Ultrasound‐guided interscalene blocks: understanding where to inject the local anaesthetic

Summary Although ultrasound‐guided regional anaesthesia has gained in popularity, few data exist describing the optimal location(s) to inject local anaesthetic. Our objective was to compare, for interscalene blocks, the effectiveness of an injection between the middle scalene muscle and brachial plexus sheath (peri‐plexus) with an injection within the brachial plexus sheath (intra‐plexus). We enrolled 170 patients undergoing shoulder surgery...