A sono-anatomical and cadaveric study of ultrasound-guided retrolaminar block.

Aim: Retrolaminar block (RB) is known to confer chest wall analgesia but, its mechanism has not been established. Our primary objective was to determine if the spread of injectate following RB extends to the paravertebral space (PVS). Second-ary objectives were to determine the predefined anatomical areas and nervous tissues contacted by injectate; the effect of volume on spread; and the extent to which experts can predict PVS spread based on examination of US videos of the injection.