Ganglion Impar Block

Ganglion impar block can be performed in patients with coccyx pain not responding to conservative treatment and simpler injections. It is also indicated in pelvic visceral pain and perineal pain.

At Pain Spa Dr Krishna is very experienced in interventional treatments. Dr Krishna always performs ganglion impar block under ultrasound or fluoroscopy guidance for greater accuracy and improved safety.

Anatomy of ganglion impar

The ganglion impar (also known as ganglion of Walther or sacrococcygeal ganglion) is the lowest node in the paravertebral sympathetic chain, and represents the fusion of the caudal end of the paired sacral sympathetic chains. The ganglion impar is a solitary retroperitoneal structure located anteriorly to the sacrococcygeal junction. This ganglion is the only unpaired autonomic ganglion in the body.

Visceral afferents innervating the perineum, distal rectum, anus, distal urethra, vulva and distal third of the vagina convey at the ganglion impar.


Ganglion impar block is used in the diagnosis and management of visceral or sympathetic-maintained pain in the perineal and coccygeal areas. Ganglion impar neurolysis has been reported in the palliative treatment for malignant pain.


Injections are generally avoided in patients with systemic infection or skin infection over puncture site, bleeding disorders or coagulopathy, allergy to local anaesthetics or any of the medications to be administered.

Technique for ganglion impar block

The procedure is done on an outpatient basis. The procedure is performed under fluoroscopy or ultrasound guidance to ensure accuracy of needle placement. Patients need to be aware that the outcome of the procedure is variable and they may not receive the desired benefits. Similarly, they must be aware of the transient nature of the therapeutic benefits and that there may need repeated injections.

Generally a mixture of local anaesthetic and steroid is injected. The local anaesthetic is probably responsible for immediate pain relief, whereas steroids are believed to be responsible for pain relief 2–6 days after their administration.

Ganglion impar pulsed radiofrequency treatment

Pulsed radiofrequency lesioning of the ganglion impar has been described and may provide pain relief in refractory cases of coccyx and perineal pain.


Complications are rare, particularly if the injections are performed using a precise needle-positioning technique. Possible complications include bruising, infection, hematoma, nerve injury and reaction to the injectates. Infection can be avoided with appropriate aseptic precautions. Severe allergic reactions to local anaesthetics are uncommon. Steroid injections may produce local reactions, occurring most often immediately after injection. These local reactions last for 24 to 48 hours, and are relieved by application of ice packs. Post-procedural pain flare-up may occasionally occur, and may be treated with painkillers. Neurological complications including paraesthesias and numbness have been described but are rare.

Injury to the rectum is a known complication of ganglion impar block but use of image guidance can help to minimize the risks to some extent.


Ganglion impar block can provide pain relief in patients with refractory coccygeal pain. Pulsed radiofrequency treatment can be used for sustained pain relief in patients who get a positive response to the ganglion impar block. It is important to note that in some cases injection treatment may not provide the desired results or the pain relief may not be sustained. At Pain Spa Dr Krishna is very experienced in interventional treatments. Dr Krishna always performs ganglion impar block under ultrasound or fluoroscopy guidance for greater accuracy and improved safety.

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