Peripheral nerve injuries: A retrospective survey of 456 cases

Quantitative assessment of cortical somatosensory digit representations after median and ulnar nerve injury in rats

Incomplete recovery of sensory function is common after peripheral nerve injury (PNI). Despite reinnervation following injury, disorganized cortical representations persist and may contribute to functional deficits. There is a dearth of literature characterizing cortical responses after PNI in rodent models. Here we develop a quantitative electrophysiological method for mapping forepaw digit responses in primary somatosensory cortex (S1) of rats. We tested the hypothesis that PNI in the forelimb would generate significant, long lasting sensory deficits, and corresponding disorganization in S1. Rats underwent a transection of the proximal segment of the median and ulnar nerves in the forelimb followed by tubular repair. 4-12 months after nerve injury, we tested mechanosensory withdrawal thresholds and mapped S1 responses to mechanical stimulation of the digits. PNI produces persistent elevation of mechanical withdrawal thresholds, consistent with an impairment in sensory function. Assessment of cortical neurophysiology reveals a substantial disorganization of S1 somatotopy. Additionally, we document degraded timing and digit specificity of cortical responses. This quantitative measurement of long-term changes in S1 digit representations after forelimb nerve injury in rodents provides a framework for further studies focused on the development of therapeutic strategies to restore cortical and sensory function.

The Use of a Hypoallergenic Dermal Matrix for Wrapping in Peripheral Nerve Lesions Regeneration: Functional and Quantitative Morphological Analysis in an Experimental Animal Model

INTRODUCTION

The aim of this research was to test, in an animal model, the nerve regeneration technique with a hypoallergenic acellular dermal matrix used to wrap the microsurgical neural suture.

MATERIALS AND METHODS

Two groups of rats received the cut of limb right median nerves. The regeneration technique considers for both groups an end-to-end nerve suture. In the experimental group (A) was used also a wrapping protocol by a conduit of collagen matrix currently used in oral surgery. The animals underwent functional grasping tests (at 1, 3, 5, and 7 months) and a histological and quantitative analysis of distal nerve was performed at the end of experimental time.

RESULT

After seven months, the grasping test reveals functional recovery in each tested animal; this improvement is more evident in Group A. The fibers appear well organized with restored myelin sheaths in both groups. Group A showed a great quantity of connective tissue surrounding the nerve. The quantitative morphology analysis in both groups shows a similar fibers density, fiber diameter, and myelin thickness. The differences between the groups in axon mean diameter are significant. In Group A M/d, D/d, and g-ratio is significantly higher compared to control group.

CONCLUSIONS

Histological and functional assessments show a functional recovery of the injured nerve in the test groups, stressed by the results of the grasping tests and the meaningful increasing in fiber diameter and higher g-ratio. Moreover, a connective tissue cuff distinguishes the distal portion of the injured nerve. Considering the easy availability and handling of the material used in this study we can conclude that this experimental technique can be considered as a valid alternative to protect nerves in nerve wrap surgery.

Development of a core outcome set for traumatic brachial plexus injuries (COMBINE): study protocol

INTRODUCTION

Traumatic brachial plexus injury (TBPI) involves major trauma to the large nerves of the arm which control the movement and sensation. Fifty per cent of injuries result in complete paralysis of the arm with many other individuals having little movement, sensation loss and unremitting pain. The injury often causes severe and permanent disability affecting work and social life, with an estimated cost to the National Health Service and the economy of £35 million per annum. Advances in microsurgery have resulted in an increase in interventions aimed at reconstructing these injuries. However, data to guide evidence-based decisions is lacking. Different outcomes are used across studies to assess the effectiveness of treatments. This has impeded our ability to synthesise results to determine which treatments work best. Studies frequently report short-term clinical outcomes but rarely report longer term outcomes and those focused on quality of life. This project aims to produce a core outcome set (COS) for surgical and conservative management of TBPI. The TBPI COS will contain a minimum set of outcomes to be reported and measured in effectiveness studies and collected through routine clinical care.

METHODS AND ANALYSIS

This mixed-methods project will be conducted in two phases. In phase 1 a long list of patient-reported and clinical outcomes will be identified through a systematic review. Interviews will then explore outcomes important to patients. In phase 2, the outcomes identified across the systematic review, and the interviews will be included in a three-round online Delphi exercise aiming to reach consensus on the COS. The Delphi process will include patient and healthcare participants. A consensus meeting will be held to achieve the final COS.

ETHICS AND DISSEMINATION

The use of a COS in TBPI will increase the relevance of research and clinical care to all stakeholders, facilitate evidence synthesis and evidence-based decision making. The study has ethical approval.

TRIAL REGISTRATION NUMBERS

CRD42018109843.

Bionic hand as artificial organ: Current status and future perspectives

Even though the hand comprises only 1% of our body weight, about 30% of our central nervous systems (CNS) capacity is related to its control. The loss of a hand thus presents not only the loss of the most important tool allowing us to interact with our environment, but also leaves a dramatic sensory-motor deficit that challenges our CNS. Reconstruction of hand function is therefore not only an essential part of restoring body integrity and functional wholeness but also closes the loop of our neural circuits diminishing phantom sensation and neural pain. If biology fails to restore meaningful function, today we can resort to complex mechatronic replacement that have functional capabilities that in some respects even outperform biological alternatives, such as hand transplantation. As with replantation and transplantations, the challenge of bionic replacement is connecting the target with the CNS to achieve natural and intuitive control. In recent years, we have developed a number of strategies to improve neural interfacing, signal extraction, interpretation and stable mechanical attachment that are important parts of our current research. This work gives an overview of recent advances in bionic reconstruction, surgical refinements over technological interfacing, skeletal fixation, and modern rehabilitation tools that allow quick integration of prosthetic replacement.

Two-Chambered Chitosan Nerve Guides With Increased Bendability Support Recovery of Skilled Forelimb Reaching Similar to Autologous Nerve Grafts in the Rat 10 mm Median Nerve Injury and Repair Model

Tension-free surgical reconstruction of transected digital nerves in humans is regularly performed using autologous nerve grafts (ANGs) or bioartificial nerve grafts. Nerve grafts with increased bendability are needed to protect regenerating nerves in highly mobile extremity parts. We have recently demonstrated increased bendability and regeneration supporting properties of chitosan nerve guides with a corrugated outer wall (corrCNGs) in the common rat sciatic nerve model (model of low mobility). Here, we further modified the hollow corrCNGs into two-chambered nerve guides by inserting a perforated longitudinal chitosan-film (corrCNG[F]s) and comprehensively monitored functional recovery in the advanced rat median nerve model. In 16 adult female Lewis rats, we bilaterally reconstructed 10 mm median nerve gaps with either ANGs, standard chitosan nerve guides (CNGs), CNGs (CNG[F]s), or corrCNG[F]s (n = 8, per group). Over 16 weeks, functional recovery of each forelimb was separately surveyed using the grasping test (reflex-based motor task), the staircase test (skilled forelimb reaching task), and non-invasive electrophysiological recordings from the thenar muscles. Finally, regenerated tissue harvested from the distal part of the nerve grafts was paraffin-embedded and cross-sections were analyzed regarding the number of Neurofilament 200-immunopositive axons and the area of newly formed blood vessels. Nerve tissue harvested distal to the grafts was epon-embedded and semi-thin cross-sections underwent morphometrical analyses (e.g., number of myelinated axons, axon and fiber diameters, and myelin thicknesses). Functional recovery was fastest and most complete in the ANG group (100% recovery rate regarding all parameters), but corrCNG[F]s accelerated the recovery of all functions evaluated in comparison to the other nerve guides investigated. Furthermore, corrCNG[F]s supported recovery of reflex-based grasping (87.5%) and skilled forelimb reaching (100%) to eventually significantly higher rates than the other nerve guides (grasping test: CNGs: 75%, CNG[F]s: 62.5%; staircase test: CNGs: 66.7%, CNG[F]s: 83.3%). Histological and nerve morphometrical evaluations, in accordance to the functional results, demonstrated best outcome in the ANG group and highest myelin thicknesses in the corrCNG[F] group compared to the CNG and CNG[F] groups. We thus clearly demonstrate that corrCNG[F]s represent promising innovative nerve grafts for nerve repair in mobile body parts such as digits.

