Residency · Residency · Chronic Pain Management

Celiac Plexus Block and Neurolysis

Introduction

The celiac plexus block (CPB) and celiac plexus neurolysis (CPN) are sympathetic interventions targeting the largest autonomic plexus in the abdomen. The celiac plexus transmits nociceptive afferents from most upper abdominal viscera, making it a primary target for managing pain from pancreatic cancer, other upper abdominal malignancies, and chronic pancreatitis. Neurolytic celiac plexus block has become a cornerstone of cancer pain management and is one of the most well-supported interventional procedures in the oncologic pain literature.

Anatomy

The celiac plexus is a dense network of ganglia and interconnecting nerve fibers located in the retroperitoneal space at the level of the T12-L1 vertebral bodies, surrounding the origin of the celiac trunk from the anterior aorta. It is composed of the right and left celiac ganglia, the superior mesenteric ganglion, and the aorticorenal ganglia, all interconnected by a network of nerve fibers. Afferent input arrives from the greater splanchnic nerve (T5-T9), lesser splanchnic nerve (T10-T11), and least splanchnic nerve (T12).

The plexus provides sympathetic and nociceptive innervation to the stomach, liver, gallbladder, pancreas, spleen, kidneys, adrenal glands, small intestine, and proximal large intestine (to the splenic flexure). Anatomically, it lies anterior to the aorta and the crura of the diaphragm, posterior to the stomach and pancreas. The retrocrural space — behind the diaphragmatic crura — contains the splanchnic nerves before they join the celiac plexus, and this distinction between the retrocrural and anterocrural compartments is important for technique selection.

<image>Anatomical illustration showing the celiac plexus in an anterior view of the retroperitoneum with overlying organs rendered semi-transparent. The celiac trunk branching from the aorta at T12-L1 is shown with the celiac ganglia and interconnecting nerve fibers surrounding it. The greater, lesser, and least splanchnic nerves are traced from the thoracic sympathetic chain through the diaphragmatic crura to the plexus. Labels identify the celiac trunk, superior mesenteric artery, aorta, diaphragmatic crura, and the organs innervated (stomach, pancreas, liver, spleen). The retrocrural space is distinguished from the anterocrural celiac plexus location.</image>

Diagnostic vs. Neurolytic Block

A diagnostic block uses local anesthetic only (10-20 mL of 0.25% bupivacaine per side) to confirm that pain is mediated through the celiac plexus; it is performed before committing to neurolysis. A therapeutic (neurolytic) block uses neurolytic agents — absolute alcohol (50-100%) or phenol (6-10%) — to destroy nerve fibers for prolonged pain relief.

Alcohol is more commonly used for celiac neurolysis because it produces Wallerian degeneration and more complete neurolysis than phenol. However, alcohol causes intense burning pain on injection, making pre-injection of local anesthetic essential. Phenol is an alternative that has inherent local anesthetic properties but may produce less complete and shorter-duration neurolysis.

Posterior Approach (Classic Technique)

Retrocrural (Splanchnic Nerve) Block

The patient is positioned prone, and needles are directed toward the anterolateral border of the T12 or L1 vertebral body. Bilateral 20-22 gauge needles are placed via a paraspinal approach, passing lateral to the vertebral body and superior to the transverse process. The needle tip position is confirmed on lateral fluoroscopy at the posterior aspect of the vertebral body, within the retrocrural space. This retrocrural injection targets the splanchnic nerves before they pass through the crura. It is technically easier and safer than the anterocrural approach but may not produce complete celiac plexus blockade. Typical volumes are 10-15 mL per side for diagnostic block and 10-20 mL of absolute alcohol per side for neurolysis.

Anterocrural (Classic Celiac Plexus) Block

For this approach, the needle tips must pass anterior to the diaphragmatic crura to reach the celiac plexus directly. On lateral fluoroscopy, the needle tips should be at the anterior border of the L1 vertebral body, anterior to the crura. This approach provides more complete blockade of the celiac plexus proper but carries a higher risk of aortic puncture, as the left-sided needle may traverse the aorta (intentionally, in the transaortic technique).

Transaortic Approach

In this single-needle variation, a left-sided needle is intentionally advanced through the aorta until the tip exits anteriorly. Position is confirmed by loss of pulsatile blood return and contrast spread anterior to the aorta. This simplifies the procedure to a single-needle technique. While it carries the theoretical risk of aortic injury, multiple studies have demonstrated the safety of this approach.

