Overview and Comparison of Interscalene Block Techniques for Brachial Plexus Pain Management

Abstract

Purpose of review: Peripheral nerve blocks are performed using local anesthetics that are commonly performed prior to surgery to either be the sole anesthetic and/or for postoperative pain management. Interscalene blocks are a specific type of nerve block that targets the superior and middle trunks of the brachial plexus inhibiting transmission of pain signals from the upper extremities to the central nervous system making them useful in mitigating pain following surgeries involving the shoulder, upper arm, and elbow.

Recent findings: Previously, interscalene blocks were performed with a nerve stimulator, which is an instrument designed to generate a twitch in surrounding muscles to verify the anesthetic block was placed in the correct location. However, this approach with a nerve stimulator alone is being done less frequently as physicians now often employ ultrasound either by itself or in conjunction with a nerve stimulator to in the block. Several clinical studies have shown that the use of ultrasound leads to improved safety and effectiveness of the interscalene block as compared to performing the block using a nerve stimulator alone. Clinical studies comparing interscalene blocks done with ultrasound versus ultrasound in conjunction with a nerve stimulator have shown the combination to be slightly safer and more efficacious with reduced side effects, though the difference in these metrics between the two is small. Interscalene blocks are highly effective for postoperative pain related to shoulder and upper extremity surgeries. Ultrasound guided blocks are more effective with reduced adverse effects when compared to nerve stimulation alone. The combination of both ultrasound and nerve stimulation allows for increased efficacy and decreaed side effects in limited clinical investigations. Therefore, more studies are needed to further compare and determine best practice interscalene techniques for shoulder and upper extremity surgeries.

Keywords: Interscalene block; Peripheral nerve blocks; Peripheral nerve stimulator; Severe postoperative pain; Ultrasound.