Intermetatarsal Neuroma
ICD-9: 355.6

  A neuroma is a localized degenerative process within a nerve caused by repetitive low-grade nerve trauma. The repetitive trauma causes swelling within the nerve and the development of subsequent scar tissue. The most common neuroma occurs between the metatarsal bones of the foot and is termed intermetatarsal neuroma. The nerves that supply skin sensation between the second through the fourth toes are most commonly involved.

  The type of symptoms encountered can be varied and may include; sharp, shooting, stabbing or burning pain, numbness, tingling or cramping sensations located on the ball of the feet extending into the toes. The most common area involved is between the third and fourth metatarsals and less commonly between the second and third metatarsals, as seen in the photo above.

  The occurrence of neuroma can be attributed to several factors. Increased motion and friction between the metatarsal bones can cause inflammation to the nerve tissue and surrounding connective tissue. The close proximity of the metatarsal bones may “impinge” or “compress” the nerve causing these changes. The ligament interconnecting the metatarsal bones (transverse metatarsal ligament) may “irritate or shear” the nerve. Finally, abnormal “pressure” on the nerve may be caused by faulty weight bearing distribution during walking. All of these factors may contribute in part to the development of the nerve trauma that causes the neuroma symptoms.

  Symptoms are usually experienced during weight bearing activities. Pain relief often time occurs after removing the shoe and “rubbing” the involved area. Removing the shoes decreases the side-to-side pressures placed on the nerve.

  X-rays are rarely needed to aid in the diagnoses of neuromas. If there is a suspicion of a metatarsal stress fracture x-rays can be useful. When examining the foot, the nerve can palpably click when the metatarsal bones are compressed (Mulder’s click) together from side-to-side. During this palpation a sharp shooting pain is typically experienced, which is similar to the discomfort experienced during standing and walking.

The conservative treatment of neuroma includes the following:

• The use of well cushioned shoes with a wide toe box. Cushioning decreases the direct pressure on the nerve while the wide toe box decreases the side-to-side impingement on the nerve. Lace-up, as well as buckle closure shoes tend to provide more room in the ball of the foot when compared to loafer or flat style shoes. Specialty retail shoe stores will provide the technical expertise in choosing your footwear.
  San Luis Podiatry Group recommends the following local shoe stores:
  
  • Takkens
  • Charles Shoes
  • The Shoe Tree
  • Mike's Shoes
• Arch supports with metatarsal pads can help stabilize the motion between the metatarsal bones and can help reduce the compression on the injured nerve Birkenstock and Powerstep can be purchased at the above specialty retail shoe stores. These arch supports will often be uncomfortable when first worn. Adjust to the orthotics slowly by wearing them initially for an hour and then gradually increasing their use each day until comfort is obtained.
• Cortisone injections are a mainstay of conservative therapy and frequently need to be repeated in a series up to three times prior to obtaining long-term pain relief. The cortisone helps reduce inflammation around the nerve. The long-term benefits of pain relief with the use of cortisone often times outweigh the small chance of complications with the use of this medicine. The main potential complication with the use of cortisone can be the thinning of the metatarsal fat pad that exists in the ball of the foot. The fat pad is the main protective cushioning for the ball of the foot.
• Oral anti-inflammatory medications like ibuprofen and aspirin may be tried initially but are often of limited value. They rarely decrease inflammation in the affected nerve tissue to reduce or eliminate the symptoms.

  Conservative therapies are successful a majority of the time in relieving pain and allowing the return to all normal daily activities. If pain is ongoing despite these conservative therapies surgical treatment may be indicated.

  The surgical procedure of removing the damaged nerve is performed in a hospital environment with local anesthesia and sedation administered by an anesthesiologist. Surgery is performed only if conservative therapies have failed to provide long-term, lasting pain relief.