An ATF3-CreERT2 Knock-In Mouse for Axotomy-Induced Genetic Editing: Proof of Principle

Genome editing techniques have facilitated significant advances in our understanding of fundamental biological processes, and the Cre-Lox system has been instrumental in these achievements. Driving Cre expression specifically in injured neurons has not been previously possible: we sought to address this limitation in mice using a Cre-ERT2 construct driven by a reliable indicator of axotomy, activating transcription factor 3 (ATF3). When crossed with reporter mice, a significant amount of recombination was achieved (without tamoxifen treatment) in peripherally-projecting sensory, sympathetic, and motoneurons after peripheral nerve crush in hemizygotes (65–80% by 16 d) and was absent in uninjured neurons. Importantly, injury-induced recombination did not occur in Schwann cells distal to the injury, and with a knock-out-validated antibody we verified an absence of ATF3 expression. Functional recovery following sciatic nerve crush in ATF3-deficient mice (both hemizygotes and homozygotes) was delayed, indicating previously unreported haploinsufficiency. In a proof-of-principle experiment, we crossed the ATF3-CreERT2 line with a floxed phosphatase and tensin homolog (PTEN) line and show significantly improved axonal regeneration, as well as more complete recovery of neuromuscular function. We also demonstrate the utility of the ATF3-CreERT2 hemizygous line by characterizing recombination after lateral spinal hemisection (C8/T1), which identified specific populations of ascending spinal cord neurons (including putative spinothalamic and spinocerebellar) and descending supraspinal neurons (rubrospinal, vestibulospinal, reticulospinal and hypothalamic). We anticipate these mice will be valuable in distinguishing axotomized from uninjured neurons of several different classes (e.g., via reporter expression), and in probing the function of any number of genes as they relate to neuronal injury and regeneration.

Evaluation of select biocompatible markers for labelling peripheral nerves on 11.7 T MRI

BACKGROUND

Peripheral nerve injury is often followed by a highly variable recovery process with respect to both rapidity and efficacy. Identifying post-nerve injury phenomena is key to assessing the merit and timing of surgery as well as to tracking nerve recovery postoperatively. Diffusion Tensor Imaging (DTI) has been investigated in the clinical and research settings as a noninvasive technique to both assess and monitor each patient's unique case of peripheral nerve damage.

NEW METHOD

We identify a MRI-suitable marker for tracking the exact site of either nerve injury or coaptation following surgical repair to aid with DTI analysis.

RESULTS

Due to artefact and disruption of tractography, silver wire and microvascular clips were not suitable markers. AxoGuard®, 4-0 vicryl suture, and 10-0 polyamide suture, although detectable, did not produce a signal easily distinguished from post-surgical changes. Silicone was easily identifiable and stable in both the acute and delayed time points, exhibited negligible impact on DTI parameters, and possessed geometry to prevent nerve strangulation.

COMPARISON WITH EXISTING METHOD

Prior studies have not assessed the efficacy of other markers nor have they assessed silicone for potential artefact with DTI parameter analysis. Furthermore, this work demonstrates the reliability and compatibility of silicone in the delayed postoperative time period and includes its unique imaging appearance on high-resolution 11.7 MRI.

CONCLUSION

Semi-cylindrical silicone tubing can be used as a safe, reliable, and readily available radiological marker to visualize and monitor a region of interest on a rodent's peripheral nerve for aiding assessments with diffusion tensor imaging.

Microsurgical repair by autografting in traumatic injuries of peripheral nerves: a series of 50 cases

BACKGROUND

Peripheral nerve injuries (PNI) with traumatic origin in upper and lower extremities are pathologies with an important quality-of-life considerations. For neurosurgeons, it is mandatory to understand their physiopathological mechanism and a proper treatment. The authors describe a series of 50 patients with traumatic PNI who underwent microsurgical reconstruction by autologous graft between 1993 and 2014.

METHODS

Patients aged less than 65, who had neurological deficit in a range 3-12 months and severe and persistent nerve injury at electrophysiological examination were included in the study. After grafting, the overall functional recovery of the neurological deficit, the main prognostic factors (age, injured nerve, damage mechanism, gap length and surgical timing) and the postoperative functional outcome were analysed. Neurological and electrophysiological follow-up was at 6-12-24-48 months after surgery.

RESULTS

The results showed that the best neurological recovery can be found in young patients with cut injuries of the upper limbs and that the outcome mainly depends on involved nerve, lesion type and minimum gap length. Moreover, follow-up for these pathologies should last till 48 months.

CONCLUSIONS

In the future, these results could be further improved by the rising new techniques of nerve repair and the advances in neurobiology.

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.

Canine Adipose-Derived Mesenchymal Stromal Cells Enhance Neuroregeneration in a Rat Model of Sciatic Nerve Crush Injury

Crush injuries in peripheral nerves are frequent and induce long-term disability with motor and sensory deficits. Due to axonal and myelin sheath disruptions, strategies for optimized axonal regeneration are needed. Multipotent mesenchymal stromal cells (MSC) are promising because of their anti-inflammatory properties and secretion of neurotrophins. The present study investigated the effect of canine adipose tissue MSC (Ad-MSC) transplantation in an experimental sciatic nerve crush injury. Wistar rats were divided into three groups: sham ( n = 8); Crush+PBS ( n = 8); Crush+MSC ( n = 8). Measurements of sciatic nerve functional index (SFI), muscle mass, and electromyography (EMG) were performed. Canine Ad-MSC showed mesodermal characteristics (CD34-, CD45-, CD44+, CD90+ and CD105+) and multipotentiality due to chondrogenic, adipogenic, and osteogenic differentiation. SFI during weeks 3 and 4 was significantly higher in the Crush+MSC group ( p < 0.001). During week 4, the EMG latency in the Crush+MSC groups had better near normality ( p < 0.05). The EMG amplitude showed results close to normality during week 4 in the Crush+MSC group ( p < 0.04). There were no statistical differences in muscle weight between the groups ( p > 0.05), but there was a tendency toward weight gain in the Crush+MSC groups. Better motor functional recovery after crush and perineural canine Ad-MSC transplantation was observed during week 2. This was maintained till week 4. In conclusion, the canine Ad-MSC transplantation showed early pro-regenerative effects between 2-4 weeks in the rat model of sciatic nerve crush injury.

Synthetic bioresorbable poly-α-hydroxyesters as peripheral nerve guidance conduits; a review of material properties, design strategies and their efficacy to date

Implantable tubular devices known as nerve guidance conduits (NGCs) have drawn considerable interest as an alternative to autografting in the repair of peripheral nerve injuries.

