Ultrasound-Guided Interscalene Block

Background and Objectives

The “stoplight” sign is a frequently described image during ultrasound-guided interscalene block, referring to 3 hypoechoic structures found between the anterior and middle scalene muscles. This study was designed to establish the ultrasound-anatomy correlation of this sign and to find any other anatomical features within the roots that could help with the interpretation of the ultrasound images obtained at the...