Trans-Sacral Nerve Block

Trans-Sacral Nerve Block

A. Indications

This technique is useful in the diagnosis and treat-ment of pelvic and perineal pain. In addition, block-ade of the S1 spinal root can help define its role in back pain.

B. Anatomy

The five paired sacral spinal nerves and one pair of coccygeal nerves descend in the sacral canal. Each nerve then travels through its respective interver-tebral foramen. The S5 and coccygeal nerves exit through the sacral hiatus.

C. Technique

While the patient is prone, the sacral foramina are identified with a needle along a line drawn 1.5 cm medial to the posterior superior iliac spine and 1.5 cm

lateral to the ipsilateral sacral cornu (Figure 47–18). Correct positioning requires entry of the needle into the posterior sacral foramen and usually produces paresthesias. The S1 nerve root is usually 1.5 cm above the level of the posterior superior iliac spine along this imaginary line. Blockade of the S5 and coccygeal nerves can be accomplished by injection at the sacral hiatus.

D. Complications

Complications are rare but include nerve damage and intravascular injection.