A Morton's neuroma, or interdigital neuroma, is a painful condition which involves a nerve on the plantar aspect (bottom) of the foot. Occasionally a neuroma develops following a bruising injury to the sole of the foot, such as might be caused by jumping onto a rock or other objects, but in general, the origin of the condition is unknown.
The pain of Morton's neuroma occurs when the nerve connecting the toe bones (metatarsal bones) becomes irritated or compressed. The exact cause of the irritation is unknown, but it may be the metatarsal bones pressing against the nerve when the gap between the bones is narrow. This causes the nerve and surrounding tissue to thicken. Some experts believe that a number of other foot problems, including flat feet, high foot arches, bunions and hammer toes, may also play a role in Morton's neuroma.
People with Morton's neuroma usually complain of pain that can start in the ball of the foot and shoot into the affected toes. However, some people just have toe pain. There may also be burning and tingling of the toes. The symptoms are usually felt up the sides of the space between two toes. For example, if the nerve between the third and fourth long bones (metatarsals) of the right foot is affected, the symptoms will usually be felt up the right-hand side of the fourth toe and up the left-hand side of the third toe. Some people describe the pain that they feel as being like walking on a stone or a marble. Symptoms can be made worse if you wear high-heeled shoes. The pain is relieved by taking your shoe off, resting your foot and massaging the area. You may also experience some numbness between the affected toes. Your affected toes may also appear to be spread apart, which doctors refer to as the 'V sign'. The symptoms can vary and may come and go over a number of years. For example, some people may experience two attacks of pain in a week and then nothing for a year. Others may have regular and persistent (chronic) pain.
The diagnosis of interdigital neuroma is usually made by physical examination and review of the patient's medical history.MRI ad High Definition Ultrasound examination may be useful to confirm the diagnoses however they may still not be 100% reliable. The commonest reason for this is de to natural substances present in between the metatarsal heads and between the fat pad and the intermetatarsal ligament. These natural substances i.e. bursa, fat, capsular thickening and even bony growths, can all be a factor in the impingement process and may need to be surgically cleared.
Non Surgical Treatment
Anti-inflammatory drugs may be recommended to dull the pain and lessen swelling. Neuropathic pain medications such as the antionvulsants and / or antidepressants may be tried as well. Many are able to recover from this issue at home by icing the area, resting the feet, and by avoiding wearing narrow or tight shoes. If these remedies do not work to alleviate symptoms, the doctor may give special devices to separate the toes and avoid the squeezing of the nerve. Steroid injections may reduce pain and swelling. Surgery may be required if these do not help.
If symptoms do not respond to any of the above measures then surgery may be suggested. This involves a short 30 minute operation to either remove tissue to take pressure off the nerve or to remove the nerve causing the pain. The surgery can be done as a day case but it will be two or three weeks before you can be fully active on your feet. There may be some lingering numbness afterwards if the nerve is removed. But surgery is successful in around 80% of cases. There is a small risk of complications such as infection and thickening of the skin on the soles of the feet.
Ensuring that shoes are well fitted, low-heeled and with a wide toe area may help to prevent Morton's neuroma.