Brachial Plexus Injury

In this book, specialists from different countries and continents share their knowledge and experience in brachial plexus surgery. It discusses the different types of brachial plexus injury and advances in surgical treatments

Volume 12, issue 2

The mission of CJS is to contribute to the effective continuing medical education of Canadian surgical specialists, using innovative techniques when feasible, and to provide surgeons with an effective vehicle for the dissemination of observations in the areas of clinical and basic science research. Visit the journal website at http://canjsurg.ca/ for more.https://ir.lib.uwo.ca/cjs/1094/thumbnail.jp

Applications of EMG in Clinical and Sports Medicine

This second of two volumes on EMG (Electromyography) covers a wide range of clinical applications, as a complement to the methods discussed in volume 1. Topics range from gait and vibration analysis, through posture and falls prevention, to biofeedback in the treatment of neurologic swallowing impairment. The volume includes sections on back care, sports and performance medicine, gynecology/urology and orofacial function. Authors describe the procedures for their experimental studies with detailed and clear illustrations and references to the literature. The limitations of SEMG measures and methods for careful analysis are discussed. This broad compilation of articles discussing the use of EMG in both clinical and research applications demonstrates the utility of the method as a tool in a wide variety of disciplines and clinical fields

Reorganization of jaw muscle activity during experimental jaw muscle pain

Background and Aims: Temporomandibular disorders are clinical conditions that often involve pain in the masticatory muscles, the temporomandibular jaw joint and/or associated structures. The association between muscle pain and muscle activity is often explained by uniform increases or decreases in motor unit activity throughout a muscle but recent evidence suggests more complex changes within a painful muscle. The general aim of this study was to determine if experimentally induced masseter muscle pain modifies temporalis muscle activity. Methods: 20 healthy participants received experimental pain through hypertonic saline (5% NaCl) infusion into the right masseter; pain intensity was maintained at 40-60/100 mm on a visual analogue scale (VAS). Standardized biting tasks were performed with an intraoral force transducer while single motor unit (SMU) activity was recorded from 2 intramuscular electrodes (right masseter and right temporalis). The tasks were repeated in 4 blocks: baseline 1, hypertonic saline infusion, isotonic saline infusion, baseline 2. Each block had 3 isometric biting tasks: a slow and a fast ramp jaw closing task and a 2 step-levels jaw closing task (2 force levels: step 1 and step 2). Results: 83 SMUs were discriminated from the temporalis and 58 from the masseter muscle. This study demonstrated that induced muscle pain in the right masseter can be associated with the activation of new SMUs and the silencing of other single motor units in the painful masseter muscle as well as in the right temporalis muscle, which did not receive noxious stimulation with the hypertonic saline. No differences between pain and no pain trials were found in thresholds and firing rates of SMUs from the temporalis muscle. Discussion and conclusion: The present findings are consistent with previous findings from the limb (Hodges and Tucker 2011; Tucker et al. 2009) and rather than supporting uniform increases or decreases in motor unit activity throughout a muscle, suggest that there is a reorganization of motor unit activity across the entire jaw motor system in experimental pain