Trends and Cost Analysis of Upper Extremity Nerve Injury Using the National (Nationwide) Inpatient Sample

OBJECTIVE

Epidemiology in upper extremity peripheral nerve injury (PNI) has not been comprehensively evaluated. The aim of this study was to calculate updated incidence of upper extremity PNIs in the United States and examine clinical trends and costs using a national database.

METHODS

The National (Nationwide) Inpatient Sample was used to evaluate patients with upper extremity PNI (International Classification of Diseases, Ninth Revision, Clinical Modification 9534, 9550-9559) in 2001-2013.

RESULTS

A weighted total of 170,579 patients experienced upper extremity PNI, representing a mean incidence of 43.8/1 million people annually. Mean (± SEM) age of patients was 38.1 ± 0.05 years, 74.3% of patients were male, and 49.0% were Caucasian. PNIs occurred to the ulnar (17.8%), radial (15.1%), digital (18.0%), median (13.0%), multiple (11.5%), and other (10.1%) nerves and brachial plexus (14.5%). The number of upper extremity PNIs decreased overall. Average care charge was $47,004 ± $185, with an average increase of $4623/year and compound annual growth rate of 9.59%. Although surgical nerve repair and home disposition were common with isolated PNIs, patients with brachial plexus PNIs did not have nerve surgery and were more likely to be discharged to skilled nursing facilities. Multivariate analysis showed that length of stay (β = 0.677, P = 0.0001) and number of procedures (β = 0.188, P = 0.0001) most affected total patient charges.

CONCLUSIONS

These results suggest an overall decrease in number of PNIs, suggesting lower incidence or frequency of detection; however, the cost of care has increased. Despite advances in nerve repair techniques, nerve surgery rates have not increased, especially for brachial plexus injuries, which may be undertreated.

Current concepts in peripheral nerve surgery

The injuries of the peripheral nerves are relatively frequent. Some of them may lead to defects which cannot be repaired with direct end-to-end repair without tension. These injuries may cause function loss to the patient, and they consist a challenge for the treating microsurgeon. Autologous nerve grafts remain the gold standard for bridging the peripheral nerve defects. Nevertheless, there are selected cases where alternative types of nerve reconstruction can be performed in order to cover the peripheral nerve defects. In all these types of reconstruction, the basic principles of microsurgery are necessary and the surgeon should be aware of them in order to achieve a successful reconstruction. The purpose of the present review was to present the most current data concerning the surgical options available for bridging such defects.

The Physicochemical Properties of Decellularized Extracellular Matrix-Coated 3D Printed Poly(ε-caprolactone) Nerve Conduits for Promoting Schwann Cells Proliferation and Differentiation

Although autologous nerve grafting remains the gold standard treatment for peripheral nerve injuries, alternative methods such as development of nerve guidance conduits have since emerged and evolved to counter the many disadvantages of nerve grafting. However, the efficacy and viability of current nerve conduits remain unclear in clinical trials. Here, we focused on a novel decellularized extracellular matrix (dECM) and polydopamine (PDA)-coated 3D-printed poly(ε-caprolactone) (PCL)-based conduits, whereby the PDA surface modification acts as an attachment platform for further dECM attachment. We demonstrated that dECM/PDA-coated PCL conduits possessed higher mechanical properties when compared to human or animal nerves. Such modifications were proved to affect cell behaviors. Cellular behaviors and neuronal differentiation of Schwann cells were assessed to determine for the efficacies of the conduits. There were some cell-specific neuronal markers, such as Nestin, neuron-specific class III beta-tubulin (TUJ-1), and microtubule-associated protein 2 (MAP2) analyzed by enzyme-linked immunosorbent assay, and Nestin expressions were found to be 0.65-fold up-regulated, while TUJ1 expressions were 2.3-fold up-regulated and MAP2 expressions were 2.5-fold up-regulated when compared to Ctl. The methodology of PDA coating employed in this study can be used as a simple model to immobilize dECM onto PCL conduits, and the results showed that dECM/PDA-coated PCL conduits can as a practical and clinically viable tool for promoting regenerative outcomes in larger peripheral nerve defects.

Epidemiological characteristics of surgically treated civilian traumatic brachial plexus injuries in Serbia

BACKGROUND

Traumatic brachial plexus injuries are generally severe, and in many cases associated with surrounding tissue injuries, which makes them hard to diagnose at the right time. This paper presents etiological and epidemiological characteristics of surgically treated civilian traumatic brachial plexus injuries.

METHODS

This retrospective study included 68 patients, operated due to the traumatic brachial plexus injuries at Clinic for Neurosurgery, Clinical Center of Serbia, during the 11-year period.

RESULTS

The vast majority of injured patients were men in full working maturity. In our study, there were seven different etiological factors. The road traffic accidents were the most common-41 (60.3%), while the motorcycle accidents were the most dominant subtype (53.7%) of all road traffic accidents, and also representing 32.4% of all causes of trauma. Supraclavicular elements of the brachial plexus were injured in more than 80% of patients. A total of 49 (72.1%) patients from our study had one or more associated injuries. The most common associated injuries were bone fractures, brain contusions, and vascular injuries.

CONCLUSION

Although rare, non-war-related severe brachial plexus injuries represent a group of patients carrying high risk of insufficient functional recovery regardless of treatment modality, or surgical technique. Epidemiological and etiological data are therefore very important to identify the groups in risk and to induce preventive actions aimed at these patients.

Immediate Enhancement of Nerve Function Using a Novel Axonal Fusion Device After Neurotmesis

Background

The management of peripheral nerve injuries remains a large challenge for plastic surgeons. With the inability to fuse axonal endings, results after microsurgical nerve repair have been inconsistent. Our current nerve repair strategies rely upon the slow and lengthy process of axonal regeneration (~1 mm/d). Polyethylene glycol (PEG) has been investigated as a potential axonal fusion agent; however, the percentage of axonal fusion has been inconsistent. The purpose of this study was to identify a PEG delivery device to standardize outcomes after attempted axonal fusion with PEG.

Materials and Methods

We used a rat sciatic nerve injury model in which we completely transected and repaired the left sciatic nerve to evaluate the efficacy of PEG fusion over a span of 12 weeks. In addition, we evaluated the effectiveness of a delivery device's ability to optimize results after PEG fusion.

Results

We found that PEG rapidly (within minutes) restores axonal continuity as assessed by electrophysiology, fluorescent retrograde tracer, and diffusion tensor imaging. Immunohistochemical analysis shows that motor axon counts are significantly increased at 1 week, 4 weeks, and 12 weeks postoperatively in PEG-treated animals. Furthermore, PEG restored behavioral functions up to 50% compared with animals that received the criterion standard epineurial repair (control animals).

Conclusions

The ability of PEG to rapidly restore nerve function after neurotmesis could have vast implications on the clinical management of traumatic injuries to peripheral nerves.

