Generality
When we talk about myositis we refer to a "muscle inflammation that causes feelings of weakness and pain in the affected muscles.
To make a correct diagnosis of myositis, you need a careful physical examination supported by blood tests, biopsy of the affected tissue and several instrumental tests.
If you intervene early and if the myositis is not particularly severe, the therapy can have satisfactory results.
What is myositis?
The medical term myositis indicates a particular pathological condition, characterized by an "inflammation of the muscles of the body.
When myositis is in progress, the muscle fibers that make up our muscles deteriorate. Initially, the damage only causes weakness (asthenia) and muscle pain (myalgia) upon contraction; later, it can also cause muscle atrophy.
Although, in most cases, myositis tends to resolve in a positive way, it should be noted that when it is not treated properly it can have serious consequences.
What is muscle atrophy?
Muscle atrophy means a reduction in muscle mass (or tone), which significantly reduces the capacity of the affected muscles. In other words, an atrophied muscle is a weak muscle, as if it is lacking in strength.
The most common causes of atrophy are very often linked to complete physical inactivity, immobilization of a limb (after a fracture), starvation or liver failure.
WHERE DOES MYOSITE ACT? MUSCLES AND NOT ONLY
Myositis mainly affects the proximal voluntary musculature, that is, all those muscles that allow movement and that are close to the trunk.
Therefore, the areas most affected by the disorder are the neck, shoulders, hips, thighs and arms.
Figure: the arm muscles of a healthy individual (left) and an individual with myositis (right). The reduction in muscle tone is evident, ie the atrophy. From the site: helpmedico.com
Furthermore, in some particular forms of myositis, or when treatments are not adequate, the distal voluntary muscles of the limbs (for example, at the calf level), the smooth muscles (of the respiratory, circulatory and digestive systems) may also be involved, the joints and ligaments.
Causes
There are many forms of myositis. Their classification is based, for reasons of convenience, on the triggering causes. It should be pointed out that not all forms of muscle inflammation expand and affect more muscles; some, in fact, remain confined to the point of onset.
THE TYPES OF MYOSITE
- Idiopathic inflammatory myopathies. They include all the rare forms of myositis that cannot be given an etiological explanation (the cause cannot be identified). The term "idiopathic" means just that. The main forms are: idiopathic polymyositis, idiopathic dermatomyositis and inclusion body myositis. Very often, these forms of myositis have characteristics of autoimmune diseases, in which the immune system, instead of defending the organism, turns against it, attacking it.
- Infectious myositis. Some viruses, parasites and bacteria can invade our body and muscles causing myositis. The microorganisms most commonly involved are influenza viruses, some respiratory tract viruses, the AIDS virus, the Trichinella parasite and staphylococcal bacteria. The latter are widespread above all in countries with a tropical climate and where health care is insufficient. Viruses, on the other hand, tend to manifest themselves in acute forms.
- Myositis associated with other pathologies. Some myositis arise in association with other diseases.
Diseases associated with myositis:
- Systemic lupus erythematosus
- Myasthenia gravis
- Hashimoto's thyroiditis
- Tumor of the ovary
- Lung cancer
- Breast cancer
- Scleroderma
- Neoplasms in general
- Myositis ossifying. The cause of this type of inflammation is the formation of an abnormal bone mass inside one or more muscles. The reasons for this anomaly are very often due to a severe muscle trauma, in which there is a very deep hematoma. Myositis ossifying remains confined to the site where the bone mass was formed.
- Drug-induced myositis. Some drugs or certain drug combinations can have side effects that cause muscle inflammation.
These consequences have been observed with two types of drugs: those that serve to lower cholesterol (statins, atorvastatin, lovastatin and simvastatin) and zidovudine, an antiviral used against the AIDS virus.
EPIDEMIOLOGY
From an epidemiological point of view, the myositis that arouse more curiosity are the idiopathic ones, because, failing to understand the causes, at least one tries to know their incidence.
These rather rare forms affect one in every 100,000 people, with a preference for women. In fact, the women affected are twice as many as men.
Although they can occur at any age, dermatomyositis and polymyositis appear mainly between the ages of 40 and 50, while inclusion body myositis occurs especially between the ages of 50 and 60.
Symptoms and Complications
The symptoms common to all forms of myositis are, in fact, three:
- Muscle weakness (asthenia)
- Muscle pain (myalgia)
- Muscle soreness
To these symptoms, based on the triggering cause, other manifestations can be added, sometimes even very serious and debilitating.
IDIOPATHIC INFLAMMATORY MYOPATHIES
In the early stages, dermatomyositis, polymyositis, and inclusion body myositis cause painless muscle weakness. After a few weeks, pain and aching in the muscles appear.
As already mentioned, initially only the proximal voluntary muscles are involved; then, when the disease worsens, there is also involvement of the distal and smooth muscles.
Polymyositis. As long as myositis is limited to the proximal muscles, the patient complains of fatigue, myalgia and difficulty in performing very simple movements, such as climbing stairs, getting up from a chair, lifting a weight, etc.
When myositis reaches distal and smooth muscles, myalgia and motor difficulties involve the hands and digestive system.
Figure: the signs of scleroderma in a patient with dermatomyositis.
