Beyond Quadratus Lumborum Block: A Technique for Ultrasound Guided Lumbar Sympathetic Block

Dear Editor, Quadratus lumborum (QL) block through the transmuscular route is commonly performed under ultrasound guidance (USG) for providing analgesia in abdominal surgeries. It involves placing a curvilinear probe on the flank of abdomen and visualizing the vertebral body along with transverse process. Around the transverse process, the three muscle groups—Psoas major, QL and erector spinae that together form the “Shamrock sign” are identified. The needle is then advanced through the QL muscle to deposit the drug between QL muscle and psoas [1]. This popular and relatively simple scanning technique has applications which go beyond the QL block. One such technique is ultrasound guided lumbar sympathetic block (LSB) which allows real time visualization of soft tissues and spread of injectate while minimizing the radiation exposure [2]. However, deeper structures and vascular spread may not be seen clearly, particularly in obese patients. In this letter, we describe a technique to perform a LSB utilizing an ultrasound guidance approach similar to that of a QL block.