Generality
Morton's neuroma is a painful condition that affects one of the nerves in the foot. In addition to pain, the patient also experiences burning, tingling and numbness in some areas of the affected foot.
The treatment includes both a conservative therapy and a surgical therapy. The procedure is usually conservative, as it is less invasive. If this is not effective, the patient can undergo surgery, not without possible complications.
Anatomy of the foot
Before describing Morton's neuroma, it is helpful to remind readers of the bone structure of the foot.
The foot is composed mainly of:
- Tarsal bones
- Metatarsal bones
- Phalanges
The metatarsal bones (or metatarsals ) are 5, arranged parallel to each other. These are long bones, at the ends of which the phalanges are articulated.
Finally, the phalanges are 14 and form the toes. Except for the big toe which is made up of 2 phalanges, all the other toes have 3 for each.
What is Morton's neuroma
Morton's neuroma is a disease that affects one of the interdigital sensory nerves of the foot. These nerves flank the metatarsal bones and reach the toes.
The term neuroma leads us to think that it is a tumor, but in reality it is not. In fact, it is a fibrosis of the nervous tissue that surrounds the affected interdigital sensory nerve.
This fibrosis appears as a thickening, which, in some cases, can feel to the touch.
Morton's neuroma sufferers experience a painful sensation at the point where fibrosis developed and at the level of the fingers reached by the affected nerve.
Figure: it is possible to recognize the interdigital nerve (in red), which runs along the two metatarsals and reaches the phalanges. Image taken from ortopediabenassini.it
WHAT IS THE NERVO MOST IMPRESSED?
The nerve most prone to fibrosis is that between the third and fourth metatarsus.
Although less frequent than the previous one, nerve fibrosis between the second and third metatarsus is also quite common. Rare, instead, are the fibrosis between the fourth and fifth metatarsal and between the first and the second.
It is very unlikely that two neuromas will develop simultaneously and in the same foot.
Epidemiology
Morton's neuroma can occur at any age, but it mostly affects individuals between the ages of 40 and 50. Three out of four people who present the disease are women.
Causes
The precise cause of Morton's neuroma is unknown. The hypotheses are different; the most accredited claims that fibrosis results from mechanical stress, equivalent to rubbing, on an interdigital nerve and metatarsal bones on its sides. This continuous rubbing determines the formation, around the nerve, of a voluminous scar tissue (hence the term fibrosis), which compresses the nerve itself, causing pain.
RISK FACTORS
As we have mentioned, some interdigital nerves are more prone to develop Morton's neuroma.
For what reason?
For anatomical reasons, related to the human foot. In fact, the space between the different metatarsals is not constant, but varies according to the metatarsal considered. Where metatarsals are closest to each other (ie between the third and fourth and second and third), rubbing between the nerve and the metatarsal bones surrounding it occurs most frequently. In some people, this anatomical feature is more pronounced and predisposes more to the disease.
Other risk factors, which predispose to Morton's neuroma, are:
- High- heeled shoes, which cause excessive stress on the toes. This explains why women are most affected.
- Shoes that are too tight, which cause a compression of the spaces between the metatarsals where the nerves reside. This is what happens to some sportsmen, such as footballers, mountaineers or skiers.
- Repetitive trauma or stress, due to the practice of sports such as running or dancing.
- Deformity of the feet, for example: flat feet, corns or hammered toes.
Symptoms and signs
To learn more: Symptoms Neuroma of Morton
The main symptoms of Morton's neuroma are:
- Ache
- heartburn
- Numbness
- Tingling
These symptoms are felt both walking and at rest. Their appearance varies from patient to patient: in fact, in some, they take on the appearance of chronic / daily disorders; in someone else, they appear instead in a transitory way.
The extent of the symptoms, very often, leads the patient to take off his shoes and massage the painful area.
The classic sign of Morton's neuroma is Mulder's sign . Although it is less indicative of the disease, even the perception, to the touch, of a slight depression can help the doctor in the diagnosis.
ACHE
The sensation of pain is felt in the forefoot area and in the toes. It is easy to guess the affected interdigital nerve, since the pain is concentrated between the two inner faces of the affected fingers. For example, when the neuroma develops between the third and fourth metatarsus of the right foot, the patient complains of a painful disorder in the two opposite regions of the third and fourth toes.
BURNING
It is felt on the sole of the foot and can radiate to the fingers reached by Morton's nerve-stricken nerve.
INTORIPIDIUS AND FORMICOLIO
Figure: maneuvers to perceive the so-called Mulder sign
The affected area is the same in which there is pain and burning. Numbness and tingling can be accentuated if you wear high-heeled shoes or shoes that are too tight.
SIGN OF MULDER
It is a click, which the doctor can warn by practicing a double and contemporary compression in well-defined areas of the foot. The first, on the sides of the sore metatarsus, with one hand. The second, with the other hand, in the interdigital area, where pain is perceived.
Diagnosis
In most cases, the diagnosis of Morton's neuroma is based on the medical history (that is, the description of symptoms exhibited by the patient) and the sign of Mulder .
