Overview of Cryoanalgesia
Throughout history, medical professionals have recognized that cold temperatures can help ease pain. This idea has been around since the days of Hippocrates, who wrote about the pain-numbing effects of snow thousands of years ago. In the 1800s, a medical officer serving under Napoleon noted that soldiers who had experienced cold weather in Russia felt less pain when they had to have a limb amputated. Around the same period, medical science discovered the pain-relieving properties of ether and ethyl chloride spray.
Cryoanalgesia, also known as cryoneuroablation or cryoneurolysis, is a specialized technique used in pain management to provide long-lasting pain relief. This modern method of cryoanalgesia was introduced in 1961 with the invention of a device using liquid nitrogen to reach extreme cold temperatures. It became popular in 1976 when a study was published showing its effectiveness in reducing persistent pain. The study involved 64 patients, with 52 of them experiencing noticeable pain relief after undergoing cryoanalgesia.
Cryoanalgesia works by applying extreme cold to tissue, freezing the targeted nerve and causing injury to the peripheral sensory nerve. This injury blocks the nerve from sending signals, similar to how local anesthetics work. The cold induces a breakdown process in the nerve, inhibiting signal transmission. The breakdown is temporary as the nerve remains intact and begins to regenerate. As it grows back, the nerve reconnects with the sensory receptors and signal transmission can commence again. This regrowth process is gradual, with sensation returning over time, usually requiring additional treatments as the pain returns.
Cryoanalgesia, a technique that’s been around for a long time, is promising for treating post-operative pain and chronic pain in certain cases. It can be used to manage several types of pain, including facial pain, chest wall pain, abdominal and pelvic pain, pain in the lower back and lower body, and pain in the upper body.
Anatomy and Physiology of Cryoanalgesia
Nerves are like bundles of cables in your body, with each individual cable being known as an axon. Each axon is wrapped in a protective layer called endoneurium. These axons are grouped into bundles, or fascicles, each encased by another protective layer called the perineurium. All these fascicles are further protected by an outer layer called the epineurium. In some nerves, the axons also have an insulation called myelin sheath, which helps in transmitting signals in the nerve.
When it comes to nerve damage, there are some types of injury that are reversible and others that are not. For example, nerve injury can be classified as neuropraxia, which is a temporary block in nerve signal with a fast recovery, and axonotmesis, which involves the loss of the axon’s connection but with potential for healing because the protective layers are still intact. These two types of injury are usually reversible.
On the other hand, some types like neurotmesis and transection are not reversible. Neurotmesis involves partial loss of the protective layers, and transection involves major loss in structure. These types cannot be treated with cryoanalgesia, a method of relieving pain by freezing the nerves.
Cryoanalgesia works by applying very cold temperature to the target nerve that causes injury and blockage of nerve signals, similar to local anesthetics. Because the protective layers of the nerve remain undamaged, the nerve can regenerate and restore its functions over time. But, in some cases, this method may need to be repeated as sensation may return over time.
The amount of nerve damage caused by cryoanalgesia depends on how close the probe is to the nerve, the size of the probe, its temperature, how long it is applied, and how the surrounding tissue reacts to the temperature change. The effectiveness of pain relief depends directly on the extent of nerve damage caused by the cryoablation probe.
Moreover, some long-term effects of cryoneuroablation may involve autoimmune reactions where the body’s immune system starts to attack the tissues at the site of injury. This immune response may explain why this treatment has long lasting effects.
The approach to using cryoanalgesia depends on where in the body it’s going to be used. The target nerve needs to be accurately identified, and this can be done with the help of tools like ultrasound and nerve stimulators. It’s important to avoid damaging motor nerves or creating a lesion near the skin or large blood vessels.
