Comparison of the Efficacy of Sacral Erector Spinae Plane Block and Caudal Epidural Injection on Chronic Coccydynia: A Randomized Controlled Trial

Coccydynia (coccygodynia, coccalgia) or coccygeal pain is a painful syndrome affecting the coccyx region. The most important etiological factors in the formation of coccydynia are external and internal trauma, though it can also occur idiopathically. The pain intensifies while sitting or standing up from a sitting position. Although it can affect individuals of all ages and genders, the average onset age is 40, with a prevalence 5 times higher in women. Coccydynia is a painful condition that impacts quality of life, and its treatment can be challenging due to the influence of various physiological and psychological factors.

Patients typically complain of pain in the tailbone area, which increases with prolonged sitting, leaning backward while sitting, standing for extended periods, and rising from a sitting position. Conservative treatments such as nonsteroidal anti-inflammatory drugs, levator ani relaxation exercises, seating cushions, and transcutaneous electrical stimulation are commonly used, but these methods are ineffective in 10% of cases.

For patients unresponsive to conservative treatments, interventional and surgical options include caudal epidural steroid injection, sacral erector spinae plane block, ganglion impar blocks, radiofrequency ablation of sacral nerves, block and radiofrequency ablation of coccygeal nerves, and coccygectomy.

Sacral erector spinae plane block under ultrasound guidance or caudal epidural injection under fluoroscopic guidance is performed under sterile conditions for patients with resistant and chronic coccydynia. For the sacral erector spinae plane block, the sacral and coccygeal cornua are visualized in a transverse position under ultrasound, followed by sagittal positioning of the probe over the sacrum for injection at the 4th and 5th sacral vertebrae. For caudal epidural injection, the fluoroscope is positioned laterally, and the injection is administered to the target area under fluoroscopic imaging. In both techniques, the injectate consists of 8 mg dexamethasone and 10 mg bupivacaine (0.5% concentration), with a total volume of 10 mL. After the procedure, patients are monitored for potential hypotension and allergic reactions as a precaution.

This study will include patients treated with sacral erector spinae plane block and caudal epidural injection for coccydynia resistant to conservative treatments. Face-to-face questionnaires, Numerical Rating Scale scores, and the Paris Functional Coccydynia Scale will be evaluated at 1, 4, and 12-week follow-ups.