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21KF-028
A new technique of ganglion impar pulsed radiofrequency

Youngchan Kim, Ji Yeong Kim, Sung Eun Sim, Subin Yoo, Mina Joo, Hue Jung Park 

Department of Anesthesiology and Pain Medicine, Seoul St. Marys Hospital, College of Medicine, The Catholic University of Korea, Seoul, Republic of Korea 

The ganglion impar block was introduced in 1990. Since then, several modified versions have been reported. However, it was difficult to determine which technique is effective. We present a new technique to implement ganglion impar RFA.
A man aged 70 years visited for pain around the right side of anus. The caudal block was performed. As there was no impact on the epidural block, the ganglion impar block was performed. The diagnostic block was performed using the transdiscal approach. The block was effective; however, the period was short.
Botulinum toxin injection was planned for lengthening the impact of block. 50 units of BOTOX® mixed with 2 mL of normal saline was injected after diagnostic 3 mL of 0.25% bupivacaine. After the injection, pain decreased to less than half for 8 weeks. However, the duration became shorter. Moreover, anal pain higher than NRS 7 persisted despite the increased dose of drugs. Consequently, the patient opted to proceed with the ganglion impar RFA.
Our new technique was modified from Huang method. The 10 cm long 22-gauge RF cannula with a 10 mm active tip was used. The length between sacrococcygeal joint(SC joint) and coccyx tip was measured in advance, and RF cannula was bent. In the prone position, the needle entry point was defined lateral to the tip of the coccyx. After adjusting the needle toward the SC joint, after contacting the coccyx, walking off the coccyx, and finally, the needle tip was positioned at the SC joint slightly inclined to the affected side. Overall, the RF thermoregulation was performed thrice at 45°C for 120 s by retracting 10 mm of RF cannula. After 16 weeks, the pain was reduced to less than half.
We did not adopt the transdiscal approach. In the chronic coccyx pain patient group, there was a report that SC joint fusion occurred in 51%. Additionally, the ganglion is more commonly located in front of the coccyx bone. Second, our technique are common in bending the needle. Third, the needle insertion point is laterally away from the midline. It was expected to reduce infection. However, there is a difference regarding skin indentation. Huang inserted needles under the transverse process of the coccyx, whereas we inserted them from the side of the coccyx tip by multiple lesioning with single needling for covering anatomic variation of the ganglion impar.