Why do People Need Cryoanalgesia
Cryoanalgesia is a treatment used to handle persistent and difficult-to-treat pain, particularly when a specific nerve close to the skin surface can be identified as the source of the pain. This treatment is commonly used for certain types of nerves that are associated with particular conditions and surgical procedures. This includes nerves associated with surgeries like laparotomy, nerves linked with severe chest pains after surgeries such as mastectomy, nerves related to pain around the rectal area, and nerves associated with pain in the lower back and legs.
This method is also helpful for managing different situations like pain in the jaw joint, certain types of severe facial pain, and unexplained pain conditions. It’s even useful for treating pain resulting from surgical procedures like total knee replacements and shoulder surgeries.
Topical cryoanalgesia, where the treatment is applied directly to the skin, has also shown good results in managing pain associated with procedures like getting an IV, taking fluid from a joint, or nerve pain caused by the herpes zoster virus.
However, it’s important to remember that cryoanalgesia might not be the right answer for everyone. You should always consult a knowledgeable healthcare professional to see if cryoanalgesia is the right treatment option for your specific pain conditions. They can help determine what will work best for you, taking into account your personal health condition and the specifics of your pain.
When a Person Should Avoid Cryoanalgesia
Cryoanalgesia, a method of pain relief that uses freezing temperatures to numb an area, may not be recommended for everyone. Some reasons why this might not be a safe option include a risk of serious bleeding due to a condition called ‘bleeding diathesis’, active infections at the site where the treatment would be done, and the patient’s refusal of the treatment.
There are also situations where doctors exercise caution before recommending cryoanalgesia. For instance, when treating areas that can be seen, such as the face, there could be risks of changes to skin colour (either darker or lighter) or potential hair loss in areas close to the eyebrows. You could also experience pain after the procedure and there’s a risk that nearby organs or structures could get harmed. If you’re getting the treatment on a very superficial spot, your skin could get frostbite.
Another area of concern is when the treatment is administered around the ribs (intercostal) during a chest surgery (thoracotomy), which has been linked to moderate to severe nerve pain. This makes it a consideration to think over before deciding whether or not to proceed with the treatment.
Cryoanalgesia should also be near the bottom of the list when dealing with conditions like Raynaud syndrome (a rare disorder of the blood vessels), cryoglobulinemia (the presence of abnormal proteins in the blood), cold urticaria (a skin reaction to cold), bleeding disorders, localized infections, or if you’re on blood-thinning medications.
This method may not be suitable if you’d be incapacitated by muscle weakness, for example, if you’re undergoing the treatment for pain relief after knee surgery and weakening the thigh muscles would prevent you from walking afterward.
Just like any procedure, it comes with a handful of potential risks like changes in skin colour, hair loss around the treated spot, skin frostbite when the ice affects the skin, bruising, and bleeding. It’s crucial that doctors explain what you should expect – the numbness, potential discomfort, and the realistic results associated with the treatment. This helps in making sure you’re well equipped with the right knowledge before giving your consent.
While there’s no documented evidence of nerve tumors or long-lasting nerve damage, some clinical studies have noted a higher chance of nerve pain after surgery when intercostal cryoanalgesia was administered during chest surgery. Nonetheless, other studies didn’t find such a link. Ultimately, cryoanalgesia shows possibility, but its use should be decided upon after weighing the risks and taking into account any drawbacks to make sure that patient safety is always at the forefront.
Equipment used for Cryoanalgesia
New improvements in cold-based technology for medical uses have led to the creation of portable, hand-held tools with specialized cold probes (known as cryoprobes). This has dramatically transformed the way we can view the structure of nerves using ultrasound images. These cryoprobes are equipped with different styles of needle tips that can form various sizes of ice balls on the targeted superficial (close to the surface) nerves. The available probes vary in size from 1.4 to 2 millimeters, with in-built nerve stimulators for accurate locating of nerves and temperature sensors at the tip of the probe. The nerve stimulator allows the operator to select between sensory (100 Hz frequency) or motor (2 Hz frequency) responses.
