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Morton's neuroma, also known as plantar neuroma, intermetatarsal neuroma, Morton's metatarsalgia, Morton's neuralgia, or Morton nerve entrapment, is a non-cancerous growth of nerve tissue (neuroma).

Introduction to Morton's neuroma

It develops in the forefoot, usually between the third and fourth toes (in the third webspace). Other less common sites are between the second and third metatarsals (second webspace) and between the first or fourth webspace. The thickening or enlargement of the nerve in a neuroma subsequently causes swelling, and progressively may damage the nerve permanently.

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The condition is the result of nerve compression and irritation which may be caused by injury, irritation, or pressure. Women are more likely to develop this neuroma than men, at a ratio of 5:1. This may be partly attributed to wearing high-heeled, narrow-toed shoes which can compress the second and third interspaces of the forefoot and increase the mechanical stress with walking. In addition, overweight people and individuals who are active in running or sports may also have higher rates of Morton's neuroma. Certain malformations such as flat feet, bunions, or hammertoes may also predispose an individual to this condition.
 

Signs and Symptoms

The symptoms of Morton's neuroma tend to worsen over time, and include the following:

  • Pain while walking - a sharp and burning type of pain may be felt most commonly between the third and fourth toes, after a short time of weight bearing. Rarely the pain may also be dull.
  • Initially, the pain becomes apparent and is aggravated when the individual wears tight, narrow or high-heeled shoes, or does activities that put pressure on the foot. Gradually, symptoms may be persistent, lasting for days and weeks.
  • The pain is usually intermittent. Patients may experience two or three attacks in a week and then none for almost a year. Between attacks, there may be no symptoms or physical signs. Recurrences are variable.
  • Parasthesia – tingling or pricking sensation, known as pins-and-needles may be experienced. Numbness is observed in the toes adjacent to the neuroma and appears to occur together with episodes of pain.
  • The symptoms become more intense as the neuroma enlarges and many affected individuals become apprehensive about walking, or even placing their foot on the ground.


The physical signs of Morton’s neuroma include the following:

  • External signs such as presence of a lump are extremely rare.
  • Firm compression of the metatarsal heads with one hand while applying direct pressure to the dorsal and plantar interspace with the other hand may bring forth radiating neuropathic pain.
  • Positive Mulder’s sign – application of direct pressure between the metatarsal heads will replicate the symptoms, as will compression of the forefoot between the finger and thumb so as to compress the transverse arch of the foot.
  • Passive and active dorsiflexion of the toe may aggravate symptoms.
  • Sensory abnormalities may be observed.
  • Palpation of the affected toe joints may reveal tenderness.
  • An x-ray should be taken to rule out fracture of the foot, arthritis and osteoarthritis.
  • An MRI scan will ensure that the compression is not caused by a tumor. MRI also ascertains the size of the neuroma and the course of treatment - conservative or surgical management.

Treatment of Morton's neuroma

Treatment for Morton's neuroma depends on several factors including the severity and duration of symptoms. Treatment strategies range from conservative to surgical intervention. A conservative approach should include evaluation of shoes for improper support. The first step in the treatment is the modification of footwears. A physical therapist can assist the physician by recommending soft-soled shoes with a wide-toed and low heel shoes.
 

Conservative Approach

The initial management includes the following:

  • Changing footwear - wearing wide-toed, flat shoes.
  • Resting the foot.
  • Massaging the foot and affected toes.
  • Using an ice pack on the affected area.
  • Using arch supports or custom-fitted orthotic devices - padding that provide support for the metatarsal arch, thereby reducing the pressure on the nerve and decreasing the compression when walking can be used. There are several metatarsal pads available OTC (over the counter) which can be placed over the neuroma.
  • Modification of activities - avoid activities which put constant pressure on the neuroma.
  • Weight reduction - significant number of obese patients with foot problems such as flat feet experience considerable improvement of symptoms on losing weight.
  • Use of non-steroidal anti-inflammatory drugs such as Ibuprofen may help reduce the pain and inflammation.
  • If symptoms are severe or persistent, the following treatment options may be recommended:
  • Corticosteroid injections – help to reduce pain and inflammation when injected into the area of the neuroma. However, the number of injections is limited due to the risk of adverse side effects including increase in blood pressure and weight gain.
  • Alcohol sclerosing injections - alcohol injections may help to ease pain and reduce the size of Morton's neuromas. Injections are usually administered every seven to ten days, and four to seven injections may be required for maximum benefit.

Read More: Morton's Neuroma

Surgical Intervention

When conservative approaches in the management fail, surgical excision of the fibrosed area may be curative. Surgery involves either removing the nerve, or removing the pressure on the nerve.

There are two surgical approaches:

  • The dorsal approach which allows an incision to be made on the top of the foot helps the patient to walk soon after surgery.
  • The plantar approach involves the incision to be made on the sole of the foot, thereby allowing the neuroma to be reached easily and removed without cutting other structures. However, the patient must use crutches for about three weeks and the resultant scar can make walking uncomfortable.

Chronic pain may develop when the treatment of Morton’s neuroma is unsuccessful. Postoperative complications such as dysesthesias (impairment sensation, especially that of touch), are possible when surgery is performed. Complications following corticosteroid injections may include transient numbness of the toes and plantar fat pad necrosis (death of fat tissues).

  • emedicine.medscape.com/article/308284-overview
  • www.mdguidelines.com/mortons-neuroma
  • www.steadyhealth.com/articles/Morton_s_Neuroma__Symptoms___Treatment_a260.html
  • www.joacp.org/index.php?