What is Morton’s Neuroma?

What is Morton’s Neuroma

Morton’s NeuromaMorton’s neuroma is a benign, painful condition usually affecting middle-aged women who walk in narrow shoes. The pain is felt in front of the foot extending to the toes, usually in response to irritation, trauma, or excessive pressure.

Around the tarsal tunnel area, the tibial nerve splits into three branches, the calcaneal branch, the lateral plantar branch, and the medial plantar branch. At the bottom of the foot, the medial and lateral plantar nerves give rise to digital nerves. The neuroma is an enlargement and inflammation of a portion of the nerve. It’s usually located in the third web space between the metatarsal heads. The reason it occurs in the third web space is because the third common digital nerve is thicker and it originate from the union of two different branches.

Symptoms

Pain from Morton’s neuroma is primarily located on the bottom of the ball of the foot. The pain is made worse by walking, especially while wearing narrow shoes and is relieved by removing the shoes. Common symptoms include:

  • numbness
  • paresthesia
  • shooting pain towards the toes

How do you diagnose Morton’s neuroma?

Morton’s neuroma is usually diagnosed by physical examination and by MRI or ultrasound. The examination may include a web space compression test, squeezing the metatarsals together with one hand and using the index finger of the other hand to compress the affected area. Applying pressure will cause pain, paresthesia, and tingling. A possible click and radiating pain into the affected toes reduces the Mulder’s Sign.

Another diagnostic tool for Morton’s neuroma is the ultrasound. We can use the dorsal approach or the plantar approach. The dorsal approach is done by placing the ultrasound on the dorsal aspect of the metatarsals and apply finger pressure in the web space from the plantar aspect of the foot. We can also use a plantar approach. You put the probe on the plantar aspect, and you squeeze the two metatarsals’ heads together. It may cause pain and paresthesia and tingling in the toes, and you will see the Mulder’s Sign. You may hear a click, and you can see the neuroma moving dorsally. This is a representation of how Mulder’s Sign is. Ultrasound is probably the best study, can also differentiate between a bursa, which is compressible, from a neuroma, which is not compressible. MRI is also helpful.

Differential diagnosis for Morton’s neuroma:

  1. Metatarsal stress fracture. The pain is usually dorsal.
  2. Metatarsalgia, the pain is under the metatarsal heads.
  3. Nerve root irritation from lumbosacral disc herniation, usually associated with lower back pain.

Treatment options

Treatment depends on the severity of the symptoms. Common treatments include:

  • therapy (physiotherapy, arch support, foot pads)
  • injection such as steroids or alcohol
  • decompression of the intermetatarsal ligament
  • excision and removal of the neuroma.