| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Interventional Radiology Case Conferences |
1 All authors: Department of Radiology, Division of Abdominal Imaging and Intervention, Massachusetts General Hospital, White 270, 55 Fruit St., Boston, MA 02114.
Received January 14, 2002;
accepted after revision February 11, 2002.
Address correspondence to P.R. Mueller.
Case History
 Top Case History References |
|---|
Dr. Titton. What is the role of the radiologist in performing a celiac plexus block?
Dr. Mueller. A celiac plexus block is an adjunctive form of palliative pain management underused by radiologists. Radiologists, having expertise in cross-sectional imaging and anatomy, can use established interventional techniques to safely and routinely inject a neurolytic agent into the celiac plexus. Patients who have chronic abdominal pain due to either benign or malignant conditions that are unresponsive to large doses of narcotic analgesics can be treated with this procedure. A celiac plexus block has been shown to reduce narcotic requirements and to limit narcotic doserelated side effects [1,2,3]. Traditionally, this procedure has been performed mostly by anesthesiologists using either fluoroscopic or CT guidance, by endoscopists [4], or by surgeons intraoperatively [5].
Dr. Titton. In which medical conditions has celiac plexus block been shown to aid palliative pain management?
Dr. Gervais. Most commonly, celiac plexus blocks have been used to treat the chronic abdominal pain associated with pancreatic cancer and have been reported to provide good or excellent pain relief in up to 85% of patients [6, 7]. Pain related to gastric cancer, esophageal cancer, colorectal cancer, liver metastasis, gallbladder cancer, and cholangiocarcinoma has also been treated effectively with a celiac plexus block [2]. The success rate of the procedure for palliative relief of all types of upper gastrointestinal cancer pain has been reported to be between 70% and 97%, regardless of the technique used [2, 7, 8]. In the pediatric population, there have been case reports of celiac plexus blocks for palliative pain management in patients with neuroblastoma and hepatoblastoma [7, 9]. Pain relief lasting up to 7 years after the procedure has been reported in 70% of patients with chronic pancreatitis [10]. Celiac plexus blocks have also been reported to effectively control pain in patients undergoing major interventional biliary procedures [10, 11].
Dr. Titton. What is the anatomy of the celiac plexus block and why is a celiac plexus block potentially effective?
Dr. Lucey. The celiac plexus is a series of one—five ganglia composed of a dense network of interconnecting presynaptic sympathetic nerve fibers derived mainly from the greater (T5-T9), lesser (T10-T11), and least (T12) splanchnic nerves [11, 12]. The celiac plexus is located anterior to the crura of the diaphragm, over the anterolateral wall of the aorta bilaterally, and just caudal to the level of the origin of the celiac artery [10, 13,14,15]. On average, the celiac plexus ganglia are 0.6 cm caudad to the celiac artery on the right and 0.9 cm caudad to the celiac artery on the left [12]. The location of the celiac plexus often varies with regard to bony landmarks and can be located anywhere from the T12-L1 disk space to the middle of the L2 vertebral body [14]. The celiac plexus supplies sympathetic, parasympathetic, and visceral sensory afferent fibers to the pancreas, liver, biliary tract, gallbladder, renal pelvis and ureter, spleen, mesentery, and bowel proximal to the transverse colon [3, 7, 16]. Injecting a neurolytic medication around the celiac artery defunctionalizes the celiac plexus, and the pain pathway is interrupted [17].
Dr. Titton. What agents are injected in celiac plexus blocks?
Dr. Boland. Nerve destructive agents such as ethanol and phenol have been used. Twenty-five to fifty milliters of alcohol in concentrations of 50-100% is the most commonly used neurolytic agent in celiac plexus blocks. The mechanism of action of alcohol is by extraction of cholesterol and phospholipids from neural cell membranes, causing precipitation of lipoproteins and mucoproteins [3]. Some authors have advocated the use of phenol in a concentration greater than 5% in water because phenol induces necrosis when applied directly to neural tissue [3, 18]. Reported disadvantages of phenol include its slower and shorter duration of action and increased viscosity, which limit its use in clinical practice. Local steroid injections mixed with local anesthetics have been used in patients with chronic pancreatitis with disappointing results. In a study by Busch and Atchison [19], only four of 16 patients with abdominal pain due to chronic pancreatitis experienced symptomatic relief after steroid celiac plexus blocks.