It’s recommended to use an introducer (a tool for inserting a larger device) for better performance of the procedure. This versatile tool keeps the electrical current isolated to the probe tip, protects the skin from the formation of ice balls when treating superficial structures, and helps with local anesthetic infiltration (injecting an anesthetic). This injected anesthetic helps isolate the specific nerve to be blocked. Ways to localize the nerve include techniques like fluoroscopy (uses x-rays to produce real-time images), ultrasound, and nerve stimulators.
Usually, a large gauge intravenous catheter (thin tube placed into a vein) is used as the introducer. It has a sharp tip that can easily pierce tissues. The stylet (a rigid wire inserted into a catheter) can be removed to make inserting the probe easier. For the 2.0 mm probe, a 12-gauge catheter is used, while the 1.4 mm probe pairs with a 14- or 16-gauge catheter. These portable devices come with a compact charger, making them compatible with ultrasound tools and easy to use in many different healthcare settings, from local clinics to large hospitals and outpatient surgery centers, where different departments may share the same tool.
The combination of widely available ultrasound devices, the growing skill of anesthesia providers in using ultrasound imaging, and the approval of hand-held anesthesia machines by regulatory authorities like the Food and Drug Administration, has transformed anesthesia based on cold (cryoanalgesia) into a practical choice for managing both acute (short-term) and chronic (long-term) pain.
Who is needed to perform Cryoanalgesia?
For a procedure called cryoanalgesia (a treatment used to numb nerves and lessen pain), you’ll find several medical professionals in the treatment room. They are all there to ensure your care and safety.
The main person leading the procedure is a clinician. This is a medical expert who has the specific knowledge and abilities to safely conduct this procedure. They might choose to have an assistant helping them out.
A nurse could also be there. Their role is to keep an eye on you, making sure your body is responding as expected to the treatment.
Furthermore, if the method called ‘fluoroscopy’ is needed, a radiology technologist will be required. Fluoroscopy is a type of medical imaging that shows a continuous x-ray image on a monitor, kind of like an x-ray movie. It’s the radiology technologist’s job to operate this specific equipment.
Preparing for Cryoanalgesia
Before a medical procedure that involves the nerves, the patient’s positioning depends largely on the nerve that’s causing the issue and where it’s located in the body. Before the procedure begins, it’s important to make sure that all necessary people and equipment are ready and that there is no room temperature gas in the system. Sedatives are not usually required for these procedures, and a heavy dose should be avoided because the patient needs to be able to respond to stimuli.
The patient’s understanding and consent for the procedure is obtained to make sure they’re fully aware of what will happen. Comfortable positioning of the patient is then ensured.
Before the procedure starts, there’s a pause and a ‘time-out’ phase. This is for triple-checking the right patient, the correct side of the body, the exact site of the procedure, and any allergies the patient may have. Lastly, an ‘aseptic technique’ is observed – this means everything is done in a way that prevents infection. This might include sterilizing equipment, wearing gloves, masks and gowns and maintaining a clean environment. This careful preparation helps to ensure the procedure goes smoothly and safely.
How is Cryoanalgesia performed
The cryoanalgesic procedure is a method to relieve pain by freezing the nerves that cause it. It all begins with accurately identifying the nerve that causes the pain. This is done using techniques like fluoroscopy, ultrasound, or nerve stimulation which helps doctors to see or track the nerves in your body.
Once the target nerve is identified, a tool known as a cryoprobe is carefully positioned at the exact location. The cryoprobe is inserted into the body using a sharp, thin sheath. After the sheath is in place, it is pulled back to expose the cryoprobe.
To ensure it is in the right spot, doctors may use nerve stimulation or inject a local anesthetic as a test. In nerve stimulation, the nerve should respond at a very low voltage, and then, it is stimulated at the maximum level to ensure no other nerves are nearby.
When everything is set, the cryoprobe is then activated. The activation typically involves freezing periods that last for two or three minutes, separated by half-minute defrosting periods. However, this may vary based on the recommendations of the cryoprobe manufacturer.
