Overview
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.
Causes
Anything that causes compression or irritation of the nerve can lead to the development of a neuroma. One of the most common offenders is wearing shoes that have a tapered toe box, or high-heeled shoes that cause the toes to be forced into the toe box. People with certain foot deformities – bunions, hammertoes, flatfeet, or more flexible feet – are at higher risk for developing a neuroma. Other potential causes are activities that involve repetitive irritation to the ball of the foot, such as running or court sports. An injury or other type of trauma to the area may also lead to a neuroma.
Symptoms
Pain is usually increased by forefoot weight bearing activities (such as running), with narrow-fitting footwear, or with high heeled shoes. It is usually painful to firmly touch the affected region and, in chronic cases, pain and sometimes an audible click, may be heard when squeezing the foot and toes together with the hand. Often a localized area of swelling may be evident at the site of injury.
Diagnosis
A thorough subjective and objective examination from a physiotherapist is usually sufficient to diagnose a Morton’s neuroma. Investigations such as an X-ray, ultrasound, MRI, CT scan or bone scan may sometimes be used to assist with diagnosis, assess the severity of the injury and rule out other conditions.
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
Surgery for Morton’s neuroma is usually a treatment of last resort. It may be recommended if you have severe pain in your foot or if non-surgical treatments haven’t worked. Surgery is usually carried out under local anaesthetic, on an outpatient basis, which means you won’t need to stay in hospital overnight. The operation can take up to 30 minutes. The surgeon will make a small incision, either on the top of your foot or on the sole. They may try to increase the space around the nerve (nerve decompression) by removing some of the surrounding tissue, or they may remove the nerve completely (nerve resection). If the nerve is removed, the area between your toes may be permanently numb. After the procedure you’ll need to wear a special protective shoe until the affected area has healed sufficiently to wear normal footwear. It can take up to four weeks to make a full recovery. Most people (about 75%) who have surgery to treat Morton’s neuroma have positive results and their painful symptoms are relieved.