This is a painful condition affecting a small nerve in the foot. It occurs when the five long bones that run the length of the foot get pushed together, pinching the nerve in between. This friction on the nerve causes it to thicken and inflame causing pain. The condition gets its name from an American surgeon, George Morton.
In many cases, a neuroma may develop as a result of excessive loading on the front of the foot. Sometimes, a patient?s anatomic alignment in the forefoot contributes to the overload. There may be some cases where the neuroma develops spontaneously, for no obvious reason. However, once the nerve is irritated, pressure from walking, and from the adjacent bony prominences (metatarsal heads), as well as from the intermetatarsal ligament that binds the heads together, all may contribute to persistent pain. Repetitive pressure on the nerve causes localized injury with resulting scarring and fibrosis of the nerve. This leads to symptoms in the distribution of the nerve.
A Morton’s neuroma usually causes burning pain, numbness or tingling at the base of the third, fourth or second toes. Pain also can spread from the ball of the foot out to the tips of the toes. In some cases, there also is the sensation of a lump, a fold of sock or a “hot pebble” between the toes. Typically, the pain of a Morton’s neuroma is relieved temporarily by taking off your shoes, flexing your toes and rubbing your feet. Symptoms may be aggravated by standing for prolonged periods or by wearing high heels or shoes with a narrow toe box.
A doctor can usually identify Morton’s neuroma during a physical exam. He or she will squeeze or press on the bottom of your foot or squeeze your toes together to see if it hurts. Your doctor may also order an X-ray of your foot to make sure nothing else is causing the pain.
Non Surgical Treatment
Initial therapies are nonsurgical and relatively simple. They can involve one or more of the following treatments. Changes in footwear. Avoid high heels or tight shoes, and wear wider shoes with lower heels and a soft sole. This enables the bones to spread out and may reduce pressure on the nerve, giving it time to heal. Orthoses. Custom shoe inserts and pads also help relieve irritation by lifting and separating the bones, reducing the pressure on the nerve. Injection. One or more injections of a corticosteroid medication can reduce the swelling and inflammation of the nerve, bringing some relief. Several studies have shown that a combination of roomier, more comfortable shoes, nonsteroidal anti-inflammatory medication, custom foot orthoses and cortisone injections provide relief in over 80 percent of people with Morton’s Neuroma.
Patients are commonly offered surgery known as neurectomy, which involves removing the affected piece of nerve tissue. Postoperative scar tissue formation (known as stump neuroma) can occur in approximately 20%-30% of cases, causing a return of neuroma symptoms. Neurectomy can be performed using one of two general methods. Making the incision from the dorsal side (the top of the foot) is the more common method but requires cutting the deep transverse metatarsal ligament that connects the 3rd and 4th metatarsals in order to access the nerve beneath it. This results in exaggerated postoperative splaying of the 3rd and 4th digits (toes) due to the loss of the supporting ligamentous structure. This has aesthetic concerns for some patients and possible though unquantified long-term implications for foot structure and health. Alternatively, making the incision from the ventral side (the sole of the foot) allows more direct access to the affected nerve without cutting other structures. However, this approach requires a greater post-operative recovery time where the patient must avoid weight bearing on the affected foot because the ventral aspect of the foot is more highly enervated and impacted by pressure when standing. It also has an increased risk that scar tissue will form in a location that causes ongoing pain.