Cryosurgery Or Sclerosing Injections: Which Is Better For Neuromas?
Dehydrated alcohol is soluble in local anesthetic. When it is introduced near nerve tissue, it causes neuritis and chemical neurolysis via Wallerian nerve degeneration.11 While the injected solution has a high affinity for nerve tissue and the desired effect on these tissues, the low concentration reportedly does not have any systemic effect as 90 to 98 percent of ethyl alcohol is oxidized by the body.12 In a 1999 study, the author showed 89 percent improvement with complete relief in 82 of 100 patients who were treated with the sclerosing injections. According to the study, follow-up ranged from six months to two years.5 Patients received a minimum of three injections and no more than seven injections. In regard to the 11 patients who failed injection therapy, the author didn’t identify any soft tissue complications and subsequently proceeded to surgical removal of the neuroma. The author did identify atrophy of the nerve tissue in the patients who failed conservative therapy and a series of sclerosing injections.5 I used these same techniques to treat intermetatarsal and recurrent neuromas, and presented my results in April 2001.7 I treated 29 neuromas (18 primary and 11 recurrent) with sclerosing injections that were given, on average, seven days apart. Marking the site of maximum tenderness prior to injection, I performed all the injections proximal to the entrapped or damaged nerve. Patients received a minimum of three injections and not more than seven injections. I discontinued the therapy if there were complete resolution of symptoms or no relief after three injections. We scheduled follow-up visits one month after the final injection and six months after the final injection in order to determine the success of therapy. (Some patients returned for other podiatric-related complaints up to three years after sclerosing therapy.) We defined success on patients’ subjective assessment that they had obtained greater than 90 percent relief. In the primary treatment group, 78 percent of neuromas (14 of 18) were treated successfully with sclerosing therapy. In the recurrent neuroma group, 82 percent of neuromas (nine of 11) were treated successfully.7 There was one side effect, which was local irritation of the plantar foot distal to the injection site but it resolved after one day. Patients who did not have successful therapy had the option of surgical intervention and we saw no injection-related complications intraoperatively or postoperatively. Clinical Exam Keys To Identifying Intermetatarsal Neuromas Before embarking on any treatment plan, one must correctly diagnose intermetatarsal neuromas as forefoot pain can be caused by a variety of conditions. When patients have an intermetatarsal neuroma, the typical presenting complaint includes pain or tingling in the ball of the foot with ambulation and occasional radiation to the digits. These symptoms are most common in the third interspace, followed by the second interspace, and infrequently in the first or fourth interspace. Patients tend to relate an increase in symptoms when they wear dress shoes, especially high heels. They will often have relief of these symptoms when they cease wearing the dress shoes or when they wear more supportive shoes. Patients may describe the pain as burning, tingling, shooting or they may say it feels like a bruised region in the forefoot. Also be aware that similar symptoms may return after the removal of a previously treated neuroma or following trauma to a nerve. While the key finding from the clinical exam is pain in the interspace at the level of the deep transverse intermetatarsal ligament, be aware that you will sometimes see edema in this region. Also keep in mind that these patients will usually have no pain directly plantar to the metatarsal heads. In order to reproduce the patient’s symptoms, one should dorsiflex the digits and palpate the deep intermetatarsal ligament. Dorsal-plantar palpation of the interspace with compression of the medial and lateral aspects of the foot often allows palpation of an inflamed nerve.