Light activated approach for large gap peripheral nerve repair

Introduction: Conventional suture repair of peripheral nerves following injury is associated with several limitations such as technical difficulty, intra- and extra-neural scar formation, axonal escape and the leakage of neurotrophic factors. These limitations are particularly relevant following nerve grafting when regenerating axons must traverse two coaptation sites. Outcomes following suture repair are notoriously poor, providing large impetus for the development of alternative methods. Photochemical tissue bonding (PTB) uses visible light to create sutureless, non-thermal bonds between two closely apposed tissue surfaces stained with a photoactive dye. When used with a human amnion nerve wrap for end-to end nerve repair, this technique results in superior functional and histological outcomes in comparison to conventional epineurial suture. When initially applied to large gap injury and nerve grafting, outcomes were unsuccessful due to proteolytic degradation of amnion and photochemical bonds during extended periods of recovery. Chemical crosslinking of nerve wraps prior to PTB may improve wrap durability and efficacy of technique. This thesis provides a comprehensive three-phase assessment of the efficacy of this novel approach when applied to the repair of large gap injuries with nerve grafts. Phase 1 assesses the ex vivo biomechanical properties of nerve wraps and light activated bonds in addition to the in vivo performance of photochemically sealed crosslinked nerve wraps against several other clinically relevant fixation methods in a rodent sciatic nerve isograft model. Following major multi-limb injury and amputation, demand for autogenous nerve graft may exceed that which can be supplied by the patient. Acellular nerve allograft (ANA) is an alternative option in these circumstances although outcomes are typically inferior to autograft. Phase 2 assesses the performance of the optimum repair strategy from phase 1 against conventional epineurial suture when applied to ANA. Most studies investigating the efficacy of novel repair techniques tend to perform repairs immediately following injury, a situation that rarely occurs clinically. Delays of weeks or months are not uncommon and have been shown to have a detrimental effect on regeneration and outcome. Phase 3 assesses the efficacy of PTB when applied to delayed nerve grafting. Additional work investigating a novel imaging technique for visualizing nerve revascularisation following injury and repair has been included. Optical frequency domain imaging (OFDI) uses low power infrared light to provide real time in vivo imaging of tissue microvasculature and flow characteristics. Originally applied to the study of tumour biology, this technique may prove useful for outcome assessment in preclinical research and eventually for the assessment of nerve viability in the clinical setting. Experiments investigating the early development of a brain body interface system (BBI) for upper limb reanimation following spinal cord injury (SCI) have also been included. The ultimate aim of this project is to restore autonomous motor control in a non-human primate (NHP) using cortically driven stimulation of peripheral nerves via implantable nerve cuffs. The experiments reported in this thesis detail the development of a selective, reversible paralysis model of elbow flexion in a NHP and demonstrate selective fascicular stimulation using acute and chronically implanted nerve cuffs in rodent and murine models. Methods: Phase 1: Three candidate nerve wraps (human amnion (HAM), crosslinked human amnion (xHAM), crosslinked swine intestinal sub-mucosa (xSIS)) and 3 fixation methods (suture, fibrin glue, PTB) were investigated. Crosslinking was performed using (1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC)/N-hydroxysuccinimide (NHS). Biomechanical tests were performed using a tensiometer. Ex vivo wrap durability was assessed using a type- 2 collagenase degradation assay. Under isoflurane anaesthesia, 110 inbred male Lewis rats had 15mm left sciatic nerve defects created and repaired with reversed isografts. 9 groups (n=10) had isografts secured by one of the aforementioned wrap/fixation combinations. PTB repairs had nerve wraps and nerve ends stained with photoactive dye (Rose Bengal) and, once nerve ends were apposed and wrapped circumferentially, the interface was illuminated with a 532nm laser. Fibrin repairs had nerve ends apposed, wrapped circumferentially and secured with Tisseel fibrin glue. Suture repairs had nerve ends apposed, wrapped circumferentially and then secured with two 10-0 nylon sutures at each coaptation site (one either side of each repair). Positive and negative control groups (n=10) were repaired with graft+suture (10-0 nylon) and no repair respectively. Phase 2: 20 sciatic nerves were harvested from Sprague Dawley rats and sent to AxoGen Inc. for decellularisation. An additional 20 male inbred Lewis rats were randomized into 2 groups (n=10). All rats had 15mm left sciatic nerve defects created and repaired