Thermocoagulation of the ganglion impar or ganglion of Walther: description of a modified approach. Preliminary results in chronic, nononcological pain.

The ganglion impar, a single structure usually found at the anterior aspect of the sacrococcygeal joint, is the lowest ganglion of the paravertebral sympathetic chain. Its blockade is indicated in visceral pain syndromes and/or sympathetic pain syndromes of the perineal region. Several approaches to this block have been described, mainly through the anococcygeal or sacrococcygeal ligaments. We propose a modified approach to thermocoagulation of the ganglion impar, using a two-needle technique, the first one, placed through the sacrococcygeal ligament, the transsacrococcygeal needle, and the second one through a coccygeal disc, the transdiscal needle. The thermocoagulation technique that we employ uses a conventional radiofrequency application of 80 degrees C for 80 seconds through each needle. In this prospective study, 13 patients with chronic perineal, noncancer-related pain were followed for a maximum of 6 months. All of these patients underwent diagnostic ganglion impar block with local anesthetic prior to inducing neurodestruction with conventional radiofrequency application, as a positive result to the diagnostic local anesthetic block was a requisite for radiofrequency neurodestruction. We measured pain using a visual analog scale (VAS) before and after treatment. Statistical significance was assessed using the Mann-Whitney U-test and Wilcoxon range summation test. Initially the VAS was equal to or greater than 7. After therapy the VAS decreased by an average of 50% in the whole group. There were no adverse events. Our result show that this proposed modified approach to the block and use of radiofrequency for the ganglion impar is useful for the treatment of perineal noncancer-related pain.