Overview of Neurolytic Blocks
A neurolytic block is a procedure that involves destroying a specific nerve or group of nerves, which is often used to stop the sensation of pain. The term ‘neuroablation’ is another way of describing techniques that interrupt the pain we feel by chemically, thermally (with heat), or surgically interfering with our nerves. All of these techniques result in Wallerian degeneration, which just means they cause the part of the nerve after the point of damage to break down.
Back in the early 1900s, chemicals were commonly used for this process. In fact, the first time chemical neurolysis was documented was in 1863. A doctor named Luton injected patients with chemicals that irritate the skin to help relieve the pain they were feeling from sciatic neuralgia, a type of severe foot and leg pain. Since then, new and safer methods have been introduced. These include radiofrequency ablation (a procedure that uses radio waves to produce heat and destroy parts of the nerve), cryoablation (where cold temperatures are used to destroy the nerve), and surgical procedures.
Our capabilities for performing these procedures have also improved over time. With advancements in imaging technology, like fluoroscopy which allows doctors to get live x-ray images during the procedure, we can perform these nerve targeting processes more precisely and efficiently.
Anatomy and Physiology of Neurolytic Blocks
The procedure varies based on which specific nerve is getting targeted. Doctors use tools like ultrasounds, x-rays, or nerve stimulation to carefully guide a needle to that nerve.
Why do People Need Neurolytic Blocks
Neurolysis, a procedure where targeted nerve destruction is used to treat various pain conditions, doesn’t have a universally agreed-upon set of use cases. However, deciding which patients are best suited for this treatment is crucial. Normally, such an intensive intervention is only considered after less invasive treatments have not achieved the desired effect.
Before deciding to perform neurolysis, doctors need to do a lot of background work. This includes a detailed personal medical history, a thorough physical examination, comprehensive lab tests, and typically a recent imaging scan like an MRI to pinpoint the source of the pain. These steps help avoid complications that might arise from the procedure. In many cases, the patient may also undergo a psychological evaluation to see if they are ready for the intervention, particularly if a neuromodulatory approach, which involves altering nerve activity, is being considered.
There are multiple conditions where neurolysis might be used. Celiac plexus neurolytic blocks, for example, can help manage internal organ pain from upper abdominal cancers like pancreatic cancer. Superior hypogastric plexus neurolysis could be used for patients experiencing pelvic pain. For individuals with pain due to trigeminal neuropathy, which impacts the facial nerve, neurolysis of the trigeminal nerve might offer relief.
For pain related to fractured ribs, cancer spread, or after-thoracic surgery symptoms, intercostal nerve neurolysis (which affects the nerves in between the ribs) could be an option. Sympathetic plexus neurolysis, affecting the network of nerves in the torso, can also be performed, particularly for patients with cancer pain and nerve pain syndromes, which could affect the chest, lower back and neck nerves. This can also help with visceral pain, or internal organ pain, that’s linked to damage to the sympathetic plexus.
Neurolysis of the medial branch of the primary dorsal ramus may help with pain originating from the small joints in the spine (facets) or the vertebrae itself. The use of alcohol and phenol for neuraxial administration (which is a method to deliver the medication close to the spinal cord) is not as popular anymore due to significant adverse effects and is typically considered in severe muscle rigidity conditions or in the end-stage of cancer.
When a Person Should Avoid Neurolytic Blocks
There are some situations in which a targeted neurolysis procedure – a treatment organized to block nerve pain – cannot be done. These include:
1. If the patient does not want to have the procedure.
2. If there is an active infection around the area where the injection would go.
3. If the patient is allergic to the chemical that is used to block the nerve (known as the neurolytic agent).
People with bleeding disorders, or people who are on medication to prevent blood clots (anticoagulation treatment), might not be able to have this procedure, particularly if the injection needs to be given in an area of the body where it’s hard to apply pressure (noncompressible sites) to stop any bleeding.
If the patient has a pacemaker, the doctor performing the procedure (proceduralist) should consult with specialists who know how to safely adjust and monitor pacemakers (pacemaker interrogation services), especially if they are thinking of using radiofrequency ablation (a type of treatment using heat generated from radio waves).
Equipment used for Neurolytic Blocks
To perform a procedure called a neurolytic block, which helps relieve severe, persistent pain by deliberately injuring specific nerves, doctors need many different tools and substances, including:
* Cleaning solutions such as Chlorhexidine gluconate or povidone-iodine
* An ultrasound device with a sterile cover and gel, if needed
* Fluoroscopy equipment, a kind of x-ray machine, if needed
* A nerve stimulator, if needed
* Local anesthetic, like 1% lidocaine, to numb the skin where the injection will happen
* Another local anesthetic, like 2% lidocaine or 1.5% mepivacaine, to test if the correct nerve was found
* A 10- to 20-mL syringe with extension tubing
* A special needle to reach the nerve or, for injections in the spine, a spinal or epidural needle. The kind of needle used depends on the patient’s body shape and the doctor’s preference
* Drugs that can damage nerves, such as alcohol and phenol, if needed
* A radiofrequency probe, if needed
For procedures called cryoablation, which use extremely low temperatures to treat disease, a cryomachine and cryoprobe with cooling agents, such as nitrous oxide and carbon dioxide, may be used if needed.
