A Closer Look At Cryosurgery For Neuromas

Can cryosurgery be an effective alternative treatment for neuromas? This author offers keys to diagnosis, shares pertinent pearls on cryosurgical techniques and emphasizes the benefits of ultrasound injection guidance.

Cryosurgery or cryoanalgesia is an accepted, well-known treatment within the pain management community. However, its acceptance within the field of podiatry has been slow. With the improvements of nerve visualization using ultrasound, clinicians are using cryosurgery more frequently. Within many specialties, surgeons are performing procedures for pain relief and even for destruction of various types of tumors and abnormal tissues.1

   Many medical specialties have embraced cryosurgery for various pain syndromes including post-thoracotomy pain, intercostal neuralgia, inguinal pain, facial pain and facet syndrome. According to Trescot, cryosurgical neuroablation uses are far reaching. He notes that clinical applications range from postherpetic neuralgia in thoracic distribution and craniofacial pain secondary to trigeminal neuralgia to sacroiliac joint pain and persistent pain after rib fractures.2

   If other specialties so widely use cryosurgery for so many indications, why is there a reluctance to use this technology in the podiatry community?

   Traditionally, physicians performed earlier applications of cryosurgery without the use of fluoroscopy and ultrasound. However, the success rates were lower due to this lack of visualization. In many cases, surgeons had to perform the procedures with direct visualization of structures that required more invasive techniques. Originally, the cryosurgery units were developed with nerve stimulators, which increased the nerve localization percentage and improved the outcome of the procedure. However, in my experience, patients were having too much pain during the procedure for me to adequately assess whether I was truly on the nerve tissue.

   Now the trend in medicine is rapidly moving to minimally invasive procedures using various types of guidance. It is my belief that most medical procedures will happen this way in the near future. Currently, many specialties use ultrasound guidance as a standard part of their procedures.3

Is Cryosurgery Still An Option For Neuromas?

According to Trescot, cryoanalgesia is a viable option for small, well-localized nerve lesions such as a neuroma. Long-lasting analgesia may happen with cryosurgery.2

   Having performed cryosurgery for about seven years, I strongly believe that cryosurgery remains an excellent treatment option for foot neuromas and other nerve conditions throughout the foot and ankle. The popularity of foot cryosurgery has waned due to the fact that there is currently no podiatry-specific cryosurgery device. However, there will likely be some excellent devices available in the near future that are currently in development.

   One factor that hinders the current advancement of cryosurgery is the lack of proper training available to allow physicians to perfect the cryosurgery technique. In the past, many physicians mistakenly believed that since they knew the anatomy of the foot, they did not require any training in cryosurgery. After all, if they could do a neuroma injection and a traditional nerve removal surgery, how could they not be proficient at cryosurgery?

   The truth is that there is a significant learning curve to performing cryosurgery. Many podiatrists are proficient at ankle injections and ankle surgery. They know the anatomy well but would they just pick up a scope and do an ankle arthroscopy without training? I hope not.

   There are techniques and methods that surgeons must follow for optimal results. In the future, continued development of standards and techniques for cryosurgery is essential. More studies would also help to better validate the effectiveness of this technique.

   However, using double-blind studies comparing cryosurgery to traditional excision would not be reasonable. The problem with a comparison is that patients are rarely willing to undergo surgeries for experimental purposes, especially not knowing which procedure they will receive. Also, there is hardly an incision with cryosurgery. So if we did not want the patient to know which procedure we did, we would likely need to make a regular incision in both cases, which is not reasonable. Personally, I rarely do a neuroma excision.

   It is in the practitioner’s best interest to provide patients with alternatives. Traditional nerve excision can cause significant postoperative disability and poorer outcomes than desired. I believe that complications, stump neuroma and poor outcomes are more frequent than previously believed, and are often not reported. A retrospective study looking at interdigital neuroma excision noted greater stump neuroma formation and complications.4 With new devices and better techniques, I believe there can be a resurgence of cryosurgery in the future. There is a need in our profession for other alternatives to traditional nerve removal and since we are the foot experts, we need to start owning alternative procedures such as cryosurgery.

