Shamrock sign: inadvertently inverted

• Published in: Regional anesthesia and pain medicine Vol. 44; no. 6; pp. 685 - 686
• Main Authors: Nielsen, Martin Vedel, Bendtsen, Thomas Fichtner, Børglum, Jens
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group Ltd 01.06.2019; Copyright by American Society of Regional Anesthesia and Pain Medicine; BMJ Publishing Group LTD
• Subjects: anatomy; Pain; PostScript; Regional anesthesia; truncal blocks; Ultrasonic imaging; ultrasound in pain medicine; ultrasound in pain medicine; anatomy; truncal blocks
• ISSN: 1098-7339; 1532-8651
• DOI: 10.1136/rapm-2019-100477

Correspondence to Dr Jens Børglum, Department of Anesthesiology and Intensive Care Medicine, Zealand University Hospital, Roskilde 4000, Denmark; jens.borglum@gmail.com To the editor, We congratulate Dr de Cassai et al 1 for their creative application of the Shamrock sign for improved pattern recognition when performing the so-called lumbar erector spinae plane block (ESPB).2 We think the idea of using the Shamrock sign for guidance of the new lumbar ESPB is basically good—presupposing that lumbar ESPB is effective, which is not supported by any solid evidence so far. Targeting the point indicated by the asterisk in the figure will most likely result in a lumbar plexus block3—generating anesthesia of the ventral rami of the spinal nerves L2–L4 (ie, the intrapsoas part of the lumbar plexus). Correct three-dimensional anatomical interpretation based on two-dimensional sonoanatomical cross-sections of the lumbar paravertebral region is challenging.