Morton neuroma (interdigital neuroma), first described in 1876, is a perineural fibrosis and nerve degeneration of the common digital nerve. Morton neuroma, or Morton's neuroma, is not a true neuroma, although it results in neuropathic pain in the distribution of the interdigital nerve secondary to repetitive irritation of the nerve. The most frequent location is between the third and fourth metatarsals (third webspace). Other, less common locations are between the second and third metatarsals (second webspace) and, rarely, between the first and second (first webspace) or fourth and fifth (fourth webspace) metatarsals.
The exact cause of Morton?s neuroma is not known, but the choice of footwear seems be a factor. Wearing high heels (shoes with heels over 2 inches) can put extra pressure on the balls of the feet. Wearing tight or pointed toed shoes may squeeze the toes together or otherwise constrict their movement. For that reason, women are about 8 to 10 times more likely to develop Morton?s neuroma compared with men. People who are born with flat feet, high arches, or an abnormal position of the toes are more prone to developing Morton?s neuroma. This may be due to instability around the toe joints. Certain conditions that develop over time, such as bunions or hammer toes, are also associated with Morton?s neuroma. Some sports that involve running, including tennis and other racquet sports, can also increase the chance of developing Morton?s neuroma due to trauma or injury to the foot.
Neuroma patients occasionally complain of a ?pins and needles? sensation that spreads through their feet, or of a feeling akin to hitting their ?funny bone.? The sensation may be described as similar to an electric shock. Some patients also say that these symptoms, as well as those listed above, will come and go, depending on what they are wearing on their feet, the activity they are doing, or on other external factors.
The diagnosis of interdigital neuroma is usually made by physical examination and review of the patient's medical history.MRI ad High Definition Ultrasound examination may be useful to confirm the diagnoses however they may still not be 100% reliable. The commonest reason for this is de to natural substances present in between the metatarsal heads and between the fat pad and the intermetatarsal ligament. These natural substances i.e. bursa, fat, capsular thickening and even bony growths, can all be a factor in the impingement process and may need to be surgically cleared.
Non Surgical Treatment
In most cases, initial treatment for this condition consists of padding and taping to disperse weight away from the neuroma. If the patient has flatfeet, an arch support is incorporated into footwear. The patient is instructed to wear shoes with wide toe boxes and avoid shoes with high heels. An injection of local anesthetic to relieve pain and a corticosteroid to reduce inflammation may be administered. The patient is advised to return in a week or 2 to monitor progress. If the pain has been relieved, the neuroma is probably small and caused by the structure of the patient's foot and the type of shoes the patient wears. It can be relieved by a custom-fitted orthotic that helps maintain the foot in a better position. Another type of therapy that may be used is alcohol sclerosing injections. In this treatment, the doctor injects a small amount of alcohol in the area of the neuroma area to help harden (sclerose) the nerve and relieve the pain. Injections are given every 7-10 days and, in many cases, 4-7 injections are needed for maximum relief. Please ask your physician for more information regarding this type of treatment.
Surgery to remove the neuroma may be recommended if more conservative treatment does not solve the problem. While surgery usually relieves or completely removes the symptoms, it often leaves a permanent numb feeling at the site of the neuroma.