with processed ANA. 1 group had nerves secured using conventional epineurial suture. The remaining group had ANA secured using photochemically sealed amnion wraps. Phase 3: 40 inbred male Lewis rats were randomized into 4 groups (n=10). All 40 rats had 15mm left sciatic nerve gaps created and reconstructed with reversed isografts harvested from donor Sprague Dawley rats. In groups 1 and 2, nerve gaps were repaired immediately with either conventional epineurial suture or photochemically sealed amnion wraps, respectively. In groups 3 and 4, repair took place 30- days following injury using either conventional epineurial suture or photochemically sealed amnion wraps, respectively. All outcomes were assessed using walking track analysis and calculation of sciatic function index (SFI). Walking track analysis and SFI was performed pre-operatively, after the 30-day delay (phase 3) and at 30-day intervals following surgery. Following sacrifice after 5-months, left (experimental) and right (control) gastrocnemius muscles were excised and weighed for calculation of muscle mass retention. Nerves were excised for histomorphometric analysis including axon count, fiber diameter, axon diameter, myelin thickness and G-ratio. For all in vivo experiments, statistical analysis was performed using ANOVA, repeated measures ANOVA and the post hoc Bonferroni test. Optical Frequency Domain Imaging (OFDI) pilot study: eight rodents were randomized into 4 groups (n=2): (1) crush injury, (2) transection and end-to-end repair, (3) transection and repair of 10mm nerve gap using contralateral autograft, (4) transection and repair of 10mm nerve gap using ANA. Under ketamine/xylazine anaesthesia, all rodents had sciatic nerves exposed through hind limb dorsolateral incisions. Imaging was performed immediately pre-injury, immediately post-injury and on post-operative days 1, 3, 5 and 7. Rodents were secured firmly to polystyrene platforms in order to reduce movement artifact during imaging Brain-Body Interface (BBI) experiments: In the upper limb of a Rhesus macaque nonhuman primate, the median nerve branch to brachialis and radial nerve branch to brachioradialis were transected, leaving elbow flexion entirely reliant on the musculocutaneous nerve. The musculocutaneous nerve was transposed into a subcutaneous position. Ultrasound guided nerve block resulted in a highly selective, reversible paralysis of elbow flexion. Under ketamine/xylazine anaesthesia, Sprague Dawley rats (n=5) and C57 Black 6 mice (n=5) had sciatic nerves exposed through dorsolateral, muscle splitting incisions. 8-channel stimulating cuff electrodes were wrapped around sciatic nerves and connected to a Tucker14 Davies stimulation/recording system. Electromyography (EMG) needle electrodes were inserted into the tibialis anterior (TA) and gastrocnemius (G) muscles to record muscle activity. Single pulses and pulse trains were delivered to each animal whilst pulse parameters were systematically varied. In one survival rat, a stimulating nerve cuff and EMG recording electrodes were implanted chronically to assess equipment biocompatibility and recording stability. Results: Phase 1: Optimal tensile strength, photochemical bond strength and resistance to collagenase degradation were achieved using 4mM EDC/1mM NHS. Following sacrifice, crosslinked nerve wraps were still present. Un-crosslinked material was completely degraded. xHAM+PTB repairs recovered greatest mean SFI although this was not statistically significant compared with standard repair (-67.9+/-1.6 vs -71.7+/-1.6 (mean+/-SEM)). xHAM+PTB repairs also recovered greatest muscle mass retention and this was significant in comparison to standard repair (67.3% +/- 1.4 vs 60.0% +/- 1.6; p=0.02). No significant difference in axon diameter existed between treatment groups. Fiber and axon diameter and myelin thickness were all significantly greater in the xHAM+PTB group in comparison to standard repair (6.87μm+/-0.04 vs. 5.47μm+/-0.03, p<0.0001; 4.51μm+/-0.04 vs. 3.50μm+/- 0.03, p<0.0001; 2.35μm+/-0.01 vs. 1.96μm+/-0.01, p<0.0001). Phase 2: Following sacrifice, all ANAs were in continuity and, on gross observation, showed evidence of regeneration. ANA repaired photochemically had less extraneural scar tissue formation in comparison to standard epineurial suture. SFI did not differ significantly between ANA+suture and ANA+PTB groups after 5-months follow up (-80.3+/-1.3 vs. -78.3+/-1.6 respectively; p=0.3). ANA+suture and ANA+PTB recovered significantly less SFI than corresponding isograft+suture and isograft+PTB. Gastrocnemius muscle mass retention did not differ significantly between ANA+suture and ANA+PTB groups (53.3%+/-1.8 vs. 55.2%+/-1.6 respectively; p=0.5). ANA+suture and ANA+PTB recovered significantly less muscle mass than isograft+suture and isograft+PTB, respectively. Muscle mass retention was statistically equivalent between ANA+PTB and isograft+suture (55.2+/-1.8% vs. 60+/-1.6%; p=0.22). With the exception of G-ratio, no significant differences existed between ANA+suture and ANA+PTB for any remaining histomorphometric parameter. ANA+PTB