Q: I think I have a Morton's neuroma causing my foot pain. Why would I get this and what can I do about it?
A: Morton's neuroma is an enlarged, thickened nerve in the foot just below the space between the third and fourth toes. Normally the nerve passing through this area is thin. However, this space is tight. If the nerve enlarges, any external pressure, like walking or tight shoes, will push the nerve against the surrounding bone and tissue, causing significant discomfort.
Exactly why a person develops an enlarged nerve forming the neuroma is not clear. Morton's neuroma is about 10 times more common in women than in men. In many cases, narrow, pointed shoes and high heels cause the problem by producing inflammation and putting pressure on the ball of the foot. Less often, Morton's neuroma develops because of physical activities that cause traumatic stress to the foot, such as running or racquet sports.
Morton's neuroma often starts off as an ache in the ball of the foot and progresses to burning pain with pins and needles and numbness in the third and fourth toes. You may feel as if a pebble is stuck inside the ball of the foot.
Doctors can usually diagnose a Morton's neuroma based on the location and description of pain and examination of the involved foot. During the foot exam, doctors typically squeeze the foot from the sides with one hand while pressing the thumb of the other hand on the ball of the foot. The test is positive if it reproduces your pain and causes a clicking sound or sensation, called Mulder's sign.
If the physical examination is inconclusive, further testing may be needed, usually an ultrasound. Your doctor may also order a foot X-ray to be sure the symptoms are not due to a stress fracture.
Treatment starts with changing shoes. Soft wide shoes with no heel or a very low heel decrease pressure on the neuroma. A foot care specialist may recommend an adhesive neuroma pad to fit under your forefoot, or custom-made orthotics to correct any structural problems in your foot that might contribute to compression of the nerves.
You can often relieve pain with over-the-counter nonsteroidal anti-inflammatory agents, such as ibuprofen or naproxen. It may also help to massage the affected area with ice. If the symptoms still persist, some doctors will inject a mixture of a corticosteroid and local anesthetic into the area.
About eighty percent of people improve, although it may be slow. Surgery to cut away part of the nerve tissue is a last resort.
(Howard LeWine, M.D., is an internist at Brigham and Women's Hospital in Boston and assistant professor at Harvard Medical School. For additional consumer health information, please visit www.health.harvard.edu.)