Conventional vs Pulsed RF in Coccydynia

Coccydynia, commonly referred to as tailbone pain, is a persistent pain condition targeting the coccyx, a small triangular bone located at the lower end of the spine. The main cause of this pain is usually abnormal movement in the coccygeal region, which leads to continuous inflammation. Coccydynia more commonly affects women than men and is often associated with obesity. Although it most frequently occurs around the age of 40, it can be seen in individuals of all ages. The origins of coccydynia are varied, including both physical and psychological factors. The main physical causes are trauma from falling onto the buttocks, repetitive minor injuries, or childbirth, which are the most common triggers. Non-traumatic causes of coccydynia include degenerative diseases of the joints or discs, abnormal movements in the sacrococcygeal joint, obesity, infections, changes in the shape of the coccyx, or cancers in the pelvic or anorectal regions. The effectiveness of treatments for coccydynia varies considerably.

Several conservative treatment options exist for coccydynia, such as nonsteroidal anti-inflammatory drugs (NSAIDs), local analgesics, hot or cold applications, transcutaneous electrical nerve stimulation (TENS), specially designed wedge-shaped cushions (coccygeal cushions), and exercises aimed at relaxing the levator ani muscle. These methods aim to reduce pain and inflammation and improve the functionality of the coccyx and surrounding muscles. When these conservative approaches fail to provide relief, more invasive procedures may be considered. Techniques such as direct local anesthetic injections to the coccyx, coccygeal nerve blocks, caudal epidural injections, and ganglion impar blocks offer minimally invasive alternatives for coccydynia treatment. Among the methods for impar ganglion blocks, pulsed RF, thermocoagulation ablation techniques, and neurolytic techniques are considered treatments that provide long-term pain palliation. The transacrococcygeal technique for impar ganglion block is an easy and safe method. This technique allows neurolysis or radiofrequency thermocoagulation ablation of the impar ganglion and can be used for diagnostic blocks depending on the response to initial diagnostic injections.

The ganglion impar (Walther ganglion) is a single sympathetic ganglion formed by the convergence of the distal ends of the lumbosacral sympathetic chains. It is the lowest ganglion of the sympathetic nervous system. Being single and medial (unlike the paired paravertebral sympathetic ganglia), it is the only solitary sympathetic ganglion. It is located retroperitoneally, anterior to the sacrum, at the level of the sacrococcygeal symphysis, and posterior to the rectum. It provides sympathetic efferent fibers and receives afferent sensory information from many pelvic structures, supplying sympathetic and nociceptive innervation to the perineum, coccyx, anus, distal rectum, vulva, urethra, and vagina. Interventions on the ganglion impar disrupt afferent sympathetic and nociceptive pathways from the pelvis, perineum, and anal region. Interventions on the ganglion impar can be performed using various agents and techniques, including local anesthetics, corticosteroids, ethanol, phenol, botulinum toxin, radiofrequency ablation (RFA) or modulation (RFM), and cryoablation. The transsacrococcygeal technique is more commonly used. Numerous technique variations exist, but the goal is to successfully direct the needle to the anterior surface of the coccyx or sacrococcygeal symphysis to deliver local anesthetics, steroids, or neurolytic agents without damaging pelvic bones or organs. Radiopaque contrast is injected to visualize proper retroperitoneal distribution of the agent along the anterior surface of the coccyx.

Visceral pain mediated by sympathetic fibers in the perineal region can be effectively treated by neurolysis of the impar ganglion. Theoretically, this procedure can also be applied for pain due to malignancy, endometriosis, complex regional pain syndrome, prostate pain, radiation-induced enteritis, postherpetic neuralgia, and refractory coccydynia. The use of sympathetic chain ablation for persistent pain in the sacral-pelvic region differs from other targets, because the anatomical variation of the impar ganglion requires careful combination of radiofrequency thermocoagulation and neurolytic agents (alcohol or phenol) to maximize pain control. When using the thermocoagulation radiofrequency ablation technique, special equipment such as electrostimulation devices and minute controllers are required. Therefore, selective destruction of nerve fibers is possible, and the size and location of the lesion can be controlled, resulting in a lower risk of complications.

The effects of conventional radiofrequency (CRF) thermocoagulation for chronic coccydynia were retrospectively analyzed (patients unresponsive to conservative treatment and local injections for 6 months. Ten patients who responded to diagnostic block with 10 mL of 0.25% bupivacaine underwent CRF treatment. Approximately 90% of patients achieved successful results at 6 months, defined as a 50% reduction in VAS scores. Transcoccygeal/intercoccygeal CRF of the ganglion impar is simple, relatively safe, and should be considered for chronic coccydynia unresponsive to conservative therapy for 6 months. Similar findings were observed by another study in a retrospective analysis of CRF in 20 patients with chronic refractory coccydynia.

No previous study has compared the superiority of these two routinely applied long-term coccyx pain treatments.

• Oswestry Disability Index (ODI) [Time frame: From enrollment to the end of treatment at 12th months]
• Pittsburgh Sleep Quality Index (PSQI) [Time frame: From enrollment to the end of treatment at 12 months]
• Global Perceived Effect (GPE) [Time frame: From enrollment to the end of treatment at 12th months]