Dr. Titton. What imaging modalities may be used to perform a celiac plexus block?
Dr. Gervais. Before the 1970s, celiac plexus blocks were performed blindly, either using an anterior or posterior abdominal approach. In 1979, Hegedüs [13] stressed the importance of using radiologic guidance with fluoroscopy for correct deposition of the neurolytic agent. Using fluoroscopic landmarks, the radiologist placed spinal needles bilaterally 6.5-7.5 cm lateral to the L1 spinous process with the patient in a prone position. Both needles were advanced anteriorly toward the midline until positioned just anterior to the cephalad portion of the L1 vertebral body [1]. In current practice, sonography and CT [14, 16] are used to locate the exact level of the celiac axis. The intraabdominal and retroperitoneal anatomy can be evaluated before the procedure to determine the safest route for needle insertion. The major proposed advantages of performing a sonographically guided celiac block are the availability of sonography, the comfort of the patient lying in the supine position with an anterior abdominal approach, and the potential for the reduced time of the procedure [20]. Das and Chapman [21] reported that in a series of nine sonographically guided celiac blocks, the procedural time taken for a sonographically guided celiac plexus block from needle insertion to withdrawal averaged less than 5 min. CT provides the advantage of specific localization of the needle tip in relation to the celiac artery and avoids penetration or injection into the spinal cord, major vascular structures, liver, kidneys, and other organs [17, 18]. In addition, when the radiologist is using CT guidance, distribution of injected alcohol can be monitored [14]. Open MR imaging—guided posterior celiac plexus blocks using MR imaging—compatible needles have been reported [22] but remain investigational.
Dr. Titton. Which approaches are available to the interventional radiologist performing a celiac plexus block?
Dr. Mueller. The interventional radiologist may perform a celiac plexus block using either an anterior or posterior approach depending on the operator's preferences and anatomic considerations in each patient. Published data have not shown any clear advantage between the anterior and posterior approaches in the coverage of the neurolytic agent [16]. In the anterior approach, the patient lies supine, and CT or sonographic guidance is used to advance a single needle to the level of the celiac artery. Puncture of the liver, stomach, colon, or pancreas may be unavoidable. The major advantage of the anterior approach is the reduced risk of neurologic complications because the tip of the needle is anterior to the spinal arteries and spinal canal [12, 16]. Using the posterior approach with the patient in either a prone or lateral decubitus position makes available several routes for injecting the neurolytic agent. The posterior retrocrural approach is the traditional technique used for a celiac plexus block. With this approach, the patient lies prone, and a needle is directed to slide past the anterior surface of the L1 vertebral body without traversing the crus of the diaphragm. This approach is actually a splanchnic nerve block, which supplies the preaortic celiac plexus [6].
The posterior anterocrural approach is a direct ablation of the entire celiac plexus and is the approach most commonly used at our institution. The posterior transaortic approach uses a single needle that is passed through the posterior and anterior walls of the aorta via a left posterior paramedian approach. This approach has a single midline needle tip that is in the direct vicinity of the celiac plexus and, therefore, requires a smaller dose of neurolytic agent [23]. Most authors advocate using 40-50 mL of 50-100% ethanol for the posterior bilateral anterocrural approach and only 25 mL of 50-100% ethanol for the transaortic approach [8, 23]. The disadvantage of the transaortic celiac plexus block is that it is associated with a higher risk of retroperitoneal hemorrhage, reported in up to 0.5% of patients [3]. The posterior transintervertebral approach involves passing a single needle posteriorly directly through the T12-L1 or L1-L2 intervertebral disk space to a paraaortic location at the level of the celiac axis [15]. The reported advantage of this approach is the increased access to the anterolateral or lateral wall of the aorta, especially in patients with abnormal retroperitoneal anatomy. This approach is less commonly used in clinical practice because of the reported disadvantages, which include the risk of diskitis, disk herniation, and spinal cord puncture [15].
