The impact of local anesthetic distribution on block onset in Ultrasound-guided interscalene block

Background Recent investigations of local anesthetic distribution in the lower extremity have revealed that completely surrounding the sciatic nerve with local anesthetic provides the advantage of more rapid and complete anesthesia in the territory served by the nerve. We hypothesized that a pattern of distribution which entirely envelops the targeted nerve roots during interscalene block would provide similar benefits of more rapid anesthesia onset.