Peripheral neural interfaces: Skeletal muscles are hyper-reinnervated according to the axonal capacity of the surgically rewired nerves.

Advances in robotics have outpaced the capabilities of man-machine interfaces to decipher and transfer neural information to and from prosthetic devices. We emulated clinical scenarios where high- (facial) or low-neural capacity (ulnar) donor nerves were surgically rewired to the sternomastoid muscle, which is controlled by a very small number of motor axons. Using retrograde tracing and electrophysiological assessments, we observed a nearly 15-fold functional hyper-reinnervation of the muscle after high-capacity nerve transfer, demonstrating its capability of generating a multifold of neuromuscular junctions. Moreover, the surgically redirected axons influenced the muscle's physiological characteristics, by altering the expression of myosin heavy-chain types in alignment with the donor nerve. These findings highlight the remarkable capacity of skeletal muscles to act as biological amplifiers of neural information from the spinal cord for governing bionic prostheses, with the potential of expressing high-dimensional neural function for high-information transfer interfaces.

Targeted muscle reinnervation in bionic upper limb reconstruction: current status and future directions.

Selective nerve transfers are used in the setting of upper limb amputation to improve myoelectric prosthesis control. This surgical concept is referred to as targeted muscle reinnervation (TMR) and describes the rerouting of the major nerves of the arm onto the motor branches of the residual limb musculature. Aside from providing additional myosignals for prosthetic control, TMR can treat and prevent neuroma pain and possibly also phantom limb pain. This article reviews the history and current applications of TMR in upper limb amputation, with a focus on practical considerations. It further explores and identifies technological innovations to improve the man-machine interface in amputation care, particularly regarding implantable interfaces, such as muscle electrodes and osseointegration. Finally, future clinical directions and possible scientific avenues in this field are presented and critically discussed.

[Prosthetic Fitting Concepts after Major Amputation in the Upper Limb - an Overview of Current Possibilities]. / Prothetische Versorgungskonzepte nach Majoramputation der oberen Extremität ­ eine Übersicht gegenwärtiger Möglichkeiten.

BACKGROUND: The upper extremity and particularly the hands are crucial for patients in interacting with their environment, therefore amputations or severe damage with loss of hand function significantly impact their quality of life. In cases where biological reconstruction is not feasible or does not lead to sufficient success, bionic reconstruction plays a key role in patient care. Classical myoelectric prostheses are controlled using two signals derived from surface electrodes in the area of the stump muscles. Prosthesis control, especially in high amputations, is then limited and cumbersome. The surgical technique of Targeted Muscle Reinnervation (TMR) offers an innovative solution: The major arm nerves that have lost their target organs due to amputation are rerouted to muscles in the stump area. This enables the establishment of cognitive control signals that allow significantly improved prosthesis control. PATIENTS/MATERIALS AND METHODS: A selective literature review on TMR and bionic reconstruction was conducted, incorporating relevant articles and discussing them considering the clinical experience of our research group. Additionally, a clinical case is presented. RESULTS: Bionic reconstruction combined with Targeted Muscle Reinnervation enables intuitive prosthetic control with simultaneous movement of various prosthetic degrees of freedom and the treatment of neuroma and phantom limb pain. Long-term success requires a high level of patient compliance and intensive signal training during the prosthetic rehabilitation phase. Despite technological advances, challenges persist, especially in enhancing signal transmission and integrating natural sensory feedback into bionic prostheses. CONCLUSION: TMR surgery represents a significant advancement in the bionic care of amputees. Employing selective nerve transfers for signal multiplication and amplification, opens up possibilities for improving myoelectric prosthesis function and thus enhancing patient care. Advances in the area of external prosthetic components, improvements in the skeletal connection due to osseointegration and more fluid signal transmission using wireless, fully implanted electrode systems will lead to significant progress in bionic reconstruction, both in terms of precision of movement and embodiment.

Transient perioperative inflammation following lung transplantation and major thoracic surgery with elective extracorporeal support: a prospective observational study.

BACKGROUND: The clinical relevance of inflammation induced by elective perioperative extracorporeal membrane oxygenation (ECMO) usage as an integral part of modern lung transplantation (LUTX) remains elusive. The aim of this study was to determine the perioperative cytokine response accompanying major thoracic surgery employing different extracorporeal devices comprising ECMO, cardiopulmonary bypass (CPB), or no extracorporeal circulation in relation to inflammation, clinically tangible as increased sequential organ failure assessment (SOFA) score, called SOFA. METHODS: In this prospective, observational pilot study 42 consecutive patients with end-stage pulmonary disease undergoing LUTX; 15 patients with chronic thromboembolic pulmonary hypertension (CTEPH) undergoing pulmonary endarterectomy and 15 patients with lung cancer undergoing major lung resections were analysed. Cytokine serum concentrations and SOFA were determined before, at end of surgery and in the following postoperative days. RESULTS: LUTX on ECMO and pulmonary endarterectomy (PEA) on CPB triggered an immediate increase in cytokine serum concentrations at end of surgery: IL-6: 66-fold and 71-fold, IL-10: 3-fold and 2.5-fold, ST2/IL-33R: 5-fold and 4-fold and SOFA: 10.5±2.8 and 10.7±1.7, that decreased sharply to baseline levels from postoperative day 1-5. Despite low perioperative mortality (3 patients, 4.1%) extremely high SOFA ≥13 was associated with mortality after LUTX. Delta-SOFA distinguished survivors from non-survivors: -4.5±3.2 vs. -0.3±1.5 (P=0.001). Increased IL-6 serum concentrations were predictive for increased SOFA (sensitivity: 97%, specificity: 80%). Peak cytokine serum concentrations correlated with ECC duration, maximal lactate, transfusion of red-blood-cells, fresh-frozen-plasma, and catecholamine support. CONCLUSIONS: LUTX and PEA on extracorporeal circulation with an excellent outcome triggered an immediate rise and concomitant fall of inflammation as observed in cytokine serum concentrations and SOFA. High absolute SOFA in the presence of an uncomplicated postoperative course may pertain to specific management strategies rather than organ failure.