Proof of concept for multiple nerve transfers to a single target muscle

Surgical nerve transfers are used to efficiently treat peripheral nerve injuries, neuromas, phantom limb pain, or improve bionic prosthetic control. Commonly, one donor nerve is transferred to one target muscle. However, the transfer of multiple nerves onto a single target muscle may increase the number of muscle signals for myoelectric prosthetic control and facilitate the treatment of multiple neuromas. Currently, no experimental models are available. This study describes a novel experimental model to investigate the neurophysiological effects of peripheral double nerve transfers to a common target muscle. In 62 male Sprague-Dawley rats, the ulnar nerve of the antebrachium alone (n=30) or together with the anterior interosseus nerve (n=32) was transferred to reinnervate the long head of the biceps brachii. Before neurotization, the motor branch to the biceps\u27 long head was transected at the motor entry point. Twelve weeks after surgery, muscle response to neurotomy, behavioral testing, retrograde labeling, and structural analyses were performed to assess reinnervation. These analyses indicated that all nerves successfully reinnervated the target muscle. No aberrant reinnervation was observed by the originally innervating nerve. Our observations suggest a minimal burden for the animal with no signs of functional deficit in daily activities or auto-mutilation in both procedures. Furthermore, standard neurophysiological analyses for nerve and muscle regeneration were applicable. This newly developed nerve transfer model allows for the reliable and standardized investigation of neural and functional changes following the transfer of multiple donor nerves to one target muscle

Prosthetic extremity reconstruction : improving the prosthetic interface to restore extremity function

PatientInnen mit Amputationen der oberen Extremität erleiden Bewegungseinschränkungen, welche allerdings mittels myoelektrischen Prothesen teilweise wiederhergestellt werden können. Durch die Schnittstelle zwischen Patient und Prothese werden Muskelbewegungen im verbliebenen Stumpf mittels Elektromyographie aufgenommen und in prothetische Bewegungen umgewandelt. Diese Schnittstelle zwischen PatientIn und Prothese ist allerdings insuffizient um intuitive Steuerung zu ermöglichen. Ziel dieser Dissertation war es die unbekannten neurophysiologischen Effekte von Targeted Muscle Reinnervation experimentell zu untersuchen um die Muskelsignale zur Steuerung der Prothese zu verbessern. Des Weiteren, wurde das implantierbare Elektromyographie System MyoPlant experimentell getestet, welches diese Muskelsignale besser aufnehmen soll. Methoden: Ein experimentelles Rattenmodell wurde entworfen um die Effekte von Targeted Muscle Reinnervation zu studieren. Mittels konventionellen neuromuskulären Analysen und einem speziell konstruiertem Protokoll zur Identifizierung von Muskelfasern wurden alle Ebenen der motorischen Einheit und die funktionelle Regeneration nach dem Nerventransfer analysiert. Das implantierbare MyoPlant-System wurde in einem Pilotversuch mit Ratten und einem Langzeitversuch im Schafmodell auf Biokompatibilität und Signalverarbeitung getestet. Resultate: Im experimentellen Rattenmodell zeigte sich, dass es nach Targeted Muscle Reinnervation zu verschiedenen neurophysiologischen Effekten kommt, wie Hyperreinnervation, die Wiederherstellungen der physiologischen Integrität der motorischen Einheit, sowie hoher funktioneller Regeneration. Allerdings wurden nur 20% der transferierten Axone im Zielmuskel aufgenommen. Das MyoPlant System war gut implantierbar, zeigte gute Biokompatibilität und nahm Elektromyographie-Signale verlässlich über vier Monate auf. Diskussion: In dieser Dissertation konnten wir zeigen, dass Targeted Muscle Reinnervation zu einer Reihe von neurophysiologischen Effekten führt, welche die Muskelsignale verbessern können. Implantierbare Systeme wie das MyoPlant System können die Signalaufnahme dieser Muskelsignale verbessern und somit die neurophysiologischen Veränderungen der Muskelsignale in verbesserte prothetische Steuerung umsetzen. Zusammenfassend bilden die Ergebnisse dieser Dissertation die Grundlage um die Funktion von Interfaces zwischen Prothesen und Patientin weiter zu verfeinern und somit in Zukunft intuitivere Prothesensteuerung zu ermöglichen.Introduction: Upper extremity amputees face severe disability, but modern myoelectric prosthesis can partly replace the lost functionality. Interfaces governing prosthetic motion access the voluntary neuronal drive of the intact corticospinal control structures by recording electromyography data from remaining stump muscles. However, this interface is currently insufficient to provide intuitive prosthetic control. Therefore, the capabilities of this interface need to be improved to ultimately provide human-like prosthetic control. The aim of this thesis was to experimentally investigate targeted muscle reinnervation and its unknown neurophysiological effects, to optimize muscle signals for controlling a prosthesis. In addition, the implantable electromyography system MyoPlant was tested experimentally to optimize recording of electromyography signals. The hypothesis of this thesis was that refinement of the muscle signals and their acquisition would greatly improve the prosthetic interface and thereby allow better prosthetic control. Methods: An experimental rat model was designed to study the effects of targeted muscle reinnervation and their nerve transfers. Using standard neuromuscular analyzes and a newly designed protocol for muscle fiber population analyzes, we assessed all motor unit levels and functional regeneration following the nerve transfer. The implantable MyoPlant system was tested in a rat pilot-trial and sheep long-term trial to assess biocompatibility and signal acquisition. Results: The experimental rat targeted muscle reinnervation model provided a reliable surgical model. The neurophysiological effects of targeted muscle reinnervation included high functional recovery and hyper-reinnervation. In addition, the physiological properties of the motor unit were restored as the targeted muscle adapted to the physiological properties of the transferred nerve. However, only 20% of the transferred axons were able to reinnervate the target muscle. The MyoPlant system was well-implantable, showed excellent biocompatibility and was able to record reliably electromyography data over the course of four months. Discussion: In this thesis we could show that targeted muscle reinnervation leads to a number of neurophysiological effects, which eventually increase the number of muscle signals that can be used for prosthesis control by the interface. Implantable interface systems such as the MyoPlant can improve muscle signal acquisition and may in the future translate the discrete neurophysiological effects of targeted muscle reinnervation into intuitive muscle signals. In conclusion, this thesis shows that combining refined targeted muscle reinnervation techniques with implantable electromyography interfaces will improve the prosthetic-interface communication and potentially enable hand-like prosthetic control.submitted by Konstantin Davide BergmeisterZusammenfassung in deutscher SpracheMedizinische Universität Wien, Dissertation, 2016OeBB(VLID)357984