What You Should Know About Ultrasound Guidance

Ultrasound guidance is especially appropriate for guidance of the cryosurgery probe to allow adequate placement onto the affected nerve. For those practitioners who fear they may be freezing other structures and not the nerve, ultrasound is the solution to avoid this problem. I have found the stimulator useful for some nerve ablation areas such as the sural nerve. However, I have found it is not accurate for interspace neuromas because it is difficult to assess patients’ response while they are having pain. The foot is especially sensitive in this area.

   For many years, I have used ultrasound guidance instead of the nerve stimulator for excellent results. The trend in other specialties for nerve cryoablation is ultrasound guidance as well.3 In my experience, I feel this is the only way one should perform cryosurgery. I often hear from other podiatrists who explain that they have no need for ultrasound because of their keen knowledge of foot anatomy. In my experience, the savviest medical specialists use guidance devices regularly instead of leaving their outcome to chance. Localization of the nerve is quicker, more accurate and safer, resulting in quicker onset of anesthesia.

   One example is the use of ultrasound guidance for popliteal nerve blocks.5 The anatomy is known yet clinicians are using ultrasound guidance for accuracy. In addition, I would argue that there are more than a few incidences of a neuroma being removed with direct visualization only to find from a pathology report that it was not nerve tissue but a blood vessel, fat or tendon. If there can be difficulty in some cases locating the nerve with direct visualization, I would argue that ultrasound is a must for closed procedures. The more we can use technology to our advantage, the better the outcomes.

   The future of most medical procedures will be minimally invasive with some type of guidance. Therefore, I believe podiatry needs to continue to develop its own techniques to move into the future. Instead, the profession may be concentrating too heavily on teaching new podiatrists reconstructive surgical procedures while leaving other options behind. The well-rounded practitioner will have many techniques, both invasive and minimally invasive, to offer his or her patients.

Pertinent Insights On The Mechanism Of Action

The cryoprobe is designed to use compressed gas such as CO2 or nitrous oxide. The compressed gas enters the probe and is released through a small opening at the closed distal chamber portion of the probe. When the gas expands in the small chamber at the probe tip, the temperature drops to about -70ºC, leading to a frozen ball of ice that surrounds the involved nerve. This phenomenon is known as the Joule-Thomson effect. The freezing of the area leads to destruction of the endoneurial capillaries, which is followed by Wallerian degeneration and axon destruction. The intensity and duration of analgesia depends on the degree of nerve damage from the ice ball.6 Accordingly, accurate placement of the ice ball is essential to obtaining a long-lasting cryolesion, leading to nerve death and prolonged analgesia.

   Since the perineurium and epineurium are preserved during the freeze, stump neuroma formation is unlikely when the nerve regeneration occurs. This is one of the major advantages of cryosurgery in comparison to traditional nerve excision and alcohol injections. The typical freeze time varies between two and three minutes with one to two defrost cycles occurring between treatments. The time varies depending on the probe and ice ball size. A delicate balance is necessary to allow for adequate freezing without damaging surrounding structures or causing an abscess.

   It is my belief that there is no larger vessel damage because of the heat sink of the blood flowing through the artery and vein. In addition, the shorter freeze times allow for nerve injury to occur rapidly before the temperature damages other tissues.

   I have seen no major vessel damage in my experience with cryosurgery. I would caution, however, that more is not better when it comes to the duration of the freeze. More freeze time will lead to complications including abscess. I would also use caution when applying cryosurgical techniques to mixed motor and sensory nerves. I do not recommend cryosurgery on motor nerves as destruction will lead to loss of function in some cases.

Essential Diagnostic Insights

A diagnosis of neuroma or nerve damage within a specific anatomic area is essential prior to performing cryosurgery. I have found ultrasound to be the best tool in identifying the neuroma in addition to clinical exams and taking a thorough history. The longitudinal view provides the practitioner with an excellent view of the neuroma. I also use this view to ensure accurate placement of the probe on the nerve for ablation.

