What Causes Mortons Neuroma

Overview

Morton?s Neuroma is a pathological condition of the common digital nerve in the foot, most frequently between the third and fourth metatarsals (third inter-metatarsal space). The nerve sheath becomes abnormally thickened with fibrous (scar) tissue and the nerve fibres eventually deteriorate.This condition is named for the American surgeon, Thomas George Morton (1835-1903), who first recognised the condition in 1876. Incidentally his father was the dentist who discovered the anaesthetics; initially Nitrous oxide, the very gas used today in cryosurgery for the condition his son lent his name to? Morton?s neuroma.

Causes

The exact cause is unknown. Doctors believe the following may play a role in the development of this condition. Wearing tight shoes and high heels. Abnormal positioning of toes. Flat feet. Forefoot problems, including bunions and hammer toes. High foot arches. Morton neuroma is more common in women than in men.

Symptoms

A Morton's neuroma causes a "burning" sharp pain and numbness on the bottom of the foot in the involved area, and this pain and numbness can radiate to the nearby toes. The pain is usually increased by walking or when the ball of the foot is squeezed together and decreased with massaging. It may force a person to stop walking or to limp from the pain.

Diagnosis

The physician will make the diagnosis of Morton's neuroma based upon the patient's symptoms as described above in an interview, or history, and a physical examination. The physical examination will reveal exceptional tenderness in the involved interspace when the nerve area is pressed on the bottom of the foot. As the interspace is palpated, and pressure is applied from the top to the bottom of the foot, a click can sometimes be felt which reproduces the patient's pain. This is known as a Mulder's sign. Because of inconsistent results, imaging studies such as MRI or ultrasound scanning are not useful diagnostic tools for Morton's neuroma. Thus the physician must rely exclusively on the patient's history and physical examination in order to make a diagnosis.

Non Surgical Treatment

Treatment strategies for Morton's neuroma range from conservative to surgical management. The conservative approach to treating Morton's neuroma may benefit from the involvement of a physical therapist. The physical therapist can assist the physician in decisions regarding the modification of footwear, which is the first treatment step. Recommend soft-soled shoes with a wide toe box and low heel (eg, an athletic shoe). High-heeled, narrow, nonpadded shoes should not be worn, because they aggravate the condition. The next step in conservative management is to alter alignment of the metatarsal heads. One recommended action is to elevate the metatarsal head medial and adjacent to the neuroma, thereby preventing compression and irritation of the digital nerve. A plantar pad is used most often for elevation. Have the patient insert a felt or gel pad into the shoe to achieve the desired elevation of the above metatarsal head. Other possible physical therapy treatment ideas for patients with Morton's neuroma include cryotherapy, ultrasonography, deep tissue massage, and stretching exercises. Ice is beneficial to decrease the associated inflammation. Phonophoresis also can be used, rather than just ultrasonography, to further decrease pain and inflammation.

Surgical Treatment

If these non-surgical measures do not work, surgery is sometimes needed. Surgery normally involves a small incision (cut) being made on either the top, or the sole, of the foot between the affected toes. Usually, the surgeon will then either create more space around the affected nerve (known as nerve decompression) or will cut out (resect) the affected nerve. If the nerve is resected, there will be some permanent numbness of the skin between the affected toes. This does not usually cause any problems. You will usually have to wear a special shoe for a short time after surgery until the wound has healed and normal footwear can be used again. Surgery is usually successful. However, as with any surgical operation, there is a risk of complications. For example, after this operation a small number of people can develop a wound infection. Another complication may be long-term thickening of the skin (callus formation) on the sole of the foot (known as plantar keratosis). This may require treatment by a specialist in care of the feet (chiropody).