GENERAL
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.
ANATOMY
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.
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INDICATIONS
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
DESCRIPTION OF THE TECHNIQUE
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.
BENEFITS
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.
COMPLICATIONS – RISKS
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.
RESULTS
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.
MEDICAL INFORMATION SOURCES
1. PAIN PRACTICE JOURNAL
2. BONICA”S MANAGEMENT OF PAIN
3. PAIN PHYSICIAN JOURNAL
4. INTERVENTIONAL PAIN MANAGEMENT BOOK
5. MANUAL OF RF TECHNIQUES (GAUCI)
JOURNAL ARTICLES
1. Agarwal-Kozlowski K, Lorke DE, Habermann CR, Am Esch JS, Beck H. CT-guided blocks and neuroablation of the ganglion impar (Walther) in perineal pain: anatomy, technique, safety, and efficacy. Clin J Pain. 2009 Sep;25(7):570-6.
2. Başağan Moğol E, Türker G, Kelebek Girgin N, Uçkunkaya N, Sahin S. [Blockade of ganglion impar through sacrococcygeal junction for cancer-related pelvic pain] Agri. 2004 Oct;16(4):48-53.
3. de Leon-Casasola OA. Critical evaluation of chemical neurolysis of the sympathetic axis for cancer pain. Cancer Control. 2000 Mar-Apr;7(2):142-8.
4. Eker HE, Cok OY, Kocum A, Acil M, Turkoz A. Transsacrococcygeal approach to ganglion impar for pelvic cancer pain: a report of 3 cases. Reg Anesth Pain Med. 2008 Jul-Aug;33(4):381-2.
5. Foye PM, Patel SI. Paracoccygeal corkscrew approach to ganglion impar injections for tailbone pain. Pain Pract. 2009 Jul-Aug;9(4):317-21. Epub 2009 May 29.
6. Foye PM. New approaches to ganglion impar blocks via coccygeal joints. Reg Anesth Pain Med 2007; 32:269.
7. Foye PM, Buttaci CJ, Stitik TP, Yonclas PP. Successful injection for coccyx pain. Am J Phys Med Rehabil 2006; 85:783-784.
8. Gupta D, Jain R, Mishra S, Kumar S, Thulkar S, Bhatnagar S. Ultrasonography reinvents the originally described technique for ganglion impar neurolysis in perianal cancer pain. Anesth Analg. 2008 Oct;107(4):1390-2.
9. Hong JH, Jang HS. Block of the ganglion impar using a coccygeal joint approach. Reg Anesth Pain Med. 2006 Nov-Dec;31(6):583-4.
10. Kabbara AI. Transsacrococcygeal ganglion impar block for postherpetic neuralgia. Anesthesiology. 2005 Jul;103(1):211-2.
11. Kim ST, Ryu SJ. Treatment of Hyperhidrosis Occurring during Hemodialysis: Ganglion Impar Block: A case report. Korean J Anesthesiol. 2005 May;48(5):553-556.
12. Kuthuru M, Kabbara AI, Oldenburg P, Rosenberg SK: Coccygeal pain relief after transsacrococcygeal block of the ganglion impar under fluoroscopy: A case report. Arch Phys Med Rehabil 2003; 84:E24.
13. Loev M, Varklet VL, Wilsey BL, Ferrante M: Cryoablation: A novel approach to neurolysis of the ganglion impar. Anesthesiology 1998; 88:1391–3.
14. McAllister RK. Paramedial approach to the ganglion impar. Reg Anesth Pain Med. 2007 Jul-Aug;32(4):367.
15. McAllister RK, Carpentier BW, Malkuch G: Sacral postherpetic neuralgia and successful treatment using a paramedial approach to the ganglion impar. Anesthesiology 2004; 101:1472-4
16. Munir MA, Zhang J, Ahmad M. A modified needle in needle technique for the ganglion impar block. Can J Anaesth 2004;51:915-917.
17. Nebab EG, Florence IM: An alternative needle geometry for interruption of the ganglion impar. Anesthesiology 1997; 86:1213–4.
18. Oh CS, Chung IH, Ji HJ, et al. Clinical implications of topographic anatomy on the ganglion Impar. Anesthesiology. 2004;101:249–250.
19. Plancarte R, Velazquez R, Patt RB: Neurolytic blocks of the sympathetic axis. In Patt RB (ed): Cancer Pain. Philadelphia, Lippincott-Raven, 1993, pp 419-442.
20. Plancarte R, Amescua C, Patt RB: Presacral blockade of the ganglion of Walther (ganglion impar). Anesthesiology 1990; 73: A751.
21. Reig E, Abejón D, del Pozo C, Insausti J, Contreras R. Thermocoagulation of the ganglion impar or ganglion of Walther: description of a modified approach. Preliminary results in chronic, nononcological pain. Pain Pract. 2005 Jun;5(2):103-10.
22. Toshniwal GR, Dureja GP, Prashanth SM. Transsacrococcygeal approach to ganglion impar block for management of chronic perineal pain: a prospective observational study. Pain Physician. 2007 Sep;10(5):661-6.
23. Wemm JR, K, Saberski L: Modified approach to block the ganglion impar (ganglion of Walther) (letter). Reg Anesth 1995; 20:544–5.