It’s crucial that the frozen tissues are allowed to warm up to above freezing point before starting the next freeze cycle. Once the final freeze cycle is done, it’s crucial to wait for proper thawing for at least two minutes before the cryoprobe is taken out. This is to prevent tissue damage from the frozen tissues sticking to the probe.
While the sheath is being removed, a small amount of local anesthetic may be applied to the tissues to soothe any discomfort or pain.
Possible Complications of Cryoanalgesia
After undergoing certain medical procedures, there might be some complications you could encounter. These typically include bleeding, infection or damage to nearby parts of your body like muscles. This damage to the muscles, known as myonecrosis, can happen within or near the area where the procedure took place.
Some complications could affect your feeling of pain, either by making you feel less pain (hypoalgesia), more pain (hyperalgesia), or experiencing pain due to a normally painless stimulus (allodynia). Numbness lasting longer than three months is also a possible complication.
For certain surface-level procedures, damage could occur to the skin causing changes in the skin’s appearance. These changes could include hair loss (alopecia), skin darkening (hyperpigmentation), or lightening of the skin (hypopigmentation). This damage can be prevented by injecting a saltwater solution under the skin to lift the skin’s surface before the procedure.
For surgical procedures involving the ribs, there have been cases of nerve tumors (neuromas) and a condition where air gets trapped in the space between the lungs and chest wall, causing the lung to collapse (pneumothorax). If a collapsed lung is caused by needle placement during the procedure, the gas used to expand the cavity could make the lung collapse worse. If you experience a collapsed lung, it’s recommended to be given 100% oxygen to help remove nitrogen, especially if nitrogen was the gas used.
What Else Should I Know About Cryoanalgesia?
Often, getting rid of pain after surgery involves using regional anesthesia, a method that targets specific pain points with numbing medications, but it doesn’t always last very long. Recently, studies have shown a technique called cryoanalgesia, which uses cold temperatures to numb the nerves, may provide better and longer-lasting pain relief, with fewer unwanted effects. Multiple studies have supported cryoanalgesia as an effective way to reduce pain after surgery.
In one study involving 55 patients, it was found that cryoanalgesia was better at relieving post-surgery pain from intercostal neuralgia (pain in the nerves between the ribs) compared to regular care for a type of surgery known as posterolateral thoracotomy (a side chest incision). Another study involving 100 patients revealed similar results and even showed improved lung function after video-assisted chest surgery. Observations from a study of 50 patients who had recently undergone chest surgery showed improvements in their pain levels, lung function, gas exchange, opioid consumption, and reduced instances of feeling sick and vomiting.
However, long-term post-surgery pain might be worsened with cryoanalgesia. A study involving 42 patients who had undergone a posterolateral thoracotomy revealed increased pain scores among those who had cryoanalgesia 8 weeks after the procedure, with more patients experiencing nerve-related pain. It’s important to note that this pain resolved by 6 months, and there was no difference seen between the groups.
Cryoanalgesia has also proven effective for ongoing (chronic) pain in patients suffering from conditions such as lumbar facet pain (pain in the joints connecting the bones in the spine), intercostal neuralgia, and phantom limb pain (pain in a limb that has been amputated). In a review of 91 patients with lumbar facet pain, average reported pain levels decreased significantly after cryoanalgesia treatment. Most of these patients continued to report low levels of pain up to 1.7 years after treatment. Another study with 145 patients suffering from severe facial nerve pain results showed that nerve freezing significantly improved pain for an average of 13 to 20 months.
Cryoanalgesia allows us to manage pain without using opioids, reducing the risk of infection and complications seen with other pain treatments. It’s a promising option during the current crisis where we’re trying to reduce the use of opioids, potentially improving pain management in both the surgery period and in day-to-day clinical practice. It’s important to note, though, that there is a potential risk of nerve damage, lingering nerve pain, and unpredictable action duration with cryoanalgesia, hence should be used with caution.