Radiofrequency ablation and phenol neurolysis of the ganglion impar are methods used in cases unresponsive to medication, particularly in patients who derive short-term or partial relief from the initial ganglion impar block. In clinical practice, clinicians frequently use these two injections in patients with treatment-resistant pain who only partially benefit from the initial blockade procedure.

To date, the medical literature lacks a comprehensive study comparing the efficacy of radiofrequency ablation and phenol neurolysis in patients who partially benefit from ganglion impar block. Therefore, this study is designed to compare the effectiveness of these two methods in patients with chronic coccydynia.

Ganglion impar radiofrequency ablation and phenol neurolysis are treatment options for patients who do not respond to medication, especially those experiencing only temporary or partial relief from an initial ganglion impar block. In clinical practice, these two injection techniques are commonly employed in managing persistent pain in such cases.

Radiofrequency Ablation (RFA):

This technique aims to eliminate pain by thermally damaging the nerves that carry pain sensations. Under real-time imaging guidance, a radiofrequency needle is advanced through the intervertebral disc from the tailbone region to the anatomical area called the ganglion impar. The needle tip location is confirmed with contrast dye. At this point, motor and sensory stimulation is applied to ensure the needle is not affecting motor function and to identify the site where the pain stimulus matches the patient's complaint. Once confirmed, heat application is initiated. Prior to heat delivery, a local anesthetic is administered to ensure the procedure is painless.

Phenol Neurolysis:

This method aims to chemically destroy the nerves carrying pain signals from the coccyx area using phenol. The procedure is performed similarly to RFA: a radiofrequency needle is inserted through the disc between spinal bones under real-time imaging guidance to reach the ganglion impar. After confirming the needle position with contrast dye, a local anesthetic is administered, and then phenol is applied to chemically ablate the sensory fibers without pain.

No major complications have been reported in the literature regarding these two procedures. However, minor complications may occur, such as vasovagal reactions (temporary fainting), minor bleeding, infection, and vascular injection.

Study Design:

The study will include patients under the care of the Marmara University Pain Medicine Department who have not responded to medication and have received short-term or partial benefit from an initial ganglion impar block. These patients will be randomly assigned via computer software into two groups. One group will undergo the radiofrequency ablation procedure described above, and the other group will receive phenol neurolysis. The patients will be followed for six months, and the effectiveness of these two widely used but yet-to-be-compared treatments will be evaluated.

Inclusion Criteria:

• Age between 18 and 65 years
• Presence of chronic coccydynia lasting at least 3 months
• Pre-procedural pain score of 4 or higher on the Numeric Rating Scale (NRS)
• Patients who have undergone a ganglion impar block within the last 3 months and experienced limited benefit (i.e., less than 50% reduction in pain compared to pre-treatment) and/or short-term relief (less than 4 weeks)

Exclusion Criteria:

• History of surgery involving the sacrococcygeal region
• Prior treatment with ganglion impar phenol neurolysis or radiofrequency ablation
• Coagulopathies (bleeding disorders)
• Infection
• Spondylolisthesis, scoliosis, or lumbar spinal stenosis
• Malignancy
• Pregnancy
• History of allergic reaction to the administered injectates
• History of major psychiatric illness