In the care of acute pain management, such as for perioperative burn and trauma patients, ultrasound-guided percutaneous cryoneurolysis offers an exciting treatment option that prolongs analgesia beyond mere hours or days. By applying extreme cold to targeted nerve tissue, this thermal neurolytic technique disrupts the conduction of pain signals from the periphery to the central nervous system, significantly diminishing or even disrupting pain for extended periods of time.

With the introduction of handheld devices specifically designed to deliver cryoneurolysis and recent advancements in ultrasound technology, anesthesiologists have pioneered the application of cryoneurolysis for acute pain management. The treatment involves the use of low temperatures to reversibly ablate peripheral nerves, disrupting nerve conduction and offering prolonged pain relief. Analgesic intensity and duration can be controlled by the degree of nerve damage from freezing based on the probe proximity to the nerve, probe size, rate and duration of freezing, ice ball size, and temperature of the surrounding tissue.

“Anesthesiologists have been applying cryoneurolysis in the chronic pain world for many years, but through regional anesthesiology – a specialty fellowship in our field – cryoneurolysis has now made its way into acute pain management,” said Nadia Hernández, MD, Associate Professor of Anesthesiology, Service Chief, Regional Anesthesia & Acute Pain Medicine, and Director of Perioperative Point-of-Care Ultrasonography at UTHealth-McGovern Medical School. “With this new method, we can cause a nerve to undergo Wallerian degeneration while maintaining its structure so that it can return to normal function. Patients can see up to three months of pain relief for small nerves.”

Dr. Hernández shared that this treatment could prove to be a significant breakthrough in an area of pain management that has been left undefined by traditional care – subacute or transitional pain lasting longer than four days, but shorter than three months.

Aside from reduced pain, one of the biggest benefits of cryoneurolysis for acute pain management is increased ambulation compared to traditional treatment methods, Dr. Hernández said. For burn patients, postoperative pain experienced at the donor site of a split-thickness skin graft causes significant discomfort that sometimes lasts up to 21 days after surgery. Beyond somatic pain from the surgical site, the donor site discomfort is often neuropathic, intensified by tactile stimuli such as rubbing clothing and limb movement.

“For burn patients, our anesthesiologists and surgeons love cryoneurolysis because it allows patients to ambulate more freely and takes away the severe pain that prevents normal functioning like walking, sleeping, and sitting in comfortable positions,” Dr. Hernández said. The same benefit has been seen in patients who suffer traumatic injuries such as rib, sternum, or lower-extremity fractures, she said. “Many of these patients use walkers to assist in ambulation, which is extremely painful without analgesia. By using cryoneurolysis, we have been able to provide prolonged analgesia, which has improved the ability to ambulate without assistance.”

Cryoneurolysis also has the benefit of offsetting opioid use. Adequate analgesia is a necessary priority to minimize pulmonary sequelae and support physical therapy, and while regional anesthesia techniques provide effective treatment of acute pain, they are often limited to a short period of treatment. As a result, patients are oftentimes dependent on opioids to treat persistent pain from traumatic injuries.

“Cryoneurolysis is an important tool for opioid sparing, but it may not be completely eliminating on some occasions, such as in special populations like burn and polytrauma patients,” Dr. Hernández said. “What it offers is an opportunity for patients to take significantly lower doses of opioids and subsequently eliminate sedation, constipation, vomiting, and itching. Instead of being dependent on opioids, patients can use just enough to help them get by.”

Traditionally, burn patients are treated with specialized dressings and regional anesthesia to manage postoperative donor site pain after split thickness graft, but often to limited effectiveness. Though the graft can be harvested from multiple donor locations, surgeons often favor the lateral thigh due to its even surface, thickness, expansiveness, convenient accessibility, elasticity and adaptability, minimized discomfort, and lower morbidity. The lateral femoral cutaneous nerve innervates the entire lateral thigh, offering a prime target for analgesia with cryoneurolysis that has shown enhanced pain management, reduced opioid consumption, and fewer sleep disruptions.

The first patient Dr. Hernández treated with cryoneurolysis fit these exact parameters. The burn patient presented in the ED with severe graft donor site pain. He had a history of opioid drug abuse, and though his pain was controlled when he was discharged, it returned afterward and he didn’t want to fill his prescription for fear of relapsing. Surgeons didn’t take the grafts from a specific pattern, but from the side and top of the leg. The patient agreed to cryoneurolysis, and Dr. Hernández applied it high on the leg. With just two ice balls, his pain decreased from a 10 to a zero, eliminating the need for opioids.

As with all emerging treatments, cryoneurolysis carries the risk of complication, though Dr. Hernández said that the standard risk of bleeding isn’t any higher than a single shot or catheter, and the risk of infection is lower than with a catheter as there is no foreign body introduced. One downside of cryoneurolysis is that it is not favorable to administer on nerves with mixed motor and sensory function because it is a prolonged block with no control over its duration.

Additional considerations include relative contraindications of certain patient conditions, including cryoglobulinemia, cold urticaria, paroxysmal cold hemoglobinuria, and Raynaud syndrome. Importantly, cryoneurolysis also increases the odds of neuroma formation and pain from the nerve injury caused by the treatment itself.. “As anesthesiologists, we don’t want to cause chronic pain – that goes against everything we stand for – so this possibility should be considered before starting treatment, even though it has never been reported with percutaneous cryoneurolysis,” Dr. Hernández said.

As cryoneurolysis becomes more widely adopted by fellowship-trained regional anesthesiologists, Dr. Hernández noted that true efficacy will need to be closely examined using multiple parameters. “When treating patients with complex pain, chronic opioid use, or multiple sources of pain, it may be difficult to prove that cryoneurolysis is better than other treatment methods by just looking at pain scores,” she said. “We will need to use specific, area-based pain scores for patients with polytrauma, compare ventilation and oxygenation for patients with chest treatment, and look at time of ambulation, ability to sleep, and involvement of physical therapy for patients treated in the lower extremities.”

With those considerations in mind, Dr. Hernández said that as a clinician, once you see the benefits of cryoneurolysis, it’s difficult to withhold the treatment from patients. “For anesthesiologists who specialize in regional anesthesia and pain management and have the appropriate skillset, cryoneurolysis is a nice option to have in your armamentarium of tools. It is a technique for targeting prolonged pain after surgery that makes me excited about the future of acute pain management.”