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

Polyethylene Glycol-Fusion Repair of Peripheral Nerve Injuries

Axons successfully repaired with polyethylene glycol (PEG) fusion tecnology restored axonal continuity thereby preventing their Wallerian degeneration and minimizing muscle atrophy. PEG fusion studies in animal models and preliminary clinical trials involving patients with digital nerve repair have shown promise for this therapeutic approach. PEG fusion is safe to perform, and given the enormous potential benefits, there is no reason not to explore its therapeutic potential.

Patient Outcomes After Peripheral Nerve Injury Depend on Bimanual Dexterity and Preserved Use of the Affected Hand

BACKGROUND

Little is known about how peripheral nerve injury affects human performance, behavior, and life. Hand use choices are important for rehabilitation after unilateral impairment, but rarely measured, and are not changed by the normal course of rehabilitation and daily life.

OBJECTIVE

To identify the relationship between hand use (L/R choices), motor performance, and patient-centered outcomes.

METHODS

Participants (n = 48) with unilateral peripheral nerve injury were assessed for hand use via Block Building Task, Motor Activity Log, and Edinburgh Handedness Inventory; dexterity (separately for each hand) via Nine-Hole Peg Test, Jebsen Taylor Hand Function Test, and a precision drawing task; patient-centered outcomes via surveys of disability, activity participation, and health-related quality of life; and injury-related factors including injury cause and affected nerve. Factor Analysis of Mixed Data was used to explore relationships between these variables. The data were analyzed under 2 approaches: comparing dominant hand (DH) versus non-dominant hand (NH), or affected versus unaffected hand.

RESULTS

The data were best explained by 5 dimensions. Good patient outcomes were associated with NH performance, DH performance (separately and secondarily to NH performance), and preserved function and use of the affected hand; whereas poor patient outcomes were associated with preserved but unused function of the affected hand.

CONCLUSION

After unilateral peripheral nerve injury, hand function, hand usage, and patient life arise from a complex interaction of many factors. To optimize rehabilitation after unilateral impairment, new rehabilitation methods are needed to promote performance and use with the NH, as well as the injured hand.

The Muscle Shortening Maneuver: a noninvasive approach to the treatment of peroneal nerve injury. A case report

BACKGROUND

The treatment of peripheral nerve injuries is a debated topic. The Muscle Shortening Maneuver (MSM), a physiotherapy approach, is noninvasive and free of side effects; it consists of a muscle shortening and a solicitation in traction applied simultaneously.

OBJECTIVE

The focus of this report is to describe the effects of the MSM combined with walking retraining in a patient with incomplete injury of the peroneal nerve.

DESCRIPTION

The patient was a 17-year-old man, who underwent osteotomy surgery of the proximal two-thirds of the fibula, due to an Ewing sarcoma that caused a partial injury of the left peroneal nerve. Our assessment plan of the left ankle movement ability comprised range of movement, muscle strength, and surface electromyography (EMG); and a gait analysis was conducted by using an iPhone application. MSM and walking retraining were administered twice and once a week, respectively, for 4 weeks.

OUTCOMES

The active range of movement substantially improved in dorsiflexion (≥15°), whereas slightly decreased in plantar flexion (-5°). Aside from the tibialis anterior, an increase in muscle strength was detected. Surface EMG showed an increased activation, particularly in the peroneus longus. A decrease in gait speed and step length was recorded from the gait analysis, with a better bilateral symmetry.

CONCLUSIONS

Positive outcomes were reported without evidence of risk or adverse events for the participant.

Repair and regeneration of peripheral nerve injuries that ablate branch points

The peripheral nervous system has an extensive branching organization, and peripheral nerve injuries that ablate branch points present a complex challenge for clinical repair. Ablations of linear segments of the PNS have been extensively studied and routinely treated with autografts, acellular nerve allografts, conduits, wraps, and nerve transfers. In contrast, segmental-loss peripheral nerve injuries, in which one or more branch points are ablated so that there are three or more nerve endings, present additional complications that have not been rigorously studied or documented. This review discusses: (1) the branched anatomy of the peripheral nervous system, (2) case reports describing how peripheral nerve injuries with branched ablations have been surgically managed, (3) factors known to influence regeneration through branched nerve structures, (4) techniques and models of branched peripheral nerve injuries in animal models, and (5) conclusions regarding outcome measures and studies needed to improve understanding of regeneration through ablated branched structures of the peripheral nervous system.