<image>Lateral fluoroscopic illustration comparing retrocrural and anterocrural needle tip positions for celiac plexus block. The retrocrural position shows the needle tip at the posterior aspect of the L1 vertebral body with contrast spread behind the diaphragmatic crura. The anterocrural position shows the needle tip at the anterior border of L1 with contrast spread anterior to the crura surrounding the celiac trunk origin. The diaphragmatic crura are highlighted as a key anatomic dividing line. The aorta and vertebral body are labeled.</image>

Anterior Approach

The anterior approach can be performed under CT guidance or endoscopic ultrasound (EUS). In the CT-guided anterior approach, the patient is supine and a needle is inserted through the anterior abdominal wall, traversing the liver or stomach to reach the celiac plexus anterior to the aorta. EUS-guided celiac plexus block or neurolysis is performed by gastroenterologists during upper endoscopy, with the transducer in the stomach providing direct visualization of the celiac trunk and aorta. Advantages include direct visualization of the plexus, real-time needle placement, and avoidance of posterior structures. Wyse et al. (2011) conducted an RCT demonstrating that early EUS-guided CPN in pancreatic cancer patients improved pain control and reduced opioid consumption compared to conventional pain management.

Indications

Cancer Pain

Pancreatic cancer is the strongest indication, supported by multiple RCTs and meta-analyses showing that CPN reduces pain and opioid requirements. Other indications include gastric, hepatobiliary, and other upper abdominal malignancies with celiac plexus-mediated pain. CPN should be considered early in the course of pancreatic cancer pain management, not reserved as a last resort.

Chronic Non-Malignant Pain

Chronic pancreatitis is the main non-malignant indication, though evidence is less robust than for cancer pain and repeated blocks may be needed. Results in chronic pancreatitis are generally inferior to cancer pain outcomes, likely because of nociceptive plasticity and central sensitization that develop in chronic conditions.

Evidence for Pancreatic Cancer Pain

Eisenberg et al. (1995) published a meta-analysis of 24 studies showing that 89% of patients had good to excellent pain relief at 2 weeks, and 90% maintained partial or complete relief until death. Wong et al. (2004) conducted an RCT of CPN versus optimized opioid management in pancreatic cancer that showed similar pain relief but reduced opioid consumption and fewer side effects in the CPN group. Arcidiacono et al. (2011) published an RCT of EUS-CPN as early intervention showing a trend toward improved pain control. CPN does not consistently improve survival but does improve quality of life by reducing opioid requirements and their associated side effects.

Complications

Transient diarrhea due to unopposed parasympathetic activity occurs in up to 40-60% of patients. Orthostatic hypotension from splanchnic vasodilation occurs in 10-30% — IV fluid preloading is recommended. Back pain at the injection site is common and self-limited. Retroperitoneal hematoma can result from vascular injury. The most devastating complication is paraplegia, which is rare but caused by injury to the artery of Adamkiewicz or anterior spinal artery, resulting in anterior spinal cord infarction. Pneumothorax can occur with high retrocrural needle placement, and visceral organ injury (kidney, liver, or bowel puncture) is more common with the CT-guided anterior approach.

Clinical Pearls

Diarrhea and orthostatic hypotension are expected pharmacologic effects of sympathetic blockade, not complications — patients should be counseled about these preoperatively. A diagnostic block with local anesthetic should be performed before neurolysis when the diagnosis of celiac plexus-mediated pain is uncertain. For pancreatic cancer pain, CPN should be considered early in the disease course rather than waiting for opioid tolerance or uncontrollable pain. The retrocrural approach is technically simpler and safer but may be less effective than anterocrural techniques for complete plexus neurolysis. An IV fluid bolus (500-1000 mL) should always be administered before neurolysis to mitigate the risk of symptomatic orthostatic hypotension.

References

1. Eisenberg E, Carr DB, Chalmers TC. Neurolytic celiac plexus block for treatment of cancer pain: a meta-analysis. Anesth Analg. 1995;80(2):290-295.
2. Wong GY, Schroeder DR, Carns PE, et al. Effect of neurolytic celiac plexus block on pain relief, quality of life, and survival in patients with unresectable pancreatic cancer: a randomized controlled trial. JAMA. 2004;291(9):1092-1099.
3. Wyse JM, Carone M, Paquin SC, et al. Randomized, double-blind, controlled trial of early endoscopic ultrasound-guided celiac plexus neurolysis to prevent pain progression in patients with newly diagnosed, painful, inoperable pancreatic cancer. J Clin Oncol. 2011;29(26):3541-3546.
4. Arcidiacono PG, Calori G, Carrara S, et al. Celiac plexus block for pancreatic cancer pain in adults. Cochrane Database Syst Rev. 2011;(3):CD007519.

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