CoccygodyniaNCT07021365
Comparison of Ganglion Impar Radiofrequency Ablation and Phenol Neurolysis Techniques for Chronic Coccydynia Treatment
A study testing Phenol Injection and Radiofrequency ablation alone in people with Coccygodynia and Coccydynia, run by Marmara University at 1 site in Turkey (Türkiye).
Trial summary
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. Read more about this study
- Who is it for?
- Ages 18 to 65 years
- Conditions the study is for
- Coccygodynia, Coccydynia
- What is being tested?
- Phenol Injection and Radiofrequency ablation alone
- Type of treatment
- Injection or infusion, Medical device
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 30 participants
- Where
- 1 siteTurkey (Türkiye)
- Study dates
- Jul 2025to Mar 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 65 years
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- 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)
Who cannot join
- 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
Show all 9Show fewer
- Pregnancy
- History of allergic reaction to the administered injectates
- History of major psychiatric illness
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
Turkey (Türkiye)1 site
Marmara University
Istanbul, Istanbul, 34854
Merve Sekizkardes, Medical Doctor, 00905367445551, merve.sekizkardes@gmail.com
About this study
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.
Read the detailed description
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.
- Conditions
- Coccygodynia, Coccydynia
- Being tested
- Phenol Injection, Radiofrequency ablation alone
- Keywords
- coccygodinia, chronic, radiofrequency ablation, phenol neurolysis, coccydynia
- Medical subject headings
- Bronchiolitis Obliterans Syndrome
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Phenol InjectionDrug
n patients diagnosed with chronic coccydynia, a ganglion impar block is initially performed following conservative treatment. In cases where this intervention provides limited benefit, ganglion impar phenol neurolysis is performed. A short-acting local anesthetic (3-4 mL of 1% prilocaine) will be administered into the skin and subcutaneous tissues. A 90 mm 22-gauge Quincke-tipped spinal needle will be advanced via the trans-coccygeal route under fluoroscopic guidance with intermittent imaging. The needle's position in the area anterior to the coccyx, where the ganglion impar is located, will be confirmed using 1-2 mL of contrast agent (iohexol). If the desired spread of contrast is observed, 5 mL of 7% phenol will be injected.
Radiofrequency ablation aloneDevice
In patients diagnosed with chronic coccydynia, a ganglion impar block is initially performed following conservative treatment. In cases where this intervention provides limited benefit, ganglion impar radiofrequency (RF) ablation-routinely used in clinical practice-will be performed by an experienced pain specialist (SŞ) with at least 10 years of expertise in this procedure.
Using fluoroscopic guidance and intermittent imaging, a 100 mm RF cannula with an injection tube will be advanced trans-coccygeally. After confirming the needle's position at the site of the ganglion impar in front of the coccyx with 1-2 mL of contrast agent (iohexol), sensory stimulation will be applied via the RF generator to confirm that the needle tip is at the patient's pain site. Motor stimulation will also be performed to ensure there is no muscle contraction. At this stage, 2 mL of lidocaine will be administered before initiating ablation at 80°C for 90 seconds.
| Study group | Role | What they receive |
|---|---|---|
| Ganglion Impar Radiofrequency Ablation | Active comparator | Not described Receives: Device: Radiofrequency ablation alone |
| Ganglion Impar Phenol Neurolysis | Active comparator | Not described Receives: Drug: Phenol Injection |
What is being measured
The primary outcome is the main question the study is designed to answer.
Numeric Rating Scale-11
A subjective outcome measure to assess pain (Min:0 Max:10). Higher scores indicate more severe pain.
Measured: Treatment to 6 months post-treatment
Secondary outcomes (2)
Short Form-12 Health Survey
The SF-12 (Short Form-12 Health Survey) is a validated instrument used to evaluate health-related quality of life, with scores ranging from 0 to 100. Higher scores reflect better overall health status.
Measured: Treatment to 6 months post-treatment.
Douleur Neuropathique 4
The DN4 (Douleur Neuropathique 4) questionnaire is a diagnostic screening tool designed to detect the presence of neuropathic pain, with scores ranging from 1 to 10. Higher scores suggest a greater probability of neuropathic pain.
Measured: Treatment to 6 months post-treatment.
