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).
Various factors have been implicated in the precipitation of Morton's neuroma. Morton's neuroma is known to develop as a result of chronic nerve stress and irritation, particularly with excessive toe dorsiflexion. Poorly fitting and constricting shoes (ie, small toe box) or shoes with heel lifts often contribute to Morton's neuroma. Women who wear high-heeled shoes for a number of years or men who are required to wear constrictive shoe gear are at risk. A biomechanical theory of causation involves the mechanics of the foot and ankle. For instance, individuals with tight gastrocnemius-soleus muscles or who excessively pronate the foot may compensate by dorsiflexion of the metatarsals subsequently irritating of the interdigital nerve. Certain activities carry increased risk of excessive toe dorsiflexion, such as prolonged walking, running, squatting, and demi-pointe position in ballet.
It usually occurs in between the 3rd and 4th toes (about 65% of cases) as is pictured to the right. It is less commonly found in the 2nd webspace, and rarely at all in the 1st or 4th webspaces. You can also experience pins and needles and/or numbness as a result of the nerve being affected. The condition tends to occur predominantly in middle aged females.
Morton's neuroma is usually diagnosed by your doctor listening to your symptoms and examining your foot. Sometimes your doctor can feel the 'neuroma', or an area of thickening in your foot, which may be tender. Sometimes, your doctor may suggest an ultrasound scan or MRI scan to confirm the diagnosis but this is not always necessary. Some doctors inject a local anaesthetic into the area where you are experiencing pain. If this causes temporary relief of pain, burning and tingling, it can sometimes help to confirm the diagnosis and show the doctor where the problem is.
Non Surgical Treatment
Wearing shoes that provide enough room in the toe box is also the first step in treating Morton?s neuroma. For instant relief when pain flares up, try taking your shoes off and rubbing the area. The nerve can get trapped below the ligament, and rubbing can move it back to its natural position. Your doctor or a foot-care specialist may recommend lower heels and metatarsal pads. These pads provide cushioning under your neuroma and better arch support to redistribute your weight. If you keep pressure off the toes and wear wide enough shoes, the problem may gradually disappear.
When medications or other treatments do not work, podiatric surgery may be required. The most common surgical procedure for treating Morton?s neuroma is a neurectomy, in which part of the nerve tissue is removed. Although this procedure effectively removes the original neuroma, sometimes scar tissue known as a stump neuroma forms at the site of the incision. This may result in tingling, numbness, or pain following surgery. Surgery is effective in relieving or reducing symptoms for Morton?s neuroma patients in about 75% to 85% of all cases. Occasionally, minimally invasive radio frequency ablation is also used to treat Morton's neuroma.
Wearing proper footwear that minimizes compression of the forefoot can help to prevent the development of and aggravation of a Morton's neuroma.