Overview of Neuraxial Neurolysis
Neurolysis is a technique that uses either chemicals or physical agents to breakdown certain nerve fibers in the body. The purpose of this is to stop nerve signals from being sent. If these nerve signals are related to pain, then breaking them down can provide relief from discomfort. This treatment often uses methods such as radiofrequency (a heat-based approach), chemoneurolysis (a chemical-based approach), and cyroablation (a cold-based approach).
This procedure is especially important for treating pain caused by cancer. Managing pain at the end of life is a huge issue that affects between 10 and 15% of all cancer patients. When traditional pain relief methods aren’t enough, neurolysis can play a key part in helping these patients to feel better. It’s able to help control severe pain in the long term, without causing many other substantial negative effects.
A specific type of neurolysis called intrathecal chemical neurolysis (ICN) is commonly used to help treat cancer pain. The procedure involves injecting certain substances, such as alcohol or phenol, into the spinal fluid. This was first done for chronic cancer pain in 1931. Up till now, no large-scale studies have been done on this procedure, so most of the knowledge about it comes from healthcare professionals’ experiences.
Even though this procedure can be risky, when it is used correctly and with the right patients, it can be significantly beneficial. Not only can it help to reduce the amount of strong painkillers a patient needs to use, it can also improve their overall quality of life. However, in recent years, less people are opting for this form of treatment due to other types of interventions for terminal cancer that have become available.
Still, this form of treatment has unique advantages. For example, it is able to provide immediate relief from pain. Therefore, it can be very useful in countries that may not have access to other, more technologically advanced pain relief methods. This is because it doesn’t require complicated imaging technology and can be done fairly quickly with fewer follow-up appointments.
Anatomy and Physiology of Neuraxial Neurolysis
The spinal cord, a significant part of your nervous system, is safeguarded by three layers known as the meninges. From the outermost to the innermost, these layers are termed as the dura mater, arachnoid mater, and pia mater. There’s a space that exists between the dura mater and the vertebrae, called the epidural space.
Another space, identified as the subarachnoid space, is found between the arachnoid and pia mater. This space is filled with a fluid called the cerebrospinal fluid (CSF). The pia mater is the layer that is in direct contact with the spinal cord, fitting closely around it.
The epidural space’s boundaries extend from the foramen magnum, which is a large opening at the base of the skull, down to the sacral hiatus in the lower back. It is shielded by two key ligaments, the ligamentum flavum and the posterior longitudinal ligament, and the periosteum of laminae, which is a thin tissue that lines the bones of the spine. The supply of blood to the spine is ensured by specific spinal nerves called dorsal rami and sinuvertebral nerves.
For certain procedures like epidural anesthesia, a needle is inserted between the vertebrae to deliver medication into the epidural space. Similarly, for specific pain relief procedures, medication is introduced into the subarachnoid space. These methods are used to help manage pain that is restricted to two or three skin areas (dermatomes), or in some severe cases involving loss of bowel, bladder, or motor control. The epidural neurolysis procedure can be beneficial to treat pain that affects both sides of the body and spans multiple areas.
Why do People Need Neuraxial Neurolysis
Choosing the right patient is crucial. A medical process called neuraxial neurolysis can help with unmanageable pain related to cancer. This is usually considered when pain relief drugs (like opioids) and cancer treatments haven’t been able to control the pain. This procedure is mainly used for somatic pain – pain coming from muscles, skin, and soft tissues.
It’s important to note that this isn’t the best treatment for all types of pain. For visceral pain (pain coming from organs) or neuropathic pain (pain caused by damage to the nervous system), this procedure might not work as well as it does for somatic pain.
When a Person Should Avoid Neuraxial Neurolysis
There are several reasons why a certain medical procedure might not be recommended for a patient. These include the patient not wanting the procedure, a problem with blood clotting called coagulopathy, or the patient not responding effectively to local anesthetics that are given around the spinal area, although this doesn’t always mean the procedure will not work. This procedure is not only used for treating certain types of pain, including pain due to loss of nerve sensation (deafferentation) or pain that is spread throughout the body and related to the sympathetic nervous system.
Equipment used for Neuraxial Neurolysis
A special thin needle of size 24-gauge, with a pencil-like tip, is required. If we use a needle that’s smaller than this, it might interfere with the smooth flow of cerebrospinal fluid (CSF), which is a clear, colorless body fluid found in the brain and spine.
Who is needed to perform Neuraxial Neurolysis?
