Treating Morton's Neuroma - An Often Misunderstood Foot Pain

According to the American Podiatric Medical Association, people in the United States log approximately 75,000 miles on their feet by age 50 years,1 making foot pain a common complaint heard in healthcare clinics across the nation.

“Abnormalities in gait, ill-fitting shoes, repetitive motion, and trauma can all result in foot pain,” said Andrew Rader, DPM, founder of Indiana Foot & Ankle in Newburgh. “One common cause is neuralgia in the intermetatarsal region of the forefoot, known as Morton's neuroma.”

Morton's neuroma is the formation of a mass of nerve fibers and cells, the cause of which can be multifactorial, including trauma, malformation, infection, or an overgrowth of vasculature/axons, Rader explained. When found in the intermetatarsal spaces, the neuroma is actually a compression neuropathy of the common digital nerve.

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“Women are up to 10 times more likely to be affected, and average age of onset is about 50 years,” Dr. Rader said.

Patients commonly described the pain as cramping, stabbing, burning, aching, gnawing, radiating, and/or throbbing and may describe the sensation as having a “rolled-up sock” feeling. It is often exacerbated by tight-fitting shoe gear and physical activity.

Clinical examination is often adequate for diagnosing the pathology. Physical findings on examination may include splaying of the toes, impaired sensation on adjacent aspects of the plantar digits, and a positive Mulder's sign. Dr. Rader emphasized that magnetic resonance imaging and diagnostic ultrasound can be used for cases in which the diagnosis is ambiguous. Imaging modalities can also be used for cases in which multiple lesions or multiple web space involvement is suspected.

Treatment options

Once a diagnosis of Morton's neuroma is made, treatment options are wide ranging but largely anecdotal, according to Dr. Radar.

Conservative treatment with accommodative shoe-gear changes improved symptoms in as many as 41% of patients in a 1995 study by Bennett and coworkers.2 A study by Saygi and colleagues in 2005 reported improvement in symptoms in 63% of individuals using footwear modification with orthoses alone.3  However, prescription padding and orthoses to control pronatory and supinatory motion forces are typically ineffectual for pain relief.

Steroid injections and local anesthetics may provide temporary, but not long-term, symptom relief. Evidence does not support the use of alcohol sclerosing injections for long-term relief.4

Surgical interventions

Although surgical nerve excision may provide pain relief for Morton's neuroma, long-term subsequent paresthesiae and shoe limitations are common. In a 2008 study by Womack et that involved 120 patients, 50% had good or excellent outcomes, 10% had fair outcomes, and 40% reported poor outcomes.5

As an alternative treatment, nerve decompression via endoscopy offers a minimally invasive option to address the pathology, while preserving nerve function.  In a 2010 study by Barrett et al, 95% of procedures performed in the third intermetatarsal space and 85% of those performed in the second intermetatarsal space had good-to-excellent outcomes for a 92% success rate.6

Data from 1979 study by Gauthier and colleagues that described decompressions performed on 304 neuromas indicated that 83% of outcomes were good, 14% fair, and 3% poor.7

Regardless of the intervention employed, the goal of treatment for Morton's neuroma is consistent:  resolution of pain associated with this common and potentially debilitating condition.

Disclosures: Andrew Rader, DPM, received honoraria from and is a member of the speaker's bureau for Organogenesis, D.N.E. SEAL External Fixation, and CE Lasers. He also received consulting fees from D.N.E SEAL External Fixation and is a stock shareholder in Fuse Medical.

References

1. American Podiatric Medical Association.  Foot health. Available at: http://www.apma.org/learn/FootHealthList.cfm?navItemNumber=498. Accessed August 17, 2015.

2. Bennett GL, Graham CE, Mauldin DM. Morton's interdigital neuroma: a comprehensive treatment protocol. Foot Ankle Int. 1995;16:760-763.

3. Saygi B, Yildirim Y, Saygi EK, Kara H, Esemenli T. Morton neuroma: comparative results of two conservative methods. Foot Ankle Int. 2005;26(7):556-559.

4. Gurdezi S, White T, Ramesh P. Alcohol injection for Morton's neuroma: a five-year follow-up.  Foot Ankle Int. 2013;34(8):1064-1067.

5. Womack JW, Richardson DR, Murphy GA, Richardson EG, Ishikawa SN. Long-term evaluation of interdigital neuroma treated by surgical excision.  Foot Ankle Int. 2008;29:574-577.

6. Barrett SL, Rabat E, Buitrago M, Rascon VP, Applegate D. Endoscopic decompression of intermetatarsal nerve (EDIN) for the treatment of Morton's entrapment—multicenter retrospective review. Open J Orthop. 2012;2:19-24.

7. Gauthier G. Thomas Morton's disease: a nerve entrapment syndrome.  A new surgical technique. Clin Orthop Relat Res. 1979;142:90-92.

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