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted15 Jun 2025
- Study startJul 2025 (estimated)
- Primary completionNov 2025 (estimated)
- Study completionMar 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (6)Papers the sponsor has linked to this study.
- Other trials for CoccygodyniaStudies of the same condition, open and under way.
- More trials run by Marmara UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind
- Who is masked
- Care provider, Investigator, Outcomes assessor
- Enrolment
- 30 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Marmara University
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07021365
- Sponsor's protocol ID
- 09.2024.1470
- Status last verified
- Jun 2025
- First submitted
- 29 May 2025
- Last updated
- 17 Jun 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes
Publications
Sagir O, Demir HF, Ugun F, Atik B. Retrospective evaluation of pain in patients with coccydynia who underwent impar ganglion block. BMC Anesthesiol. 2020 May 11;20(1):110. doi: 10.1186/s12871-020-01034-6.
PubMed 32393277Demircay E, Kabatas S, Cansever T, Yilmaz C, Tuncay C, Altinors N. Radiofrequency thermocoagulation of ganglion impar in the management of coccydynia: preliminary results. Turk Neurosurg. 2010 Jul;20(3):328-33. doi: 10.5137/1019-5149.JTN.2852-09.0.
PubMed 20669105Howard PD, Dolan AN, Falco AN, Holland BM, Wilkinson CF, Zink AM. A comparison of conservative interventions and their effectiveness for coccydynia: a systematic review. J Man Manip Ther. 2013 Nov;21(4):213-9. doi: 10.1179/2042618613Y.0000000040.
PubMed 24421634Kircelli A, Demircay E, Ozel O, Coven I, Isik S, Civelek E, Kabatas S. Radiofrequency Thermocoagulation of the Ganglion Impar for Coccydynia Management: Long-Term Effects. Pain Pract. 2019 Jan;19(1):9-15. doi: 10.1111/papr.12698. Epub 2018 May 16.
PubMed 29617062Sencan S, Kenis-Coskun O, Demir FGU, Cuce I, Ercalik T, Gunduz OH. Ganglion Impar block improves neuropathic pain in coccygodynia: A preliminary report. Neurol Neurochir Pol. 2018 Sep-Oct;52(5):612-617. doi: 10.1016/j.pjnns.2018.08.006. Epub 2018 Aug 28.
PubMed 30195465Karadimas EJ, Trypsiannis G, Giannoudis PV. Surgical treatment of coccygodynia: an analytic review of the literature. Eur Spine J. 2011 May;20(5):698-705. doi: 10.1007/s00586-010-1617-1. Epub 2010 Nov 3.
PubMed 21046173
Study at a glance
From the registry record, last updated by the sponsor on 17 Jun 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Comparison of Ganglion Impar Radiofrequency Ablation and Phenol Neurolysis Techniques for Chronic Coccydynia Treatment
- ClinicalTrials.gov ID
- NCT07021365
- Acronym / sponsor ID
- 09.2024.1470
- Conditions
- Coccygodynia, Coccydynia
- Keywords
- coccygodinia, chronic, radiofrequency ablation, phenol neurolysis, coccydynia
- Study type
- Interventional
- Recruitment status
- Not yet recruiting
- Enrolment
- 30 participants (estimated)
- Lead sponsor
- Marmara UniversityUniversity, hospital or other
- Study start
- Jul 2025 (estimated)
- Primary completion
- Nov 2025 (estimated)
- Study completion
- Mar 2026 (estimated)
- First posted
- 15 Jun 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed description
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.
