Introduction

Splanchnic and celiac plexus block are utilized for diagnostic and therapeutic purposes in the treatment of abdominovisceral pain. The richly innervated plexus provides sensory input about pathologic processes in the liver, pancreas, spleen, omentum, alimentary tract to the mid-transverse colon, adrenal glands and kidney. In cases where pain relief cannot be sustained by pharmacologic management, both blocks may be considered. Fluoroscopy, computed tomography (CT) endoscopic ultrasound (US) may be used during the splanchnic and celiac plexus block.

Anatomy of Splanchnic and Celiac Plexus

The splanchnic nerves are formed by the greater, lesser, and least splanchnic nerves. The greater splanchnic nerve is derived from the T5–T10 spinal roots. The lesser splanchnic nerve arises from the T10–T11 roots whereas the least splanchnic nerve arises from the T11–T12 spinal roots. All these three nerves coalesce in the celiac plexus. They are pre-ganglionic fibers entering the celiac plexus. These nerves lie in a narrow tubular space bounded by the vertebral body medially, pleura laterally, the posterior mediastinum ventrally and crura of the diaphragm caudally (Figure 31.1).

Anatomy of the Celiac Plexus

The celiac plexus is a complex network of nerves located in the abdomen, near the celiac trunk and superior mesenteric artery of the aorta. It is located behind the stomach and the omental bursa, and lies in front of the crura of the diaphragm, at the level of the L1 vertebra. The plexus is formed (in part) by the greater and lesser splanchnic nerves of both sides, and parts of the right vagus nerve. The celiac plexus proper consists of the celiac ganglia and a network of interconnecting fibers. The aorticorenal ganglia are often considered to be part of the celiac ganglia and, thus, part of the plexus. The celiac plexus includes several smaller plexuses: hepatic plexus, splenic plexus, gastric plexuses, pancreatic plexus, and suprarenal plexus. Other plexuses that are derived from the celiac plexus are the renal plexus, testicular plexus/ovarian plexus, superior mesenteric plexus, and inferior mesenteric plexus. The celiac plexus provides innervation to the following abdominal viscera: pancreas, stomach, liver, biliary tract, spleen, kidneys, adrenals, omentum, small bowel, and large bowel (to the level of the splenic flexure) [1] (Figures 31.2a,b).

Indications

• For pain due to upper abdominal viscera
  
• Cancer of the upper abdominal viscera (stomach and duodenum)
  
• Pancreatic cancer
  
• Cancer of the adrenal glands
  
• Chronic pancreatitis.

Contraindications

• Local or systemic infection
  
• Coagulopathy and patients using anticoagulants
  
• Congenital abnormalities
  
• Bowel obstruction
  
• Intraabdominal infection.

A list of complications of celiac plexus blocks is shown in Table 31.1.

Technique for Splanchnic Block

There are two common approaches for the splanchnic block. Posterior approaches are as follows:

1. Retrocrural approach (of Hartel)
   
2. Paravertebral lateral approach
   
3. Radiofrequency (RF) lesioning (Described by P. Raj).

Paravertebral Transthoracic Approach

After identifying the 12th ribs under the posteroanterior view with the C-arm, mark the entry point approximately 6 cm from the midline. The needle is advanced 45° toward the midline and about 35° cephalad toward the anterolateral aspect of the T11 vertebral body, passing beneath the 11th rib. Then the C-arm is positioned laterally and the needle is advanced until it reaches the junction of the anterior one-third and posterior two-thirds of the vertebral body. One should always have a bony contact with the vertebral body while advancing the needle. The position of the needle is confirmed by injecting 2–3 ml of contrast solution. The contrast material should be confined just lateral to the vertebral body on the posteroanterior view. Also, confirm spread in the lateral view. If the needle is too superficial, the contrast solution may spread to the epidural space and, if too deep, it will contact the diaphragm. Inject 3–6 ml of 6% phenol in glycerine or saline or iohexol for neurolysis (RF lesioning and other techniques can be found in Pain Relieving Procedures: The Illustrated Guide, P. Raj, S. Erdine [1]) (Figures 31.3a–31.6).

Celiac Plexus Block

There are three approaches:

1. Posterior retrocrural approach
   
2. Posterior anterocrural approach
   
3. Transaortic approach.

Posterior Retrocrural Approach

Place the C-arm in the posteroanterior view first. The anatomic landmarks to be identified are the 12th ribs and the vertebral body of L1. Draw a line from the inferior edge of the L1 vertebral body to intersect the 12th ribs bilaterally. The intersection is approximately 7.5 cm on each side. Draw a triangle joining this line with the cephalic portion of the L1 vertebral body to form an isosceles triangle to guide needle positioning. Marked, there is a risk of penetrating the kidney or ureteropelvic junction. Insert a 20-or 22G 15 cm needle, just beneath the twelfth rib, 45° with the skin toward the midline and 15° cephalad until a bony contact is made. Measure the depth of the needle during the bony contact. Withdraw the needle slightly, redirect increasing the angle to 60°, until the bony contact with the vertebral body is lost.

Position the C-arm laterally, advance the needle 1.5–2 cm anterior to the vertebral body under lateral view. An aspiration test should be done at this stage and should be negative for any fluids (blood, cerebrospinal fluid, or chyle) on both sides. Inject 2 ml of contrast solution and check again that the tip of the needle is not in a vessel. The contrast solution should spread as a smooth line in front of the vertebral body.

Position the C-arm in the posteroanterior view again. The contrast solution should be confined to the midline beneath the T12–L1 level. First, administer 2 ml of local anesthetic as a test dose to verify that the needle is not in the intrathecal or epidural space. One should wait for a few minutes. After repeating the aspiration test again, inject 20 ml of local anesthetic, saline and absolute alcohol solution if neurolysis is performed on each side. The alcohol concentration varies from 50 to 90%. The patient may feel severe pain for a few minutes after the alcohol injection. The patient should be informed in advance. It may be better to inject 5 ml of 2% lidocaine before injecting the alcohol solution. Other techniques can be found in Pain Relieving Procedures: The Illustrated Guide, P. Raj, S. Erdine [1] (Figures 31.7–31.9).

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