Morton?s neuroma is inflammation, thickening, or enlargement of the nerve between the bones of the toes (metatarsal bones). The condition is also called intermetatarsal neuroma. The thickening is usually found between bones of the third and fourth toes of the foot, but sometimes it may develop between the second and third toes. It occurs when the medial plantar nerve near the bones of those toes becomes compressed or irritated, possibly because the metatarsal bones press against the nerve in the narrow gap between the toes. If left untreated, Morton?s neuroma can cause a sharp, burning, or shooting pain that often gets worse over time. The pain becomes worse when a person walks or stands on the ball of the foot. Sometimes the pain reaches the toes next to the neuroma and a sensation of tingling or numbness is felt.
There are many reasons to develop a neuroma. Improper shoe gear is probably the most likely cause. Repetitive activity and excessive pressure on the ball of the foot are common. Heredity and genetic factors may also be involved. In many cases the structure of the foot may predispose the condition. Associated conditions that may cause neuroma include: bunion, hammer toes, ligament laxity, and/or a tight calf muscle. Some patients may have thinning of the fat pad on the ball of the foot, which may result in increased pressure of the nerves. Tight pointy shoes (and high heels) without padding may induce pain in the ball of the foot. Neuroma may occur suddenly, or develop over time.
Symptoms include tingling in the space between the third and fourth toes, toe cramping, a sharp, shooting, or burning pain in the ball of the foot and sometimes toes, pain that increases when wearing shoes or pressing on the area, pain that gets worse over time. In rare cases, nerve pain occurs in the space between the second and third toes. This is not a common form of Morton neuroma, but treatment is similar.
The diagnosis of a Morton's neuroma can usually be made by the doctor when the history of pain suggests it and the examination elicits the symptoms. The foot is generally tender when the involved area is compressed and symptoms of pain and sometimes tingling can be elicited when the sides of the foot are squeezed. Magnetic resonance imaging (MRI) or ultrasound testing can be used to confirm the diagnosis if necessary.
Non Surgical Treatment
If symptoms are severe or persistent and self-help measures did not help, the doctor may recommend corticosteroid injections, a steroid medication that reduces inflammation and pain is injected into the area of the neuroma. Only a limited number of injections are advised, otherwise the risk of undesirable side effects increases, including hypertension (high blood pressure) and weight gain. Alcohol sclerosing injections, studies have shown that alcohol injections reduce the size of Morton's neuromas as well as alleviating pain. This is a fairly new therapy and may not be available everywhere. The doctor injects alcohol in the area of the neuroma to help sclerose (harden) the nerve and relieve pain. Injections are typically administered every 7 to 10 days. For maximum relief 4 to 7 injections are usually needed.
Operative treatment of Morton?s neuroma should be entertained only after failure of non-operative management. Standard operative treatment involves identifying the nerve and cutting (resecting) it proximal to the point where it is irritated/injured. This is usually done through an incision on the top (dorsal) aspect of the foot, although an incision on the sole (plantar) aspect of the foot can be used. Some physicians will attempt to treat Morton?s neuroma by releasing the intermetatarsal ligament, and freeing the nerve of local scar tissue. This may also be beneficial.