A systematic review and meta-analysis of studies comparing muscle-in-vein conduits with autologous nerve grafts for nerve reconstruction

The gold-standard method for reconstruction of segmental nerve defects, the autologous nerve graft, has several drawbacks in terms of tissue availability and donor site morbidity. Therefore, feasible alternatives to autologous nerve grafts are sought. Muscle-in-vein conduits have been proposed as an alternative to autologous nerve grafts almost three decades ago, given the abundance of both tissues throughout the body. Based on the anti-inflammatory effects of veins and the proregenerative environment established by muscle tissue, this approach has been studied in various preclinical and some clinical trials. There is still no comprehensive systematic summary to conclude efficacy and feasibility of muscle-in-vein conduits for reconstruction of segmental nerve defects. Given this lack of a conclusive summary, we performed a meta-analysis to evaluate the potential of muscle-in-vein conduits. This work’s main findings are profound discrepancies regarding the results following nerve repair by means of muscle-in-vein conduits in a preclinical or clinical setting. We identified differences in study methodology, inter-species neurobiology and the limited number of clinical studies to be the main reasons for the still inconclusive results. In conclusion, we advise for large animal studies to elucidate the feasibility of muscle-in-vein conduits for repair of segmental defects of critical size in mixed nerves.

Nerve reconstruction with muscle-in-vein conduits VS autologous nerve grafts - a systematic review and meta-analysis of preclinical and clinical studies

The gold-standard method for reconstruction of segmental nerve defects, the autologous nerve graft, has several drawbacks in terms of tissue availability and donor site morbidity. Therefore, feasible alternatives to autologous nerve grafts are sought. Muscle-in-vein conduits have been proposed as an alternative to autologous nerve grafts almost three decades ago, given the abundance of both tissues throughout the body. Based on the anti-inflammatory effects of veins and the proregenerative environment established by muscle tissue, this approach has been studied in various preclinical and some clinical trials. There is still no comprehensive systematic summary to conclude efficacy and feasibility of muscle-in-vein conduits for reconstruction of segmental nerve defects. Given this lack of a conclusive summary, we performed a meta-analysis to evaluate the potential of muscle-in-vein conduits. This work’s main findings are profound discrepancies regarding the results following nerve repair by means of muscle-in-vein conduits in a preclinical or clinical setting. We identified differences in study methodology, inter-species neurobiology and the limited number of clinical studies to be the main reasons for the still inconclusive results. In conclusion, we advise for large animal studies to elucidate the feasibility of muscle-in-vein conduits for repair of segmental defects of critical size in mixed nerves.

Cervical spinal tuberculosis combined with brucellosis

Introduction: In some developing countries, tuberculosis and brucellosis, which are commom causes of spinal infections, are still common infectious diseases. However, co-occurrence of spinal tuberculosis and brucellosis is rare. Methodology: We report a case a 47-year-old male engaged in aquaculture with a medical history of numbness, weakness, fever, and night sweats in both upper limbs for about 10 days. Serum agglutination test (SAT) for Brucella revealed brucella infection. Cervical computed tomography (CT) scan and magnetic resonance imaging (MRI) suggested C6, C7 vertebral destruction and corresponding segmental nerve compression. Based on preoperative clinical symptoms and auxiliary examination, brucellar spondylitis was first suspected. According to the postoperative pathological examination, the patient was finally diagnosed as cervical spinal tuberculosis combined with brucellosis. Results: The preoperative symptoms of the patient decreased significantly after surgery, and the patient recovered and leaved hospital within two weeks of starting treatment. At the 6-month follow-up, the patient's clinical symptoms completely disappeared, and all laboratory tests returned to normal. Conclusion: Cervical spinal tuberculosis combined with brucellosis is a relatively rare condition. In areas with high rates of tuberculosis and brucellosis, we should conduct comprehensive examinations to avoid misdiagnosis and missed diagnosis.

A case of pediatric paraspinal arteriovenous fistula with multiple fistulas

Paraspinal arteriovenous fistula (AVF) is a rare vascular malformation. This is the first described case of a pediatric paraspinal AVF along nonvertebral segmental nerve with multiple fistulas. An 8 months-old girl was found to have a continuous murmur on the back on chest auscultation. Enhanced computed tomography revealed a segmental nerve AVF of the right thoracic spine. Selective angiography of the right T8 and T9 intercostal arteries demonstrated a high flow fistula at the level of the neural foramen, with drainage to the epidural and azygos veins. The fistulas point was visualized using Volume rendering(VR) and Minimum Intensity Projection(MIP) images. Endovascular treatment from the right T8 and T9 feeding arteries was provided using coils and n-butyl-2-cyanoacrylate(NBCA). Postembolization angiography demonstrated complete occlusion of the fistulas. The postoperative course was uneventful. We discuss the first case of a pediatric paraspinal AVF along nonvertebral segmental nerve with double holes of fistulas with literature review.

Tyrosine-Derived Polycarbonate Nerve Guidance Tubes Elicit Pro-Regenerative Extracellular Matrix Deposition When Used to Bridge Segmental Nerve Defects in Swine

Promising biomaterials should be tested in appropriate large animal models that recapitulate human inflammatory and regenerative responses. Previous studies have shown tyrosine-derived polycarbonates (TyrPC) are versatile biomaterials with a wide range of applications across multiple disciplines. The library of TyrPC has been well studied and consists of thousands of polymer compositions with tunable mechanical characteristics and degradation and resorption rates that are useful for nerve guidance tubes (NGTs). NGTs made of different TyrPCs have been used in segmental nerve defect models in small animals. The current study is an extension of this work and evaluates NGTs made using two different TyrPC compositions in a 1 cm porcine peripheral nerve repair model. We first evaluated a nondegradable TyrPC formulation, demonstrating proof-of-concept chronic regenerative efficacy up to 6 months with similar nerve/muscle electrophysiology and morphometry to the autograft repair control. Next, we characterized the acute regenerative response using a degradable TyrPC formulation. After 2 weeks in vivo, TyrPC NGT promoted greater deposition of pro-regenerative extracellular matrix (ECM) constituents (in particular collagen I, collagen III, collagen IV, laminin and fibronectin) compared to commercially available collagen-based NGTs. This corresponded with dense Schwann cell infiltration and axon extension across the lumen. These findings confirmed results reported previously in a mouse model and reveal that TyrPC NGTs were well tolerated in swine and facilitated host axon regeneration and Schwann cell infiltration in the acute phase across segmental defects - likely by eliciting a favorable neurotrophic ECM milieu. This regenerative response ultimately can contribute to functional recovery.