CHAPTER 39 PERMANENT NEURAL BLOCKADE AND CHEMICAL ABLATION Michael M. Hanania, MD, Charles E. Argoff, MD 1. What is neurolysis? Neurolysis is the application of a chemical or physical destructive agent to a nerve to create a long-lasting or permanent interruption of neural transmission. 2. List the types of agents commonly used in neurolysis Chemical agents commonly used in neurolysis include alcohol, phenol, glycerol, ammonium compounds, chlorocresol, and aminoglycosides. Hypotonic or hypertonic solutions may also be used. The most commonly used physical agents are cold (cryotherapy) and heat (radiofrequency lesions or laser). 3. What are the indications for neurolysis? Neurolysis is almost exclusively reserved for the treatment of intractable cancer pain. Rarely, some forms of nonmalignant pain can be treated with these neurolytic agents (for example, intractable postherpetic neuralgia and chronic pancreatitis). Neurolysis using cryoanalgesia or radiofrequency is more precise and reversible; thus these agents are often used for chronic nonmalignant pain conditions. Several requisites must be met before neurolysis is performed. In most cases, successful pain relief should be demonstrated with temporary blockade. The painful area must be sufficiently limited to be served by a readily accessible nerve or plexus. A thorough knowledge of the relevant anatomy and the mechanism by which the agent destroys nerve tissue are essential. Neurolysis should be regarded as an irreversible and potentially permanent procedure to be considered only when other treatment modalities have failed. 4. What are the potential side effects or complications of neurolysis? Extravasation or malplacement of the solution, resulting in injury to nerves other than the target nerve, can produce unwanted sensory and motor block. Neuritis, anesthesia dolorosa, or pain in the deafferentated area may occur. Systemic effects, such as hypotension, can be severe enough to require resuscitation. 5. How do commonly used neurolytics, such as alcohol and phenol, work? Alcohol and phenol cause protein coagulation and necrosis of the axon without disruption of the Schwann cell tube. Thus, axonal regeneration can occur. Recovery is faster with phenol than with alcohol. However, if cell bodies are destroyed along with axons, as is more likely with alcohol, regeneration is not possible, and permanent blockade results. 6. What are the indications for celiac plexus neurolysis? Celiac plexus neurolysis is a commonly performed neurolytic procedure that is useful in reducing visceral pain from structures that have sensory fibers passing through the celiac plexus. The structures innervated through the celiac plexus include the lower esophagus, stomach, small intestine, large intestine to the midtransverse colon, liver, pancreas, adrenals, and kidneys. Pancreatic cancer pain is most commonly treated with this block. 7. Under what circumstances is celiac plexus neurolysis preferred over systemic opioids for the management of pain from pancreatic cancer? Most patients do well with systemic opioids and require no further intervention for controlling pain from pancreatic cancer. In fact, analgesia after celiac neurolysis may not be superior to that after treatment with systemic opioids. However, patients who develop severe side effects from systemic opioids benefit most from celiac neurolysis. Following celiac neurolysis, a decreased need for opioids is observed as well as fewer associated side effects, such as sedation, confusion, nausea, and constipation. 8. Where is the celiac plexus? What are the approaches and techniques for celiac plexus blockade? The celiac plexus is the largest plexus of the sympathetic nervous system. It lies near the aorta, just anterior to the body of the first lumbar vertebra. Guidance by fluoroscopy or computed tomography (CT) scan must be used when injecting neurolytic solution to ensure correct needle placement. One technique is a posterior percutaneous approach using a needle to pass transaortic or anterior to the crura of the diaphragm at the level of L1 where the celiac plexus is situated. Variations of this approach exist, including using two needles for bilateral injection in the retrocrural region. Recently, an anterior percutaneous approach was described. 9. What must be done prior to actual neurolysis of the celiac plexus? A celiac plexus block using local anesthetic must be performed first to determine if significant pain relief is likely with celiac neurolysis. The patient should therefore reduce opioid consumption the day of the procedure so that pain relief can be assessed. 