Ultrasonographic-Assisted Ganglion Impar Neurolysis

Abstract

In Response: It is encouraging to receive appreciation from Dr. Plancarte,1 the originator of the technique of ganglion impar neurolysis. We use the SonoSite® MicroMaxx® ultrasound system (SonoSite INC, Bothell, WA; http://www.sonosite.com/downloads/MicroMaxxTransducerGrid.pdf) with a HFL38/13-6 MHz transducer for sonographic guidance2 for ganglion impar neurolysis. The MicroMaxx system offers a wide range of transducers for multiple clinical applications with broadband linear array with varying scan depths of 6–9 cm that can be used for this technique. Though transrectal transducer for ultrasound-guided ganglion impar neurolysis may be a better alternative in patients with benign chronic coccydynia, we have used a transcutaneous transducer as our patient population presenting with perianal cancer pain usually has varying degrees of ulceroproliferative and obstructive ano-rectal lesions. In our original description,2 we used the straight 22-G 15-cm long-Echotip® Chiba needle for accessing the ganglion impar. However, in a subsequent case series,3 we reported a technical improvement with the Pakter curved needle set (Cook Medical Incorporated, Bloomington, IN; http://www.cookmedical.com/di/dataSheet.do?id=4730) containing both a stainless steel straight needle with trocar tip 21-gauge 10-cm long and nitinol curved disposable Chiba needle 25-gauge 15-cm long (http://www.cookmedical.com/di/content/mmedia/CURVE201.pdf). There is no technical difference observed with both the lateral and prone positioned patients, although lateral positioning during the procedure is more comfortable for the patients. Using the Echotip® Chiba needle technique, the needle is introduced through the ano-coccygeal ligament just distal to the tip of the coccyx and directed cephalad as parallel to the sacro-coccygeal curve with no predefined angling or bending because real-time ultrasonographic guidance and visualization is utilized to avoid the accidental placement in the rectal wall without the need for simultaneous digital rectal examination. The ultrasound probe is placed on the cutaneous surface of the coccyx with median plane inclination so that insonation is parallel to the sacrococcygeal curve and the long axis of anteriorly situated rectum. Once the tip of needle (ultrasonography guided in the sagittal image of the median plane) is inserted into the retroperitoneal space posterior to rectum and in the precoccygeal space, the bevel of the needle is then rotated posteriorly to direct the spread of the injectate solution away from rectum and toward the anterior surface of the coccyx. Although contrast-enhanced ultrasound may further delineate the spread of solution, we have found no difficulty in appreciating a good spread of the neurolytic solution with the noncontrast-enhanced ultrasound. Using the Pakter curved needle set, the straight needle is introduced and directed cephalad through the anococcygeal ligament in the intergluteal area. The tip of the straight needle (ultrasonically guided in the sagittal image of the median plane) is inserted into the retroperitoneal space posterior to rectum and in the precoccygeal space. The curved needle is then introduced through the straight needle with the bevel of the curved needle pointing posteriorly to allow the projection of the curved needle on to the anterior surface of the coccyx. Hence, the tip of the curved needle anatomically reaches the anterior surface of the intercoccygeal joints where the ganglion impar is located.4 In conclusion, ultrasound guidance may provide easy access to ganglion impar with either needle set so that severe perianal pain can be managed in the pain physician’s office settings. Deepak Gupta, MD Seema Mishra, MD Sanjay Thulkar, MD Sushma Bhatnagar, MD Department of Anesthesiology and Radiology Institute Rotary Cancer Hospital, All India Institute of Medical Sciences New Delhi, India [email protected]