was statistically equivalent to isograft+suture for all histomorphometric parameters. Phase 3: After 5-months, in both immediate and delayed repairs, PTB resulted in greater mean SFI values but these results were not statistically significant (-72.3+/-1.5 vs. -68.5+/-1.5; p=0.4 and -80.1+/-1.4 vs. -77.3+/-1.5; p=1). Both suture and PTB fixation methods resulted in significantly greater recovery of SFI when performed immediately rather than after a 30-day delay after injury (- 72.3+/-1.5 vs. -80.1+/-1.4; p=0.003 and -68.5+/-1.5 vs. -77.3+/-1.5; p=0.002). Significantly greater muscle mass retention occurred following PTB fixation in both immediate and delayed repairs (64.9%+/-1.8 vs. 59.0%+/-1.1; p=0.03 and 60.2%+/-1.4 vs. 54.1%+/-1.7; p=0.04). No significant difference existed between immediate suture and delayed suture, or immediate PTB and delayed PTB groups. Muscle mass retention was not significantly different between immediate suture and delayed PTB (59.0+/-1.1% vs. 60.2+/-1.4%; p=1). No significant differences in axon count or density existed between groups. Fiber diameter, axon diameter, myelin thickness and G-ratio were not significantly different between immediate suture and delayed PTB. With the exception of G-ratio, all other histomorphometric parameter comparisons were significantly different between treatment groups, with immediate PTB achieving greatest recovery and delayed suture being poorest. OFDI: OFDI successfully provided real time images of nerve microvasculature. Vessels of the mesoneurial and epineurial longitudinal plexus were readily identifiable in uninjured nerve. Marked tortuosity of these vessels was apparent. Different light scattering properties of muscle and nerve permitted easy differentiation between tissues. Injury sites were easily visible as areas of relative hypovascularity. Following crush injury, the longitudinal intrinsic plexus remained intact. Following end-to-end neurorrhaphy, although initially hypovascular, by post-operative day 7, a florid angiogenic response had occurred at the repair site. Following repair of 10mm autografts, the re-establishment of longitudinal vessels was apparent by day 4. Following repair of 10mm ANA, grafts remained relatively avascular. A predominance of inosculated longitudinal vessels existed with a relatively minor centripetal contribution from the surrounding muscle bed. BBI: Highly selective, reversible paralysis of non-human primate (NHP) elbow flexion was achieved. Application of nerve cuff electrodes around small animal sciatic nerves was technically simple and permitted muscle stimulation in all animals. Needle EMG electrodes successfully recorded muscle activity in all animals. In 9 animals, selective activation of tibial and common peroneal fascicles was possible, allowing the plotting of muscle recruitment curves as a function of stimulation amplitude. Following 6 months of chronic implantation, the nerve cuff and EMG electrodes were well tolerated and stimulation and recording was still possible. Conclusions PTB: Chemical crosslinking of biological nerve wraps improves tensile strength and in vivo resistance to biodegradation, whilst preserving the formation of light-activated bonds. Light activated sealing of crosslinked amnion around nerve isograft coaptation sites results in significant improvements in muscle mass retention and nerve histomorphometry in comparison to conventional suture repair. SIS wraps were unsuitable for bonding around small diameter nerves although when applied to larger caliber nerves, may still be useful. Outcomes following ANA were inferior to those achieved following isograft reconstruction in phase 1. No significant difference was detected between photochemically sealed ANA and sutured ANA although the increase in mean values for muscle mass retention and histomorphometry were comparable to epineurial suture, the current standard of care. Immediate repairs performed significantly better than delayed repairs and light-activated repairs performed significantly better than sutured repairs. Delayed PTB repairs were statistically comparable to immediate suture. Light-activated sealing leads to superior outcomes in comparison to suture when applied to nerve isografts and may improve outcomes following the use of ANA and when repairs occur following a surgical delay. OFDI provides a real time, in vivo imaging modality for the assessment of nerve revascularisation following injury and repair. This has potential applications for pre-clinical outcome assessment in peripheral nerve research and also as a means of assessing peripheral nerve viability in the clinical setting. BBI: We have shown that selective fascicular stimulation of sub-1mm peripheral nerves can be achieved using implantable cuff electrodes. In combination with a highly selective and reversible paralysis of elbow extension in a non-human primate model, these cuffs will be used to deliver cortically recorded signals directly into upper limb nerves. Through operant conditioning and feedback, this BBI should enable the NHP to regain movement during paralysis

