Cancer pain: Plexus block

There are two neurolytic plexus blocks performed for patients whose pain is not amenable to more conservative therapies. These include the celiac plexus neurolysis (CPN), which is used to treat upper abdominal malignancy (visceral) pain (e.g., from pancreatic cancer) and the superior hypogastric plexus neurolysis (SHPN), which is used in patients with visceral pelvic pain. CPN is safe and effective in patients with pain that persists despite a systemic opioid therapy trial or if they prefer a nonpharmacologic approach. It is performed using fluoroscopy or computed tomography guidance (percutaneously) or endoscopically (intraoperatively) using ultrasound guidance. The superior hypogastric plexus extends from the anterior aspect of L5 to the superior sacrum, and it receives afferent fibers (sympathetic postganglionic fibers) from the pelvic viscera. SHPN is performed percutaneously with fluoroscopy or computed tomography guidance via a bilateral posterior approach.

An initial local anesthetic block is often employed to predict responsiveness to a neurolytic block. In patients with advanced abdominal and pelvic cancers, several prospective case series indicate that both of these procedures reduce opioid consumption, have decreased adverse events, and produce excellent pain relief in more than 70% of patients. Potential but rare complications include orthostatic hypotension and diarrhea from sympathetic blockade, aorta, iliac artery, bladder, lumbar plexus, or spinal cord injury, retroperitoneal bleeding, and cholesterol plaque embolization.