The Ultrasound Guided Ganglion Impar Block
Physical Medicine and Rehabilitation Specialist
Fellow of Interventional Pain Practice
Chronic perineal pain is a widespread problem that can lower quality of life and present a challenge to the treating physician. It can be difficult for both patient and practitioner to pinpoint the source of pain in the perineal region, which contains many shared nerve pathways.
Blockade of the ganglion impar is a simple procedure used to treat chronic perineal pain of sympathetic origin , or painful conditions of the lower third of the rectum, vagina and urethra; vulva, anus, coccyx, and perineum. The ganglion impar or ganglion of Walther is a single retroperitoneal bundle of nerves at the level of the sacrococcygeal junction in the low back. It provides sympathetic innervation to perineal structures. Injection of various medications into the ganglion impar can impede transmission of painful messages from perineal structures to the brain, and serve as a diagnostic test to help physicians identify which structures responsible for a patient’s pain .
The ganglion impar is a single ganglion at the bottom of the paravertebral sympathetic chain . The sympathetic chain is part of the autonomic sympathetic nervous system, which conveys nociceptive (painful) messages from the viscera (internal organs) to the brain. The sympathetic chain is composed of two parallel nerve trunks running from the base of the skull to the coccyx (tailbone) on either side of the vertebral column. At the foot of the sympathetic chain, the two sympathetic trunks join to form the ganglion impar, which innervates many of the structures located in this region, including the lower third of the rectum, vagina and urethra; vulva, anus, coccyx, and perineum .
Numbing or destroying the nervous tissue that comprises the ganglion impar can impede transmission of painful messages from structures in the perineal region to the brain. This can be immensely therapeutic for individuals who suffer from chronic pain in this area.
A ganglion impar block involves injection of anesthetic ,phenol , botox ,or other medications with a fine needle into the ganglion impar through the low back. In order to ensure injection accuracy, fluoroscopy ,CT , or ultrasound guidance is often used. Also, depending on the preference of the physician, a range of needle types and technical approaches such as paramedian, transcoccygeal joint, and paracoccygeal corkscrew ; may be chosen to perform the injection.
During the procedure, the lower back and intergluteal cleft are prepped and draped in a sterile fashion, and local anesthesia is used to numb the injection area. Using fluoroscopic (x-ray) or other guidance, the physician places the needle into the ganglion impar and confirms correct placement with contrast dye. Once accurate position is established, a diagnostic block or a therapeutic block is executed.
Infiltration of the ganglion impar with local anesthetic provides pain relief for the duration of action of the medication in two thirds of patients . Once pain relief from a ganglion impar block is documented in a patient, he or she may receive additional therapeutic blocks in the future. Alternatively, he or she may be eligible for more permanent pain relief through procedures such as radiofrequency ablation, chemical destruction with alcohol, or surgical section to achieve longer-lasting results .
In general, ganglion impar block has been shown to be a safe and effective treatment for neuropathic perineal pain. Researchers who studied this procedure in 43 patients concluded it results in a significant reduction of pain scores and carries virtually no hazards (Agarwal-Kozlowski et al, 2009). The patients received ganglion impar block for perineal pain of unknown origin (15 patients), carcinoma of the prostate (eight patients), colorectal carcinoma (seven patients), postsurgery of thrombosis of perineal veins (three patients), postherpetic neuralgia (four patients), malformation of the spinal cord (two patients), vaginal protrusion (two patients), failed back surgery syndrome (one patient), and ablation of testis (one patient). CT-guided puncture was not associated with any adverse events and resulted in a reduction of numeric rating scale values from 8.2+/-1.6 to 2.2+/-1.6 immediately at discharge and to 2.2+/-1.4 at four months after the procedure.
Repeatedly, ganglion impar blockade has been found to be a safe treatment modality and there are few, if any, complications reported in the literature. However, as with any medical procedure, there is a risk of adverse outcomes. These could include unintentional damage to pelvic structures, mild pain at the injection site, and infection. Discitis and needle breakage appear to be the only unusual complications reported by practitioners (Munir et al, 2004). Fortunately, the ganglion impar block is a fairly straightforward procedure in the hands of a skilled practitioner and complications are rare.
Impar ganglion block has been shown to provide pain relief in patients who suffer from sympathetically mediated pain arising from disorders of viscera and somatic structures within the pelvis and perineum .
Although ganglion impar block is considered safe and effective in general, it may not be efficacious in all people. This is because the location, shape, and size of the ganglion impar have been shown to be variable, making it challenging to target . After performing anatomical dissections on 50 subjects, researchers found that the location of the ganglion impar can range from the sacrococcygeal junction to approximately 10mm in front of the tip of the coccyx. Such anatomical variation may contribute to the possible inefficacy of this nerve block in some patients.
In addition, the pain relief provided by a ganglion impar block varies in amount and duration between patients. Some individuals report relief that lasts for weeks, while others can benefit from the block for years. Fortunately, the procedure is a low risk, nonsurgical treatment that can be administered multiple times to produce dramatic relief.
آدرس مطب : اصفهان خیابان شمس آبادی چهارراه قصر ساختمان قصر نور واحد 305
تلفن : 32240068 - 031
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