Chapter 71 Neurolytic Visceral Sympathetic Blocks Flashcards
KEY POINTS 1. Neurolytic blocks of the sympathetic axis are an important adjunct to pharmacologic therapy for the relief of severe visceral pain experienced by cancer patients. The goal of performing these blocks is to maximize the analgesic effect of opioid and nonopioid analgesics while reducing their dosage to alleviate untoward side effects. 2. Neurolytic celiac plexus block for patients with pancreatic cancer pain results in excellent analgesia, reduced opioid utilization, and decreased
Pain associated with cancer may be
somatic, visceral, and neuropathic in origin, and about 50% of all cancer patients have a combination of pain types at the time of diagnosis.
When visceral structures 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.
referred pain
shoulder pain that appears when the diaphragm is invaded with tumor, and nausea/ vomiting
Visceral pain associated with cancer may be relieved
with oral pharmacologic therapy that include
combinations of nonsteroidal anti-inflammatory agents, opioids, and coadjuvant therapy. Neurolytic blocks of the sympathetic axis are also extremely effective in controlling visceral cancer pain.
neurolysis of the sympathetic axis should be judged as an important adjunct to pharmacologic therapy for the relief of severe pain experienced by cancer patients. As such, these blocks can rarely eliminate cancer pain, because
patients also frequently experience coexisting somatic and neuropathic pain.
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.
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 the celiac and superior mesenteric arteries. The plexus continues inferiorly to form the superior and the inferior mesenteric plexus
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 supply to the liver, pancreas, gallbladder, stomach, spleen,
kidneys, intestines, and adrenal glands, as well as to the
blood vessels.
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
celiac plexus block—multiple posterior percutaneous approaches to block nociceptive impulses from the viscera of the upper abdomen.
the classic retrocrural approach, block of the splanchnic nerves, the anterocrural (or transcrural) approach, and the transaortic approach.
Celiac Plexus Block
the common posterior approaches
the two needles are inserted at the level of the first lumbar vertebra, 5 to 7 cm from the midline. The tip of the needle is then directed toward the body of L1 for the retrocrural and anterocrural approaches and to the body of T12 for neurolysis of the splanchnic nerves. The left needle is positioned just posterior to the aorta and the right needle is advanced 1 cm deeper with a retrocrural or splanchnic nerve approach. Fluoroscopy reveals spread of contrast anterior to the vertebral body and posterior to the diaphragm. The needles must be advanced through the diaphragm using the anterocrural approach. This is relatively easy on the right side, but more difficult on the left side, because of the position of the aorta.
the common posterior approaches relatively easy on the
right side, but more difficult on the left side, because of
the position of the aorta. Two solutions have been described:
confirmation with computed tomography (CT) scan and use of a single-needle, transaortic injection on the left side. The left needle is inserted closer to the midline and placed anterolateral to the aorta with CT
scan, or into and through the aorta with the transaortic
approach
DRUG AND DOSING For neurolytic blocks
50% to 100% alcohol, 20 ml per side, is utilized
When injected by itself, alcohol can produce severe pain. Thus, it is recommended to
first inject 5 to 10 ml of 0.25% bupivacaine 5 min prior to
the injection of alcohol, or to dilute 100% alcohol by 50%
with local anesthetic (0.25% bupivacaine).
Phenol
in a 10% final concentration may also be used, and it has the advantage of being painless on injection. Both agents appear to have the same efficacy.
Complications associated with celiac plexus blocks
appear to be related to the technique used: retrocrural, transcrural, or transaortic.Orthostatic hypotension transient diarrhea paraplegia and bladder and bowel dysfunction
Orthostatic hypotension management
bed rest, avoidance of sudden changes in position, and fluid replacement. Once compensatory vascular reflexes are fully activated, this side effect disappears. Wrapping of the lower extremities from the toe to the upper thighs with elastic bandages has been used with success in patients who developed orthostatic hypotension and needed to ambulate during the first week after the block
Backache may result from
(a) local trauma during the needle placement resulting in a retroperitoneal hematoma, (b) alcohol irritation of the retroperitoneal structures, or (c) injury to the lumbar plexus
Patients with a backache should have at least two
hematocrit measurements at a 1-hour interval. If there is a decrease in the hematocrit, radiologic imaging is indicated to rule out a retroperitoneal hematoma.
A urine analysis positive for red cells suggests
renal injury
Retroperitoneal hemorrhage
Patients who present with backache and orthostatic hypotension after a celiac plexus block should be admitted to the hospital for serial hematocrit monitoring. If a low or a decreasing hematocrit is demonstrated, patients should undergo radiologic evaluation to rule out injury to the kidneys, the aorta, or other vascular structures. A surgical consult should be obtained as soon as feasible
Diarrhea may occur due to
sympathetic block of the bowel. Treatment includes hydration and antidiarrheal agents. Oral loperamide is a good choice, although any anticholinergic may be used.
Abdominal aortic dissection
The mechanism of aortic injury is direct damage with the needle during the performance of the block. As expected, the anterocrural approach is more frequently associated with this complication. Thus, if there were evidence of atherosclerotic disease of the abdominal aorta, it would seem appropriate to avoid this approach
Paraplegia and transient motor paralysis have
occurred after celiac plexus block
these neurologic complications may occur due to spasm of the lumbar segmental arteries that
perfuse the spinal cord.
