Sala-Blanch, Xavier

ABSTRACT The microvasculature of peripheral nerve not only is important for the understanding of the development of compression syndromes, but it plays a critical role in the evolution of other nerve pathologies, including, for example, the distribution of intraneural ganglion cysts and lymphoma. We investigated the anatomical course of vessels around the human sciatic nerve and its bifurcation in eight human cadavers. Specifically, the presence of fenestrations on the epineurium and paraneurium's thickness in relation to the intraneural vessels was investigated. The sciatic, tibial, peroneal and sural nerves at the level of the bifurcation are surrounded by different layers, including the epineurium and paraneurial layers. Multiple fenestrations were observed in all membranes surrounding these nerves, which formed openings for the transfer of adipocytes and vessels from one compartment to the neighboring one. The openings were relatively large compared to the size of the vessels. In conclusion, vessels always travel through a natural opening in the paraneurial and epineurium. These vessels are important connections between the extrinsic and intrinsic nerve vasculature. In addition, the fenestration provides an important anatomical explanation for the possibility of transfer of anesthetic agents or different nerve pathologies, including intraneural ganglion cyst and tumors.

Background The Midclavicle Block achieves balanced methylene blue spread across both anterosuperior and posteroinferior periosteal surfaces in cadavers with intact clavicles. Objective To evaluate the anatomical distribution pattern of the Midclavicle Block in cadaveric specimens with midshaft clavicle fractures, with a focus on periosteal coverage and involvement of the fracture site. Methods An anatomical study was conducted on 10 cadavers (20 clavicular regions). A midshaft clavicle fracture model was created, and the Midclavicle Block technique was applied under ultrasound guidance. A methylene blue solution was injected, and dissections were performed to evaluate dye spread primarily in the deep muscular and the clavicular plane, including the fracture site. Probabilistic maps of dye distribution were generated. Results The anatomical dissection in the deep muscular plane revealed consistent staining of the fracture site in all specimens, along with the subclavius muscle and the clavipectoral fascia, while the pectoralis minor muscle remained unaffected in every case. As the dissection progressed toward the infraclavicular brachial plexus plane, no staining of the plexus was observed, with dye spread restricted to the subclavius muscle and adjacent clavipectoral fascia. The mean staining of the anterosuperior and posteroinferior periosteal surfaces was 55.5% (95% CI: 50.6% to 60.4%) and 53.8% (95% CI: 49.5% to 58.1%), respectively. The highest dye concentration was observed in the middle third of the clavicle, corresponding to the fracture zone. Conclusion The Midclavicle Block resulted in effective periosteal coverage and targeted fracture site staining. Clinical studies are needed to confirm its in vivo efficacy, given the limitations inherent to cadaveric specimens.

Background Inconsistent nomenclature and anatomical descriptions of regional anesthetic techniques hinder scientific communication and engender confusion; this in turn has implications for research, education and clinical implementation of regional anesthesia. Having produced standardized nomenclature for abdominal wall, paraspinal and chest wall regional anesthetic techniques, we aimed to similarly do so for upper and lower limb peripheral nerve blocks. Methods We performed a three-round Delphi international consensus study to generate standardized names and anatomical descriptions of upper and lower limb regional anesthetic techniques. A long list of names and anatomical description of blocks of upper and lower extremities was produced by the members of the steering committee. Subsequently, two rounds of anonymized voting and commenting were followed by a third virtual round table to secure consensus for items that remained outstanding after the first and second rounds. As with previous methodology, strong consensus was defined as ≥75% agreement and weak consensus as 50%–74% agreement. Results A total of 94, 91 and 65 collaborators participated in the first, second and third rounds, respectively. We achieved strong consensus for 38 names and 33 anatomical descriptions, and weak consensus for five anatomical descriptions. We agreed on a template for naming peripheral nerve blocks based on the name of the nerve and the anatomical location of the blockade and identified several areas for future research. Conclusions We achieved consensus on nomenclature and anatomical descriptions of regional anesthetic techniques for upper and lower limb nerve blocks, and recommend using this framework in clinical and academic practice. This should improve research, teaching and learning of regional anesthesia to eventually improve patient care.