Dr. Titton. What is the importance of needle tip position in a celiac axis block?
Dr. Boland. The success of the celiac plexus block is mainly dependent on effective distribution of the neurolytic agent throughout the entire celiac plexus [16, 24]. The injected neurolytic agent should infiltrate freely in the preaortic soft tissues. According to a study by DeCicco et al. [24], the ideal needle tip position in a patient with no regional anatomic abnormality should be cephalic to the celiac artery to achieve a wider neurolytic distribution, despite the location of the celiac plexus just caudad to the celiac artery.
Dr. Titton. How was the celiac block performed in this type of patient?
Dr. Lucey. We performed the celiac plexus block using the posterior bilateral anterocrural approach. The patient's existing medications, including narcotics, were continued during the period before the procedure. IV access was established, and the patient was placed on continuous ECG, blood pressure, and respiratory monitoring with pulse oximetry. The patient was administered normal saline IV during the procedure to avoid hypotension and was initially placed in the left lateral decubitus position on the CT table. After scout images of the abdomen were obtained, the axial level of the celiac artery was identified and marked on the skin. After subcutaneous injection of local anesthetic using 1% Xylocaine ([lidocaine] Astra USA, Marlborough, MA), a 22-gauge 15-cm Chiba needle (Cook, Bloomington, IN) was advanced into the anterocrural space approximately 1-2 cm anterior to the aorta at the level of the celiac axis (Fig. 1A). After a needle aspiration to ensure no blood return, 5 mL of 30% iodinated contrast material was injected without resistance. Correct placement of the needle was confirmed by observing contrast material tracking along the anterolateral wall of the aorta and along the left lateral aspect of the celiac artery. After confirmation of the correct position of the needle tip, 20 mL of absolute 100% ethanol was injected into the retroperitoneal space immediately anterior to the aorta adjacent to the origin of the celiac axis (Fig. 1B). Two milliliters of saline was injected through the needle before needle withdrawal to minimize spread of the neurolytic agent along the needle path. The patient was then turned to the right lateral decubitus position, and the same procedure was repeated. An additional 20 mL of ethanol was injected into the right anterocrural periceliac region, for a total injected dose of 40 mL of absolute 100% ethanol (Fig. 1C). A postprocedural image showed contrast material, air, and ethanol surrounding the anterior aspect of the aorta and along the origin of the celiac artery (Fig. 1D).
|
|
|
|
Dr. Titton. Is it necessary to inject a local anesthetic around the celiac axis before the injection of the neurolytic agent?
Dr. Mueller. Some authors advocate injecting a test dose (10-30 mL) of a local anesthetic such as 2% lidocaine or 0.25% bupivicaine hydrochloride before injecting the neurolytic agent to predict the efficacy of the neurolytic block [3]. This test dose is not used at our institution because the diagnostic celiac plexus block may be misleading. A successful diagnostic celiac plexus block with a local anesthetic does not predict the outcome of a neurolytic celiac plexus block in up to 28% of patients [3].
Dr. Titton. The patient reported a sensation of posterior abdominal burning during the injection of absolute ethanol. Is this sensation expected?
Dr. Gervais. Local posterior abdominal or back pain has been reported during or immediately after a celiac plexus block in up to 96% of patients [2] because of the ablative effect of the neurolytic agent on the sensory nerve fibers of the celiac plexus. Patients may also report a sensation of a dull aching back pain or shoulder pain that may persist for up to 72 hr after the procedure, which is thought to be related to irritation of the diaphragm [3]. If the patient reports a sensation of anterior abdominal pain during or immediately after neurolytic injection, peritoneal irritation should be suspected, and the position of the needle tip should be immediately evaluated to exclude an intraperitoneal location of the needle.
Dr. Titton. Within 24 hr after the celiac plexus block, the patient had adequate pain control, with oxycodone given for episodes of breakthrough pain. His pain relief lasted until his death 4 months later. What are the major reasons why a celiac plexus block would fail to improve pain?