How to Avoid Paraplegia and transient motor paralysis have occurred after celiac plexus block.
it may be empirically suggested that alcohol should not be used if there is evidence of significant atherosclerotic disease of the aorta, suggesting that the circulation to the spinal cord may also be impaired. However, there is also a report of paraplegia after phenol use, suggesting that other factors, such as direct vascular or neurologic injury or retrograde spread to the spinal cord, may come into play.
there is evidence to suggest that chronic use of high doses of opioids may have a negative effect on immunity. Thus, analgesic techniques that lower opioid consumption
should have positive effects on patient outcomes
SUPERIOR HYPOGASTRIC PLEXUS
BLOCK indication
pelvic pain associated with cancer and that seen
with chronic nonmalignant conditions
Analgesia to the organs in the pelvis is possible with superior hypogastric plexus because
the afferent fibers innervating these structures travel with the sympathetic nerves, trunks, ganglia, and rami and are accessible for neurolytic block. Thus, a sympathectomy for visceral pain is analogous to a peripheral neurectomy or dorsal rhizotomy for somatic pain.
The superior hypogastric plexus is situated in
the retroperitoneum, bilaterally, extending from the lower third of the fifth lumbar vertebral body to the upper third of the first sacral vertebral body.
SUPERIOR HYPOGASTRIC PLEXUS BLOCK TECHNIQUE
Patients are placed in the prone position with a pillow
under the pelvis to flatten the lumbar lordosis. Local infiltration of the intervening muscle planes can be performed. Needle insertion sites are 5 to 7 cm lateral to the midline, depending on patient’s height and girth, at the level of the L4–L5 interspace. Two 7- to 9-inch, 22-gauge short beveled needles are inserted with the bevel directed medially, 45 degrees mesiad and 30 degrees caudad, so that the needle tips lie anterolateral to the L5–S1 intervertebral space. Aspiration is important to avoid injection into the iliac vessels. If blood is aspirated, a transvascular approach can be used.
SUPERIOR HYPOGASTRIC PLEXUS BLOCK TECHNIQUE
Biplanar fluoroscopy is used to verify accurate needle
placement. Anteroposterior (AP) views should reveal
the tip of the needle at the level of the junction of the
L5 and S1 vertebral bodies. Lateral views will confirm
placement of the needle tip just beyond the vertebral
body’s anterolateral margin. The injection of 2 to 3 ml
of water-soluble contrast medium is used to verify
accurate needle placement and to rule out intravascular
injection. In the AP view, the spread of contrast should
be confined to the midline region. In the lateral view, a
smooth posterior contour corresponding to the anterior
psoas fascia indicates that the needle is at the appropriate depth.
SUPERIOR HYPOGASTRIC PLEXUS BLOCK DRUG AND DOSING
For a prognostic hypogastric plexus blockade; a volume
of 6 to 8 ml of 0.25% bupivacaine through each needle
is recommended. For therapeutic purposes, a total of 6 to 8 ml of 10% aqueous phenol or 80% alcohol can be
injected through each needle
SUPERIOR HYPOGASTRIC PLEXUS BLOCK COMPLICATIONS
Potential complications include retroperitoneal hematoma formation and acute ischemia of the foot, due to the dislodgement of an atherosclerotic plaque from the iliac vessels
Ganglion Impar
solitary retroperitoneal structure located at the level of the sacrococcygeal junction. This ganglion marks the end of the two sympathetic chains
effectively treated with neurolysis of the ganglion impar (the ganglion of Walther)
Visceral pain in the perineal area associated with malignancies
Patients who will benefit from this ganglion impar blockade will frequently present with
vague and poorly localized pain, which is burning in
character and frequently accompanied by sensations of
urgency.
GANGLION IMPAR BLOCK
TECHNIQUE
This block may be performed with the patient in the left
lateral decubitus position with the knees flexed, in the
lithotomy position, or in the prone position. The initial
technique employs a 22-gauge, 3.5-inch spinal needle that is manually bent to facilitate placement of the needle tip anterior to the concavity of the sacrum and coccyx. The needle is introduced through the anococcygeal ligament with its concavity oriented posteriorly and, under fluoroscopic guidance, is directed along the midline to contact bone at or near the sacrococcygeal junction. Contrast dye confirms retroperitoneal spread; on the lateral view, it is shaped like a comma.
GANGLION IMPAR BLOCK
TECHNIQUE
transcoccygeal approach
performed with the patient in the prone position. This approach has been reported to be both effective and safe. A 20-gauge, 1.5-inch needle is inserted through the sacrococcygeal ligament in the midline. The needle is then advanced until the tip is placed posterior to the rectum. For diagnostic blocks, 4 to 8 ml of 1% lidocaine or 0.25% bupivacaine is selected; for neurolytic block, 4 (to 8) ml of 10% phenol is used. Although the technique is relatively straightforward, care is needed to prevent perforation of the rectum and injection into the periosteum.
Neurolysis of the sympathetic axis is a safe and costeffective way to treat
visceral pain associated with cancer
Neurolysis of the sympathetic axis benefits
not limited to improved analgesia but also include a decrease in opioid consumption.
