Department of Anaesthesiology and Intensive Care Therapy, Philipps University Marburg, Baldingerstr., 35032 Marburg, Germany.
Br J Anaesth. 2010 Feb;104(2):245-53. doi: 10.1093/bja/aep366. Epub 2009 Dec 22.
In regional anaesthesia, there is a risk of direct nerve injury. The purpose of this study was to determine whether the diameter of the applied needle is associated with the magnitude of nerve injury after needle nerve perforation.
In five anaesthetized pigs, the brachial plexus were exposed bilaterally. Up to eight nerves underwent needle nerve perforation using a 24 G pencil-point cannula (small diameter) or a 19 G pencil-point needle (large diameter). After 48 h, the nerves were resected during anaesthesia. The specimens were processed for visual examination and the detection of inflammatory cells, myelin damage and intraneural haematoma. The grade of nerve injury was scored ranging from 0 (no injury) to 4 (severe injury).
Forty-eight nerves were examined. The applied injury score was significantly lower in the small-diameter group [median (inter-quartile range) 2.0 (2.0-2.0)] compared with the large-diameter group [3.5 (3.0-4.0) P<0.01]. Myelin damage and intraneural haematoma occurred predominantly in the large-diameter group. Signs of post-traumatic regional inflammation were comparable among both groups.
The severity of nerve injury after needle nerve perforation was related to the diameter of the applied cannula. However, no such difference exists for regional inflammation. Functional consequences of these findings need to be determined. Currently, small-diameter cannulae may be advisable for peripheral nerve blocks to minimize the risk of nerve injury in the case of nerve perforation.
在区域麻醉中，存在直接损伤神经的风险。本研究旨在确定应用的针的直径是否与针神经穿孔后神经损伤的程度相关。
在五只麻醉的猪中，双侧暴露臂丛神经。使用 24 G 笔尖套管（小直径）或 19 G 笔尖针（大直径）对多达 8 根神经进行针神经穿孔。48 小时后，在麻醉下切除神经。将标本进行视觉检查和检测炎性细胞、髓鞘损伤和神经内血肿。神经损伤程度评分范围从 0（无损伤）到 4（严重损伤）。
检查了 48 根神经。与大直径组[中位数（四分位间距）3.5（3.0-4.0），P<0.01]相比，小直径组的应用损伤评分明显较低[2.0（2.0-2.0）]。髓鞘损伤和神经内血肿主要发生在大直径组。两组的创伤后区域性炎症迹象相当。
针神经穿孔后神经损伤的严重程度与应用的套管直径有关。然而，区域性炎症则没有这种差异。需要确定这些发现的功能后果。目前，在神经穿孔的情况下，为了尽量减少神经损伤的风险，小直径套管可能更适合用于周围神经阻滞。
