A Morton's neuroma usually develops between the third and fourth toes. Less commonly, it develops between the second and third toes. Other locations are rare. It also is rare for a Morton's neuroma to develop in both feet at the same time. The condition is much more common in women than men, probably as a result of wearing high-heeled, narrow-toed shoes. This style of shoe tends to shift the bones of the feet into an abnormal position, which increases the risk that a neuroma will form. Being overweight also increases the risk of a Morton's neuroma.
There are a number of common causes for Morton?s Neuroma, (though the condition can arise spontaneously for reasons still unknown). The Neuroma often occurs in response to irritation, pressure or traumatic injury to one of the digital nerves leading to the toes. A thickening of nerve tissue results as part of the body?s response to the irritation or injury. Abnormal foot movement used to compensate for bunions, hammertoes, flatfeet and other conditions can lead to irritation and development of Morton?s Neuroma. Pronation of the foot may cause the heads of the metatarsal bones to rotate slightly, thereby pinching the nerve running between the metatarsal heads. Chronic pressure or pinching causes the nerve sheath to enlarge, becoming increasingly squeezed, producing worsening pain over time, if not addressed. Morton?s Neuroma can be exacerbated when tight shoes providing little room for the forefoot are worn. Activities which over-pronate the foot (such as walking barefoot in sand) may increase the pain associated with Morton?s Neuroma, as will any high-impact activity, such as jogging.
While the condition may at first only appear during heavy repetitive stress or when wearing particular shoes which aggravate the foot, the Neuroma can become increasingly inflamed and produce more constant discomfort, lasting days or weeks. Runners may experience pain pushing off from starting blocks. Tight or narrow shoes as well as high heels likewise aggravate the Neuroma. A checklist of symptoms includes burning pain, occasionally numbness in the ball of the foot. Radiating pain from the ball of the foot to the toes. Intensifying pain during activity and when wearing shoes. Occasional numbness, discomfort, tingling or ?electrical shock sensation? in the toes. Pain between the third and fourth toes, often occurring from the outer side of one toe to the inner side of the adjoining toe. Pain upon leaving the starting blocks in running sports.
The exact cause of Mortons neuroma can often vary between patients. An accurate diagnosis must be carefully made by the podiatrist through thorough history taking and direct questioning to ensure all possible causes are addressed. The podiatrist will also gather further information about the cause through a hands on assessment where they will try to reproduce your symptoms. A biomechanical and gait analysis will also be performed to assess whether poor foot alignment and function has contributed to your neuroma.
Non Surgical Treatment
Treatment for Morton?s neuroma will depend on how long you've had the condition and its severity. Simple non-surgical treatments are effective for some people. Others may need surgery. If Morton's neuroma is diagnosed early, treatment will aim to reduce the pressure on the affected nerve. This is usually the nerve between the third and fourth toe bones (metatarsals). Your GP or podiatrist (foot specialist) may recommend changing the type of shoes you usually wear, shoes with a wider toe area may help ease the pressure on the nerve in your foot. Using orthotic devices, such as a support for the arch of your foot to help relieve the pressure on the nerve. Anti-inflammatory painkillers or a course of steroid injections into the affected area of your foot may help ease the pain and inflammation. Alcohol and local anaesthetic is injected into your foot using ultrasound for guidance, studies have shown that this type of treatment is effective. Resting your foot and massaging your toes may also help to relieve the pain. You can make an ice pack by freezing a small bottle of water and rolling it over the affected area.
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.