Maga Joni, Missair Andres, Visan Alex, Kaplan Lee, Gutierrez Juan F, Jain Annika R, Gebhard Ralf E
Departments of Anesthesiology, Perioperative Medicine, and Pain Management (J.M., A.M., A.V., J.F.G., A.R.J., R.E.G.) and Orthopedics and Rehabilitation (L.K., R.E.G.), University of Miami, Miller School of Medicine, Miami, Florida USA.
J Ultrasound Med. 2016 Feb;35(2):279-85. doi: 10.7863/ultra.15.01059. Epub 2015 Dec 29.
Ultrasound-guided interscalene brachial plexus blocks are commonly used to provide anesthesia for the shoulder and proximal upper extremity. Some reviews identify a sheath that envelops the brachial plexus as a potential tissue plane target, and current editorials in the literature highlight the need to establish precise and reproducible injection targets under ultrasound guidance. We hypothesize that an injection of a local anesthetic inside the brachial plexus sheath during ultrasound-guided interscalene nerve blocks will result in enhanced procedure success and provide a consistent tissue plane target for this approach with a reproducible and characteristic local anesthetic spread pattern.
Sixty patients scheduled for shoulder surgery with a preoperative interscalene block for postoperative pain management were enrolled in this prospective randomized observer-blinded study. Each patient was randomly assigned to receive a single-shot interscalene block either inside or outside the brachial plexus sheath.
The rate of complete motor and sensory blocks of the axillary nerve territory 10 minutes after local anesthetic injection for the inside group was 70% versus 37% for the outside group (P < .05). At all measurement intervals beyond 10 minutes, however, neither group showed a statistically significant difference in complete sensory blockade. The incidence rates of transient paresthesia during needle passage were 6.7% for the outside group and 96.7% for the inside group (P < .05).
Except for faster onset, this prospective randomized trial did not find any advantages to performing an interscalene block inside the brachial plexus sheath. There was a higher incidence of transient paresthesia when injections were performed inside compared to outside the sheath.
超声引导下的肌间沟臂丛神经阻滞常用于为肩部及上肢近端提供麻醉。一些综述将包裹臂丛神经的鞘膜视为潜在的组织平面靶点，并且当前文献中的社论强调了在超声引导下确定精确且可重复的注射靶点的必要性。我们假设在超声引导下的肌间沟神经阻滞过程中，将局部麻醉药注射到臂丛神经鞘膜内会提高操作成功率，并为该方法提供一个一致的组织平面靶点，伴有可重复且具有特征性的局部麻醉药扩散模式。
本前瞻性随机观察者盲法研究纳入了60例计划行肩部手术且术前采用肌间沟阻滞进行术后疼痛管理的患者。每位患者被随机分配接受单次肌间沟阻滞，分别将药物注射到臂丛神经鞘膜内或鞘膜外。
局部麻醉药注射后10分钟，鞘膜内组腋神经区域完全运动和感觉阻滞率为70%，而鞘膜外组为37%（P < 0.05）。然而，在10分钟后的所有测量时间点，两组在完全感觉阻滞方面均未显示出统计学上的显著差异。穿刺过程中短暂性感觉异常的发生率，鞘膜外组为6.7%，鞘膜内组为96.7%（P < 0.05）。
除起效更快外，这项前瞻性随机试验未发现臂丛神经鞘膜内进行肌间沟阻滞有任何优势。与鞘膜外注射相比，鞘膜内注射时短暂性感觉异常的发生率更高。
