What Causes Mortons Neuroma

Overview

Morton’s Neuroma is a common problem in runners, and there are a number of simple fixes you can try before resorting more drastic solutions like sclerosing or surgery. A Morton’s Neuroma normally causes a burning pain in the forefoot, just behind the 3rd and 4th toes (sometimes behind the 2nd and 3rd toes). The pain often radiates towards the toes, and sometimes there is numbness rather than pain. The underlying cause is inflammation of the nerve between the bones of the forefoot, often triggered by narrow or tight shoes. I have had good results with the simple fixes described below, and I have had reports of other runners with similar success.

Causes

Wearing shoes that are too tight can make the pain of Morton’s neuroma worse. This is because the toe bones are more likely to press on the affected nerve if your shoes are too tight. High-heeled shoes, particularly those over 5cm (2 inches), or shoes with a pointed or tight toe area, can also compress your toes and make the pain worse. This is why women tend to be affected by Morton’s neuroma more than men.

Foot conditions.

Symptoms

The most common presenting complaints include pain and dysesthesias in the forefoot and corresponding toes adjacent to the neuroma. Pain is described as sharp and burning, and it may be associated with cramping. Numbness often is observed in the toes adjacent to the neuroma and seems to occur along with episodes of pain. Pain typically is intermittent, as episodes often occur for minutes to hours at a time and have long intervals (ie, weeks to months) between a single or small group of multiple attacks. Some patients describe the sensation as “walking on a marble.” Massage of the affected area offers significant relief. Narrow tight high-heeled shoes aggravate the symptoms. Night pain is reported but is rare.

Diagnosis

To diagnose Morton’s neuroma the podiatrist commonly palpates the area to elicit pain, squeezing the toes from the side. Next he or she may try to feel the neuroma by pressing a thumb into the third interspace. The podiatrist then tries to elicit Mulder’s sign, by palpating the affected interspace with one hand and squeezing the entire foot at the same time with the other hand. In many cases of Morton’s neuroma, this causes an audible click, known as Mulder’s sign. An x-ray should be taken to ensure that there is not a fracture. X-rays also can be used to examine the joints and bone density, ruling out arthritis (particularly rheumatoid arthritis and osteoarthritis).

Non Surgical Treatment

Conservative treatment involves a reduction in the inflammation and removing the impingement factor. Reduction in inflammation is achieved via rest, elevation, ice, and massage with anti-inflammatory gels. Removing foot wear and and/r wearing broad type footwear would also help. Injection therapy is useful in reducing symptoms but not very successful in providing long term relief. The only time when it is most appropriate is when the cause of the space occupying object is not a neuroma but an inflamed bursa. Injection would help to relieve symptoms, and often cortisone is not even necessary.interdigital neuroma

Surgical Treatment

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.

Prevention

Wearing proper footwear that minimizes compression of the forefoot can help to prevent the development of and aggravation of a Morton’s neuroma.

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