Ganglion Impar Block/Neurolysis is a procedure performed to reduce some of the symptoms of chronic pelvic or rectal pain caused due to vaginal or vulvar cancer, scrotal cancer, rectal/anal cancer, or bladder cancer, by blocking nerve impulses. The ganglion impar is a structure that is located at the level of a small triangular bone at the base of the spinal column formed of fused vestigial vertebrae, known as coccyx. The doctor numbs your skin with a small needle and uses an X-ray machine to guide the needle into the correct spot. Local anesthetic and steroids are then injected through the needle. Your pain may improve immediately after the injection because of the local anesthesia. But, the steroid usually takes two to three days to have an effect.