   To confirm the diagnosis, I will do an ultrasound-guided injection of the nerve with approximately 1 cc of bupivacaine directly surrounding the area just proximal to the neuroma. This will provide significant relief and confirmation that the nerve is truly the pain source. Flooding the area with larger amounts of anesthetic will not provide an adequate confirmation.

   I have found magnetic resonance imaging (MRI) to be unpredictable. This is likely due to foot placement by the technician and a lack of familiarity with neuroma by some radiologists. With that being the case, I also do not rely on the MRI results to diagnose neuromas. I often see patients who have had treatment based on MRI and, in my opinion, have capsulitis, plantarflexed metatarsals and fat pad atrophy as opposed to a neuroma.

   Other considerations when evaluating a patient would be the abnormal foot structure and motion that likely lead to abnormal stress and neuroma. One should evaluate all patients for orthoses. This is critical considering that the nerve typically does regrow and if it is subjected to abnormal forces, the nerve will likely become damaged, resulting in a recurrent neuroma.

Making The Case For Cryosurgery In Podiatry

One can easily perform this minimally invasive procedure in the office with more rapid recovery postoperatively. I have found that patients have increasing demands on their time because of work and family, and they often request treatment options that require less time off and less recovery. The idea of traditional surgery and the time needed for post-op healing are often undesirable. They also want to return to activities much faster.

   One can repeat the cryosurgery procedure if there is recurrence. If the procedure does not provide relief, the patient may still undergo traditional nerve excision or any other types of treatments that may be available.

   Cryosurgery is a more cost-effective procedure than taking the patient to an outpatient surgical facility. With future changes in our healthcare system, insurance companies will likely be looking for more cost-effective procedures and relying on physicians to complete treatment courses in shorter time periods.

   I do recommend that patients wear a controlled ankle motion walker postoperatively to help ensure adequate offloading and prevent edema. After all, this is still a surgical procedure and requires adequate time for tissue healing. In my personal experience, allowing early ambulation in a regular shoe leads to too much activity and slower healing. Congestion of the area with edema may slow the ability of the macrophages to access the area for more rapid destruction of the nerve.

In Summary

Cryosurgery for neuromas is an excellent, minimally invasive procedure that should develop further to give practitioners alternatives to traditional surgery. In addition, since podiatrists are the most highly trained physicians of the foot, it only makes sense that our specialty should champion and refine this procedure. Offering improved targeted treatment accuracy and reduced post-op recovery, guided minimally invasive procedures appear to be more in vogue, and cryosurgery fits the bill perfectly.

   Cryosurgery is in use throughout various medical specialties, continues to be promising and is often the treatment of choice in the hands of many physicians. I would encourage podiatrists to learn more about this valuable treatment and consider adopting the procedure as part of a comprehensive treatment protocol.

   Dr. Katz is in private practice in Tampa, Fla. He is a Fellow of the American Professional Wound Care Association.

References
1. Adam R, Akpinar E, Johann M, et al. Place of cryosurgery in the treatment of malignant liver tumors. Ann Surg. 1997; 225(1):39–50.
2. Trescot AM. Cryoanalgesia in interventional pain management. Pain Physician. 2003; 6(3):345–360
3. Rhame E, DeBonet A, Simopoulos T. Ultrasonographic guidance and characterization of cryoanalgesic lesions in treating a case of refractory sural neuroma. Case Rep Anesthesiol. 2011; 2011: 691478.
4. Stamatis E, Myerson M. Treatment of recurrence of symptoms after excision of an interdigital neuroma. J Bone Joint Surg (Br). 2004; 86-B(1):48-53.
5. Sala-Blanch, X, et al. Ultrasound-guided popliteal sciatic block with a single injection at the sciatic division results in faster block onset than the classical nerve stimulator technique. Anesth Analg. 2012; 114(5):1121-1127.
6. Myers RR, Heckman HM, Powell HC. Axonal viability and the persistence of thermal hyperalgesia after partial freeze lesions of nerve. J Neurol Sci. 1996; 139(1):28-38.

   For further reading, see “Case Studies In Cryosurgery For Heel Pain” in the November 2007 issue of Podiatry Today or “Cryosurgery Or Sclerosing Injections: Which Is Better For Neuromas?” in the June 2004 issue.