Modern MRI Diagnostics of Upper-Extremity-Related Nerve Injuries—A Prospective Multi-Center Study Protocol for Diagnostics and Follow Up of Peripheral Nerve Injuries

(1) Background: Peripheral nerve injuries are severe injuries with potentially devastating impairment of extremity function. Correct and early diagnosis as well as regular regeneration observation is of utmost importance for individualized reconstruction and the best possible results. Currently, diagnoses and follow-up examinations are based on clinical examinations supported with electroneurography, which often causes delays in treatment and can result in impaired healing. However, there is currently no diagnostic device that can reliably correlate the anatomic–pathological parameters with the functional–pathological changes initially and during therapy. With new technologies such as MR neurography (MRN), precise visualization of potential nerve damage and visualization of the reinnervation processes is assumed to accelerate clinical decision making and accompaniment of individualized treatment. (2) Methods/Design: This prospective clinical study will examine 60 patients after peripheral nerve lesion aged 18–65 years from trauma timepoint onward. Patients should be observed over a period of 18–24 months with regular clinical examinations, electroneurography, and ultrasound to compare the potential of MRN to current gold-standard diagnostic tools. Furthermore, 20 patients with the same inclusion criteria stated above, with an internal fixation and osteosyntheses of humerus fractures, will be examined to determine the visibility of peripheral nerve structures in close proximity to metal. (3) Discussion: Peripheral nerve injuries are often accompanied with severe, expensive, and long-lasting impairment of extremity function. An early and precise diagnosis of the nerve lesion, as well as the healing course, is crucial to indicate the right therapy as soon as possible to save valuable time for nerve regeneration. Here, new technologies such as MRN aim to visualize nerve injuries on fascicular level, providing not only early diagnosis and therapy decisions, but also providing a precise tool for monitoring of reinnervation processes. As severe injuries of a nerve are often accompanied with bone fractures and internal fixation, we also aim to evaluate the visualization feasibility of nerves in close proximity to metal, and ultimately improve the outcome and extremity function of patients after a peripheral nerve injury