10. What is the success rate with celiac plexus neurolysis for pancreatic cancer pain? A success rate of 85% to 94% of good to excellent pain relief has been obtained in several large series of patients undergoing neurolytic celiac plexus block for pain from pancreatic cancer. In a series of 136 patients, analgesia was present until the time of death in 75% of cases. Repetition of the block is required in some patients. The earlier in the disease process the block is performed, the better the results. This may be due to better spread of neurolytic solution around the celiac plexus when tumor infiltration is minimal. 11. List the potential complications of celiac neurolysis Reported complications of celiac neurolysis include pneumothorax, chylothorax, pleural effusion, convulsions, and paraplegia. Postural hypotension and diarrhea occur frequently secondary to the sympathetic blockade, but they are usually self-limited. 12. What is intrathecal neurolysis? When is it used? Intrathecal neurolysis is a form of chemical rhizotomy in which a neurolytic agent is introduced into the cerebrospinal fluid to block specific dermatomes. This can be performed at any spinal level up to the midcervical region. At higher levels, there is risk of spread of neurolytic agent to the medullary centers. Indications for intrathecal neurolysis include any peripheral pain within a specific dermatomal distribution. 13. How is intrathecal neurolysis performed using phenol or alcohol? Studies have demonstrated that all nerve fibers are affected indiscriminately by both phenol and alcohol. The concentration and quantity of agent used determines the extent of nerve fiber destruction and, therefore, the degree and extent of sensory loss. Phenol is hyperbaric relative to cerebrospinal fluid; therefore, the patient should be positioned so that the sensory nerve roots are aligned with gravity (i.e., semisupine). Alcohol is hypobaric, so the nerve roots involved need to be in the up position or against gravity (i.e., semiprone). Positioning of the patient and use of small incremental doses of neurolytic solution are critical for obtaining the proper block. Average duration of analgesia is 3 to 4 months, with a wide range of distribution. 14. Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: Neuroimaging in the Patient with Pain Pharmacologic Management Postoperative Pain Management Sympathetic Neural Blockade Cancer Pain Syndromes Temporary Neural Blockade Stay updated, free articles. Join our Telegram channel Join Tags: Pain Management Secrets Jun 14, 2016 | Posted by admin in PAIN MEDICINE | Comments Off on Permanent Neural Blockade and Chemical Ablation Full access? Get Clinical Tree
CHAPTER 39 PERMANENT NEURAL BLOCKADE AND CHEMICAL ABLATION Michael M. Hanania, MD, Charles E. Argoff, MD 1. What is neurolysis? Neurolysis is the application of a chemical or physical destructive agent to a nerve to create a long-lasting or permanent interruption of neural transmission. 2. List the types of agents commonly used in neurolysis Chemical agents commonly used in neurolysis include alcohol, phenol, glycerol, ammonium compounds, chlorocresol, and aminoglycosides. Hypotonic or hypertonic solutions may also be used. The most commonly used physical agents are cold (cryotherapy) and heat (radiofrequency lesions or laser). 3. What are the indications for neurolysis? Neurolysis is almost exclusively reserved for the treatment of intractable cancer pain. Rarely, some forms of nonmalignant pain can be treated with these neurolytic agents (for example, intractable postherpetic neuralgia and chronic pancreatitis). Neurolysis using cryoanalgesia or radiofrequency is more precise and reversible; thus these agents are often used for chronic nonmalignant pain conditions. Several requisites must be met before neurolysis is performed. In most cases, successful pain relief should be demonstrated with temporary blockade. The painful area must be sufficiently limited to be served by a readily accessible nerve or plexus. A thorough knowledge of the relevant anatomy and the mechanism by which the agent destroys nerve tissue are essential. Neurolysis should be regarded as an irreversible and potentially permanent procedure to be considered only when other treatment modalities have failed. 4. What are the potential side effects or complications of neurolysis? Extravasation or malplacement of the solution, resulting in injury to nerves other than the target nerve, can produce unwanted sensory and motor block. Neuritis, anesthesia dolorosa, or pain in the deafferentated area may occur. Systemic effects, such as hypotension, can be severe enough to require resuscitation. 5. How do commonly used neurolytics, such as alcohol and phenol, work? Alcohol and phenol cause protein coagulation and necrosis of the axon without disruption of the Schwann cell tube. Thus, axonal regeneration can occur. Recovery is faster with phenol than with alcohol. However, if cell bodies are destroyed along with axons, as is more likely with alcohol, regeneration is not possible, and permanent blockade results. 