42
Complications of Ganglion Impar Block

Ricardo Plancarte Sánchez MD, PhD, FIPP, Angel Manuel Juárez Lemus CIPS, ASRA, PMUC,Berenice Carolina Hernández Porras CIPS, FIPP, and María del Rocño Guillén Nuñez MD

National Institute of Cancer, México City, México

Introduction

More than 60% of the 14 million new cancer cases worldwide in 2012 were reported in the developing countries. Since the disease can seldom be treated, even with the best available treatment modalities, symptom management and providing comfort care to these patients is essential [1].

Perineal pain significantly affects quality of life and its treatment is a great challenge because of its unclear pathogenesis and complex neuroanatomy, comprising a diverse anatomic structure with mixed somatic, visceral, and autonomic innervations [2].

Since the first description of this technique in 1990 by Plancarte et al., the attention to this structure has grown because the Ganglion Impar (also known as Walther´s ganglion) was recognized as a key mediator to the sympathetic system and the block carries low morbidity and risk [3, 4].

This structure is the most caudal ganglion of the sympathetic trunk. It is a single, retroperitoneal ganglion located anterior to the sacrococcygeal junction. This ganglion innervates the perineum, distal rectum, anus, distal urethra, vulva, and distal third of the vagina. Its inhibition is considered an important adjunct to pharmacologic therapy for the relief of intractable visceral, somatic, and neuropathic pain originating from perineal and pelvic structures [5].

The technique was initially described using a 22G spinal needle through the anococcygeal ligament. A series of patients treated in this manner experienced reduction of both the VAS and morphine consumption with no complications encountered [6].

Nebab described a modification using a curved needle. However, the proposal of Dr. Plancarte using a “C” or half-moon shaped needle is more frequently used because this allows and facilitates the sacrococcygeal transligament approach in any curvature of the sacrococcygeal spine. The transacrococcygeal pathway was described by Wemm using a 25G spinal needle through a 22G needle [7] (Figures 42.1 and 42.2).

**Figure 42.1** Alternatives in the geometry of the needles used.

**Figure 42.2** Final needle-tip location of curved needle.

Anatomy

The triangular sacrum is made up of the five fused sacra dorsally convex vertebrae that are dorsally convex and inserts in between the two iliac bones, articulating superiorly with the fifth lumbar vertebra and caudally with the coccyx.

The coccyx has a triangular shape and consists of three to five rudimental vertebrae. The sacral hiatus has a U-shape and is formed by the incomplete midline fusion of the posterior elements of the lower portion of the S4 and the entire S5 vertebrae covered posteriorly by the sacrococcygeal ligament. A relationship of the superior border of the sacral hiatus and the S3 and S4 sacral foramina exists in the dorsal surface of the sacrum and coccyx. The sacrococcygeal joint is fused in 51% of humans compared with only 12% fusion at the first intercoccygeal joint [8].

Human cadaver studies have shown that the ganglion impar is usually located at the upper coccyx, rather than at the sacrococcygeal joint. Oh, et al. reported that the shape of the ganglion was oval (26%), irregular (20%), triangular (14%), elongated (10%), rectangular (8%) and “U” Shaped (8%) [9] Figure 42.3.

**Figure 42.3** Anterior view of the sacrum showing the location of the impar ganglion (red circle).

Indications

Ganglion Impar blockade is indicated for visceral perineal pain that is sympathetically maintained in both cancer and non-cancer patients [10]:

Perineal pain
Proctitis
Distal urethral pain
Vulvodynia
Scrotal pain
Female distal pelvic/vaginal pain
CRPS
Endometriosis
Chronic prostatitis
Proctalgia fugax [11]
Coccygodynia
Postherpetic neuralgia [12]
Burning and localized perineal pain associated with urgency.

Contraindications

Absolute Contraindications

Infection
Coagulopathy.

Relative Contraindications

Distordal anatomy (posttrauma or post-surgical, exaggerated anterior curve, and rectal fistula).

Technique

Transsacrococcygeal Ligament Technique (Classic Technique)

Position: Lateral decubitus position with the hips flexed toward the abdomen.

The skin in the puncture site should be prepared using aseptic technique.

Take a lateral fluoroscopic image.

Infiltrate with 2–3 cc of lidocaine 1% in the anococcygeal ligament (between the anus and the tip of the coccyx).

A 22G spinal needle previously bent according to the curvature of the coccyx is then introduced, maintaining the tip of the needle in the midline and outside the rectal wall. Inserting the index finger in the rectum facilitates placement of the needle’s tip at the level of the sacrococcygeal junction.

After negative aspiration, inject 2 cc of non-ionic contrast under live-fluoroscopy on lateral view and the contrast dye should give a “reverse comma” (Figures 42.4.a,b).

**Figure 42.4** **(a)** and **(b)** Lateral and AP fluoroscopy view after 2 cc of non-ionic contrast.

Biplanar fluoroscopy are used to verify appropriate needle placement.

Once proper placement is achieved, proceed to inject the medication slowly (a little resistance is normal).

Total volume: 4–6 ml.

In case of neurolysis, this is performed with 3 ml of 10% phenol.

The needle should be flushed with saline or lidocaine 1% and withdrawn.

Sterile dressing is applied.

Sacrococcygeal Transdiscal Approach [13]

Position: Prone or Lateral decubitus (abducting the legs and heels).

The skin in the puncture site should be prepared using aseptic technique.

Take an AP fluoroscopic image.

Infiltrate with 2–3 cc of lidocaine 1%.

Puncture with 22G 3.5-inch spinal needle.

Advance the needle anteriorly through sacrococcygeal junction (SCJ) into the midline aspect until contact is made with bone.

The needle is advanced slowly in lateral view until the needle tip is just anterior to the SCJ in the retroperitoneal space.

After negative aspiration, inject 2 cc of non-ionic contrast under live-fluoroscopy on lateral view and the contrast dye should give a “reverse comma”.

Biplanar fluoroscopy is used to verify that contrast is not in the rectum, the SCJ, intravascular, or outside the space.

Once proper placement is achieved, proceed to inject the medication slowly (a little resistance is normal).

Total volume: 4–6 ml.

In case of neurolysis 3 cc 10% phenol.

The needle should be flushed with saline or lidocaine 1% and withdrawn.

Sterile dressing is applied.

This approach can be useful in patients with normal anatomy but may prove challenging in patients with arthritic changes in the bones and calcification of the ligaments of the sacrum and coccyx.

“Needle-inside-needle” Approach [14]

This approach utilizes a 22G 1.5-inch needle inserted over the sacrococcygeal just below the sacral hiatus. Advance the needle under lateral fluoroscopic view until the tip is through the disc. A 25G 2-inch spinal needle is introduced through the 22G needle.