A neuroma is a benign growth of nerve tissue that can occur to any of the nerves in the foot. Forefoot nerves are more susceptible to this process because of their specific location. The ball of the forefoot undergoes a great deal of motion as the toes flex and extend. There is also a limited amount of space between the metatarsal heads through which the forefoot nerves travel before dividing into digital nerves to provide sensation to the toes. The increased motion and limited space of the forefoot can cause the nerves to be stretched, tethered, or compressed; all of which can start the process of neuroma formation. Certain activities that require an increase in forefoot motion and stress (i.e., dance, baseball catcher) or occupations that require squatting (i.e., tile or carpet layer) can also aggravate the forefoot nerves leading to possible neuroma development. Acute or repetitive trauma to any nerve in the foot can lead to perineural fibrosis (scar tissue surrounding nerve) or neuroma formation.
By far, the most common site in the foot for a neuroma to occur is between the third and fourth toes in an area called the third intermetatarsal space. A neuroma in this region affects the third common plantar digital nerve and is commonly referred to as a “Morton’s Neuroma”.The region of nerve undergoing neuroma formation appears thickened and swollen. Patients complain of a lump under the forefoot, the sensation of a sock rolled up in the area, numb toes, shooting electrical pain, or pain and discomfort so great that, at times, they must take off their shoes and massage their forefoot. The condition is usually progressive.
Conservative treatment consists of orthoses with metatarsal accommodations, injections of local anesthetic mixed with a steroid, proper selection of shoes, and/or a short course of physical therapy or anti-inflammatories to reduce perineural fibrosis and swelling.Surgical excision, either from the dorsal or plantar approach, is recommended only after failed conservative care. Procedures are usually performed as an outpatient.