Clinical Research Directory

The sacral plexus is located within a fascial plane formed by the pelvic fascia anteriorly, the sacrum medially, the piriformis and gluteus maximus muscles posteriorly, and the ischium laterally. The piriformis muscle has no attachment to the ischium and attaches to the greater trochanter laterally. A fascial plane exists between the piriformis muscle and the ischium; this fascial plane extends to the sacral plexus. Venkataraju et al. stated that in PIP block demonstrations, the needle should be directed and placed towards the posteromedial surface of the ischium. After bone contact, the medication was injected, and it was observed that the medication spread from under the piriformis muscle towards the sacral plexus.

This block, defined by the parasacral approach, targets the exit point of the plexus at the level of the foramen ischiadicum majus. Unlike distal sciatic blocks, blocking at this level includes the posterior cutaneous femoral nerve, superior/inferior gluteal nerve, and pudendal nerve, along with the ischial nerve. In current practice, ultrasonography (USG) has become the "gold standard"; visualizing the neural structures deep to the piriformis muscle by placing the probe between the lateral sacrum and the iliac wing increases the success rate while minimizing the risk of complications.