic conduits and processed nerve allografts have been developed as less morbid and more convenient alternatives to autografts, but the reported outcomes have been uneven. Engineered neural tissues show great promise in inducing nerve regeneration across a gap.

Functional and electrophysiological outcome after autogenous vein wrapping of primary repaired ulnar nerves

PURPOSE

This study aimed at assessing the functional and electrophysiological recovery after vein wrapping of primary repaired ulnar nerves

METHODS

From January 2010 till December 2012, 23 patients (diagnosed with distal ulnar nerve injury) were prospectively studied where they were divided into two groups; group one (11 patients) and group two (12 patients). The injury was sharp in all cases but for one. The first group was managed by primary epineurorraphy. The second group was managed by primary epineurorraphy and autogenous vein wrapping. Final outcome was based on sensory recovery, motor recovery, and the presence or absence of electrophysiological response

RESULTS

Clinically, only one case in each group exhibited negative Tinel's sign. The second group achieved statistically significant superiority regarding motor recovery (P = 0.018), sensory recovery (P = 0.042) and electrophysiological recovery (P = 0.044). Group one showed two good, two satisfactory, six moderate, and one bad results while the second group showed five good, six satisfactory, one bad and no moderate results (P = 0.026). The first time to show clinical response in group one was the third month while in the second group it was at 1.5 month (P < 0.001). In addition, the first time to show electromyographic response in group one was at the sixth month while in group two it was at the third month

CONCLUSIONS

Vein wrapping is a simple technique that could be used reliably to augment primary neurorrhaphy particularly in cases with associated vascular or tendon injuries to prevent scarring and enhance functional and electrophysiological recovery.

Management of neuromas of the upper extremity

Neuromas primarily arise from iatrogenic injury, trauma, or chronic irritation. Given the disabling symptoms of neuromas, an array of treatment strategies exist, with varied results. Successful treatment relies on accurate identification of the offending nerve, containment of the regenerating fascicles, and cessation of mechanical or other noxious stimuli over the regenerating nerve end. The choice of treatment depends in part on the nerve affected, whether it involves critical or noncritical sensation, and its location.

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.

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.

Reconstructive treatment of soft tissue sarcoma of the upper extremity

Limb-sparing surgery is currently the cornerstone of treatment for most patients with soft-tissue sarcoma of the upper extremity. To achieve the best outcome, the reconstructive surgeon must be part of a multidisciplinary team and is required to have a thorough understanding of the whole treatment concept. This article provides an update for the current surgical management of patients with soft tissue sarcoma of the upper extremity. Relevant nonsurgical aspects are also highlighted.

Muscle-in-vein nerve guide for secondary reconstruction in digital nerve lesions

PURPOSE

Although vein conduits filled with fresh skeletal muscle have been used to bridge nerve defects both experimentally and clinically with good results, this approach has never been considered a valuable tool for reconstruction of nerve defects, and the technique has been abandoned. The purpose of this study was to evaluate the application of muscle-in-vein conduits for secondary digital nerves reconstruction, with particular emphasis on the surgical technique and results.

METHODS

We present a retrospectively selected consecutive series of 21 digital nerve defects in 17 patients who were treated with vein conduits filled with fresh skeletal muscle for secondary nerve reconstruction. After a minimum follow-up of 18 months, all patients were studied with static and moving 2-point discrimination, Semmes-Weinstein monofilament testing, Visual Analog Scale, and Disabilities of the Arm, Shoulder, and Hand questionnaire. Outcome data were stratified according to the American Society for Surgery of the Hand guidelines, the modified Highet and Sander's criteria, and the Logic Tree.

RESULTS

The average nerve gap bridged with the muscle-in-vein conduit was 2.2 cm (range, 1-3.5 cm). We classified 14 of 22 reconstructed nerves as excellent or good according to American Society for Surgery of the Hand guidelines, whereas 17 were between S4 and S3 using modified Highet and Sander's criteria. The Logic Tree yielded results between S4 and S3 in 14 of 21 reconstructed nerves. The average Disabilities of the Arm, Shoulder, and Hand survey scores were 22.5 for the disability/symptoms module and 21.4 and 17 for the sports/music and work subcomponents, respectively.

