Ultrasound-guided sciatic nerve block—parasacral approach

The sciatic nerve originates from the L4~S3 spinal nerves. It is one of the main branches of the sacral plexus and the thickest branch of the peripheral nerves. The L4~S3 spinal nerves pass through the deep surface of the sacrum to form the sciatic nerve and other branches. At the greater sciatic foramen, the sciatic nerve is located deep to the gluteus maximus and piriformis muscles, and exits the pelvic cavity through the inferior piriformis foramen.

The parasacral approach of ultrasound-guided sciatic nerve block can also be understood as a high approach or a proximal approach. The sciatic nerve here is adjacent to the sacral plexus, and due to the diffusion of local anesthetics, it is easy to produce a certain degree of sacral plexus block effect. The puncture point of this approach is located in the greater sciatic foramen. Sciatic nerve block (or combined with lumbar plexus block) here can be used for chronic pain analgesia or surgical anesthesia in the hip and below.