A doctor who specializes in treating pain, also known as an interventional pain physician, is the one who typically does this procedure. In the United States, these doctors undergo extensive training. After they finish their basic medical studies, they receive further training in specific fields like anesthesiology (dealing with pain control during operations), neurology (study of the nervous system and the brain), or psychiatry (treatment of mental health issues). They then have to complete a one-year special training, known as a fellowship, accredited by ACGME (an organization that ensures the medical training programs meet high standards). This comprehensive training helps them to best manage and treat your pain.
Preparing for Neuraxial Neurolysis
Before starting the procedure, it’s important for the patient to have a good intravenous (IV) line in place. This is where medication and fluids can be given directly into a vein. The patient needs to be able to communicate with the doctor during the procedure, so using sedatives or hypnotics (drugs that can make you feel relaxed or sleep) isn’t recommended. There will also be an assistant who will help with positioning the patient properly and regularly checking vital signs, which are measurements of body functions like heart rate and temperature.
The patient is then prepared and draped in a clean, safe way to help prevent infections. This means the area where the procedure will be done is cleaned, and then covered with a sterile drape. This drape has a hole where the surgery will happen, to keep the rest of the body protected and clean.
How is Neuraxial Neurolysis performed
Chemical neurolysis is a procedure that uses agents like alcohol, phenol, or botulinum toxin to disrupt nerve function and provide relief from pain. It works by breaking down various components of the nerves. For instance, alcohol can break down substances like cholesterol, phospholipids, and lipoproteins in the nerves. It typically requires a 35 to 60% concentration and often needs large amounts since it spreads quickly from where it’s injected.
Phenol, used in a concentration of 5% to 7%, is another common choice. It disrupts the axons (nerve fibers) and Schwann cells (cells that support nerve function) within the protective coatings around nerves.
The doctor generally uses a thin needle to inject these chemicals into the subarachnoid space, an area surrounding your spinal cord. In intrathecal neurolysis, one type of chemical neurolysis, it’s important that the needle is placed where the targeted nerve root (branch of the nerve) leaves the spine and not where it passes through the holes between the bones of the spine. It’s crucial to ensure that the chemical doesn’t leak to any nerve roots that aren’t supposed to be targeted.
Phenol is denser than the cerebrospinal fluid (CSF), the fluid that surrounds your brain and spinal cord. To best use this property, patients are positioned so that the painful side is dependent. On the other hand, alcohol is less dense than CSF. To make sure the alcohol spreads to the targeted area, the patient is positioned with the painful side up. Usually, alcohol injections result in a burning sensation, while phenol has local anesthetic properties, often causing a feeling of warmth. After injection, the concentration of both phenol and alcohol in CSF decreases quickly. The patient should hold their position for at least 30 minutes after the injection.
Epidural neurolysis is another, less common, type of neuraxial neurolysis. For this procedure, the needle or catheter insertion point is close to the vertebral level that matches the level of pain. This process involves inserting a tube (epidural catheter) and carrying out multiple injections over several days.
Possible Complications of Neuraxial Neurolysis
Neuroablation, a procedure that destroys certain nerves to help manage pain, can sometimes cause a different kind of pain known as deafferentation pain. This is why it’s usually only recommended for people expected to live less than a year. This treatment can also affect the quality of life for people with cancer by potentially causing muscle weakness, loss of bladder control, sexual problems, or a loss of sense of body position. It also can cause slowed movement of the bowel, but this is quite rare, happening in less than 1 percent of patients.
There are different types of neuroablation, two of the most common being epidural neurolysis and subarachnoid neurolysis. Compared to subarachnoid neurolysis, epidural neurolysis has a lower risk of causing the complications mentioned above. Another possible side effect is a type of headache that occurs after a puncture in the spinal cord, known as a post-dural puncture headache.
What Else Should I Know About Neuraxial Neurolysis?
In a study of 5020 patients, it was found that 60% of patients experienced good pain relief while 22% had moderate pain relief using alcohol as a treatment for nerve pain. In another study of 1982 patients, it was found that 58% of patients experienced good pain control, while a quarter had poor pain control using phenol, another type of treatment.
These treatment methods can help improve the quality of life for patients with terminal cancer, who often have few other treatment options. However, it’s crucial that patients understand the potential side effects and complications, and have realistic expectations of the treatment outcomes.
Currently, bigger and more well-designed studies are needed to determine how effective these nerve pain relief techniques are when compared to other treatments for patients dealing with cancer pain.