Ganglion Impar Injection

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Ganglion Impar Injection
Indication	Coccydynia, chronic prostatitis, chronic proctitis, pelvic malignancies, and chronic perineal pain
Syringe	10mL
Needle	38mm 23g needle
Steroid	40mg
Local	1% lidocaine or 0.25% bupivicaine
Volume	3-5mL of 1% lidocaine or 10mL of 0.25% bupivicaine and 40mg of methylprednisolone

Injection treatment of the ganglion impar with local anaesthetic with or without corticosteroid is a procedure to treat Coccydynia, chronic perineal pain, and other conditions. Needle placement is generally done by piercing through the sacrococcygeal disc space. A single injection can provide long lasting relief of pain.

Radiofrequency treatments such as pulsed radiofrequency is a newer technique and may provide better results than blockade.

Anatomy

The ganglion impair is a midline sympathetic ganglion anterior to the upper coccyx, formed by the caudal termination of paired sympathetic chains. The ganglion provides both sympathetic and visceral innervation to the coccyx, perineum, and anal regions. The size and location can vary, and in some people the ventral ramus of the sacral nerve roots run close by. It is classically at the level of the sacrococcygeal junction.

Technique

The optimum technique uses a combination of ultrasound and fluoroscopy. Ultrasound uses loss of resistance as the modality can't alone accurately assess needle depth, while fluroscopy alone cannot accurately identify the sacrococcygeal junction nor its angulation due to bowel gas. In the combined technique the needle is first inserted under ultrasound guidance, and then the depth verified by fluoroscopy. This provides optimum accuracy and safety.

A needle inside needle technique had been described. This uses an initial 22-gauge 38mm needle inserted through the sacrococcygeal junction. A 25-gauge 50mm needle is placed through the 22 gauge needle. This approach is theorised to reduce the risk of discitis and reduce the risk of needle breakage from using a long needle.

Ultrasound Guided Transsacrococcygeal Injection

Ultrasound guided techniques have been described such as by Ghai et Al. Loss of resistance is used and this appears to be patient and operator dependent.

• Position: prone, lower limbs internally rotated, toes pointing to the opposite foot. Optional pillow under the abdomen to reduce lumbar lordosis. This all helps to separate the buttocks and provide a flatter sacral hiatus site.
• Place the transducer in the transverse position and visualise the sacral hiatus, the two sacral cornuae, and the sacrococcygeal ligament which traverses the sacral hiatus above the epidural space
• Obtain a longitudinal position of the sacral hiatus, the proximal portion of the transducer resting between the two cranial sacral cornuae. The first cleft caudal to the sacral hiatus is the sacrococcygeal junction.
• Confirm the location of the sacrococcygeal junction by pressing with a long forceps under sonographic monitoring.
• Anaesthetised the overlying skin
• Advance a 23 gauge needle through the sacrococcygeal junction using an out of plane technique.
• Advance the needle until a loss of resistance is felt, which indicates that the needle tip is ventral to the sacrococcygeal ligament. Note that this is not always felt, hence the ideal use of combined imaging with fluoroscopy to confirm needle depth. Ultrasound cannot visualise the ventral coccyx
• Inject 3-5mL of 1% lidocaine or 10mL of 0.25% bupivicaine and 40mg of methylprednisolone.

Fluoroscopic Guidance

Fluoroscopic lateral view of ganglion impar block, confirmation by the “comma sign” in the retroperitoneal space. Courtesy of Sir et al

Transsacrococcygeal Technique

This is the preferred method

Original Plancarte Technique

Uses a per rectal finger during the injection.

Paramedian Approach

Using a curved needle

Non-ultrasound Guided

This is not recommended

Complications

Neuritis, inadvertant injection into the rectum, infection. There is an increased risk of discitis and needle breakage with the transsacrococcygeal approach which may be reduced by the needle through needle technique.