Graphene-Based Materials Prove to Be a Promising Candidate for Nerve Regeneration Following Peripheral Nerve Injury

Peripheral nerve injury is a common medical condition that has a great impact on patient quality of life. Currently, surgical management is considered to be a gold standard first-line treatment; however, is often not successful and requires further surgical procedures. Commercially available FDA- and CE-approved decellularized nerve conduits offer considerable benefits to patients suffering from a completely transected nerve but they fail to support neural regeneration in gaps > 30 mm. To address this unmet clinical need, current research is focused on biomaterial-based therapies to regenerate dysfunctional neural tissues, specifically damaged peripheral nerve, and spinal cord. Recently, attention has been paid to the capability of graphene-based materials (GBMs) to develop bifunctional scaffolds for promoting nerve regeneration, often via supporting enhanced neural differentiation. The unique features of GBMs have been applied to fabricate an electroactive conductive surface in order to direct stem cells and improve neural proliferation and differentiation. The use of GBMs for nerve tissue engineering (NTE) is considered an emerging technology bringing hope to peripheral nerve injury repair, with some products already in preclinical stages. This review assesses the last six years of research in the field of GBMs application in NTE, focusing on the fabrication and effects of GBMs for neurogenesis in various scaffold forms, including electrospun fibres, films, hydrogels, foams, 3D printing, and bioprinting.

Evaluation of muscle strength following peripheral nerve surgery: A scoping review

Peripheral nerve injury (PNI) can result in devastating loss of function, often with poor long-term prognosis. Increased use of peripheral nerve surgical techniques (eg, nerve transfer, nerve grafting, and nerve repair) has resulted in improved muscle strength and other functional outcomes in patients with PNI. Muscle strength has largely been evaluated with the British Medical Research Council (MRC) scale. MRC is convenient to use in clinical settings, but more robust measures of muscle function are necessary to fully elucidate patient recovery. This scoping review aims to examine alternative instruments used to assess muscle function in studies of peripheral nerve surgery for PNI of the upper and lower limbs. A scoping review was conducted using Ovid MEDLINE, CINAHL, EMBASE, and PubMed databases in May and December of 2020, yielding a total of 20 studies pertaining to the review question. Studies pertaining to handheld dynamometry, grip and pinch dynamometry, Rotterdam Intrinsic Hand Myometers, isokinetic dynamometry, ultrasonography, and electromyography were reviewed. We provide a synopsis of each method and current clinical applications and discuss potential benefits, disadvantages, and areas of future research.

Effective decellularization of human nerve matrix for regenerative medicine with a novel protocol

Injuries to the peripheral nerves represent a frequent cause of permanent disability in adults. The repair of large nerve lesions involves the use of autografts, but they have several inherent limitations. Overcoming these limitations, the use of decellularized nerve matrix has emerged as a promising treatment in tissue regenerative medicine. Here, we generate longer human decellularized nerve segments with a novel decellularization method, using nonionic, zwitterionic, and enzymatic incubations. Efficiency of decellularization was measured by DNA quantification and cell remnant analysis (myelin, S100, neurofilament). The evaluation of the extracellular matrix (collagen, laminin, and glycosaminoglycans) preservation was carried out by enzyme-linked immunosorbent assay (ELISA) or biochemical methods, along with histological and immunofluorescence analysis. Moreover, biomechanical properties and cytocompatibility were tested. Results showed that the decellularized nerves generated with this protocol have a concentration of DNA below the threshold of 50 ng/mg of dry tissue. Furthermore, myelin, S100, and MHCII proteins were absent, although some neurofilament remnants could be observed. Moreover, extracellular matrix proteins were well maintained, as well as the biomechanical properties, and the decellularized nerve matrix did not generate cytotoxicity. These results show that our method is effective for the generation of decellularized human nerve grafts. The generation of longer decellularized nerve segments would allow the understanding of the regenerative neurobiology after nerve injuries in both clinical assays and bigger animal models. Effective decellularization of human nerve matrix for regenerative medicine with a novel protocol. Combination of zwitterionic, non-ionic detergents, hyperosmotic solution and nuclease enzyme treatment remove cell remnants, maintain collagen, laminin and biomechanics without generating cytotoxic leachables.

