SIR 2024
Pain Management/MSK
Sabeeha Chowdhury, MD
Fellow
MedStar Georgetown University Hospital
Financial relationships: Full list of relationships is listed on the CME information page.
Hwa-Pyung Lim, MD
Integrated Interventional Radiology Resident
MedStar Georgetown University Hospital
Disclosure information not submitted.
John B. Smirniotopoulos, MD
Assistant Professor of Radiology
MedStar Georgetown University Hospital
Financial relationships: Full list of relationships is listed on the CME information page.
Patients are selected for SIJ RFA based on clinical history, reproducible pain following specific physical exam maneuvers, and at least 70% reduction of pain after an initial prognostic nerve block. For both the block and the subsequent ablation, the patient is placed prone and the image intensifier is positioned in a steep caudal angle to visualize the S1 superior endplate. The sacral ala is then targeted as well as the S1, S2, and S3 posterior neuroforamina. The overlying skin is marked and anesthetized at each target site and a 22G spinal needle is advanced under fluoroscopic guidance such that the tip terminates just lateral to each foraminal aperture, and the sacral ala for the L5 target. Upon confirming appropriate depth of the needle tip on lateral projection, approximately 1.5mL of local anesthetic is injected at each site to achieve the nerve block.
The cooled radiofrequency ablation (RFA) procedure is performed in a similar fashion with the additional steps of probe placement at each fluoroscopic target, motor stimulatory testing to minimize non-target motor neuron ablation for L5, and ablation for 2 minutes 30 seconds at 80˚ C. Of note, the S1 and S2 targets are adjusted cranial and caudal by 1cm for a total of 3 ablations at those levels, and the S3 is adjusted cranial by 1 cm for 2 ablations at this level. Bupivacaine with triamcinolone is administered at each site prior to placement and removal of the probes to relieve muscle irritation.
The effects on pain relief of SFA RFA are reported to be relatively immediate, last for months, and can be repeated as often as needed for future pain relief. The reported benefits are expected to have synergistic effects with physical therapy, which is often prescribed at time of procedure.
Conclusion and/or Teaching Points: SIJ pain commonly goes as an underdiagnosed cause of lower back or hip pain due to lack of appropriate physical examination. SIJ RFA has been shown to be both safe and effective for pain relief especially in combination with physical therapy.