Dr. Lucey. Assuming correct needle tip positioning, the most important reason for failure of a celiac plexus block is regional tumor infiltration or scar tissue and fibrosis that distort anatomy, limiting access to the celiac plexus [18]. In patients with tumor or fibrotic involvement of the celiac area, delivery of the neurolytic agent to the entire celiac plexus area may be limited by the regional anatomic alterations, which will limit long-term pain relief [24]. The procedure may also be technically unsuccessful if an insufficient volume of neurolytic agent is injected around the celiac plexus [12, 16]. If the patient does not experience any symptomatic pain relief after a technically successful celiac plexus block, metastatic disease to the abdominal wall or to the viscera with innervation outside the celiac plexus should be considered [3]. The skin, subcutaneous soft tissues, and peritoneum are not anesthetized by the celiac block [10]. Celiac plexus block generally provides pain relief for 6 months—1 year after the procedure because new nerve routes of pain may regenerate after 6-12 months [20].
Dr. Titton. What are complications of the procedure?
Dr. Boland. Up to 30% of patients experience hypotension after celiac plexus block due to loss of sympathetic tone and splanchnic vasodilatation [3, 10]. This reaction usually manifests itself within the first 12 hr. Up to 60% of patients report diarrhea due to sympathetic blockade and unopposed parasympathetic efferent influence after celiac plexus block, which usually resolves within 48 hr [8]. Neurologic complications, including paraplegia, leg weakness, sensory deficits, and paresthesias, have been reported in up to 1% of celiac plexus blocks [8, 12, 25]. A study by Davies [25] reported four cases of paraplegia after 2730 celiac plexus blocks. Paraplegia was attributed to either direct injury of the spinal cord during the procedure or to injection into the anterior spinal artery [25]. Other uncommon complications include impotence, gastroparesis, superior mesenteric vein thrombosis, chylothorax, pneumothorax, chemical pericarditis, chemical peritonitis, aortic pseudoaneurysm, aortic dissection, retroperitoneal hemorrhage, and retroperitoneal fibrosis [3, 17, 26, 27]. Complications related to puncture of the pancreas, liver, stomach, and colon are rare [3, 22].
Dr. Titton. How does the effect of a celiac plexus block compare with that of medication regimens alone?
Dr. Gervais. In a 1996 study, Kawamata et al. [1] evaluated 21 patients with pancreatic cancer who had chronic intractable abdominal pain. The patients were randomly distributed into two groups: 10 who received a celiac plexus block in combination with oral narcotics and 11 who received narcotics and nonsteroidal antiinflammatory drugs alone. The patients who underwent a celiac plexus block had improved performance status and reported less pain by the visual analog pain scale (0, no pain; 10, intolerable pain) when compared with the control group. The patients who underwent celiac plexus block were also shown to have a statistically significant reduction of morphine consumption. On average, the patients who received a celiac plexus block required 75 mg of morphine less per day than the patients who received the combination of narcotics and nonsteroidal antiinflammatory drugs. The patients who received celiac plexus blocks in combination with lower doses of narcotics reported reduced side effects from the narcotics. The patients who received the celiac plexus block had improved appetites, improved bowel motility, reduced nausea, and improved sleeping habits. This study showed that patients who underwent celiac plexus blocks had less deterioration of quality of life when compared with the group of patients with pancreatic cancer who received medications alone. Most patients with cancer who receive celiac plexus blocks continued to experience partial or complete symptomatic pain relief until the time of death [1, 2].
Dr. Titton. Can you summarize the utility of celiac plexus block and the role of radiologists in performing this procedure?
Dr. Mueller. Celiac plexus block is an effective tool for palliative pain management that has been traditionally overlooked by the radiology community. Using imaging modalities such as CT and sonography, radiologists can use their expertise in anatomy and cross-sectional imaging to routinely and safely perform this procedure by either an anterior or a posterior approach. Adverse effects may occur but, generally, are temporary and mild. Complications are infrequent. After this procedure, patients with cancer generally report partial or complete symptomatic pain relief for the remainder of their lives.
|
TopCase HistoryReferences |
|---|
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
