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Can J Anaesth. 2004 Nov;51(9):915-7.

A modified needle-inside-needle technique for the ganglion impar block.

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Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, Massachusetts, USA.



The ganglion impar is the fused terminus of the paired sympathetic chain located at the level of the sacrococcygeal junction. It has been blocked using a bent and a curved spinal needle via the anococcygeal ligament. It has also been approached through the sacrococcygeal disc using a straight spinal needle. We describe a needle-inside-needle modification of the latter approach.Technical features: A 22-gauge (G), 1(1/2)-inch (38 mm) needle is introduced through the sacrococcygeal ligament under fluoroscopy via the sacrococcygeal disc. A 25-G, 2-inch (50 mm) needle is introduced through the 22-G needle. Placement is confirmed with injection of iopamidol 300, 0.2 mL in the retroperitoneal space with the comma sign.


The bent and curved needle techniques are associated with significant discomfort, tissue trauma and risk of rectal perforation due to difficulty in obtaining a midline needle tip position. The straight spinal needle approach minimizes these problems, however there is increased risk of discitis and a longer spinal needle may help also raise incidence of needle breakage. The needle-inside-needle technique may reduce these risks.

[Indexed for MEDLINE]

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