Role of nerve ultrasound versus electrophysiological studies in the evaluation of nerve injuries

Background

High-resolution ultrasonography (US) is a non-invasive, readily applicable imaging modality capable of depicting real-time static and dynamic information concerning the peripheral nerves and their surrounding tissues. Although electrophysiological studies are the gold standard in the evaluation of nerve injuries, US can be used also to evaluate the morphological changes of nerve injuries.

Objectives

To evaluate the role of the high-resolution US in the assessment of nerve injuries and to compare it to the role of electrodiagnostic studies.

Subjects and methods

A total of 30 nerves from 22 consecutive patients with clinically definite nerve injury were considered. Two independent and blinded clinicians perform electrodiagnosis and US. The clinical, neurophysiological, and US findings were collected, and the contribution of US was then classified as “ contributive” or “non-contributive”, according to whether US confirmed the clinical and neurophysiological diagnosis or not.

Results

US was “contributive” (confirming the electrophysiological diagnosis) in 66.67% of cases (n = 20), providing information about continuity of the nerve, morphological changes after injury as swelling, scar tissue formation, or neuroma formation with sensitivity of 75% compared to the electrodiagnostic studies and accuracy of 66.67%.

Conclusion

Ultrasound can be used, when available, as a complementary tool for electrodiagnostic studies to provide anatomical information about the injured nerves in case of complete axonal lesion.

Perspectives on 3D Bioprinting of Peripheral Nerve Conduits

The peripheral nervous system controls the functions of sensation, movement and motor coordination of the body. Peripheral nerves can get damaged easily by trauma or neurodegenerative diseases. The injury can cause a devastating effect on the affected individual and his aides. Treatment modalities include anti-inflammatory medications, physiotherapy, surgery, nerve grafting and rehabilitation. 3D bioprinted peripheral nerve conduits serve as nerve grafts to fill the gaps of severed nerve bodies. The application of induced pluripotent stem cells, its derivatives and bioprinting are important techniques that come in handy while making living peripheral nerve conduits. The design of nerve conduits and bioprinting require comprehensive information on neural architecture, type of injury, neural supporting cells, scaffold materials to use, neural growth factors to add and to streamline the mechanical properties of the conduit. This paper gives a perspective on the factors to consider while bioprinting the peripheral nerve conduits.

The electrostimulation and scar inhibition effect of chitosan/oxidized hydroxyethyl cellulose/reduced graphene oxide/asiaticoside liposome based hydrogel on peripheral nerve regeneration in vitro

The application of hollow nerve conduits in the repair of peripheral nerve defects is effected by inferior recovery, and nerve extension is hampered by the scar tissue generated during the repair process. In this study, the filler in hollow nerve conduit, chitosan/oxidized hydroxyethyl cellulose (CS/OHEC) hydrogel loaded asiaticoside liposome and the conductive reduced graphene oxide (rGO) were developed and used to reform the microenvironment for peripheral nerve regeneration. The physiochemical properties of CS/OHEC/rGO/asiaticoside liposome hydrogel were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and compressive modulus, porosity, swelling ratio, degradation and conductivity. In addition, the asiaticoside release profiles in vitro were investigated. The hydrogel had a continuous porous network structure with pore size distribution in the range of 50-250 μm. The majority of the hydrogels had porosities above 70%, and a compressive modulus of 0.45 MPa. The weight loss rate of hydrogel reached 76.14 ± 4.45% within 8 weeks. The conductivity of the hydrogel was 5.27 ± 0.42 × 10^-4 S/cm. The hydrogel was non-toxic and suitable for adhesion and proliferation of nerve cells in vitro. In addition, the application of electrical stimulation after the addition of rGO can promote the differentiation and proliferation of nerve cells, accelerating nerve regeneration. The asiaticoside released from the hydrogel had a significant inhibitory effect on the growth and collagen secretion of fibroblasts, eliminating scars for regenerative nerves, which can promote the function recovery of defected peripheral nerve. Together, these positive results indicate that the hydrogel would be a promising candidate for peripheral nerve regeneration.

