Morton's neuroma
Morton's neuralgia, Morton's neurinoma, Morton's interdigital neuralgia

A Morton's neuroma is a localized thickening of a sensory nerve located between the toes. Usually this is between the third and fourth toe, counting from the big toe. This swelling is caused by increased pressure on the nerve.

A Morton's neuroma may cause pain and tingling that radiates into the toes. Walking, in particular, can be very unpleasant as a result. This disorder is named after the American surgeon Thomas Morton.

Description of condition

Many nerves branch throughout the foot, including between the tips of the metatarsals under the ball of the foot. That is where a Morton's neuroma can develop.

This condition involves irritation of the nerve, which causes extra nerve tissue to form at that spot. Although this is a benign nerve proliferation, it may still cause unpleasant symptoms. Because it involves a sensory nerve, only sensation is affected in this condition. The motor functions remain intact, so there is no loss of muscle function.

A Morton's neuroma can develop in anyone at any age, but the condition is up to 10 times more common in women.

Cause and history

A Morton's neuroma is caused by pinched and/or damaged nerves, usually between the 3rd and 4th toe. The cause of the entrapment is not always clear, but the condition is often seen in combination with a foot deformity such as flat feet, a splayed foot or high arches. Direct injury to the foot or nerve may also be a cause.

Wearing ill-fitting shoes and shoes that are too tight is an obvious risk factor, which can irritate or damage the affected nerve.

Signs & symptoms

Symptoms that may occur with a Morton's neuroma are:

• Pain under the ball of the foot possibly radiating toward the toes.
  
• The pain increases when weight-bearing or when wearing shoes that are (too) tight or have high heels.
  
• Insensitivity, numbness, prickling and/or tingling of toes.
  
• Taking the load off the foot reduces the symptoms.
  
• Most often present between the 3rd and 4th toe.

Diagnosis

By asking questions of the patient, the doctor or physiotherapist will try to find out what the symptoms are and what is causing them. Then a physical examination is carried out, during which local pressure pain and sensation are examined. This usually provides sufficient information to make the diagnosis of Morton's neuroma.

An ultrasound can confirm the diagnosis and at the same time visualize the size of the neuroma. Possible additional examinations, in the form of MRI or X-ray, may be used to identify any other causes of pain in the foot and toes.

Treatment

A valuable tip is to wear footwear that is not too tight around the front of the foot. It may also be useful to wear a shoe support to increase the space between the metatarsals and so reduce the pressure on the nerve.

A next step might be to get an injection of corticosteroids. Unfortunately, this often only works temporarily because it does not tackle the cause of the symptoms.

Surgery
If these non-surgical treatment methods do not help sufficiently, surgery may be considered. This involves removing the neuroma, with (part of) the nerve it belongs to. This results in permanent numbness in the area that is innervated by this nerve.

Another option is to leave the neuroma where it is, but create more space to reduce the pressure on the neuroma. Afterwards, the annoying feeling caused by the neuroma will often disappear.

The foot is fully healed again after six weeks. To prevent the symptoms from recurring, it is important to wear good shoes and possibly support the foot with an inlay.

Exercises

You can check your symptoms using the online physiotherapy check or make an appointment with a physiotherapy practice in your locality.

References
Brukner, P. & Khan, K. (2010). Clinical sports medicine. McGraw-Hill: Australia. 3e druk.
Brukner, P. & Khan, K. (2016). Clinical sports medicine (Nederlandse bewerking). 4th edition. Michel van Troost. PreVision, Eindhoven.
Verhaar, J.A.N. & Linden, A.J. van der (2005). Orthopedie. Houten: Bohn Stafleu van Loghum.