Study design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Triple blind (care provider, investigator, outcomes assessor)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Ganglion Impar Radiofrequency Ablation | Active comparator | Device: Radiofrequency ablation alone |
| Ganglion Impar Phenol Neurolysis | Active comparator | Drug: Phenol Injection |
Who may qualify
- Ages
- 18 to 65 years
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (4 listed)
- 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)
Key exclusion criteria (9 listed)
- 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
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Phenol Injectionn patients diagnosed with chronic coccydynia, a ganglion impar block is initially performed following conservative treatment. In cases where this intervention provides limited benefit, ganglion impar phenol neurolysis is performed. A short-acting local anesthetic (3-4 mL of 1% prilocaine) will be administered into the skin and subcutaneous tissues. A 90 mm 22-gauge Quincke-tipped spinal needle will be advanced via the trans-coccygeal route under fluoroscopic guidance with intermittent imaging. The needle's position in the area anterior to the coccyx, where the ganglion impar is located, will be confirmed using 1-2 mL of contrast agent (iohexol). If the desired spread of contrast is observed, 5 mL of 7% phenol will be injected. | Drug | Ganglion Impar Phenol Neurolysis |
| Radiofrequency ablation aloneIn patients diagnosed with chronic coccydynia, a ganglion impar block is initially performed following conservative treatment. In cases where this intervention provides limited benefit, ganglion impar radiofrequency (RF) ablation-routinely used in clinical practice-will be performed by an experienced pain specialist (SŞ) with at least 10 years of expertise in this procedure. Using fluoroscopic guidance and intermittent imaging, a 100 mm RF cannula with an injection tube will be advanced trans-coccygeally. After confirming the needle's position at the site of the ganglion impar in front of the coccyx with 1-2 mL of contrast agent (iohexol), sensory stimulation will be applied via the RF generator to confirm that the needle tip is at the patient's pain site. Motor stimulation will also be performed to ensure there is no muscle contraction. At this stage, 2 mL of lidocaine will be administered before initiating ablation at 80°C for 90 seconds. | Device | Ganglion Impar Radiofrequency Ablation |
Primary outcome
Numeric Rating Scale-11
Time frame: Treatment to 6 months post-treatment
A subjective outcome measure to assess pain (Min:0 Max:10). Higher scores indicate more severe pain.
2 secondary outcomes
Short Form-12 Health Survey
Time frame: Treatment to 6 months post-treatment.
Douleur Neuropathique 4
Time frame: Treatment to 6 months post-treatment.
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 17 Jun 2025.
- Background: PubMed 32393277Sagir O, Demir HF, Ugun F, Atik B. Retrospective evaluation of pain in patients with coccydynia who underwent impar ganglion block. BMC Anesthesiol. 2020 May 11;20(1):110. doi: 10.1186/s12871-020-01034-6.
- Background: PubMed 20669105Demircay E, Kabatas S, Cansever T, Yilmaz C, Tuncay C, Altinors N. Radiofrequency thermocoagulation of ganglion impar in the management of coccydynia: preliminary results. Turk Neurosurg. 2010 Jul;20(3):328-33. doi: 10.5137/1019-5149.JTN.2852-09.0.
- Background: PubMed 24421634Howard PD, Dolan AN, Falco AN, Holland BM, Wilkinson CF, Zink AM. A comparison of conservative interventions and their effectiveness for coccydynia: a systematic review. J Man Manip Ther. 2013 Nov;21(4):213-9. doi: 10.1179/2042618613Y.0000000040.
- Background: PubMed 29617062Kircelli A, Demircay E, Ozel O, Coven I, Isik S, Civelek E, Kabatas S. Radiofrequency Thermocoagulation of the Ganglion Impar for Coccydynia Management: Long-Term Effects. Pain Pract. 2019 Jan;19(1):9-15. doi: 10.1111/papr.12698. Epub 2018 May 16.
- Background: PubMed 30195465Sencan S, Kenis-Coskun O, Demir FGU, Cuce I, Ercalik T, Gunduz OH. Ganglion Impar block improves neuropathic pain in coccygodynia: A preliminary report. Neurol Neurochir Pol. 2018 Sep-Oct;52(5):612-617. doi: 10.1016/j.pjnns.2018.08.006. Epub 2018 Aug 28.
- Background: PubMed 21046173Karadimas EJ, Trypsiannis G, Giannoudis PV. Surgical treatment of coccygodynia: an analytic review of the literature. Eur Spine J. 2011 May;20(5):698-705. doi: 10.1007/s00586-010-1617-1. Epub 2010 Nov 3.
- Individual participant dataSharing planned: Yes
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Phenol Injection and Radiofrequency ablation alone in people with Coccygodynia and Coccydynia, run by Marmara University at 1 site in Turkey (Türkiye).
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 4 inclusion and 9 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: opening soon, as of the sponsor's last update on 17 Jun 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Turkey (Türkiye). Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact Savas Sencan, Associate Professor (00905370665713, savas-44@hotmail.com), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Numeric Rating Scale-11 (time frame: Treatment to 6 months post-treatment). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT07021365, which also lists 6 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 17 Jun 2025.