15 Mar Let’s Talk about Morton’s Neuroma
The condition often referred to as Morton’s neuroma, which was named after Dr Morton who first described this condition in 1876, describes a neuroma (thickening and swollen nerve fibre) located between the long bones (metatarsals) of the foot
Due to the intimacy of the interdigital nerves and the long bones in the foot, the nerves are readily compressed between the long bones during walking and running.
It most commonly affects the nerve between the third and fourth metatarsal bones, causing pain and numbness in the third and fourth toes, but can also affect the nerve between the second and third metatarsal bones, causing symptoms in the second and third toes.
Morton’s neuroma can affect one, or less commonly, both feet.
What causes a neuroma?
There are a number of theories to what causes the neuroma formation:
- Mechanical compression (squeezing) is the obvious culprit resulting in long-standing (chronic) stress and irritation of a plantar digital nerve gets pinched between the metatarsals, imagine trapping an elastic band with chopsticks and that crudely helps picture the type of mechanism involved. This leads to thickening (fibrosis) and swelling may then develop around a part of the nerve. The largest contribution to the compression is footwear and footwear fit.
- Anatomy of the bones of the foot is also thought to contribute to the development of a neuroma. The space between the long bones in the foot is narrower between the second and third, and between the third and fourth metatarsals. This means that the nerves that run between these metatarsals are more likely to be compressed and irritated.
Who gets a neuroma?
There is no one group of people that will develop a neuroma but there are a number of associated findings with the condition:
- Approximately 70% of the neuromas are in female feet.
- It commonly affects people between the ages of 40 and 50 but can occur at any age.
- The foot structure tends to be wider than the average foot size.
The relevance of the wider foot and the female foot is in regard to footwear suitability regarding fit. Poorly fitting or constricting shoes can contribute to a neuroma and the last fitting of female footwear tends be a narrow when compared against the actual female foot size.
- It is more common in women who habitually wear high-heeled shoes or in men who wear slip on footwear.
- Participating in high-impact athletic activities such as running subject the feet to repetitive trauma and this increases the risk of developing problems at a foot level but is not guaranteed to.
- Sports that feature tight footwear and synthetic uppers, such as skiing or rock climbing and cycling can increase the compression acting on the forefoot and lead to neuroma formation.
- Multi-directional sports on hard surfaces such as tennis and other racquet sports increase the mechanical load acting on the forefoot and create a shearing (sliding) force on the forefoot and this can lead to symptoms.
What are the symptoms of Morton’s neuroma?
Symptoms can include:
- Pain that can start in the ball of the foot and shoot into the affected toes.
- Non specific toe pain, generally in toes 2-4.
- Burning and tingling of the toes.
- The feeling of walking on a stone or a marble under the front of the foot.
The symptoms can vary and may come and go over a number of years. Some people may experience two attacks of pain in a week and then nothing for a year. Others may have regular and persistent (chronic) pain.
How is Morton’s neuroma diagnosed?
Diagnosis is made according to the description and location of the symptoms alongside some simple clinical tests performed during a foot examination.
During the examination the neuroma can be felt as an area of thickening in your foot and this may be tender when squeezed.
Ultrasound or an MRI scan can be used to confirm the diagnosis but this is not always necessary. A diagnostic local anesthetic can also be injected into the area where you are experiencing pain and if this causes temporary relief from the symptoms it can sometimes help to confirm the diagnosis.
What are the treatment options for a neuroma?
Simple treatments may be all that are needed for some people with a neuroma, these include:
- Correct Footwear to ensure appropriate fit and also includes avoidance of high-heeled shoes which will increase the forefoot pressure.
- Insoles / Orthotics can help in influencing foot position and also be designed to improve how pressure is absorbed at the front of the foot.
- Steroid or local anaesthetic injections (or a combination of both) into the affected area of the foot may be needed if the simple footwear changes do not fully relieve symptoms. However, the footwear modification measures should still be continued.
- Sclerosant injections involve the injection of alcohol and local anaesthetic into the affected nerve under the guidance of an ultrasound scan. Some studies have shown this to be as effective as surgery.
- Cryotherapy or freezing is sometimes used but is not widely available in the UK.
What is the outlook (prognosis) for neuroma management?
In the main the majority (70%) of neuroma’s are responsive to conservative (non surgical) intervention. The duration of time the individual has had symptoms for can be an important factor in the response to conservative treatment.
Generally, the longer the symptoms the greater the degree of nerve fibre thickening and swelling and the higher the risk of needing treatments that are more interventional such as injections and surgery.
Seek a professional opinion on any forefoot pain or foot pain in general as early as possible particularly if the pain is associated with wearing footwear and occurs during weight bearing activity.
Blog compiled by Mark Gallagher, Podiatrist at Halo
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