Morton's neuroma: causes, symptoms, diagnosis and treatment

By Cristiano Antonino On Jul 20, 2023

Morton’s Neuroma is a particular pathology affecting the foot, specifically the nerves. This disease is named after the doctor who discovered it, Thomas G. Morton, who in 1876 discovered a pathology due to swelling of an interdigital sensory nerve in the foot

Morton’s neuroma is in fact characterised by a thickening and subsequent compression of the nerves of the foot known as the ‘interdigital’ nerves.

The symptoms of this disease are unfortunately very painful, which is why it is important to seek a rapid diagnosis so that the necessary treatment can be obtained and future complications are not risked.

Morton’s disease mainly affects adults, particularly female patients.

The majority of those who suffer from this disease are in fact women between 40 and 50 years of age.

It is rarer, however, for this pathology to affect men and patients under 35 years of age.

Here is all the information on this pathology, such as symptoms, causes and treatments.

What is Morton’s Neuroma

Morton’s neuroma is known by several names, such as interdigital neuroma or Morton’s metatarsalgia.

This condition, which is much more common in women than in men, is a degenerative condition of the plantar nerve.

Symptoms may affect one or both feet and one or more plantar spokes, thus involving different parts of the foot.

It usually affects the interdigital nerve between the third and fourth metatarsals.

The basis of the symptomatology is severe pain between the metatarsal heads, in particular this pathology affects the digital nerves that are located between two neighbouring toes.

Morton’s pathology is characterised by a slow but steady increase in size of the nerve, which thus leads to the swelling noted by Dr. Thomas G. Morton.

This swelling is the main symptom, along with pain, of this pathology and is the consequence of a progressive proliferation of fibrous tissue.

As the diameter of this area increases, there is pressure and progressive thinning of the nerve fibres.

Which parts of the body are affected by Morton’s Neuroma

Before understanding what Morton’s Neuroma is, it is important to understand the functioning and structure of the foot so that it is clear which areas are affected by this pathology.

One must consider the bone structure in particular, as the foot is composed of different types of bones: tarsals, metatarsals and phalanges.

The tarsus is the group of bones that connects the ankle to the phalanges of the toes.

Between the tarsus and the phalanges is the metatarsal, which can be divided into five bones, one for each phalanx.

Morton’s Neuroma usually affects the nerves near the metatarsus, creating a fibrosis of the tissue that reaches the sensory nerve.

This interdigital nerve is thus compressed, causing the pain.

Usually the nerve most affected by this pathology is the one between the third and fourth metatarsals, while those of the second and third metatarsals and the first and second metatarsals are rarer.

Symptoms of Morton’s Neuroma

There are usually four symptoms and they can change in intensity depending on the stage the condition is at.

Among the most common symptoms among patients suffering from this degenerative disease are:

severe pain
burning
numbness in the foot
continuous tingling (paresthesia)

Special attention should be paid to the type of pain that Morton’s Neuroma causes.

The pain that characterises this condition is indeed very strong, often compared to a sudden twinge or an electric shock.

Especially at the beginning, this pain is not constant but alternates with moments of peace, i.e. a lack of symptoms and pain.

These sudden twinges, which are especially characteristic of the onset of the disease, thus force Morton’s Neuroma sufferers to feel the need to remain shoeless and at rest.

Despite this condition, however, the neuroma can also affect lying or sitting and even sleeping.

Causes

Studies on the causes of Morton’s Neuroma are still ongoing and at present, the real reason why this degenerative disease occurs is still not entirely clear.

Certainly, there are several factors that can lead to an increased likelihood of incurring it and several patient characteristics that lead to an increased predisposition to the disease.

Among the risk factors for Morton’s Neuroma are:

the structure of the foot, as the anatomy of the foot is certainly one of the aspects that most appears to influence susceptibility to this pathology. Those who have a smaller space between one metatarsal and the other, in fact, are more prone to contract this disease. The smaller space between the bones makes rubbing and greater interdigital sensitivity easier;
abnormalities and deformities of the feet can also lead to a predisposition for this disease;
postural factors can lead to poorer balance in foot support, as well as overloading of a specific area of the foot, which can lead to nerve entrapment;
wearing narrow or uncomfortable shoes can lead to a crushing of the foot and, consequently, to the appearance of Morton’s Neuroma;
trauma of various kinds.

How to diagnose Morton’s Neuroma

Making a timely diagnosis of Norton’s Neuroma is essential because only after a careful examination is it possible to have the prescription of targeted and effective treatments.

The first step in obtaining an accurate diagnosis is certainly to have a discussion with one’s GP to check that the symptoms correspond to a possible nerve problem.

The doctor may also request a specialist examination, during which various tests may be requested, including

X-rays of the feet under load. These tests are used to rule out possible problems with similar symptoms. Swelling and pain may in fact usually be related to microfractures or other bone problems. Neuroma cannot be diagnosed by an X-ray, but this test can be used to rule out other conditions;
following the X-ray, an ultrasound scan may be prescribed, in which an initial diagnosis of Norton’s Neuroma can be detected and made. Ultrasound can also be used to rule out many pathologies, such as bursitis or capsulitis;
an electroneuromyography, if the question is specific, can detect the problem through interdigital nerve conduction studies;
finally, if further investigation is needed to identify the specific area to be treated, an MRI may be required.

Treatments for Morton’s Neuroma

As mentioned above, diagnosing Morton’s Neuroma at an early stage is crucial in order to obtain a treatment that can help one live with this degenerative condition.

When the neuroma is detected in the early stages of the disease, i.e. when it has been present for less than six months, it is possible to adopt treatments that can greatly help with this problem and to live with it.

Among the best known and most widely used therapies for Morton’s Neuroma at this stage are:

physiotherapy, which is done constantly and often with the use of technology such as ultrasound and laser to increase its effectiveness;
sclero-alcoholisation, i.e. the injection of diluted alcohol that weakens the nerve sheaths, making them softer and significantly reducing pain. This type of treatment is not always effective: it is estimated that 20% of people with Morton’s Neuroma do not experience relief from this technique;
cryotherapy, which uses cold and its analgesic effect to reduce pain and swelling. Cold also decreases the speed of signal transmission through the nerves;
the use of orthotics is a more traditional and certainly less innovative method, but it helps to obtain a benefit when walking. Despite this initial benefit, it is essential to combine this with therapy.

In cases where the diagnosis of Norton’s Neuroma is later, it is possible to proceed towards pharmacological treatment instead.

There are several drugs that can be prescribed when suffering from this degenerative condition.

The most common are:

Anti-inflammatories, to reduce pain and decrease inflammation. Corticosteroids are often prescribed orally or through local infiltrations.
Anaesthetics, which may be prescribed in cases of severe pain, particularly in local form.
Often, these pharmacological treatments are discontinued or their dosages are changed as many of these drugs, particularly corticosteroid treatments, can lead to ligament and tendon damage in the foot.
Finally, surgery may be recommended in more complex cases.

This operation is prescribed when symptoms have been present for at least 6 months and the methods prescribed above are ineffective.