Some sources claim that entrapment of the plantar nerve because of compression between the metatarsal heads, as originally proposed by Morton, is highly unlikely, because the plantar nerve is on the plantar side of the transverse metatarsal ligament and thus does not come in contact with the metatarsal heads. It is more likely that the transverse metatarsal ligament is the cause of the entrapment. Despite the name, the condition was first correctly described by a chiropodist named Durlacher, and although it is labeled a "neuroma", many sources do not consider it a true tumor, but rather a perineural fibroma (fibrous tissue formation around nerve tissue).
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.
Feelings of numbness, tingling or tenderness in the ball of the foot (the area just behind the base of the toes) are some of the first signs of a condition known as Morton?s Neuroma. However, the condition is somewhat unpredictable, and symptoms may vary from patient to patient. Generally, however, the discomfort gets worse rather than better, and the patient may feel pain or a burning sensation that radiates out to the toes. Eventually, wearing shoes becomes uncomfortable (or even unbearable), and the patient may complain that the feeling is similar to that of having a stone bruise, or walking on a marble or pebble constantly, even though no there is no trauma to the skin, and no visible bump or lump on the sole of the foot.
To arrive at a diagnosis, the foot and ankle surgeon will obtain a thorough history of your symptoms and examine your foot. During the physical examination, the doctor attempts to reproduce your symptoms by manipulating your foot. Other tests or imaging studies may be performed. The best time to see your foot and ankle surgeon is early in the development of symptoms. Early diagnosis of a Morton?s neuroma greatly lessens the need for more invasive treatments and may avoid surgery.
Non Surgical Treatment
Most patients' symptoms subside when they change footwear to a wide soft shoe with a metatarsal support inside to relieve the pressure on the involved area. If this treatment fails, a cortisone injection into the nerve is occasionally helpful.
When conservative measures are unsuccessful, surgery can be a good choice in the treatment of Morton's neuroma. The operation for Morton's neuroma does not require an overnight hospital stay. The anesthetic used is an ankle block, which completely numbs the foot during the surgery. The physician removes the neuroma from an incision made on the top of the foot between the involved metatarsal heads. The nerve to the interspace is exposed and cut next to the metatarsal heads.
Ensuring that shoes are well fitted, low-heeled and with a wide toe area may help to prevent Morton's neuroma.