Fas Ligand Gene (Faslg) Plays an Important Role in Nerve Degeneration and Regeneration After Rat Sciatic Nerve Injury

Wallerian degeneration (WD) is associated with changes in the expression levels of a large number of genes. However, the effects of these up- or down-regulated genes are poorly understood. We have reported some key factors that are differentially regulated during WD in our previous research. Here, we explored the roles of Fas ligand gene (Faslg) in WD after rat sciatic nerve injury. The data showed that Faslg was up-regulated in injured nerves. Expression changed of Faslg in Schwann cells (SCs) resulted in alterations in the release of related factors. Silencing or overexpression of Faslg affected SC proliferation, migration, and apoptosis through β-catenin, nuclear factor-κB (NF-κB), and caspase-3 pathways in vivo and in vitro. Our data suggest that Faslg is a key regulatory gene that affects nerve repair and regeneration in peripheral nerve injury. This study sheds new light on the effects of Faslg on peripheral nerve degeneration and/or regeneration.

Comparative Evaluation of Chitosan Nerve Guides with Regular or Increased Bendability for Acute and Delayed Peripheral Nerve Repair: A Comprehensive Comparison with Autologous Nerve Grafts and Muscle-in-Vein Grafts

Reconstruction of joint-crossing digital nerves requires the application of nerve guides with a much higher flexibility than used for peripheral nerve repair along larger bones. Nevertheless, collapse-resistance should be preserved to avoid secondary damage to the regrowing nerve tissue. In recent years, we presented chitosan nerve guides (CNGs) to be highly supportive for the regeneration of critical gap length peripheral nerve defects in the rat. Now, we evidently increased the bendability of regular CNGs (regCNGs) by developing a wavy wall structure, that is, corrugated CNGs (corrCNGs). In a comprehensive in vivo study, we compared both types of CNGs with clinical gold standard autologous nerve grafts (ANGs) and muscle-in-vein grafts (MVGs) that have recently been highlighted in the literature as a suitable alternative to ANGs. We reconstructed rat sciatic nerves over a critical gap length of 15 mm either immediately upon transection or after a delay period of 45 days. Electrodiagnostic measurements were applied to monitor functional motor recovery at 60, 90, 120, and 150 (only delayed repair) days postreconstruction. Upon explanation, tube properties were analyzed. Furthermore, distal nerve ends were evaluated using histomorphometry, while connective tissue specimens were subjected to immunohistological stainings. After 120 days (acute repair) or 150 days (delayed repair), respectively, compression-stability of regCNGs was slightly increased while it remained stable in corrCNGs. In both substudies, regCNGs and corrCNGs supported functional recovery of distal plantar muscles in a similar way and to a greater extent when compared with MVGs, while ANGs demonstrated the best support of regeneration. Anat Rec, 301:1697-1713, 2018. © 2018 Wiley Periodicals, Inc.

Nerve trauma of the lower extremity: evaluation of 60,422 leg injured patients from the TraumaRegister DGU® between 2002 and 2015

Background

Nerve lesions are well known reasons for reduced functional capacity and diminished quality of life. By now only a few epidemiological studies focus on lower extremity trauma related nerve injuries. This study reveals frequency and characteristics of nerve damages in patients with leg trauma in the European context.

Methods

Sixty thousand four hundred twenty-two significant limb trauma cases were derived from the TraumaRegister DGU® between 2002 and 2015. The TR-DGU is a multi- centre database of severely injured patients. We compared patients with additional nerve injury to those with intact neural structures for demographic data, trauma mechanisms, concomitant injuries, treatment and outcome parameters.

Results

Approximately 1,8% of patients with injured lower extremities suffer from additional nerve trauma. These patients were younger (mean age 38,1 y) and more likely of male sex (80%) compared to the patients without nerve injury (mean age 46,7 y; 68,4% male). This study suggests the peroneal nerve to be the most frequently involved neural structure (50,9%). Patients with concomitant nerve lesions generally required a longer hospital stay and exhibited a higher rate for subsequent rehabilitation. Peripheral nerve damage was mainly a consequence of motorbike (31,2%) and car accidents (30,7%), whereas leg trauma without nerve lesion most frequently resulted from car collisions (29,6%) and falls (29,8%).

Conclusion

Despite of its low frequency nerve injury remains a main cause for reduced functional capacity and induces high socioeconomic expenditures due to prolonged rehabilitation and absenteeism of the mostly young trauma victims. Further research is necessary to get insight into management and long term outcome of peripheral nerve injuries.

Schwann cell durotaxis can be guided by physiologically relevant stiffness gradients

Background

Successful nerve regeneration depends upon directed migration of morphologically specialized repair state Schwann cells across a nerve defect. Although several groups have studied directed migration of Schwann cells in response to chemical or topographic cues, the current understanding of how the mechanical environment influences migration remains largely understudied and incomplete. Therefore, the focus of this study was to evaluate Schwann cell migration and morphodynamics in the presence of stiffness gradients, which revealed that Schwann cells can follow extracellular gradients of increasing stiffness, in a form of directed migration termed durotaxis.

Methods

Polyacrylamide substrates were fabricated to mimic the range of stiffness found in peripheral nerve tissue. We assessed Schwann cell response to substrates that were either mechanically uniform or embedded with a shallow or steep stiffness gradient, respectively corresponding to the mechanical niche present during either the fluid phase or subsequent matrix phase of the peripheral nerve regeneration process. We examined cell migration (velocity and directionality) and morphology (elongation, spread area, nuclear aspect ratio, and cell process dynamics). We also characterized the surface morphology of Schwann cells by scanning electron microscopy.

Results

On laminin-coated polyacrylamide substrates embedded with either a shallow (∼0.04 kPa/mm) or steep (∼0.95 kPa/mm) stiffness gradient, Schwann cells displayed durotaxis, increasing both their speed and directionality along the gradient materials, fabricated with elastic moduli in the range found in peripheral nerve tissue. Uniquely and unlike cell behavior reported in other cell types, the durotactic response of Schwann cells was not dependent upon the slope of the gradient. When we examined whether durotaxis behavior was accompanied by a pro-regenerative Schwann cell phenotype, we observed altered cell morphology, including increases in spread area and the number, elongation, and branching of the cellular processes, on the steep but not the shallow gradient materials. This phenotype emerged within hours of the cells adhering to the materials and was sustained throughout the 24 hour duration of the experiment. Control experiments also showed that unlike most adherent cells, Schwann cells did not alter their morphology in response to uniform substrates of different stiffnesses.

Conclusion

This study is notable in its report of durotaxis of cells in response to a stiffness gradient slope, which is greater than an order of magnitude less than reported elsewhere in the literature, suggesting Schwann cells are highly sensitive detectors of mechanical heterogeneity. Altogether, this work identifies durotaxis as a new migratory modality in Schwann cells, and further shows that the presence of a steep stiffness gradient can support a pro-regenerative cell morphology.

Electronic supplementary material

The online version of this article (10.1186/s40824-018-0124-z) contains supplementary material, which is available to authorized users.

Ultrasound Diagnosis of Postoperative Complications of Nerve Repair

BACKGROUND

Peripheral nerve injuries often undergo surgical repair, but poor postoperative functional recovery is frequently observed.

CASE DESCRIPTION

We describe 4 cases of traumatic nerve lesions in whom postoperative recovery was prevented by complications such as detachment of nerve sutures or neuroma growth. To the best of our knowledge, no similar cases have been reported in literature so far. It is important to obtain an early diagnosis of such condition because it prevents recovery and delays reintervention, which should be performed before complete muscle denervation and atrophy.

CONCLUSION

Nerve ultrasound is a valuable tool in traumatic nerve injury and has proven to be useful in postoperative follow-up, especially in diagnosing surgical complications such as detachment of nerve direct sutures.

