Mortons neuroma

Interdigital neuroma more commonly known as Mortons neuroma or "foot neuroma" is an entrapment of a nerve that passes into the toes of the foot. The nerve gets entrapped or “pinched” by the metatarsal bones, which are the bones just behind the toes. Typically this type of pain in the ball of the foot is the result of wearing shoes that are too narrow or with very flimsy soles, or in the case of women, high heel shoes. Other factors that will cause this condition can be the specific architecture of a person’s foot structure as well as occupational hazards such as those who work low to the ground forcing them to kneel down for long periods. An example would be someone who spends long hours planting flowers in a garden; the ball of the foot is being constantly overstretched.

This condition can be very painful. Typically, a person will be walking in shoes (although the condition can be painful out of shoes as well), and will develop a sharp pain just behind the third and fourth toes.

Below is a picture of the most common site, represented by the red arrow, (but not the only site) for neuroma pain. This is the true Mortons neuroma.

Other conditions that occur in this area of the foot may mimic neuroma pain with no actual neuroma present. A bursitis in between the two metatarsal bones may put pressure on the nerve and create neuroma type pain.

Secondly, a condition called capsulitis may also give similar symptoms as a true interdigital neuroma. Click here for more information on capsulitis and its relationship to neuroma as a source of foot pain.

Below is a short (15 second) video demonstrating how the nerve gets irritated and then enlarges from this irritation.

There are a number of treatments for Mortons neuroma depending on the severity. Sometimes, just identifying the certain pair of shoes that sets off the pain and no longer wearing them will eradicate the problem.

Anti-inflammatory medication can be helpful, but this should be considered temporary relief and should not be considered for long-term treatment, as there are potential systemic problems with taking this type of medication for long periods of time.

A foot specialist (podiatrist) may recommend an orthotic device, which is a sophisticated arch support, custom made to the structure of the patient’s foot. The purpose of which is to control the abnormal structural components of the foot, which is contributing to the condition. Many times a neuroma spacer pad can be build into the orthotic which then attempts to spread apart the adjacent metatarsal bones and thereby remove the pressure on the nerve, thus reducing pain. I generally reserve this type of Mortons neuroma treatment for patients who are not candidates for other types of treatment as I consider it a “stop gap” measure. For more information on orthotics and Mortons neuroma, click here.

Injection of the area can also be very helpful. Some doctors will inject cortisone in an effort to reduce inflammation of Mortons neuroma. Others may recommend injecting denatured alcohol, which attempts to sclerose, or deaden the nerve. Both can be very effective. My preferred treatment is multiple injections of denatured alcohol. Anywhere from one to seven injections repeated on a weekly basis are necessary. I have found the success rate to be in the 80-85 percent range.

Another nonsurgical option that has become available in recent years is the use of cryosurgery. As it relates to neuroma, the growth is "frozen" via the insertion of a probe into the area of the neuroma. This freezing of the neuroma deadens the nerve thus eliminating the pain. The procedure is an office procedure performed under local anesthesia. There may be some mild post procedure discomfort that should be relieved with a mild analgesic.

Below is a video of the procedure.

When all else fails, surgical excision is usually recommended. This is an out patient procedure where the entrapped nerve is removed. As with any surgery there are potential complications and your doctor should explain these to you. The two biggest complications are misdiagnosis of the Mortons neuroma; the nerve is removed and the patient still has pain. The second, more common complication is not resecting enough of the nerve and being left with what we call a stump neuroma. The patient will continue having pain while eradication of this new problem becomes much more difficult.

As a side note to surgical excision of neuromas podiatry has always been a leader and innovator of minimal incision surgery, the art of surgical correction of a problem using a minimum amount of dissection and thus trauma to the surgical site. This type of surgery obviously leads to a less painful post operative experience and quicker overall healing time.

Within the last few years a new procedure called "minimally invasive nerve decompression" or MIND has been developed. This type of surgery is a minimally invasive procedure where a very small incision is made, special surgical instruments designed solely for this procedure are then introduced into the surgical site and instead of excising the neuroma, the pressure exerted on the neuroma mass is relieved (decompressed) by simply cutting the transverse metatarsal ligament. The idea here is that even though the nerve is enlarged, if there is no pressure on it from other surrounding structures, in this case the transverse metatarsal ligament and adjacent metatarsal bones, then there should be no pain. by cutting this ligament the two adjacent metatarsal bones which usually aggravate the formation of neuroma are separated slightly thus relieving the ongoing pressure on the nerve.

It is my understanding that preliminary studies have demonstrated a success rate at least equal to surgical excision with the obvious benefits of less pain post-operatively and quicker return to normal shoes and activity.