From the Research
The most effective method for performing a sacral lateral branch block is using ultrasound guidance, as it requires a shorter performance time, fewer needle passes, and carries a lower risk of vascular breach compared to fluoroscopy guidance, as demonstrated in a randomized trial 1.
Procedure Overview
The procedure begins with positioning the patient prone on a table. After sterile preparation and draping, the physician identifies the target sacral foramina (typically S1-S3) using ultrasound guidance. Local anesthetic is administered at the skin entry points.
Key Steps
- For each level, a 22-gauge block needle is advanced under ultrasound guidance to the lateral aspect of the sacral foramen where the lateral branches exit.
- Proper needle placement is confirmed with contrast medium injection to ensure no vascular uptake.
- Then, a small volume (1.5 mL) of local anesthetic (such as 2% lidocaine) is injected on the lateral crest at the mid-point between S2 and S3, followed by two more injections of 0.5 mL on the lateral crest, immediately cephalad to S2 and at the S1 level.
Post-Procedure Care
The patient should be monitored for 15-30 minutes after the procedure for any adverse reactions. Pain relief following the block helps confirm that the sacral lateral branches are contributing to the patient's pain.
Rationale
This procedure is effective because it interrupts pain signals from the sacroiliac joint that are transmitted through these lateral branches, providing diagnostic information and potentially therapeutic benefit for patients with sacroiliac joint dysfunction, as supported by studies on the validity of sacral lateral branch blocks and the effectiveness of sacral lateral branch thermal radiofrequency neurotomy 2, 3, 4, 5.