Overview
Morton's neuroma is an enlarged nerve that usually occurs in the third interspace, which is between the third and fourth toes. To understand Morton's neuroma further, it may be helpful to look at the anatomy of the foot. Problems often develop in the third interspace because part of the lateral plantar nerve combines with part of the medial plantar nerve here. When the two nerves combine, they are typically larger in diameter than those going to the other toes. Also, the nerve lies in subcutaneous tissue, just above the fat pad of the foot, close to an artery and vein. Above the nerve is a structure called the deep transverse metatarsal ligament. This ligament is very strong, holds the metatarsal bones together, and creates the ceiling of the nerve compartment. With each step, the ground pushes up on the enlarged nerve and the deep transverse metatarsal ligament pushes down. This causes compression in a confined space.
Causes
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.
Symptoms
Symptoms typically include pain, often with pins and needles on one side of a toe and the adjacent side of the next toe. Pain is made worse by forefoot weight bearing and can also be reproduced by squeezing the forefoot to further compress the nerve. Pressing in between the third and forth metatarsals for example with a pen can also trigger symptoms.
Diagnosis
An MRI scan (magnetic resonance imaging) is used to ensure that the compression is not caused by a tumor in the foot. An MRI also determines the size of the neuroma and whether the syndrome should be treated conservatively or aggressively. If surgery is indicated, the podiatrist can determine how much of the nerve must be resected. This is important, because different surgical techniques can be used, depending on the size and the position of the neuroma. Because MRIs are expensive, some insurance companies are reluctant to pay for them. If the podiatrist believes an MRI is necessary, he or she can persuade the insurance company to pay for it by presenting data to support the recommendation.
Non Surgical Treatment
Treatment for Morton's neuroma may depend on several factors, including the severity of symptoms and how long they have been present. The earlier on the condition is diagnosed, the less likely surgery is required. Doctors will usually recommend self-help measures first. These may include resting the foot, massaging the foot and affected toes. Using an ice pack on the affected area (skin should not be directly exposed to ice, the ice should be in a container or wrapped in something) Changing footwear, wearing wide-toed shoes, or flat (non high-heeled) shoes. Trying arch supports (orthotic devices). A type of padding that supports the arch of the foot, removing pressure from the nerve. The doctor may recommend a custom-made, individually designed shoe-insert, molded to fit the contours of the patient's foot. There are several OTC (over the counter, non-prescription) metatarsal pads or bars available which can be placed over the neuroma. Taking over-the-counter, non-prescription painkilling medications. Modifying activities, avoiding activities which put repetitive pressure on the neuroma until the condition improves. Bodyweight management,if the patient is obese the doctor may advise him/her to lose weight. A significant number of obese patients with foot problems, such as flat feet, who successfully lose weight experience considerable improvement of symptoms.
Surgical Treatment
If these non-surgical measures do not work, surgery is sometimes needed. Surgery normally involves a small incision (cut) being made on either the top, or the sole, of the foot between the affected toes. Usually, the surgeon will then either create more space around the affected nerve (known as nerve decompression) or will cut out (resect) the affected nerve. If the nerve is resected, there will be some permanent numbness of the skin between the affected toes. This does not usually cause any problems. You will usually have to wear a special shoe for a short time after surgery until the wound has healed and normal footwear can be used again. Surgery is usually successful. However, as with any surgical operation, there is a risk of complications. For example, after this operation a small number of people can develop a wound infection. Another complication may be long-term thickening of the skin (callus formation) on the sole of the foot (known as plantar keratosis). This may require treatment by a specialist in care of the feet (chiropody).
Morton's neuroma is an enlarged nerve that usually occurs in the third interspace, which is between the third and fourth toes. To understand Morton's neuroma further, it may be helpful to look at the anatomy of the foot. Problems often develop in the third interspace because part of the lateral plantar nerve combines with part of the medial plantar nerve here. When the two nerves combine, they are typically larger in diameter than those going to the other toes. Also, the nerve lies in subcutaneous tissue, just above the fat pad of the foot, close to an artery and vein. Above the nerve is a structure called the deep transverse metatarsal ligament. This ligament is very strong, holds the metatarsal bones together, and creates the ceiling of the nerve compartment. With each step, the ground pushes up on the enlarged nerve and the deep transverse metatarsal ligament pushes down. This causes compression in a confined space.
Causes
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.
Symptoms
Symptoms typically include pain, often with pins and needles on one side of a toe and the adjacent side of the next toe. Pain is made worse by forefoot weight bearing and can also be reproduced by squeezing the forefoot to further compress the nerve. Pressing in between the third and forth metatarsals for example with a pen can also trigger symptoms.
Diagnosis
An MRI scan (magnetic resonance imaging) is used to ensure that the compression is not caused by a tumor in the foot. An MRI also determines the size of the neuroma and whether the syndrome should be treated conservatively or aggressively. If surgery is indicated, the podiatrist can determine how much of the nerve must be resected. This is important, because different surgical techniques can be used, depending on the size and the position of the neuroma. Because MRIs are expensive, some insurance companies are reluctant to pay for them. If the podiatrist believes an MRI is necessary, he or she can persuade the insurance company to pay for it by presenting data to support the recommendation.
Non Surgical Treatment
Treatment for Morton's neuroma may depend on several factors, including the severity of symptoms and how long they have been present. The earlier on the condition is diagnosed, the less likely surgery is required. Doctors will usually recommend self-help measures first. These may include resting the foot, massaging the foot and affected toes. Using an ice pack on the affected area (skin should not be directly exposed to ice, the ice should be in a container or wrapped in something) Changing footwear, wearing wide-toed shoes, or flat (non high-heeled) shoes. Trying arch supports (orthotic devices). A type of padding that supports the arch of the foot, removing pressure from the nerve. The doctor may recommend a custom-made, individually designed shoe-insert, molded to fit the contours of the patient's foot. There are several OTC (over the counter, non-prescription) metatarsal pads or bars available which can be placed over the neuroma. Taking over-the-counter, non-prescription painkilling medications. Modifying activities, avoiding activities which put repetitive pressure on the neuroma until the condition improves. Bodyweight management,if the patient is obese the doctor may advise him/her to lose weight. A significant number of obese patients with foot problems, such as flat feet, who successfully lose weight experience considerable improvement of symptoms.
Surgical Treatment
If these non-surgical measures do not work, surgery is sometimes needed. Surgery normally involves a small incision (cut) being made on either the top, or the sole, of the foot between the affected toes. Usually, the surgeon will then either create more space around the affected nerve (known as nerve decompression) or will cut out (resect) the affected nerve. If the nerve is resected, there will be some permanent numbness of the skin between the affected toes. This does not usually cause any problems. You will usually have to wear a special shoe for a short time after surgery until the wound has healed and normal footwear can be used again. Surgery is usually successful. However, as with any surgical operation, there is a risk of complications. For example, after this operation a small number of people can develop a wound infection. Another complication may be long-term thickening of the skin (callus formation) on the sole of the foot (known as plantar keratosis). This may require treatment by a specialist in care of the feet (chiropody).