If you sometimes feel that you are "walking on a marble," and you have persistent pain in the ball of your foot, you may have a condition called Morton's neuroma. A neuroma is a benign tumor of a nerve. Morton's neuroma is not actually a tumor, but a thickening of the tissue that surrounds the digital nerve leading to the toes. Morton's neuroma occurs as the nerve passes under the ligament connecting the toe bones (metatarsals) in the forefoot. Morton's neuroma most frequently develops between the third and fourth toes, usually in response to irritation, trauma or excessive pressure. The incidence of Morton's neuroma is 8 to 10 times greater in women than in men.
There are many reasons to develop a neuroma. Improper shoe gear is probably the most likely cause. Repetitive activity and excessive pressure on the ball of the foot are common. Heredity and genetic factors may also be involved. In many cases the structure of the foot may predispose the condition. Associated conditions that may cause neuroma include: bunion, hammer toes, ligament laxity, and/or a tight calf muscle. Some patients may have thinning of the fat pad on the ball of the foot, which may result in increased pressure of the nerves. Tight pointy shoes (and high heels) without padding may induce pain in the ball of the foot. Neuroma may occur suddenly, or develop over time.
Patients will feel pain that worsens with walking, particularly when walking in shoes with thin soles or high heels. Also, anything that squeezes the metatarsal heads together may aggravate symptoms, such as narrow shoes. A patient may feel the need to remove the shoe and rub the foot to soothe the pain.
The clinical symptoms should quickly lead your doctor to suspect a neuroma. When examined, the doctor may feel a "click" which is known as Mulder's sign. There may be tenderness in the interspace. The metatarsal bones will also be examined both clinically (and often with an xray). Tenderness at one of the metatarsal bones can suggest an overstress reaction (pre-stress fracture or stress fracture) in the bone. An ultrasound scan can confirm the diagnosis and is a less expensive and at this time, at least as sensitive a test as an MRI. An x-ray does not show neuromas, but can be useful to "rule out" other causes of the pain.
Non Surgical Treatment
Orthotics and corticosteroid injections are widely used conservative treatments for Morton?s neuroma. In addition to traditional orthotic arch supports, a small foam or fabric pad may be positioned under the space between the two affected metatarsals, immediately behind the bone ends. This pad helps to splay the metatarsal bones and create more space for the nerve so as to relieve pressure and irritation. It may however also elicit mild uncomfortable sensations of its own, such as the feeling of having an awkward object under one's foot. Corticosteroid injections can relieve inflammation in some patients and help to end the symptoms. For some patients, however, the inflammation and pain recur after some weeks or months, and corticosteroids can only be used a limited number of times because they cause progressive degeneration of ligamentous and tendinous tissues.
Interdigital neurectomy (removal of the diseased nerve) in right hands, should give satisfactory results almost all the time. Some of the reasons behind failure is when not enough nerve is dissected, mistakes in initial diagnosis, or bad handling of adjacent nerves, tendons and joint capsules during the operation. It is very common and acceptable to have some numbness in the area where the nerve used to be. This never causes any discomfort and often gets better in few years. It is crucial to address the biomechanical pathologies underlying the impingement of the nerve during and after the surgery.