Haptics: Science, Technology, Applications

This open access book constitutes the proceedings of the 13th International Conference on Human Haptic Sensing and Touch Enabled Computer Applications, EuroHaptics 2022, held in Hamburg, Germany, in May 2022. The 36 regular papers included in this book were carefully reviewed and selected from 129 submissions. They were organized in topical sections as follows: haptic science; haptic technology; and haptic applications

The effect of noxious stimulation of the right masseter muscle on single motor unit activity at two sites in the masseter muscle during standardized jaw closing tasks

Background and aims: The Pain Adaptation Model and the Vicious Cycle Theory are older theories of the effects of pain on motor activity. While some data sets are consistent with these theories, other data sets are not, and a number of new models (the Integrated Pain Adaptation Model; Theory of Motor Adaptation to Pain) have been proposed. Two of these models propose a reorganization of motor activity in pain. The aim of the present study was to determine whether experimental masseter muscle pain resulted in a change in muscle activity at two different sites within the masseter muscle during the performance of isometric jaw-closing tasks in asymptomatic participants. Methods: Single motor unit (SMU) activity was recorded with bipolar fine wire electrodes at 2 sites within the right masseter muscle during the performance of standardized isometric biting on an intraoral force transducer in 17 healthy participants. Participants performed standardized biting trials during infusion of 5% hypertonic saline into the right masseter (pain), and during isotonic saline infusion (control). Recruitment patterns, force thresholds and firing rates were compared between pain and control trials. Results: A total of 50 SMUs were discriminated from the 2 sites. Changes in recruitment patterns of SMUs at one site within the masseter muscle during pain in comparison with control was observed during the tasks and some of these changes were different to the changes occurring at the other site. There were no changes in thresholds of SMU firing nor in SMU firing rates between pain and control trials. Inter-individual variability in the motor response to pain was observed at the two different sites of the masseter. Discussion and Conclusions: In general, the data are not consistent with the earlier models of pain-motor interactions, but provide support for more recent models proposing a re-organization of motor activity in the presence of pain

