Cryosurgery Or Sclerosing Injections: Which Is Better For Neuromas?
Comparing Alcohol Injections To Cryosurgery
I have used 4% alcohol injections for many years but with mixed results. Some patients do respond favorably to this treatment but many continue to have neuroma pain.
In my experience, many patients have severe pain associated with the alcohol injections and approximately 50 percent of patients do not complete the series of injections because of pain associated with these injections. We recently had two patients who were treated in the emergency room later in the day because of burning pain at the injection site.
I am also concerned about the effect of the alcohol on the peripheral nerves. Presumably the alcohol destroys the axon and its myelin sheath but it cannot be tissue specific and must also destroy the endoneurium, perineurium and epineurium. If the destruction of the nerve is complete, there will be a neurotomesis that will invariably form a stump neuroma as the axons regenerate. In this sense, the nerve destruction may carry the same risks as neuroma excision. It’s also important to keep in mind that the long-term results of alcohol injections have not been reported.
With cryosurgery, the destruction of the axons is almost completely painless. I used to perform the procedure using only 1/2 cc of local anesthetic for the skin where I made the incision. I did not use any anesthetic to block the nerve. When I applied the ice ball to the neuroma, the patients experienced only a mild burning sensation that resolved after one to two minutes. There was only minimal postoperative discomfort that was controlled with NSAIDs.
More significantly, cryogenic neuroablation does not destroy the epineurium or perineurium, the basic architecture of the nerve. As a result, stump neuromas do not form as the nerve regenerates. Having performed this procedure for approximately 200 patients over the last three years, I have found that very few patients have had a recurrence of their neuroma pain. If the pain returns a year or two later, I simply repeat the procedure.
Axons regenerate at the rate of 1 to 3 mm per day. The prevailing thinking is that the ice ball destroys a 1-cm portion of the nerve. Therefore, the axon regeneration should be complete within several weeks. It appears the long lasting relief is due to the reduction of neural edema and fibrosis of the neuroma. Researchers have also reported similar long-term relief using cryosurgery to treat painful trigeminal nerve pathology.5,6
Pertinent Pointers On The Cryosurgery Technique
In regard to the specific technique, I first palpate the area of the greatest neuroma pain on the plantar surface of the foot and mark it with a surgical pen. Then I inject the local anesthetic, injecting 3 cc of 1% plain lidocaine into the intermetatarsal space and injecting an additional 1 cc of lidocaine with epinephrine just below the skin dorsally for homeostasis.
One should prep the surgical site with betadine and make a 3-mm incision dorsally with a number 65 beaver blade. Use a trocar or angiocatheter to separate the tissue as you advance to the area of pain that you have marked. You will see the deep transverse metatarsal ligament, which you may section if you prefer.
Proceed to insert the 2-mm cryoneedle into the area of the neuroma and administer a three-minute freeze cycle. This is followed by a 30-second defrost and another three-minute freeze cycle. Irrigate the wound with 2 cc of 0.5% plain Marcaine and 0.25 cc of steroid.
How Should You Handle Postoperative Care?
No sutures are required but you should apply a mildly compressive dressing. Give the patient a NSAID to reduce postoperative discomfort.
If the patient has only undergone the percutaneous cryosurgery procedure performed, have him or her reduce activity for the next two to three days and apply ice to the surgical site when resting. These patients can remove the dressing the next morning, shower and use a Band-Aid with a topical antibiotic. The incision usually heals in about three days.
The destruction of the axons is immediate with cryosurgery so the patients should only feel mild discomfort, which usually resolves in about one week. The patients are usually able to wear normal shoes and be reasonably active during this period.
However, if the deep transverse ligament has been released, the surgical site is more uncomfortable and may take two to three weeks to heal.