CONCLUSIONS

Use of muscle-in-vein conduits should be considered and promoted for sensory nerve reconstruction for a number of reasons: the encouraging results with the technique; the abundant availability of both donor tissues; the flexibility of the conduit resulting from the combination of muscle and vein; the simplicity with which tubes can be fashioned; immunological compatibility; and the absence of adjunctive costs.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Neuromas of the hand and upper extremity

The painful neuroma is an often debilitating sequela of nerve injury about the hand. The exact pathophysiology of this condition is poorly understood. After sharp trauma to a peripheral nerve, as nerve ends try to connect with their end organs and "find" the distal nerve stump, fascicular escape and scarring can lead to the development of a painful neuroma. Painful neuromas can even be associated with blunt trauma or retraction of a nerve when the nerve is not actually divided. Green's definition of a neuroma is "the inevitable, unavoidable, and biologic response of the proximal stump after it has been divided in situations where regenerating axons are impeded from re-entering the distal stump."(1) A number of unknown factors make certain patients more susceptible to neuroma formation. In addition, certain nerves such as the superficial radial nerve are more prone to the development of a painful neuroma. Treatment of neuromas of the hand is important because they can be quite debilitating and painful, often preventing patients from continuing with their normal daily activities. There are a number of approaches to the painful neuroma, and the treatment plan must be tailored to the individual patient.

[Retrospective monocentric comparative evaluation by sifting of vein grafts versus nerve grafts in palmar digital nerves defects. Report of 32 cases]

AIM

Palmar digital nerves defects can be treated by conventional nerve grafts or by means of a conduit, such as a vein. We compared a vein graft technique to a nerve graft technique in a retrospective monocentric study.

MATERIAL AND METHOD

A surgeon who was not involved in the treatment reviewed blind 15 nerve grafts and 17 vein grafts. The evaluation concerned sensitivity, pain, donor site morbidity, social integration and autoassessment of the benefits by the patient. Data were compacted by a sifting method eliminating bad results. The classical functional scores (British Medical Research Council, Möberg, Chanson, Alnot, Dumontier) were also used.

RESULTS

The evaluation was carried out at least 11 months after treatment. Defect was never greater than 30 mm. After sifting, vein grafts appeared less efficient than nerve grafts (41% good results against 73%), except in emergencies (86% good results).

CONCLUSION

For defect loss of no more than 30 mm in emergencies, the authors propose to use vein grafting. In other situations, the surgeon must take into account the patient's profile and the hemi-pulp concerned, dominant or non-dominant, before opting for a nerve or a vein graft.

Peripheral nerve considerations in the management of extremity soft tissue sarcomas

Evaluation of peripheral nerves, both clinically and with imaging, is critical in the evaluation of patients with extremity soft tissue sarcomas. If an essential peripheral nerve is felt to be adjacent to a soft tissue sarcoma but not circumferentially surrounded, it can usually be salvaged using the technique of epineural dissection in the setting of adjuvant radiation. If, however, a critical nerve is circumferentially involved with tumor, it must be sacrificed for the sake of local control. Various reconstruction techniques are available in this situation, including nerve grafting, distal nerve transfer, and tendon transfer, with each technique having specific indications. Regardless of the technique, it is important to inform the patient that normal extremity function is not likely to be achieved. The issue of nerve involvement therefore becomes a critical factor in determining the possibility of limb salvage in borderline cases. For the situation in which postoperative function is already expected to be compromised due to vascular, bone, or extensive soft tissue resection, nerve resection may be the ultimate deciding factor in recommending amputation rather than limb salvage.

Video-gait analysis of functional recovery of nerve repaired with chitosan nerve guides

Quantitative analysis of peripheral nerve regeneration using nerve guides is commonly evaluated through histomorphometry and walking track analysis. We conducted a unique assessment of functional sciatic nerve recovery treated with chitosan nerve guides. We used video-gait analysis to evaluate the extent of functional nerve recovery by measuring the ankle angle at different gait cycle phases. We also correlated the gastrocnemius muscle weight measurements and histological analysis to functional nerve recovery. The chitosan group showed increased functional improvement compared to the control groups at the end of a 12-week period ( p < 0.05). Although both control and chitosan angle measurements were lower than those recorded for presurgery animals, the angle measurements significantly improved over the 12-week period. Stance phase duration of the gait cycle was also recorded, which showed a significant increase over the 12-week time period. The muscle weight parameter indicated a significant decrease in muscle atrophy and restoration of functional strength. Histological analysis revealed that the chitosan nerve guide provided significantly increased axonal growth. The functional results indicated that chitosan nerve guides enhanced functional improvement over no repair processes.