A neuroma is a growth, or benign tumor, in nerve cells. A Morton’s neuroma is when the inflamed nerve, which is not an actual tumor but a thickening of the tissue that surrounds the digital nerves leading to the toes, is located between the third and fourth toes. It occurs as the nerve passes under the ligament connecting the toe bones (metatarsals) in the forefoot, and usually develops in response to irritation, trauma or excessive pressure.
Morton’s neuroma is a painful condition which can cause a sharp, burning pain in the ball of the foot. The toes may also sting, burn or feel numb. Patients often compare the feeling to that of standing on a pebble in his or her shoe.
Normally, there are no outward signs, such as a lump, because the nerve is deep within the foot. The most common symptom is burning pain in the ball of the foot that may radiate into the toes which may intensify with activity or wearing shoes and there may also be numbness in the toes, or an unpleasant feeling in the toes. Runners may feel pain as they push off from the starting block. High-heeled shoes, which put the foot in a similar position to the push-off, can also aggravate the condition. Tight, narrow shoes also aggravate this condition by compressing the toe bones and pinching the nerve. Examination usually reveals a mass that can be felt between the toes and a “click” may occur when pressure is applied between the bones which may replicate the pain. Other conditions will also be excluded by examination and x-rays.
Treatment generally involves changes in footwear with the avoidance of high heels or tight shoes, allowing the bones to spread out and may reduce pressure on the nerve, giving it time to heal. Custom or over-the-counter shoe inserts and pads also help relieve irritation by lifting and separating the bones, reducing the pressure on the nerve, and on occasion, an injection of a corticosteroid medication is necessary to reduce the swelling and inflammation of the nerve.
If conservative treatment does not relieve symptoms, surgery may be considered. This specifically involves resecting a small portion of the nerve and releasing the tissue and ligaments overlying the nerve. This outpatient procedure can be performed under ankle block anesthetic (local anesthetic), and involves two weeks in a rigid orthopaedic shoe with immediate weight bearing. Transition to a regular shoe occurs as soon as swelling allows.
Modified from the AAOS