The role of undifferentiated adipose-derived stem cells in peripheral nerve repair

Peripheral nerve injuries impose significant health and economic consequences, yet no surgical repair can deliver a complete recovery of sensory or motor function. Traditional methods of repair are less than ideal: direct coaptation can only be performed when tension-free repair is possible, and transplantation of nerve autograft can cause donor-site morbidity and neuroma formation. Cell-based therapy delivered via nerve conduits has thus been explored as an alternative method of nerve repair in recent years. Stem cells are promising sources of the regenerative core material in a nerve conduit because stem cells are multipotent in function, abundant in supply, and more accessible than the myelinating Schwann cells. Among different types of stem cells, undifferentiated adipose-derived stem cell (uASC), which can be processed from adipose tissue in less than two hours, is a promising yet underexplored cell type. Studies of uASC have emerged in the past decade and have shown that autologous uASCs are non-immunogenic, easy to access, abundant in supply, and efficacious at promoting nerve regeneration. Two theories have been proposed as the primary regenerative mechanisms of uASC: in situ trans-differentiation towards Schwann cells, and secretion of trophic and anti-inflammatory factors. Future studies need to fully elucidate the mechanisms, side effects, and efficacy of uASC-based nerve regeneration so that uASCs can be utilized in clinical settings.

Adult Stem Cell-Based Strategies for Peripheral Nerve Regeneration

Peripheral nerve injuries (PNI) occur as the result of sudden trauma and can lead to life-long disability, reduced quality of life, and heavy economic and social burdens. Although the peripheral nervous system (PNS) has the intrinsic capacity to regenerate and regrow axons to a certain extent, current treatments frequently show incomplete recovery with poor functional outcomes, particularly for large PNI. Many surgical procedures are available to halt the propagation of nerve damage, and the choice of a procedure depends on the extent of the injury. In particular, recovery from large PNI gaps is difficult to achieve without any therapeutic intervention or some form of tissue/cell-based therapy. Autologous nerve grafting, considered the "gold standard" is often implemented for treatment of gap formation type PNI. Although these surgical procedures provide many benefits, there are still considerable limitations associated with such procedures as donor site morbidity, neuroma formation, fascicle mismatch, and scarring. To overcome such restrictions, researchers have explored various avenues to improve post-surgical outcomes. The most commonly studied methods include: cell transplantation, growth factor delivery to stimulate regenerating axons and implanting nerve guidance conduits containing replacement cells at the site of injury. Replacement cells which offer maximum benefits for the treatment of PNI, are Schwann cells (SCs), which are the peripheral glial cells and in part responsible for clearing out debris from the site of injury. Additionally, they release growth factors to stimulate myelination and axonal regeneration. Both primary SCs and genetically modified SCs enhance nerve regeneration in animal models; however, there is no good source for extracting SCs and the only method to obtain SCs is by sacrificing a healthy nerve. To overcome such challenges, various cell types have been investigated and reported to enhance nerve regeneration.In this review, we have focused on cell-based strategies aimed to enhance peripheral nerve regeneration, in particular the use of mesenchymal stem cells (MSCs). Mesenchymal stem cells are preferred due to benefits such as autologous transplantation, routine isolation procedures, and paracrine and immunomodulatory properties. Mesenchymal stem cells have been transplanted at the site of injury either directly in their native form (undifferentiated) or in a SC-like form (transdifferentiated) and have been shown to significantly enhance nerve regeneration. In addition to transdifferentiated MSCs, some studies have also transplanted ex-vivo genetically modified MSCs that hypersecrete growth factors to improve neuroregeneration.

Biodegradable Bisvinyl Sulfonemethyl-crosslinked Gelatin Conduit Promotes Regeneration after Peripheral Nerve Injury in Adult Rats

In our previous study, we found that gelatin-based materials exhibit good conductivity and are non-cytotoxic. In this study, gelatin was cross-linked with bisvinyl sulfonemethyl (BVSM) to fabricate a biodegradable conduit for peripheral nerve repair. First, BVSM on the prepared conduit was characterized to determine its mechanical properties and contact angle. The maximum tensile strength and water contact angle of the gelatin-BVSM conduits were 23 ± 4.8 MPa and 74.7 ± 9°, which provided sufficient mechanical strength to resist muscular contraction; additionally, the surface was hydrophilic. Cytotoxicity and apoptosis assays using Schwann cells demonstrated that the gelatin-BVSM conduits are non-cytotoxic. Next, we examined the neuronal electrophysiology, animal behavior, neuronal connectivity, macrophage infiltration, calcitonin gene-related peptide localization and expression, as well as the expression levels of nerve regeneration-related proteins. The number of fluorogold-labelled cells and histological analysis of the gelatin-BVSM nerve conduits was similar to that observed with the clinical use of silicone rubber conduits after 8 weeks of repair. Therefore, our results demonstrate that gelatin-BVSM conduits are promising substrates for application as bioengineered grafts for nerve tissue regeneration.

The effect of co-transplantation of nerve fibroblasts and Schwann cells on peripheral nerve repair

Combinations of fibroblasts (Fbs) and corresponding epithelial cells have been widely used in many tissues, such as the skin and breast tissues, to augment tissue repair and remodeling. Recently, a large amount of new data has indicated that nerve Fbs play critical roles in Schwann cells (SCs) and axons in vitro. However, little is known regarding the effects of co-transplanting nerve Fbs and SCs on peripheral nerve repair in vivo. The aim of this study was to investigate the effect of co-transplanting sciatic nerve Fbs (SN-Fbs) and sciatic nerve SCs (SN-SCs) on nerve regeneration. We developed a 5 mm nerve-defect model in mice using a polyurethane (PUR) catheter and then injected one of four different mixtures of cells into the catheters to form the following four groups: pure Matrigel (Control group), SN-Fbs alone (SN-Fb group), SN-Fbs combined with SN-SCs at a ratio of 1:2 (Fb&SC group) and SN-SCs alone (SN-SC group). Histological and functional analyses were performed 3 months later. The results indicated that in vitro, the expression levels of NGF, BDNF and GDNF were significantly higher, and in vivo, a more moderate amount of extracellular matrix was produced in the Fb&SC group than in the SN-SC group. Compared to the other groups, co-transplanting SN-Fbs with SCs at a 1:2 ratio had significantly positive effects on nerve regeneration and functional recovery.

Optimal timing for repair of peripheral nerve injuries

BACKGROUND

Data regarding outcomes after peripheral nerve injuries is limited, and the optimal management strategy for an acute injury is unclear. The aim of this study was to examine timing of repair and specific factors that impact motor-sensory outcomes after peripheral nerve injury.

METHODS

This was a single-center, retrospective study. Patients with traumatic peripheral nerve injury from January 2010 to June 2015 were included. Patients who died, required amputation, suffered brachial plexus injury, or had missing motor-sensory examinations were excluded. Motor-sensory examinations were graded 0 to 5 by the Modified British Medical Research Council system. Operative repair of peripheral nerves was analyzed for patient characteristics, anatomic nerve injured, level of injury, associated injuries, days until repair, and repair method.

