During certain activities, particularly weight-bearing activities (e.g. walking or running) a compressive force, is sometimes placed on the interdigital nerves and surrounding soft tissue, between the metatarsal bones (this is often the case with tight fitting shoes or in patients with flat feet). If this force is repetitive enough and beyond what the nerve and soft tissue can withstand, swelling to the nerve and soft tissue may occur. This may result in pain, tenderness, pins and needles or numbness in the forefoot or toes. When this happens, the condition is known as a Morton's neuroma.
The source of this pain is an enlargment of the sheath of an intermetatarsal nerve in the foot. This usually occurs in the third intermetatarsal space, the space between the third and fourth toes and metatarsals. It occurs here, at the site third intermetatarsal nerve, since this intermetatarsal nerve is the thickest being comprised of the joining of two different nerves. It also may occur in the other intermetatarsal areas, with the second interspace being the next most common location.
Symptoms of interdigital neuroma typically manifest as a sharp, burning or tingling sensation in the forefoot. The pain radiates toward the lesser toes and is aggravated by shoe wear. The pain is relieved when the shoe is removed and the forefoot is massaged. Sometimes the symptoms involve specific toes.
Your health care provider can usually diagnose this problem by examining your foot. A foot x-ray may be done to rule out bone problems. MRI or high-resolution ultrasound can successfully diagnose Morton's neuroma. Nerve testing (electromyography) cannot diagnose Morton's neuroma, but may be used to rule out conditions that cause similar symptoms. Blood tests may be done to check for inflammation-related conditions, including certain forms of arthritis.
Non Surgical Treatment
Conservative treatment for Morton?s neuroma involves footwear that allows your forefoot to spread. High-heeled shoes cause neuromas by squeezing and stretching your involved intermetatarsal nerve across the ball of your foot and should be avoided as often as possible. A shoe that possesses any toe spring will also place more stress on your foot nerves and increase your likelihood of developing a neuroma. Test shoes before you buy them to see if they are appropriate for your feet. Select shoes that have a removable liner or insole, and stand on the liner, noting the position of your foot. If your foot is wider than your liner, that shoe will irritate your neuroma by squeezing your metatarsal bones together.
Surgery to excise the neuroma is usually performed under general anaesthetic in a day surgery facility. After surgery you will have to keep your foot dry for two weeks. Generally neuroma surgery allows for early weight bearing and protection in some type of post op shoe gear. Some neuromas may reoccur, but this is rare. Most studies on patient satisfaction after neuroma surgery show approximately 90% reduction of pain and about 85% of all patients rated the overall satisfaction with the results as excellent or good.