Electromyographic Biofeedback in Motor Function Recovery After Peripheral Nerve Injury: An Integrative Review of the Literature

Electromyographic biofeedback (EMG-BF) has been applied to treat different types of peripheral nerve injuries (PNI). However, despite the clinical practice widespread use its evidence is controversial. With the objective of summarize the available evidence on the electromyographic biofeedback effectiveness and efficacy to help motor function recovery after PNI an integrative review was performed. A secondary objective was to identify the conceptual framework and strategies of EMG-BF intervention, and the quality of technical description of EMG-BF procedures. To conduct this integrative review a systematic search of the literature was performed between October 2013 and July 2018, in PUBMED, ISI and COCHRANE databases for EMG-BF original studies in PNI patients of any etiology, in English, Portuguese, Spanish or French, published after 1990. Exclusion criteria were poor description of EMG-BF treatment, associated treatment that could impair EMG-BF effect, inclusion of non-PNI individuals and case studies design. The PEDro scale was used to evaluate study quality of randomized clinical trials (RCTs) included. This resulted in 71 potential articles enrolled to full reading, although only nine matched the inclusion criteria. PNI included facial paralysis, acute sciatic inflammation and carpal tunnel syndrome. The average quality score of the included RCTs was five, corresponding to low methodological quality. Due to the small number of included articles, low quality studies and heterogeneity of interventions, outcomes and population we concluded that there is limited evidence of EMG-BF effectiveness and efficacy for motor function recovery in PNI patients.

Current and novel polymeric biomaterials for neural tissue engineering

The nervous system is a crucial component of the body and damages to this system, either by of injury or disease, can result in serious or potentially lethal consequences. Restoring the damaged nervous system is a great challenge due to the complex physiology system and limited regenerative capacity.Polymers, either synthetic or natural in origin, have been extensively evaluated as a solution for restoring functions in damaged neural tissues. Polymers offer a wide range of versatility, in particular regarding shape and mechanical characteristics, and their biocompatibility is unmatched by other biomaterials, such as metals and ceramics. Several studies have shown that polymers can be shaped into suitable support structures, including nerve conduits, scaffolds, and electrospun matrices, capable of improving the regeneration of damaged neural tissues. In general, natural polymers offer the advantage of better biocompatibility and bioactivity, while synthetic or non-natural polymers have better mechanical properties and structural stability. Often, combinations of the two allow for the development of polymeric conduits able to mimic the native physiological environment of healthy neural tissues and, consequently, regulate cell behaviour and support the regeneration of injured nervous tissues.Currently, most of neural tissue engineering applications are in pre-clinical study, in particular for use in the central nervous system, however collagen polymer conduits aimed at regeneration of peripheral nerves have already been successfully tested in clinical trials.This review highlights different types of natural and synthetic polymers used in neural tissue engineering and their advantages and disadvantages for neural regeneration.

Management of an iatrogenic injury to the tibial nerve in a 24-year-old hurdle runner

According to previously published papers, neurovascular injuries seem to be the most unfortunate complications after surgical procedures. In this report, we present our therapeutic approach to iatrogenic injury of the posterior tibial nerve that occurred during ankle arthroscopy in a 24-year-old patient. The outcome of the therapy was a full sensory return and partial motor return (S4 and M3 according to the Medical Research Council Grading System for Nerve Recovery). Our patient was able to resume her typical training. In comparison with available reports, our therapeutic approach enabled earlier functional recovery after nerve injury. While sensory return is beneficial, motor improvement is also important. However, we are conscious of the poor functional outcomes reported by other researchers.

Non-invasive peripheral nerve stimulation via focused ultrasound in vivo

Focused ultrasound (FUS) has been employed on a wide range of clinical applications to safely and non-invasively achieve desired effects that have previously required invasive and lengthy procedures with conventional methods. Conventional electrical neuromodulation therapies that are applied to the peripheral nervous system (PNS) are invasive and/or non-specific. Recently, focused ultrasound has demonstrated the ability to modulate the central nervous system and ex vivo peripheral neurons. Here, for the first time, noninvasive stimulation of the sciatic nerve eliciting a physiological response in vivo is demonstrated with FUS. FUS was applied on the sciatic nerve in mice with simultaneous electromyography (EMG) on the tibialis anterior muscle. EMG signals were detected during or directly after ultrasound stimulation along with observable muscle contraction of the hind limb. Transecting the sciatic nerve downstream of FUS stimulation eliminated EMG activity during FUS stimulation. Peak-to-peak EMG response amplitudes and latency were found to be comparable to conventional electrical stimulation methods. Histology along with behavioral and thermal testing did not indicate damage to the nerve or surrounding regions. The findings presented herein demonstrate that FUS can serve as a targeted, safe and non-invasive alternative to conventional peripheral nervous system stimulation to treat peripheral neuropathic diseases in the clinic.