Ganglion Impar Block

Dimitris Papadopoulos MD Fellow Of Interventional Pain Practice (FIPP)

Updated 26 January, 2011


Ganglion IMPAR block is used to treat perineal pain and coccygodynia (coccygeal pain). Perineal pain is a neuropathic type of pain often accompanied with a heat sensation in the perineum and urinary urgency. Once an expert urologist excludes other pain causes (urinary infection, sexually transmitted diseases, chronic prostatitis, malignant conditions etc), the patient is a potential candidate for Ganglion IMPAR block. Due to the sympathetic fibres ending to the ganglion IMPAR, its blockade may resolve the problem of perineal hyperhidrosis.


Ganglion IMPAR is the last ganglion of the two chains of the sympathetic system coursing bilateral to the spine. It is located in front of the sarococcygeal joint, retroperitoneally. However, Oh et al have found that the position, shape and size of the ganglion Impar varies from person to person. This anatomic variability observed could be the cause of a potential block failure.

Ganglion IMPAR receives afferent sensory fibres transmitting pain signals from the perineum, urethra, vulva, lateral third of vagina, anus, distal rectal segment and coccyx. So, blocking this specific ganglion can relieve pain originating from the above areas. Due to the sympathetic fibres ending to the ganglion IMPAR, its blockade  may resolve the problem of perineal hyperhidrosis.  The postganglionic nerve fibres of the ganglion are connected bilaterally with the sacral and coccygeal nerves through rami communicans of the sympathetic chain.


Perineal pain that originates from:
•    perineum
•    distal rectal segment
•    anus
•    distal urethral segment
•    vulva
•    lateral third of vagina

Perineal pain secondarily due to:

•    cancer metastases to perineum
•    post-herpetic neuralgia in sacrum
•    vaginal prolapse
•    testicle cauterization


There are various ways of approaching the ganglion under fluoroscopic guidance (proximally through the sacrococcygeal ligament, through the sacrococcygeal joint, with paramedian approach and with different needles).  The patient is placed in the prone position with a pillow under the pelvis to reduce the normal lumbar lordosis of the spine. Under local anaesthesia and fluoroscopic guidance, a needle is advanced to the proper point in front of the coccyx and its position is confirmed with infusion of contrast medium. After identifying the proper needle site, a drug solution is administered for diagnostic or therapeutic reasons. Following the same technique, radiofrequency can also be applied to the ganglion to fully deactivate it after first having performed a diagnostic block with local anaesthetic to confirm the patient’s pain relief. Radiofrequency therapy prolongs the therapeutic effect for a long period of time. Alternatively, the neurolysis of the ganglion can  be conducted by injecting a small quantity of alcohol that ablates the ganglion; its diffusion, however,  is uneven and special caution is needed so as not to harm the neighbouring tissues. On the contrary, neurolysis with the use of radiofrequency is absolutely targeted.


Ganglion IMPAR block is a minimally invasive technique that can cure chronic neuropathic perineal and coccygeal pain. It should always be tried before the patient undergoes other more invasive techniques or before resorting to drastic drugs with numerous side-effects.


No serious complications have been reported from applying this technique. The most common adverse event is block failure due to anatomic variability. In this case, there has to be a second attempt following a different approach technique.


A number of observation studies have shown that the technique was effective in approximately 65-70% of patients with pain of benign or malignant aetiology to whom the ganglion Impar block was applied. The duration of the result varies from some weeks to even a few years and is not predictable. Radiofrequency neurolysis offers longer duration of analgesia compared to blockade with local anaesthesia. Due to the very few adverse events, blockade and neurolysis can be repeated as many times as necessary if they give satisfactory results which do not, however,  last long.








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