Sensores em fibra ótica para o estudo biomecânico do disco intervertebral

Doutoramento em Engenharia MecânicaO presente trabalho teve como objetivo principal estudar o comportamento mecânico do disco intervertebral recorrendo a sensores em fibra ótica. Na expetativa de efetuar o melhor enquadramento do tema foi efetuada uma revisão exaustiva das várias configurações de sensores em fibra ótica que têm vindo a ser utilizadas em aplicações biomédicas e biomecânicas, nomeadamente para medição de temperatura, deformação, força e pressão. Nesse âmbito, procurou-se destacar as potencialidades dos sensores em fibra ótica e apresentá-los como uma tecnologia alternativa ou até de substituição das tecnologias associadas a sensores convencionais. Tendo em vista a aplicação de sensores em fibra ótica no estudo do comportamento do disco intervertebral efetuou-se também uma revisão exaustiva da coluna vertebral e, particularmente, do conceito de unidade funcional. A par de uma descrição anatómica e funcional centrada no disco intervertebral, vértebras adjacentes e ligamentos espinais foram ainda destacadas as suas propriedades mecânicas e descritos os procedimentos mais usuais no estudo dessas propriedades. A componente experimental do presente trabalho descreve um conjunto de experiências efetuadas com unidades funcionais cadavéricas utilizando sensores convencionais e sensores em fibra ótica com vista à medição da deformação do disco intervertebral sob cargas compressivas uniaxiais. Inclui ainda a medição in vivo da pressão intradiscal num disco lombar de uma ovelha sob efeito de anestesia. Para esse efeito utilizou-se um sensor comercial em fibra ótica e desenvolveu-se a respetiva unidade de interrogação. Finalmente apresenta-se os resultados da investigação em curso que tem como objetivo propor e desenvolver protótipos de sensores em fibra ótica para aplicações biomédicas e biomecânicas. Nesse sentido, são apresentadas duas soluções de sensores interferométricos para medição da pressão em fluídos corporais.The present work aimed to study the mechanical behavior of the intervertebral disc using fiber optic sensors. To address the theme an exhaustive review of the various configurations of fiber optic sensors that have been used in biomechanical and biomedical applications, in particular for measuring temperature, strain, force and pressure, was conducted. In this context, an effort was made to highlight the advantages of fiber optic sensors and present them as an alternative or even a substitution technology to conventional sensors. In view of the application of fiber optic sensors to study intervertebral disc behavior an exhaustive review of the spine and, particularly, of the spinal motion segment was made. Along with an anatomical and functional description of the intervertebral disc, the adjacent vertebrae and spinal ligaments, their mechanical properties were also highlighted as well as the most common procedures and guidelines followed in the study of these properties. The experimental section of the present work describes a set of tests performed with cadaveric spinal motion segments using conventional and fiber optic sensors to assess strain of the intervertebral disc under uniaxial compressive loads. This section also includes an experience reporting in vivo pressures measured in the lumbar disc of a sheep under general anesthesia. In this case, a commercial fiber optic sensor and a purpose-built interrogation unit were used. Finally, the results of ongoing research aiming to develop fiber optic sensors prototypes for biomedical and biomechanical applications are presented. Thus, the proof of concept of two possible interferometric configurations intended for pressure measurement in body fluids was presented

MUSME 2011 4 th International Symposium on Multibody Systems and Mechatronics

El libro de actas recoge las aportaciones de los autores a través de los correspondientes artículos a la Dinámica de Sistemas Multicuerpo y la Mecatrónica (Musme). Estas disciplinas se han convertido en una importante herramienta para diseñar máquinas, analizar prototipos virtuales y realizar análisis CAD sobre complejos sistemas mecánicos articulados multicuerpo. La dinámica de sistemas multicuerpo comprende un gran número de aspectos que incluyen la mecánica, dinámica estructural, matemáticas aplicadas, métodos de control, ciencia de los ordenadores y mecatrónica. Los artículos recogidos en el libro de actas están relacionados con alguno de los siguientes tópicos del congreso: Análisis y síntesis de mecanismos ; Diseño de algoritmos para sistemas mecatrónicos ; Procedimientos de simulación y resultados ; Prototipos y rendimiento ; Robots y micromáquinas ; Validaciones experimentales ; Teoría de simulación mecatrónica ; Sistemas mecatrónicos ; Control de sistemas mecatrónicosUniversitat Politècnica de València (2011). MUSME 2011 4 th International Symposium on Multibody Systems and Mechatronics. Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/13224Archivo delegad