Morton's Neuroma

Burning and tingling sensations in the feet are a problem many people experience. While any part of the foot may be involved, the most common area is throughout the ball of the foot. In addition, these feelings may or may not be coupled with pain. Named after T.G. Morton of Philadelphia, Morton's neuroma is a common condition that elicits such symptoms. Identified as an enlargement of the nerve at the base of the third and fourth toes, Morton's neuroma is benign and poses no acute danger to those affected.

The exact cause of a Morton's neuroma remains unknown. However, most consider this condition to be that of an entrapped nerve. At the site of symptoms, many important structures exist which are thought to play a part in creating a neuroma. The metatarsal heads are the bones in the ball of the foot which accept the pressures of weight bearing. Connecting these bones is a ligament called the deep transverse metatarsal ligament. It is at the junction of the third and fourth metatarsal heads and the deep transverse metatarsal ligament that compression of the nerve takes place.

Most neuromas occur in those with a pronated, or flat, foot. The flat foot leads to increased stretching of the nerves and motion of the bones. This results in repeated pressure on the nerves and formation of a neuroma.

As with most other foot problems, shoe wear may play a role in the development of a Morton's neuroma. High heels force weight onto the front of the foot while extending the toes in a cramped area. This may lead to bunching of the toes and other bones in the front of the foot causing compression of the nerve. Activities requiring crouching and stooping can place unnecessary stretching on the nerves as well thus leading to pain and irritation of the nerve.

With mild forms of a Morton's neuroma, people often experience:

• A feeling of walking on a wrinkled or crunched up sock or bump in the front of the shoe
• Numbness and tingling of the third and fourth toes

As the neuroma becomes more bothersome, additional symptoms start to develop:

• Sharp, burning, shock-like sensations in the local area of the base of the third and fourth toes with occasional shooting throughout the ball of the foot may occur
• A clicking feeling most often with barefoot weight bearing is also common.

As the symptoms progress, pain becomes more noticeable. This can range from a dull aching pain to more severe sharp pains worsening with increased activities. If the neuroma becomes large enough, spreading of the toes can occur. Difficulty with tight shoewear and inability to carry out certain activities usually accompanies a long-standing neuroma.

Manual evaluation of the area can reproduce the painful symptoms. Pressing directly at the base of the third and fourth toes or squeezing from top to bottom will compress the inflamed nerve and cause burning, tingling, numbness or pain. These sensations may also be reproduced with compressing the foot from side to side. Combining side to side compression with direct pressure may cause a clicking feeling known as Mulder's sign.

Conservative, non-surgical treatment of Morton's neuroma can alleviate and prevent future recurrence in the majority of cases, up to 80%. Like other common foot and ankle maladies, treatment begins with patient education and the right kind of shoe wear.

• Shoes with a wide toe box and a lower heel work to prevent compression of and reduce weight bearing to the ball of
  the foot.
• In cases where a flat foot is part of the problem, shoe inserts to aid with arch support can help alleviate some of the symptoms associated with the neuroma.
• Small pads known as "cookie pads" may be placed in the
  shoe at the ball of the foot just behind the area of maximal tenderness to further reduce pressure when walking or standing.

When further treatment is necessary, the foot and ankle specialist may recommend injection therapy. The first line option is steroid, or cortisone, injections. These act as a "jump start" to the healing process, utilized to decrease overall inflammation associated with the Morton's neuroma. The injections are administered either from the top, and rarely the bottom, of the ball of the foot. Steroid injections are typically given in rounds of three with adequate periods of time separating each to avoid potential complications. Results have shown that up to 50% of patients may experience adequate relief with these injections. Additionally, other injection materials such as alcohol solutions or vitamin B12 may be
used successfully.

Surgical treatment of Morton's neuromas is considered once
non-surgical options have been exhausted and fail to alleviate symptoms. Either decompression or removal of the neuroma are
the most common techniques.

Decompression

• Decompression of the nerve may be performed arthroscopically (with a small incision) or with an open incision. This approach involves releasing the deep transverse metatarsal ligament, preventing repetitive compression while walking or carrying out activities. Any adhesions around the nerve are released as well to avoid recurrence.

Neurectomy

• A true neurectomy, or removal of the nerve, is a more commonly used surgical treatment. A discussion with the patient includes the likelihood of permanent numbness to the area between the third and fourth toes and the possibility of a painful recurrence. The incision utilized for removal of the neuroma can be placed either on the top or bottom of the foot. The nerve is identified between the metatarsal bones and followed into the toes. At the near side of the enlarged area of nerve, a sharp transection is completed and the severed nerve is removed. In some instances, the remaining nerve stump is sutured into the surrounding muscle to further prevent another neuroma from forming.

Other surgical treatments have been utilized successfully, including freezing of the nerve and laser sealing of recurrent neuromas.

The post-operative course for neuroma surgery is both surgeon- and procedure-dependent. This ranges from immediate weight bearing to a short three- to four-week period of non-weight bearing with the use of crutches or other assistive devices. Physical therapy is not typically indicated but may be recommended depending on the post-operative progress. Success rates of conservative and surgical therapies combined have been reported to be as high as 95% with a majority of patients stating that they would have the procedure again.

This information on foot, leg and lower body health conditions is provided by The Podiatry Institute, dedicated to advancing the standard of care in podiatric medicine and its effects on musculoskeletal health. The Podiatry Institute does not endorse a specific treatment, product, or therapy. This information is not intended to be a substitute for professional medical advice, diagnosis or treatment. Please consult your health care provider on all matters relating to this or any other condition that may affect your health.