Morton’s Neuroma is a fairly common foot disease. In particular, it is a metatarsalgia: an inflammatory pain in the metatarsals located in the front part of the foot.
By Morton’s Neuroma we mean a suffering of the III common digital nerve, an exclusively sensory nerve that innervates the 3rd and 4th toe, caused by chronic microtraumas at the point of transition between the heads of the III and IV metatarsals.
Among the symptoms, the most distinctive is localized pain. It is generally a pain that occurs in sharp pains rather than being constant, patients describe it as a burning or like electric shocks inside the foot.
The actual causes are unknown. Sometimes facilitating factors can be identified, such as:
- The excessive proximity between two metatarsal heads which over time can end up causing a constant microtrauma on the nerve in that location.
- Compression exerted by a metatarsal ligament that is too tight: some consider it, in fact, as a canalicular syndrome, i.e. a nerve compression caused by a “bottleneck” along its course.
- Presence of a pes cavus with excessive load on the anterior part and therefore repeated micro trauma on the nerve in this anatomical area.
The therapies can be, at first, conservative and, therefore, do not require the use of surgery. For example, let’s talk about cortisone infiltrations. However, this approach does not always lead to definitive results, since the pain often tends to recur and it is not recommended to repeat cortisone infiltrations for too long. If the size of the neuroma exceeds 4-5 mm, surgical treatment is recommended.
What is Morton’s Neuroma?
Morton’s Neuroma, also known as Morton’s disease or Morton syndrome, is a degenerative disease affecting the interdigital nerve.
In the front part of the foot there are five bones, called metatarsal bones or metatarsals, from which the phalanges that make up the toes start. The term metatarsalgia indicates an inflammatory pain that affects this area of the foot. Metatarsalgia can have different causes.
Morton’s is linked to a continuous stress of one of the interdigital nerves (nerves that run under and between the metatarsals), which causes the formation of excess fibrous tissue and therefore a thickening in a section of the nerve. It is precisely this thickening that takes the name of “neuroma”.
It develops as a result of compressive microtraumas which, over time, lead to the formation of fibrous tissue within the nerve and therefore increase its size. Passing between the heads of the metatarsals, the thickened nerve is compressed and hence the symptoms.
The causes of these microtraumas can be found in the conformation of the foot: hallux valgus, flat foot or cavus foot, are all conditions that are associated with a forefoot support problem.
But how does Morton’s Neuroma differ from other metatarsalgias? We immediately recognize it from a stabbing pain, similar to an electric shock, associated above all with foot support, which radiates towards the toes and from which the patient often finds relief only by taking off his shoes.
The pain, however, is not constant, but alternates with asymptomatic moments (even days) and can also appear associated with tingling, or with the foot at rest, even while sleeping.
Symptoms of Morton’s Neuroma
Among the symptoms of Morton’s Neuroma in the foot, the most distinctive is localized pain. It is generally a pain that occurs in sharp pains rather than being constant, patients describe it as a burning or like electric shocks inside the foot.
At the beginning the stitches can also be rare and alternate with moments of no pain. With the persistence of the pathology, they become more and more frequent. Furthermore, the pain is also perceived on palpation of the point where the Neuroma was formed. Some patients report pain in the entire forefoot, not just in correspondence with the metatarsals, because the pain can radiate laterally or forward, also involving the toes. Another symptom that may appear after some time is tingling or loss of sensation in that area of the foot.
The pain is exacerbated by walking but can also occur at rest and the symptoms can occur daily or only on a few particular days.
If the specialist properly investigates the type and appearance of pain in the patient, the diagnosis can be simpler than it seems.
In the case of mechanical metatarsalgia, in fact, there will be plantar hyperkeratosis (plantar callosity under the sole of the foot at the level of the metatarsal heads). The pain will be exacerbated by acupressure of the metatarsal heads and if observed standing while walking, the patient will most likely present with a valgus or rigid hallux, perhaps in the initial phase and therefore not yet symptomatic.
In the case of Morton’s Neuroma, the pain will be limited to the third inter-metatarsal space, and we will not have plantar hyperkeratosis. But the Mulder test will be positive (Mulder’s sign).
By pressing the foot laterally, a classic “click” is felt at the level of the third interdigital space and the patient perceives the pain under the sole of the foot typical of the shock.
If we talk about mechanical metatarsalgia, the patient has pain right at the level of the metatarsals, it is a pain that is always present both with bare feet and with shoes. Conversely, in Morton’s Neuroma, the patient reports a burning, jerking pain, which can be relieved by removing the shoe and walking barefoot. THE
It can occur at any age, but women between the ages of 40 and 50 are most commonly affected. Why are women more affected? For the type of footwear they most frequently wear! Heeled shoes.
Causes and risk factors
The causes in Morton’s Neuroma are unknown. However, there are several risk factors, such as the use of inadequate footwear, postural imbalances, morphological alterations of the foot, rheumatoid arthritis, trauma or repetitive stress.
As stated above, there is no single cause that causes Morton’s disease. However, the study of the pathology has identified a series of factors that negatively stimulate the interdigital nerves and make them more prone to the development of the pathology.
The causes in Morton’s Neuroma: most common factors
The most common factors are:
- The habitual use of high heels, which leads to greater weight being loaded on the forefoot. It may also be for this reason that Morton’s syndrome generally affects women more.
- The use of narrow footwear that compresses the forefoot, especially the metatarsal heads.
- Hollow foot, because even if to a lesser extent than with high heels, the fact of not fully supporting the sole because the plantar arch is very accentuated, in any case involves a distribution of the load more inclined towards the front part of the foot.
- Obesity or a significant state of being overweight. This, as we know, is a factor that affects many pathologies.
- Constant practice of running or walking, due to the continuous micro-traumas to which the feet are inevitably subjected during these sports.
- Some congenital malformation of the foot, even slight. For example, if two metatarsal heads are too close together, they already put the nerve into a state of compression.
- Hallux valgus. This is often associated with the onset of Morton’s Neuroma for the same reason as the previous factor. With the only difference that hallux valgus is not congenital but occurs with age.
- Incorrect foot posture. Many people land their foot badly when walking and are not aware of it. In the long run, this can cause various problems and pains, including Morton’s Neuroma. That is why it is advisable to always carry out a preventive gait analysis.
- Trauma, such as a broken bone in the foot or a sprain resulting in swelling.
- In diabetic patients it is necessary to pay greater attention because the increase in pressure at the plantar level is a risk factor for skin ulceration with the consequent development of an entrapment of the nerve itself or of the Neuroma where present.
Diagnostics and instrumental tests
The diagnosis of Morton’s Neuroma is made by analyzing the patient’s clinical history, and by carrying out clinical and instrumental tests. Deformities of the toes, pes cavus or pes pes cavus, and previous metatarsal osteotomies may be contributory factors, but may not be implicated as the main causative factors of Morton’s neuroma, which may also be idiopathic in origin.
The most commonly used clinical tests are Mulder’s sign, which is performed by compressing the forefoot in a transverse direction and simultaneously applying plantar and dorsal pressure with the other hand. The positive result is a “click”, often painful for the patient, which can be felt by the doctor.
Following the visit, the orthopedist may prescribe further examinations such as an x-ray of the foot, an ultrasound or an MRI. He will determine the most suitable test to perform for a correct diagnosis. Only after a confirmation of Morton’s Neuroma, he will define the treatment to follow, which can be conservative or surgical.
Conservative treatment is aimed at reducing inflammation and pain. Examples are cortisone injections, the use of orthotics or physiotherapy…