RESULTS

Three hundred eleven patients met inclusion criteria. Two hundred fifty-eight (83%) patients underwent operative management, and 53 (17%) underwent nonoperative management. Those who required operative intervention had significantly more penetrating injuries 85.7% versus 64.2% (p < 0.001), worse initial motor scores 1.19 versus 2.23 (p = 0.004), and worse initial sensory examination scores 1.75 versus 2.28 (p = 0.029). Predictors of improved operative motor outcomes on univariate analysis were Injury Severity Score less than 15 (p = 0.013) and male sex (p = 0.006). Upper arm level of injury was a predictor of poor outcome (p = 0.041). Multivariate analysis confirmed male sex as a predictor of good motor outcome (p = 0.014; Adjusted Odds Ratio, 3.88 [1.28-11.80]). Univariate analysis identified distal forearm level of injury (p = 0.026) and autograft repair (p = 0.048) as predictors of poor sensory outcome. Damage control surgery for unstable patients undergoing laparotomy (p = 0.257) and days to nerve repair (p = 0.834) did not influence motor-sensory outcome. Outcomes did not differ significantly in patients who underwent repair 24 hours or longer versus those who were repaired later.

CONCLUSION

Outcomes were primarily influenced by patient characteristics and injury level rather than operative characteristics. Peripheral nerve injuries can be repaired after damage control surgery without detriment to outcomes.

LEVEL OF EVIDENCE

Prognostic study, level III.

Comparative study between standard and inside-out vein graft techniques on sciatic nerve repair of rats. Muscular and functional analysis

Purpose:

To compare the functional result of standart vein grafts and inside-out vein graft technique on sciatic nerve repair.

Methods:

We used 24 male Wistar rats divided into 4 groups: control group (CG), standard vein graft group (SVG), Inside-out vein graft group (IOVG) and denervated Group (DG). SVG, IOVG and DG underwent total section of the sciatic nerve, SVG and IOVG however underwent nerve repair surgery using a graft with normal jugular vein and inside-out jugular vein, respectively. Histological analysis of the soleus and Extensor Digitorum Longus (EDL), and Sciatic Functional Index were used to compare the results after 6 weeks.

Results:

Both grafts acted favorably in muscle recovery and improved functionality; They were similar in all parameters, however, in more points SVG achieved similar to the CG, in the other hand IOVG more times was similar to DG. Fact that makes the graft with normal vein the most viable option between the two options.

Conclusion:

Both types of grafts acted beneficially wherein the graft normal vein has proved to be the best option.

Reflex-based grasping, skilled forelimb reaching, and electrodiagnostic evaluation for comprehensive analysis of functional recovery-The 7-mm rat median nerve gap repair model revisited

INTRODUCTION

The rat median nerve injury and repair model gets increasingly important for research on novel bioartificial nerve grafts. It allows follow-up evaluation of the recovery of the forepaw functional ability with several sensitive techniques. The reflex-based grasping test, the skilled forelimb reaching staircase test, as well as electrodiagnostic recordings have been described useful in this context. Currently, no standard values exist, however, for comparison or comprehensive correlation of results obtained in each of the three methods after nerve gap repair in adult rats.

METHODS

Here, we bilaterally reconstructed 7-mm median nerve gaps with autologous nerve grafts (ANG) or autologous muscle-in-vein grafts (MVG), respectively. During 8 and 12 weeks of observation, functional recovery of each paw was separately monitored using the grasping test (weekly), the staircase test, and noninvasive electrophysiological recordings from the thenar muscles (both every 4 weeks). Evaluation was completed by histomorphometrical analyses at 8 and 12 weeks postsurgery.

RESULTS

The comprehensive evaluation detected a significant difference in the recovery of forepaw functional motor ability between the ANG and MVG groups. The correlation between the different functional tests evaluated precisely displayed the recovery of distinct levels of forepaw functional ability over time.

CONCLUSION

Thus, this multimodal evaluation model represents a valuable preclinical model for peripheral nerve reconstruction approaches.

Predictors of Nerve Injury After Gunshot Wounds to the Upper Extremity

BACKGROUND

The purpose of this study is to examine the incidence of nerve injury, clinical variables associated with nerve palsy, and predictive factors of nerve laceration after gunshot wounds to the upper extremity.

METHODS

Forty-one patients from a level I trauma center with gunshot wounds to the upper extremity who underwent surgical exploration between 2007 and 2014 were identified retrospectively. Patients with proximal ipsilateral injuries, inadequate documentation, imaging, or with a pre-existing neurologic deficit were excluded. Patient demographics, clinical sensory and motor examination, the presence of retained bullet fragments, fracture, vascular injury, and compartment syndrome were recorded. Univariate analysis was performed to determine significant predictors of intraoperative nerve laceration. Significance was set at P < .05.

RESULTS

Fifty-nine nerves were explored in 41 patients. There were higher frequencies of fractures, retained fragments, vascular injury, and compartment syndrome in patients with nerve palsies, although none were associated with nerve laceration. Patients with palsies on presentation were significantly more likely to have a nerve laceration found intraoperatively.

CONCLUSIONS

Gunshot wounds to the upper extremity with focal nerve deficits remain a difficult problem for orthopedic surgeons. The present study provides evidence that may help guide operative decision making in treatment of these injuries.

Stab injury to the preauricular region with laceration of the external carotid artery without involvement of the facial nerve: a case report

Background

Open injuries to the face involving the external carotid artery are uncommon. These injuries are normally associated with laceration of the facial nerve because this nerve is more superficial than the external carotid artery. Hence, external carotid artery lesions are usually associated with facial nerve dysfunction. We present an unusual case report in which the patient had an injury to this artery with no facial nerve compromise.

Case presentation

A 25-year-old Portuguese man sustained a stab wound injury to his right preauricular region with a broken glass. Immediate profuse bleeding ensued. Provisory tamponade of the wound was achieved at the place of aggression by two off-duty doctors. He was initially transferred to a district hospital, where a large arterial bleeding was observed and a temporary compressive dressing was applied. Subsequently, the patient was transferred to a tertiary hospital. At admission in the emergency room, he presented a pulsating lesion in the right preauricular region and slight weakness in the territory of the inferior buccal branch of the facial nerve. The physical examination suggested an arterial lesion superficial to the facial nerve. However, in the operating theater, a section of the posterior and lateral flanks of the external carotid artery inside the parotid gland was identified. No lesion of the facial nerve was observed, and the external carotid artery was repaired. To better understand the anatomical rationale of this uncommon clinical case, we dissected the preauricular region of six cadavers previously injected with colored latex solutions in the vascular system. A small triangular space between the two main branches of division of the facial nerve in which the external carotid artery was not covered by the facial nerve was observed bilaterally in all cases.

Conclusions

This clinical case illustrates that, in a preauricular wound, the external carotid artery can be injured without facial nerve damage. However, no similar description was found in the reviewed literature, which suggests that this must be a very rare occurrence. According to the dissection study performed, this is due to the existence of a triangular space between the cervicofacial and temporofacial nerve trunks in which the external carotid artery is not covered by the facial nerve or its branches.

Open surgical implantation of a viable cryopreserved placental membrane after decompression and neurolysis of common peroneal nerve: a case series

Background

The purpose of this study is to report on the rehabilitative outcomes associated with common peroneal nerve (CPN) decompression and neurolysis revision when performed with open surgical implantation of a viable cryopreserved placental membrane (vCPM).

Methods

Seven patients who underwent secondary CPN decompression and neurolysis with open surgical implantation of a viable cryopreserved placental membrane (vCPM) after previously failed surgery without vCPM utilization were identified through a retrospective medical record review and outcomes were analyzed. Primary mechanism of injury, severity of symptoms at time of referral, pre-operative and post-operative evaluations on edema with ultrasound, Medical Research Council (MRC) scale for motor strength, range of motion, nerve conduction velocity (NCV), and electromyography (EMG) were analyzed.

