A neuroma is an inflammation of the covering of a nerve, called a nerve sheath. This thickening of the sheath is usually caused by irritation that results when two bones repeatedly rub together as in the case of an intermetatarsal neuroma. A neuroma can also occur along other areas of nerve structures where there is irritation or friction from another foot structure. The most commonly treated neuroma in the foot is commonly called a Mortonӳ neuroma. The area between the third and fourth toes is most commonly affected, but can involve any of the toes.
Symptoms of a Mortonӳ Neuroma are usually burning, tingling, cramping, or numbness sensations between the long bones of your foot or your toes. It may feel like your walking on a marble or a rolled up piece of sock. The pain can radiate to the tip of the toes, or up the ankle as your nerve courses both directions. When you rub your foot or as you walk you may also feel a clicking or popping sensation. Usually this is the enlarged nerve as it rolls against the bones in your foot.
Causes of a neuroma can be due to your foot structure in which the bone deformities place extra pressure against the nerve. Pronation allows for the metatarsals to shift excessively and allow for compression of the nerve in some cases. The nerve may not only be compressed but also stretching the nerve excessively may be a causative factor. In occupations where the toes are repetitively hyperextended the neuroma is more likely to exist. Narrow toed dress shoes and high heel shoes may also cause hyperextension stretching forces as well as direct compression of the nerve on the metatarsal bones. Neuromuscular diseases may affect the pull and normal function of the muscles and tendons in your foot causing an imbalance and deformation of the foot structure. Trauma or surgery to the bones and muscles in the foot can cause structural damage resulting in the nerve compression.
Prevention of a neuroma may entail controlling the foot structure with arch supports or orthotics. Since there is a strong genetic predisposition for the structure of your foot, there is not a lot we can do to change this factor. Proper shoe wear at all times may be the best prevention. A shoe with a wider toe box to accommodate the foot structure as well as avoiding high heeled shoes is necessary. Sometimes extra pressure can be relieved by metatarsal padding to place weight behind the metatarsal heads, or “balls” of your feet. This takes some of the compressive forces off of the nerve when you walk on your foot as the weight is dispersed over your foot. If the area is irritated with redness, swelling, and pain some ice and anti-inflammatory medications may be helpful. The best prevention may be to get advice from your podiatrist.
Podiatric Care may include using anti-inflammatory oral medications or an injection of medication and local anesthetic to reduce this swelling. When you go to your doctor, x-rays are usually required to evaluate the structure of your foot and determine if a neuroma is truly the problem. They may advise you on different shoewear or prescribe a custom made orthotic to try and control the foot structure especially if you have excessive pronation. Your podiatric physician may also recommend a surgical procedure to actually fix the structural problem of your foot.
Surgery to correct a neuroma may be the best option for you if conservative measures do not work and control the pain. Your podiatrist will give you advise on this. To relieve the pain of the neuroma the actual damaged inflammed nerve is removed. Removing a portion of nerve may mean long term numbness where this nerve normally produces sensation. The skin incision may be on the top of the foot or through the bottom depending on your surgeons preference.
Post-operative Care and Risks with excision of a Mortonӳ neuroma is usually with a soft bandage with a post-operative shoe for protection. Weight bearing is usually allowed if tolerated. You should expect some pain following surgery as well as swelling. Especially for the first 48 hours you should keep your leg elevated and an occasional ice pack placed over the area of surgery (about 20 minutes per hour). Surgical cuts are made through the skin so a scar is expected. If you are a keloid former, let your surgeon know. Surgical cuts are not only made through skin but through other layers of tissue as well. A scar may form within your foot and lead to adhesions. Typically you can get back into a supportive tennis shoe in 3-5 weeks following healing of the wound and stitches are removed. You may use crutches, a walker, or wheelchair to help you keep weight off of this foot if needed for post-operative pain. Healing time is influenced by many factors including your nutrition, circulation, and other medical conditions. If you are a smoker you can expect to take longer to heal. If you are required to keep pressure off of your foot your leg muscles are not being used as they were before surgery. This allows for slower movement of the blood through the leg vessels. Occasionally this can lead to a blood clot in the leg which can become life threatening. Hip and knee flexion and extension exercises as well as wiggling your toes gently can help prevent this from occurring. If you have a history of blood clots you should let your surgeon know. Any time a nerve is cut the patient may experience a variety of feelings following surgery for several months, including some tingling, burning, and phantom pains. Of course if the nerve is removed partially you will experience some numbness permanently following surgery.