From the Centro de Estudios Universitarios (CEU) San Pablo University School of Medicine, Madrid, Spain (M.A.R.) the Department of Anesthesiology, Madrid-Montepríncipe University Hospital, Madrid, Spain (M.A.R., E.M.) the Human Anatomy and Embryology Unit, Faculty of Medicine, University of Barcelona, Barcelona, Spain (X.S.-B.) the Division of Acute and Perioperative Pain Medicine, Department of Anesthesiology (O.C.N., A.P.B.) the Department of Orthopedic Surgery (A.P.B.), University of Florida College of Medicine, Gainesville, Florida the Department of Anesthesiology, University of Maryland School of Medicine, Baltimore, Maryland (P.E.B.).
Anesthesiology. 2019 Jun;130(6):1007-1016. doi: 10.1097/ALN.0000000000002647.
There is confusion regarding the spread of intraneurally injected local anesthetic agents during regional anesthesia. The aim of this research was to deliberately inject a marker that does not leave the neural compartment into which it is injected, and then to study the longitudinal and circumferential spread and possible pathways of intraneural spread.
After institutional review board approval, we intraneurally injected 20 and 5 ml of heparinized blood solution under ultrasound guidance into 12 sciatic nerves in the popliteal fossa and 10 median nerves, respectively, of eight fresh, unembalmed cadavers using standard 22-gauge "D" needles, mimicking the blocks in clinical conditions. Ultrasound evidence of nerve swelling confirmed intraneural injection. Samples of the nerves were then examined under light and scanning electron microscopy.
Extrafascicular spread was observed in all the adipocyte-containing neural compartments of the 664 cross-section samples we examined, but intrafascicular spread was seen in only 6 cross-sections of two nerves. None of the epineurium, perineurium, or neural components were disrupted in any of the samples. Spread between the layers of the perineurium was a route of spread that included the perineurium surrounding the fascicles and the perineurium that formed incomplete septa in the fascicles. Similar to the endoneurium proper, subepineural compartments that did not contain any fat cells did not reveal any spread of heparinized blood solution cells. No "perineural" spaces were observed within the endoneurium. We also did not observe any true intrafascicular spread.
After deliberate intraneural injection, longitudinal and circumferential extrafascicular spread occurred in all instances in the neural compartments that contained adipocytes, but not in the relatively solid endoneurium of the fascicles.
在区域麻醉期间，局部麻醉剂在神经内的扩散存在混淆。本研究的目的是故意注射一种不会离开注射部位的神经间隙的标记物，然后研究神经内扩散的纵向和周向扩散以及可能的扩散途径。
在机构审查委员会批准后，我们使用标准的 22 号“D”针，在 8 个未经防腐处理的新鲜尸体的每个尸体的腘窝中的 12 条坐骨神经和 10 条正中神经中分别超声引导下注入 20 和 5ml 的肝素化血液溶液，模拟临床条件下的阻滞。神经肿胀的超声证据证实了神经内注射。然后在光镜和扫描电子显微镜下检查神经样本。
在我们检查的 664 个横截面样本中，所有含有脂肪细胞的神经间隙都观察到了神经外扩散，但只有 2 根神经的 6 个横截面观察到了神经内扩散。在任何样本中，神经外膜、神经内膜或神经成分都没有被破坏。在神经内膜之间的层间扩散是一种包括围绕束的神经内膜和在束内形成不完全隔的神经内膜的扩散途径。与真正的神经内膜相似，不包含任何脂肪细胞的神经内膜下间隙没有显示出肝素化血液溶液细胞的任何扩散。在神经内膜内没有观察到任何真正的神经内扩散。
在故意神经内注射后，在含有脂肪细胞的神经间隙中，所有情况下都发生了纵向和周向的神经外扩散，但在束内相对坚实的神经内膜中则没有发生扩散。
