Histological confirmation of needle tip position during ultrasound-guided interscalene block: a randomized comparison between the intraplexus and the periplexus approach.

Purpose: Ultrasound-guided interscalene block can be performed using either periplexus or intraplexus needle placement. In this novel study, we histologically examined the needle tip position in relation to the neural tissues with the two techniques. Our objective was to investigate the variable risk of subepineurial needle tip placement resulting from the two ultrasound-guided techniques.