Parasacral Ischial Plane Block in Lower Extremity Surgery

Condition(s) studied

Investigational drug(s) / intervention(s)

Parasacral Ischial Plan Block: 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.

Sacral plexus block: 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.

Study summary

The parasacral ischial plane block is a novel fascial plane approach targeting the sacral plexus. This technique is technically less challenging and eliminates the requirement for direct visualization of the sacral plexus. The aim of this prospective observational study is to evaluate the efficacy of the conventional sacral plexus block versus the parasacral ischial plane block in patients undergoing lower extremity surgery.

Eligibility

Primary outcome measure(s)

• Sensory and motor block onset time — 1 hour
  This approach is based on the volume-dependent spread of local anesthetic into the plane between the sacral plexus and the deep pelvic muscle fascia; sensory blockade begins proximally to distally within 10-20 minutes, while motor blockade usually develops later and gradually around 20-30 minutes.

Trial sites (1)

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