The substances used to damage the nerves, called neurolysis, can vary. Most common are alcohol, in concentrations of 50% to 100%, and phenol, in concentrations of 5% to 15%. Other substances, like very salty water (hypertonic saline), glycerol, ammonium salt solutions, and chlorocresol, have also been used. The alcohol damages the nerve by removing important components of its cells and making proteins stick together. When phenol enters a nerve, it damages proteins and causes them to break down.
Radiofrequency probes are important tools for many treatments. They work by producing electricity at a specific frequency, which creates heat and burns a small area to damage a specific nerve. There are different types of radiofrequency treatments, like conventional radiofrequency ablation, pulsed radiofrequency ablation, and cooled radiofrequency ablation, and they all vary in the way they use and control heat to create the damage.
Cryoprobes, which are used in cryoablation procedures, damage nerves by exposing them to extremely cold temperatures. This cuts off the blood supply to the nerve and causes it to die. Cryoablation may also help to reduce the chance of certain pain conditions after the procedure, when compared to radiofrequency ablation.
Last but not least, a procedure called surgical neurolysis or neurectomy, which involves directly cutting a nerve, is generally used only in rare cases where the prognosis is poor. This procedure carries a high risk of causing an unpleasant type of pain due to loss of normal nerve input, which may be even worse than the original symptoms before the treatment.
Who is needed to perform Neurolytic Blocks?
A specialist in pain medicine who is experienced in using ultrasound and X-ray images for guiding nerve injections is the best choice for performing a procedure called neurolysis. This procedure involves intentionally damaging certain nerves to reduce pain. Other medical staff like nurses who are trained to give sedative drugs, which help patients sleep or feel relaxed, can also assist during this procedure. Their support will ensure that you, as a patient, are safe and comfortable throughout the process.
Preparing for Neurolytic Blocks
Before the medical procedure, the doctor will ask the patient to give their informed consent, which means they understand and agree to the treatment plan. Depending on which nerve is being targeted, the patient will be placed in a suitable position. Usually, mild or no sedation (medication to help the patient relax or fall asleep) is needed. However, in certain procedures like chemical neurolysis with alcohol (a treatment to block a nerve that’s causing pain), which can be somewhat painful, or radiofrequency ablation (a procedure that uses heat to relieve back and neck pain), more powerful sedation might be used. It’s important that the doctor and healthcare team always use aseptic technique throughout the procedure. This means everything they do is done in a way that keeps everything clean and free from germs to prevent infection.
How is Neurolytic Blocks performed
To treat certain conditions, a procedure called a nerve block may be needed. This is done in a very clean environment to avoid any infections. The doctor uses special imaging tools, like an X-ray or ultrasound, or a nerve stimulator to locate the specific nerve that needs treatment.
After that, a local anesthetic is used to numb your skin where the treatment will take place. Then, the doctor guides a needle or probe towards the targeted nerve. Before the actual treatment, the doctor might do a test block using anesthetic to ensure the needle is in the right position.
The actual nerve block treatment may involve various methods – injecting alcohol or phenol, or applying a radiofrequency ablation, which is a type of heat treatment. The anesthetic test helps them determine how successful the nerve block will likely be.
During the procedure, your heart rate and blood pressure are carefully monitored, and the healthcare team is prepared to provide emergency care if needed. It’s important for patients to know that the full effects of the treatment, especially if chemicals are used, may take a few days to be noticed.
Possible Complications of Neurolytic Blocks
Just like any medical procedure, there can be complications during or after a treatment, such as bleeding, infection, pain, or damage to tissues near the treatment area. If the treatment involves injecting a chemical inside blood vessels (intravascular injection), it can sometimes result in side-effects like toxicity in the body depending on the chemical used. Procedures involving cooling of tissues (cryoablation) from the surface can sometimes cause damage to the skin, leading to symptoms like hair loss, lightening or darkening of the skin.
In rare cases, inflammation of the nerves (neuritis) may occur after a partial nerve treatment with a chemical. This can sometimes lead to the regrowth of the nerve and cause intense sensitivity or pain, which may be more severe than the original pain. If a nerve controlling muscle movement undergoes such treatment, it may lead to long-term muscle paralysis. Furthermore, the treatment can sometimes lead to issues with bowel, bladder, and sexual functions.
What Else Should I Know About Neurolytic Blocks?
A neurolytic block is a type of treatment that destroys a specific nerve or a group of nerves (nerve plexus). This treatment can help reduce pain. Common methods include chemical treatment, radiofrequency ablation (using high-frequency electrical currents to produce heat), cryoablation (using extreme cold), and neurosurgical procedures (brain-related surgeries).
These methods are often performed with fluoroscopy, a type of medical imaging technique, to improve accuracy and efficiency. Fluoroscopy allows doctors to see an internal part of the body in real-time, like an X-ray movie. This helps them target the right nerves more precisely. As a result, patients often experience a significant reduction in pain.