6. What are the indications for celiac plexus neurolysis? Celiac plexus neurolysis is a commonly performed neurolytic procedure that is useful in reducing visceral pain from structures that have sensory fibers passing through the celiac plexus. The structures innervated through the celiac plexus include the lower esophagus, stomach, small intestine, large intestine to the midtransverse colon, liver, pancreas, adrenals, and kidneys. Pancreatic cancer pain is most commonly treated with this block. 7. Under what circumstances is celiac plexus neurolysis preferred over systemic opioids for the management of pain from pancreatic cancer? Most patients do well with systemic opioids and require no further intervention for controlling pain from pancreatic cancer. In fact, analgesia after celiac neurolysis may not be superior to that after treatment with systemic opioids. However, patients who develop severe side effects from systemic opioids benefit most from celiac neurolysis. Following celiac neurolysis, a decreased need for opioids is observed as well as fewer associated side effects, such as sedation, confusion, nausea, and constipation. 8. Where is the celiac plexus? What are the approaches and techniques for celiac plexus blockade? The celiac plexus is the largest plexus of the sympathetic nervous system. It lies near the aorta, just anterior to the body of the first lumbar vertebra. Guidance by fluoroscopy or computed tomography (CT) scan must be used when injecting neurolytic solution to ensure correct needle placement. One technique is a posterior percutaneous approach using a needle to pass transaortic or anterior to the crura of the diaphragm at the level of L1 where the celiac plexus is situated. Variations of this approach exist, including using two needles for bilateral injection in the retrocrural region. Recently, an anterior percutaneous approach was described. 9. What must be done prior to actual neurolysis of the celiac plexus? A celiac plexus block using local anesthetic must be performed first to determine if significant pain relief is likely with celiac neurolysis. The patient should therefore reduce opioid consumption the day of the procedure so that pain relief can be assessed. 10. What is the success rate with celiac plexus neurolysis for pancreatic cancer pain? A success rate of 85% to 94% of good to excellent pain relief has been obtained in several large series of patients undergoing neurolytic celiac plexus block for pain from pancreatic cancer. In a series of 136 patients, analgesia was present until the time of death in 75% of cases. Repetition of the block is required in some patients. The earlier in the disease process the block is performed, the better the results. This may be due to better spread of neurolytic solution around the celiac plexus when tumor infiltration is minimal. 11. List the potential complications of celiac neurolysis Reported complications of celiac neurolysis include pneumothorax, chylothorax, pleural effusion, convulsions, and paraplegia. Postural hypotension and diarrhea occur frequently secondary to the sympathetic blockade, but they are usually self-limited. 12. What is intrathecal neurolysis? When is it used? Intrathecal neurolysis is a form of chemical rhizotomy in which a neurolytic agent is introduced into the cerebrospinal fluid to block specific dermatomes. This can be performed at any spinal level up to the midcervical region. At higher levels, there is risk of spread of neurolytic agent to the medullary centers. Indications for intrathecal neurolysis include any peripheral pain within a specific dermatomal distribution. 13. How is intrathecal neurolysis performed using phenol or alcohol? Studies have demonstrated that all nerve fibers are affected indiscriminately by both phenol and alcohol. The concentration and quantity of agent used determines the extent of nerve fiber destruction and, therefore, the degree and extent of sensory loss. Phenol is hyperbaric relative to cerebrospinal fluid; therefore, the patient should be positioned so that the sensory nerve roots are aligned with gravity (i.e., semisupine). Alcohol is hypobaric, so the nerve roots involved need to be in the up position or against gravity (i.e., semiprone). Positioning of the patient and use of small incremental doses of neurolytic solution are critical for obtaining the proper block. Average duration of analgesia is 3 to 4 months, with a wide range of distribution. 14. Only gold members can continue reading. Log In or Register to continue Share this:Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window) Related Related posts: Neuroimaging in the Patient with Pain Pharmacologic Management Postoperative Pain Management Sympathetic Neural Blockade Cancer Pain Syndromes Temporary Neural Blockade Stay updated, free articles. Join our Telegram channel Join Tags: Pain Management Secrets Jun 14, 2016 | Posted by admin in PAIN MEDICINE | Comments Off on Permanent Neural Blockade and Chemical Ablation Full access? Get Clinical Tree