The perception of the depression, on the other hand, is not always reliable, as it may indicate a different pathological circumstance, for example a microfracture.
Due to the similarity of symptoms, Morton's neuroma can be confused with:
- Capsulitis, ie inflammation of the metatarsal ligaments
- Bursitis and arthritis
- Microfractures
- Metatarsal osteochondrosis, also known as Freiberg's disease
Therefore, for greater safety, the doctor can subject the patient to three different diagnostic tests: X-rays, ultrasound and nuclear magnetic resonance.
Through them, the pre-diagnosis is ascertained and other pathological disorders are excluded.
The following table summarizes the instrumental tests to undergo to confirm Morton's neuroma.
| Diagnostic examination | Why is it run? |
| X-ray | It serves to exclude:
|
| Ultrasound | It reveals:
|
| Nuclear magnetic resonance | It reveals:
|
Therapy
To learn more: Morton's Neuroma Cure Drugs
Morton's neuroma therapy can be conservative or surgical.
Conservative therapy aims to solve the problem in the least invasive way possible, without removing the portion of nerve affected by fibrosis. In this regard, several treatments have been completed. They consist of:
- Use of special orthotics
- Local cortisone injection
- Sclero-PEI
- Cryotherapy
- Physiotherapy
If these treatments do not have the desired effect, surgery must be used.
Surgery is called neurectomy .
NB: for those suffering from Morton's neuroma, it is recommended, first of all, not to wear shoes that are too tight or heels. It should not be forgotten that this is the first therapeutic measure to be implemented.
Conservative Therapy
orthotics
The orthotics are usually tailor-made for the patient. They are positioned at the forefoot, inside the shoe. Their function is to decrease the compression of the area where the fibrosis was formed and to increase the space between the metatarsal bones.
cortisone injection
Cortisone injection is local, that is directly at the point where the ultrasound has identified the neuroma. Cortisone is also associated with an anesthetic solution. The function of the treatment is to reduce inflammation and irritation caused by the rubbing of the interdigital nerve against metatarsals. As a result, pain should also be alleviated.
Disadvantages : the treatment has, in some cases, temporary efficacy. In fact, after a period of relief, the painful sensation may reappear. In these circumstances, further injections of cortisone can damage the tendon and ligament tissue of the foot.
Scléro-FORTIFICATION
The sclero-alcoholization is a technique being perfected, but it seems to be a valid alternative to cortisone and surgery. It consists in the preparation of a solution based on diluted alcohol, which is injected into the neuroma area.
Alcohol has a toxic function on the scar tissue of fibrosis. They are carried out from 2 to 7 injections per treatment cycle. Between one cycle and another, you must wait 7 to 21 days.
Benefits: pain reduction, even when the patient walks.
CRYOTHERAPY
Cryotherapy is a minimally invasive therapeutic practice, which involves reaching temperatures close to -100 ° C. In this way, the aim is to interrupt nerve transmission, which causes the patient to feel pain. It is not always effective and the problems can recur.
PHYSIOTHERAPY
Physiotherapy consists of performing stretching exercises, which help the patient to reduce compression on the foot.
Surgical intervention
Morton's neuroma surgical therapy consists of neuroctomy .
Usually, neuroctomy consists in removing part of the nerve affected by the neuroma. But, in some cases, it can also be limited to creating more space around the nerve compressed by scar tissue.
The surgical incision needed to operate can be made on the back of the foot or on the plant.
The following table shows the advantages and disadvantages of the two engraving methods.
| Surgery | Advantages | Disadvantages |
| Incision on the back of the foot | Faster post-operative course | The nerve is covered by the transverse metatarsal ligament. This must be removed in order to reach the affected nerve |
| Incision on the sole of the foot | You have direct access to the nerve to be removed | Very long post-operative course. The sole of the foot is the most stressed point when walking; consequently, an incision in this area heals very slowly |
Surgery is often decisive. However, as in all surgical operations, complications can occur:
- In some patients, the post-operative course is characterized by the re-formation of new scar tissue at the point where neurectomy was performed. This causes the symptoms prior to the operation to recur.
- Nerve removal can result in a permanent sensation of numbness in the fingers affected by the neuroma.
- At the point of incision an infection or a callous area may develop, known as plantar keratosis .
Prognosis and prevention
The prognosis of Morton's neuroma varies from patient to patient. Therefore, it is opportune to make some premises. First of all, the anatomy of each individual's foot plays a fundamental role on the responses to conservative and surgical therapies. Secondly, it is very important not to wear shoes that compress the interdigital nerves anymore. This last measure is both a therapeutic and a preventive measure.
STATISTICS
It has been observed that about one person in four does not require any surgery. In these cases, it is sufficient to undergo a cortisone / anesthetic treatment and change the shoes used.
Three out of four people, on the other hand, who have undergone neurectomy, show excellent recovery results. However, when the operation is not successful, Morton's neuroma returns, even in a more acute form.