Results

Five patients (71.4%) achieved full recovery of motor function MRC grade 5/5, and the remaining two patients achieved MRC grade 4/5. At the 7-month follow-up visit, NCV tests indicated improved conduction velocity and normal amplitude for all 7 patients, and all patients demonstrated proper gait pattern with a return to normal activities of daily living. There were no vCPM-related adverse events.

Conclusions

The use of vCPM wrap as an adjunct to surgical repairs of CPN injuries may contribute to positive clinical outcomes.

The Effects of Two Different Exercise Programs on the Ultrastructural Features of the Sciatic Nerve and Soleus Muscle After Sciatic Crush

Peripheral nerve injuries constitute a significant medical problem and the recovery is critically dependent on post-injury treatment. In this study, following sciatic nerve crush, we investigated the effects of a 4-week endurance training program (ET) and balance and coordination training program (BCT) on the ultrastructural features of the sciatic nerve and soleus muscle. The animals were randomly divided into Sham, non-trained (NT), ET, and BCT groups each of which included three animals. Ultra-thin cross and longitudinal sections (70-85 nm) were digitized and analyzed comparatively. The electron micrographic analysis of the sciatic nerve showed similar organelles features in the injury groups (myelin debris and swelling mitochondria). Nonetheless, the ET group presented better ultrastructural features as demonstrated by the greater predominance of rounded fibers and more defined organization in the myelinated axon bundles. In the soleus muscle's analyses, the injured groups demonstrated similar organelles' features (nucleus contained highly heterochromatic nuclei and smaller mitochondria). However, ET and BCT groups showed apparently enlarged myofibril cross-sectional areas and less collagen around muscle fibers, although, the ET group displayed reduced intermyofibrillar spaces and more closely aligned myofilaments when compared with the BCT group. Based on electron micrographic analysis, our findings suggest the presence of ultrastructural differences between the Sham, NT, and the trained groups. Therefore, exercise type seems to be responsible for producing some different positive features in the trained groups, while ET seems to have a more pronounced influence on the ultrastructural features of the sciatic nerve and the soleus muscle after a crush injury. Anat Rec, 300:1654-1661, 2017. © 2017 Wiley Periodicals, Inc.

Median and ulnar nerve injuries reduce volitional forelimb strength in rats

INTRODUCTION

Peripheral nerve injuries (PNI) are among the leading causes of physical disability in the United States. The majority of injuries occur in the upper extremities, and functional recovery is often limited. Robust animal models are critical first steps for developing effective therapies to restore function after PNI.

METHODS

We developed an automated behavioral assay that provides quantitative measurements of volitional forelimb strength in rats. Multiple forelimb PNI models involving the median and ulnar nerves were used to assess forelimb function for up to 13 weeks postinjury.

RESULTS

Despite multiple weeks of task-oriented training following injury, rats exhibit significant reductions in multiple quantitative parameters of forelimb function, including maximal pull force and speed of force generation.

DISCUSSION

This study demonstrates that the isometric pull task is an effective method of evaluating forelimb function following PNI and may aid in development of therapeutic interventions to restore function. Muscle Nerve 56: 1149-1154, 2017.

Combining Gene and Stem Cell Therapy for Peripheral Nerve Tissue Engineering

Despite a substantially increased understanding of neuropathophysiology, insufficient functional recovery after peripheral nerve injury remains a significant clinical challenge. Nerve regeneration following injury is dependent on Schwann cells, the supporting cells in the peripheral nervous system. Following nerve injury, Schwann cells adopt a proregenerative phenotype, which supports and guides regenerating nerves. However, this phenotype may not persist long enough to ensure functional recovery. Tissue-engineered nerve repair devices containing therapeutic cells that maintain the appropriate phenotype may help enhance nerve regeneration. The combination of gene and cell therapy is an emerging experimental strategy that seeks to provide the optimal environment for axonal regeneration and reestablishment of functional circuits. This review aims to summarize current preclinical evidence with potential for future translation from bench to bedside.

Experimental immunological demyelination enhances regeneration in autograft-repaired long peripheral nerve gaps

Peripheral nerve long gap defects are a clinical challenge in the regeneration field. Despite the wide variety of surgical techniques and therapies, autografting is the "gold standard" for peripheral nerve gap reconstruction. The pathological process of Wallerian degeneration from the time of acute injury to efficient regeneration requires several weeks. Regeneration time is critical for nerve reconstruction. Immunological demyelination induced by anti-galactocerebroside antibodies plus guinea pig complement was used to shorten the treatment time. Based on an antigen-antibody complex reaction, the demyelinating agent induced an acute and severe demyelination, leading to the pathological process of Wallerian degeneration during the demyelinating period. This method was used to treat a 12 mm-long sciatic nerve defect in rats. The control groups were injected with one of the demyelinating agent components. The results indicated that anti-galactocerebroside antibodies plus guinea pig complement can significantly shorten treatment time and promote nerve regeneration and functional recovery. In addition, the demyelinating agent can increase the mRNA levels of nerve growth factors and can regulate inflammation. In conclusion, treatment with anti-galactocerebroside antibodies plus guinea pig complement can promote axonal regeneration. This therapy provides a novel method to improve functional recovery in the treatment of long nerve defects.

RetroDISCO: Clearing technique to improve quantification of retrograde labeled motor neurons of intact mouse spinal cords

BACKGROUND

Quantification of the number of axons reinnervating a target organ is often used to assess regeneration after peripheral nerve repair, but because of axonal branching, this method can overestimate the number of motor neurons regenerating across an injury. Current methods to count the number of regenerated motor neurons include retrograde labeling followed by cryosectioning and counting labeled motor neuron cell bodies, however, the process of sectioning introduces error from potential double counting of cells in adjacent sections.

NEW METHOD

We describe a method, retroDISCO, that optically clears whole mouse spinal cord without loss of fluorescent signal to allow imaging of retrograde labeled motor neurons using confocal microscopy.

RESULTS

Complete optical clearing of spinal cords takes four hours and confocal microscopy can obtain z-stacks of labeled motor neuron pools within 3-5min. The technique is able to detect anticipated differences in motor neuron number after cross-suture and conduit repair compared to intact mice and is highly repeatable.

COMPARISON WITH EXISTING METHOD

RetroDISCO is inexpensive, simple, robust and uses commonly available microscopy techniques to determine the number of motor neurons extending axons across an injury site, avoiding the need for labor-intensive cryosectioning and potential double counting of motor neuron cell bodies in adjacent sections.

CONCLUSIONS

RetroDISCO allows rapid quantification of the degree of reinnervation without the confounding produced by axonal sprouting.

Repeated bouts of fast eccentric contraction produce sciatic nerve damage in rats

INTRODUCTION

We evaluated sciatic nerve impairment after eccentric contractions (ECs) in rat triceps surae.

METHODS

Wistar rats were randomly assigned to different joint angular velocity: 180°/s (FAST), 30°/s (SLOW), or nontreated control (CNT). FAST and SLOW groups were subjected to multiple (1-4) bouts of 20 (5 reps, 4 sets) ECs. Nerve conduction velocity (NCV) and isometric tetanic ankle torque were measured 24 h after each ECs bout. We also assessed nerve morphology.

