Superior hypogastric plexus block and ganglion impar (Walther)

The superior hypogastric plexus is formed by pelvis visceral afferents and efferent sympathetic nerves from branches of the aortic plexus, and fibers from the splanchnic nerves. Pelvic viscera innervated by the superior hypogastric plexus include the bladder, uterus, vagina, prostate, testes, urethra, descending colon, and rectum. Because of the diffuse and poorly localized nature of visceral pain, the source of it may be difficult to elucidate. Superior hypogastric block is indicated in patients with pelvis pain, including cancer pain, endometriosis, pelvic inflammatory diseases, and adhesions. Initial favorable results in cancer pain patients lead to the implementation of superior hypogastric blocks for patients with other pelvic visceral pain disorders like dysmenorrhea, dyspareunia, and burning tenesmus after rectal anastomosis and radiation injury of pelvic viscera, with high success rates. The impar ganglion, a solitary retroperitoneal structure located at the level of the sacroccygeal junction marks the end of the paravertebral sympathetic chain. The percutaneous interruption of this ganglion may be useful in the treatment of perineal pain of sympathetic origin. In conclusion, sympathetic blockade at the level of the superior hypogastric plexus or the impar ganglion may provide an alternative therapy for those patients with lower abdominal or perineal visceral pain, reducing the doses and side effects of chronic opioid therapy.