Morton’s neuroma is a foot condition in which the nerve sheath of a digital nerve between the third and fourth metatarsals (i.e. the third / fourth web space) is irritated and enlarged. Neuromas can develop in any web spaces, but only one that develops in the third / fourth web space is called Morton’s Neuroma.
Patients who have Morton’s Neuroma often complain about pain (stabbing pain, shooting pain, pins and needles, or electrical shock type pain), numbness, and feeling a lump / pebble in the shoe when walking. The pain is usually at the web space but sometimes can radiate to the toes. Also, it is not always there – it can come and go!
There are several factors that can cause Morton’s Neuroma. For example, your foot type – both flat foot (pes planus) and high-arch foot (pes cavus), can lead to the development of neuroma. In the flatfoot type, hypermobility of the forefoot due to over-pronation can cause nerve irritation and compression. There is an excessive forefoot loading on high-arch foot type when weight bearing, which can cause compression of the digital nerve. Similarly, people who are actively involved in a sport, such as running and racquet sports, that put pressure on the forefoot are often affected via the same mechanism.
Ill-fitting or impractical footwear is another common cause - high heeled shoes and flat shoes with a narrow toe box can both create a problem. This might explain why nearly five times more women than men get this condition!
The diagnosis of Morton’s neuroma is easy. Your health practitioners can use some clinical tests, such as Mulder’s click or Gauthier test, along with your signs and symptoms to make a diagnosis. But the definite diagnosis is done by ultrasound or MRI. This is because some other foot conditions (such as bursitis and synovitis) can mimic Morton’s neuroma. Ultrasound and MRI can help to rule these out.
The treatment is closely linked to the causes. If footwear is the problem, avoiding narrow, high heeled shoes may just do the trick. If the foot type is the cause, your podiatrist can indirectly treat it by prescribing you some insoles to treat hypermobility, to redistribute your plantar pressure or to improve shock absorbency.
For small neuromas, a steroid injection or alcohol injection ablation can help. There is a relatively new method called Cryosurgery (i.e. freezing and so destroying the neuroma via inserting a small probe into the foot) to treat neuroma, which has been popular in the United States.
However, if all of these conservative treatments fail or the neuromas are too big and persistent, surgical removal of the neuroma is a last resort. A side-effect of the surgery is often to leave the area permanently numb and patients can have post-operative complications, such as stump neuroma formation, scar tissue problems and digital deformity.
Other Neuromas / Conditions
It should be notes that neuromas which develop in other web spaces have different names. Misunderstandings sometimes arrive when both patients and medical practitioners, including many GPs, refer to all foot neuromas as Morton’s neuroma. This is probably because the third / fourth web space is the most common place for neuroma formation and so that the name is more well-known.
A neuroma that develops in the first/second web space is called Houser’s neuroma; one that affects the second / third web space is called Heuter’s neuroma; one that is in the fourth / fifth web space is called Islen’s neuroma.
Finally, Joplins neuroma refers to a painful condition of the medial digital nerve to the hallux (the big toe).
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