RESULTS

After 4 ECs bouts, NCVs and isometric torque in the FAST group were significantly lower than those in the CNT (NCV: 42%, torque: 66%; P < 0.05). After 4 bouts, average nerve diameter was significantly smaller in the FAST group [2.39 ± 0.20 μm vs. 2.69 ± 0.20 μm (CNT) and 2.93 ± 0.24 μm (SLOW); P < 0.05] than that in other two groups.

CONCLUSIONS

Chronic ECs with high angular velocity induce serious nerve damage. Muscle Nerve 54: 936-942, 2016.

Effects of age and insulin-like growth factor-1 on rat neurotrophin receptor expression after nerve injury

INTRODUCTION

Neurotrophin receptors, such as p75(NTR) , direct neuronal response to injury. Insulin-like growth factor-1 receptor (IGF-1R) mediates the increase in p75(NTR) during aging. The aim of this study was to examine the effect of aging and insulin-like growth factor-1 (IGF-1) treatment on recovery after peripheral nerve injury.

METHODS

Young and aged rats underwent tibial nerve transection with either local saline or IGF-1 treatment. Neurotrophin receptor mRNA and protein expression were quantified.

RESULTS

Aged rats expressed elevated baseline IGF-1R (34% higher, P = 0.01) and p75(NTR) (68% higher, P < 0.01) compared with young rats. Post-injury, aged animals expressed significantly higher p75(NTR) levels (68.5% above baseline at 4 weeks). IGF-1 treatment suppressed p75(NTR) gene expression at 4 weeks (17.2% above baseline, P = 0.002) post-injury.

CONCLUSIONS

Local IGF-1 treatment reverses age-related declines in recovery after peripheral nerve injuries by suppressing p75(NTR) upregulation and pro-apoptotic complexes. IGF-1 may be considered a viable adjuvant therapy to current treatment modalities. Muscle Nerve 54: 769-775, 2016.

Electrophysiological Predictors of Clinical Outcome in Traumatic Neuropathies: A Multicenter Prospective Study

Objectives. This prospective, observational, multicentre study aims to identify electrodiagnostic (EDX) markers of clinical recovery in patients with traumatic neuropathy (TN) receiving surgical (S) and nonsurgical (NS) treatments. Methods. Subjects referred to the Italian Traumatic Neuropathy Network between 2010 and 2011 (307 patients, for a total of 444 TN) were evaluated with serial clinical/EDX evaluations at 6, 12, 24, and 36 months of follow-up. Results. Primary surgery was performed in 21 subjects with open lesions and evidence of neurotmesis, while closed lesions were treated with either conservative medical approach (216 patients) or secondary surgery (70 patients), according to the clinical spontaneous recovery at 4–6 months. Clinical improvement correlated with the increase of the compound muscle action potential amplitude (OR 3.76; CI 1.61–8.76), particularly in the S group (OR 7.25; CI 1.2–43.87), and with sensory nerve action potential amplitude in the NS group (OR 4.35; CI 1.14–16.69). No correlations were found with needle electromyography qualitative evaluations, changes in maximal voluntary recruitment, age, and gender. Conclusions. Nerve conduction studies (NCS) represent the more accurate neurophysiological markers of clinical outcome in patients with TN. Significance. Serial NCS assessments predict the functional recovery in TN, increasing the accuracy of peripheral nerves surgical decision-making process.

Nerve injuries of the upper extremity associated with vascular trauma-surgical treatment and outcome

Peripheral nerve injuries are often associated with injuries of adjacent tissue. As a result of anatomic proximity between nerves and vascular structures, there is a high chance of combined injuries of these structures (23 %). The aim of our study is to describe and analyze associated nerve and vascular injuries of the upper extremity in patients treated at the Clinic of Neurosurgery in Belgrade over a 10-year period. This study included 83 patients that received surgical treatment at the Clinic of Neurosurgery in Belgrade after having been diagnosed with upper extremity nerve injury. The study included all patients that satisfied these criteria over a period of 10 years. The patients with associated vascular injuries, 36 of them, were considered our study group, while 47 patients without associated vascular injuries were considered our control group. Finally, we compared treatment outcome between these groups. The final outcome evaluation was performed 2 years after surgical treatment. In our study group, 84.8 % surgical nerve repair was successful (fair, good, and excellent outcome), while in the control group (patients without vascular injury), surgical nerve repair was successful in 87.9 %. The overall satisfactory neurological outcome (M3-M5) was present in 86.6 % of nerve repairs. Our study shows that there is no significant difference between the treatment outcome in patients with associated nerve and vascular injuries and patients with isolated nerve injuries if they are diagnosed in time and treated appropriately. Successful treatment can only be accomplished through a multidisciplinary approach undertaken by a highly qualified medical team.

Effects of hyaluronic acid and tacrolimus on the prevention of perineural scar formation and on nerve regeneration after sciatic nerve repair in a rabbit model

PURPOSE

Scar formation after injured peripheral nerve repair is a significant clinical problem because it prevents nerve regeneration. The aim of this study was to investigate and compare the effects of hyaluronic acid (HA) and tacrolimus (FK506) on peripheral nerve regeneration in rabbits after the drugs were topically applied at the site of nerve repair.

METHODS

Thirty adult male European rabbits (Oryctolagus cuniculus), ranging in weight from 2.5 to 3 kg, were randomly assigned to three groups: the HA and FK506 groups comprised the experimental groups, while the saline group served as the control. At week 12, macroscopic and microscopic evaluations were performed and analyzed.

RESULTS

In general, the macroscopic evaluations (skin and muscle fascia closure and nerve adherence), microscopic evaluations (cellular components, scar tissue formation index, and histomorphological organization), and measurements of nerve diameter and gastrocnemius muscle wet weight demonstrated the positive effects of topical application of these pharmacological agents (HA and FK506); HA and FK506 prevented scar formation and enhanced nerve regeneration. No significant differences in the parameters described above were observed between the HA and FK506 groups (P > 0.05). However, significant differences were observed between both the HA and FK506 groups and the saline group (P < 0.05).

CONCLUSION

Based on our findings, topical application of HA and FK506 exhibits equally positive effects, preventing perineural scar formation and enhancing nerve regeneration after peripheral nerve repair.

Peripheral nerve injuries: Long term follow-up results of rehabilitation

BACKGROUND

Peripheral nerve injury (PNI) is a common problem in the world resulting with severe disability. Etiological data is different in studies because of the study period, patient population, economic status, and workplace safety policies of the different countries.

OBJECTIVE

To define epidemiological and etiological data of our patients with peripheral nerve injury and to identify factors influencing efficacy of rehabilitation methods and recovery.

METHODS

Patients were compared by means of electromyography and muscle strength changes. Influence of orthotics use, disease interval and type of physical therapy (electrical stimulation or EMG biofeedback) was assessed.

RESULTS

There was no significant difference between groups. But we found weak correlation between EMG and motor changes. There was no difference in EMG and motor score changes in terms of orthotics use and type of physical therapy. When the patients were grouped according to EMG changes, we found significant difference by disease interval. Disease interval was longest in patients with no change in EMG. When the patients were grouped according to motor score changes, there was no significant difference by disease interval.

CONCLUSION

Etiology of the patients didn't affect long term results in peripheral nerve injury. The results of this study might help rehabilitation teams to guide their follow-up.