Abstract
Pain associated with cancer may be somatic, visceral, or neuropathic in origin, and approximately 50% of all cancer patients have a combination of pain types at the time of diagnosis. Visceral pain associated with cancer may be relieved with oral pharmacologic therapy that includes combination of nonsteroidal antiinflammatory agents, opioids, and coadjuvant therapies. Neurolytic blocks of the sympathetic axis are also effective in controlling visceral cancer pain. The focus of this chapter is neurolytic blocks including the celiac plexus block, superior hypogastric plexus block, and ganglion impar block.
Keywords
cancer pain, celiac plexus block, ganglion impar block, neurolysis, neurolytic sympathetic blocks, superior hypogastric plexus block
Pain associated with cancer may be somatic, visceral, or neuropathic in origin, and approximately 50% of all cancer patients have a combination of pain types at the time of diagnosis. When viscera are stretched, compressed, invaded, or distended, a poorly localized noxious pain is reported. Patients experiencing visceral pain often describe the pain as vague, deep, squeezing, crampy, or colicky in nature. Other signs and symptoms include referred pain, such as shoulder pain due to diaphragm invasion by tumor, nausea, and vomiting.
Visceral pain associated with cancer may be relieved with oral pharmacologic therapy that includes combinations of nonsteroidal antiinflammatory agents, opioids, and coadjuvant therapies. Neurolytic blocks of the sympathetic axis are also effective in controlling visceral cancer pain. Thus neurolysis of the sympathetic axis should be judged as an important adjunct to pharmacologic therapy for the relief of severe cancer-related pain. These blocks rarely eliminate cancer pain, however, due to coexisting somatic and neuropathic pain. Thus oral pharmacologic therapy must often be continued, albeit at lower doses. The goal of performing a neurolytic block of the sympathetic axis is to (1) maximize the analgesic effect of opioid and nonopioid analgesics, and (2) reduce the dosage of these agents to alleviate untoward side effects.
Neurolytic techniques are not without risk. Thus sound clinical judgment and complete patient understanding are essential to minimize undesirable effects. The detailed description of the techniques for these blocks is beyond the scope of this review. Thus the reader is directed to other publications for this purpose.
Keywords
cancer pain, celiac plexus block, ganglion impar block, neurolysis, neurolytic sympathetic blocks, superior hypogastric plexus block
Pain associated with cancer may be somatic, visceral, or neuropathic in origin, and approximately 50% of all cancer patients have a combination of pain types at the time of diagnosis. When viscera are stretched, compressed, invaded, or distended, a poorly localized noxious pain is reported. Patients experiencing visceral pain often describe the pain as vague, deep, squeezing, crampy, or colicky in nature. Other signs and symptoms include referred pain, such as shoulder pain due to diaphragm invasion by tumor, nausea, and vomiting.
Visceral pain associated with cancer may be relieved with oral pharmacologic therapy that includes combinations of nonsteroidal antiinflammatory agents, opioids, and coadjuvant therapies. Neurolytic blocks of the sympathetic axis are also effective in controlling visceral cancer pain. Thus neurolysis of the sympathetic axis should be judged as an important adjunct to pharmacologic therapy for the relief of severe cancer-related pain. These blocks rarely eliminate cancer pain, however, due to coexisting somatic and neuropathic pain. Thus oral pharmacologic therapy must often be continued, albeit at lower doses. The goal of performing a neurolytic block of the sympathetic axis is to (1) maximize the analgesic effect of opioid and nonopioid analgesics, and (2) reduce the dosage of these agents to alleviate untoward side effects.
Neurolytic techniques are not without risk. Thus sound clinical judgment and complete patient understanding are essential to minimize undesirable effects. The detailed description of the techniques for these blocks is beyond the scope of this review. Thus the reader is directed to other publications for this purpose.
Celiac Plexus Block
The celiac plexus is situated retroperitoneally in the upper abdomen. It is at the level of the T12 and L1 vertebrae, anterior to the crura of the diaphragm. It surrounds the abdominal aorta and celiac artery. The plexus continues inferiorly to form the superior and the inferior mesenteric plexus.
The celiac plexus is composed of a network of nerve fibers, both from the sympathetic and parasympathetic systems. It contains one to five large ganglia, which receive sympathetic fibers from the three splanchnic nerves (greater, lesser, and least). The thoracic splanchnic nerves lie above and posterior to the diaphragm, anterior to the T12 vertebra. The celiac plexus also receives parasympathetic fibers from the vagus nerve, and provides autonomic innervation to the liver, pancreas, gallbladder, stomach, spleen, kidneys, intestines, and adrenal glands, as well as to the blood vessels.
Indications
Neurolytic blocks of the celiac plexus have been used for malignant and chronic nonmalignant pain. In patients with acute or chronic pancreatitis, it has been used with significant success. Likewise, patients with cancer in the upper abdomen who have a significant visceral pain component have responded well to this block.
Technique
There are multiple posterior percutaneous approaches to block nociceptive impulses from the viscera of the upper abdomen. These include the splanchnic nerve block that is accomplished using a retrocrural approach and the celiac plexus block, which uses the anterocrural (or transcrural) approach, which may be transaortic. For the retrocrural approach, the two needles are inserted bilaterally at the level of the first lumbar vertebra, 5–7 cm from the midline. The tip of the needle is then directed toward the vertebral body of T12, or more commonly L1 for the retrocrural and anterocrural approaches. The left needle is positioned just posterior to the aorta, and the right needle can be advanced 1 cm deeper. If a transdiscal retrocrural approach is used, then a single needle approach may be positioned so it ultimately lies at midline of the vertebral body. Similarly, for the anterocrural approach, unilateral needle insertion with the needle tip’s final position at midline is often adequate, although a bilateral needle approach may be used as well. As the name indicates, for the anterocrural approach, the needle(s) must be advanced through the diaphragm. This is relatively straightforward on the right side, but more difficult on the left side, due to the proximity of the aorta. Thus, on the left side, the use of a single-needle transaortic technique allows the operator to confirm, using aspiration, passage through the aorta. Regardless of whether the approach is retrocrural or anterocrural, fluoroscopy should reveal spread of contrast posterior to the diaphragm and anterior to the vertebral body.
In addition to the fluoroscopic guidance techniques, computed tomography (CT) scan and ultrasound use for percutaneous celiac plexus block have also been described. For the posterior percutaneous CT-guided approach, unilateral or bilateral approaches may be employed, where the left needle is inserted closer to the midline and placed anterolateral to the aorta or through the aorta. Figs. 71.1–71.3 illustrate the final position of the needles and the expected spread of contrast medium after successful placement. Pain specialists also perform neurolysis of the celiac plexus using a transabdominal approach with the assistance of CT and/or ultrasound guidance. This approach is frequently used when patients are unable to tolerate either the prone or lateral decubitus position, or when the liver is so enlarged that a posterior approach is not feasible.
