What is a Morton’s (Interdigital) Neuroma?
A Morton’s neuroma is condition that affects the nerve as it passes between the bones at the base of two of the toes it occurs most commonly between the third and fourth toe.
Why does it develop?
There are a number of reasons why the changes that occur in the nerve, are thought to develop.
– the wearing of high heels is thought to increase the pressure on (and thereby damage to) the digital nerve by the overlying transverse intermetatarsal ligament
– trauma to the foot can either directly or indirectly lead to the damage to the nerve
– the presence of any mass (swelling) in the space around the nerve can cause pressure on and damage to the nerve
There are also features of the anatomy of the foot that mean that the nerve between the third and fourth toes is most vulnerable to damage.
What symptoms does it cause?
Pain: this is felt in the ’ball’ of the foot and may radiate to the toes, the affected toes potentially feeling numb. It may be burning, aching or cramping in nature and classically occurs when wearing tight shoes and is relieved by removing them. It may cause pain at other times, both in and out of shoes and is usually increased with walking, easing with rest.
What options are there for treatment?
Shoes with a wide toe box (the region of the shoe in which the toes lie) allow the metatarsals to spread out thereby reducing the pressure on the nerve.
b. Pain relieving medication
Simple pain ’killers’ or anti-inflammatory medication can ease the discomfort.
Injections around the affected nerve can be performed with or without the guidance of ultrasound, these ease the pain significantly in about 2/3 of patients.
Insoles (orthotics) with a metatarsal dome relieve the pressure from under the metatarsal heads and allows them to spread out a little can ease the pain in some patients. Metatarsal pads can be placed in the shoes in an attempt to achieve the same objective, however these need to be correctly placed and often slide around in the shoe and therefore may not be effective.
If the above measures have failed to adequately control the pain then surgery can be considered, this involves removal of the affected nerve (or occasionally just decompression of the nerve) and is usually performed as a day case. (see: Morton’s Neuroma Excision).