What is the role of sciatic nerve block in pain management?

Updated: Jun 19, 2018
  • Author: Anthony H Wheeler, MD; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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The sciatic nerve is derived from the L4, L5, and the S1-S3 nerve roots; these nerve roots become enjoined on the anterior surface of the piriformis muscle. The nerve then travels inferiorly and leaves the pelvis just below the piriformis muscle via the sciatic notch. The sciatic nerve lies anterior to the gluteus maximus muscle and is halfway between the greater trochanter and the ischial tuberosity. The sciatic nerve courses downward past the lesser trochanter to lie posterior and medial to the femur. In the mid thigh, the nerve gives off branches to the hamstring muscles and the adductor magnus muscle. In most patients, the nerve divides to form the tibial and common peroneal nerves in the rostral popliteal fossa.

A posterior sciatic nerve block is useful for evaluation and management of distal lower extremity pain that is thought to be caused by the sciatic nerve. Sciatic nerve block with local anesthetic can be used during differential neural blockade to determine the anatomy of distal lower extremity pain. If destruction of the sciatic nerve is considered, this technique is sometimes useful as a prognostic indicator of the degree of motor and sensory impairment that the patient may hope to experience.

In some cases of acute pain, sciatic nerve block with local anesthesia may be used to provide urgent relief. Examples of this clinical scenario include distal lower distal extremity fractures or trauma. Sciatic nerve block can alleviate pain while waiting for other pharmacologic methods to become effective. Sciatic nerve block combining local anesthetic and corticosteroids is occasionally used to treat persistent distal lower extremity pain that is thought to be secondary to inflammation or when entrapment of sciatic nerve by the piriformis muscle is suspected. Destruction of the sciatic nerve is occasionally indicated for palliation of persistent distal lower extremity pain secondary to malignancies.

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