From the site: the-rheumatologist.org
Patients at this stage of the disease suffer from dysphagia (complicated swallowing) and have problems writing, buttoning a shirt, using the computer keyboard, etc. The muscles of the eyes, face, heart and sole of the foot are rarely compromised; it is also unusual for the tendons to be affected.
In the more advanced and severe stages of the disease, the muscles appear tender on palpation and may undergo atrophy.
Dermatomyositis. The characteristic that distinguishes dermatomyositis is that this form also manifests itself in the skin.
In fact, the typical skin signs, which accompany myalgia, asthenia and muscle atrophy, are the so-called skin rash (or rash) and scleroderma.
An ongoing skin rash causes red-purple spots in the eyelids, chest, face, and joints (knee and shoulder, in particular).
Scleroderma, on the other hand, causes multiple disorders not only on the skin, but also to internal organs, with sometimes serious consequences.
The effects of scleroderma:
- Stiff, thickened and shiny skin
- Reynaud's phenomenon
- Cutaneous calcinosis
- Swelling of the hands and feet
- Cardiopulmonary problems
- Hyperpigmentation and hypopigmentation
- Dry mouth and eyes
- Arthritis
- Dysphagia
- Esophagitis
- Digestive difficulties and gastrointestinal ulcers
Inclusion Body Myositis. When it arises, it causes weakness of the proximal muscles of the legs (first) and arms (later). As the disease progresses, the distal muscles in the hands and feet are also involved, and the smooth muscles of the esophagus (resulting in dysphagia). Muscle atrophy is likely to occur.
INFECTIOUS MYOSITIS
Infectious myositis, in addition to presenting with muscle pain and weakness, are also characterized by:
- High fever
- Chills of cold
- Sore throat, cough
- Fatigue
- Skin redness
- A runny nose
This symptomatology can sometimes vary and be enriched with other clinical signs, depending on the infectious agent that caused the myositis. For example, if the triggering microorganism is Trichinella, the patient can also suffer from diarrhea and vomiting; base c "is a respiratory tract virus, the patient can suffer from more or less severe respiratory crises.
MYOSITIS ASSOCIATED WITH OTHER DISORDERS
When a certain pathology also causes myositis, the patient shows both the symptoms of the responsible pathology and those of muscle inflammation.
In other words, the symptoms vary depending on whether at the origin there is for example a myasthenia gravis, a Hashimoto's thyroiditis, a tumor of the ovary, etc.
An interesting fact, regarding the association between myositis and tumors, is the following: it seems that 10-20% of neoplasms trigger muscle inflammations similar to dermatomyositis.
OXIFYING MYOSITE
The formation of abnormal bone mass causes weakness and pain on palpation of the affected muscle. Symptoms do not appear immediately, but several weeks after the muscle trauma.
A particular sign, which usually anticipates ossifying myositis, is the appearance of a post-traumatic hematoma.
DRUG-INDUCED MYOSITIS
In addition to muscle pain and asthenia, the patient also suffers from frequent cramps. The onset of symptoms in this type of myositis occurs immediately after taking the drugs responsible for the disorder.
N.B: remember that myositis is a possible side effect of zidovudine (antiviral used against AIDS) and some drugs that reduce cholesterol. Therefore, this side effect may not always be present.
COMPLICATIONS
Before talking about the possible complications due to myositis, it should be specified that not all types of muscle inflammation described so far are equally dangerous. There are, in fact, more serious forms (such as idiopathic inflammatory myopathies and myositis associated with other pathologies) and less severe forms (such as ossifying, drug-induced, and infectious myositis).
The most serious forms can have very dangerous complications for the patient; just think that cardio-respiratory problems caused by scleroderma can degenerate into heart block, pericarditis, myocardial infarction, etc.
The less severe forms, on the other hand, involve a limited number of muscles.
Complications of the most severe myositis:
- Gastrointestinal ulcerations
- Pneumonia
- Heart attack
- Cardiac arrhythmia
- Pericarditis
- Myocardial infarction
- Highly impaired swallowing and digestive abilities
Diagnosis
A physical examination supported by instrumental and laboratory tests is needed to establish the diagnosis of myositis.
OBJECTIVE EXAMINATION
During the physical examination, the initial step involves questioning the patient about the symptoms felt. At this stage, the important information to gather from the patient's voice is: the location of the muscle pain, the feeling of weakness and how long these disorders have been present.
In the next step, the doctor investigates the patient's clinical history (current and previous illnesses and disorders) and any drug intake.
The third and final step is the control, on palpation, of the muscles; often, the muscles affected by myositis are tender, painful and as if they have granules inside them.
If these three checks lead to believe that it is indeed a "muscle inflammation, we proceed with more in-depth examinations.
LABORATORY EXAMS
Laboratory tests consist of:
- Blood tests
- Muscle biopsy
Blood tests. Through a simple blood sample, it is possible to measure the quantities of certain enzymes and molecules (antibodies, auto-antibodies and tumor antigens), which in a healthy patient reach certain levels and in myositis sufferers reach others.
For example, the creatine kinase enzyme is quantified, which in affected patients can be 50 times higher than normal, and if the muscle inflammation is due to an infectious agent, certain antibodies are also searched; the presence of auto-antibodies can also be probed, given that some myositis have an "autoimmune origin; finally, certain tumor antigens are measured to understand if myositis may be due to a neoplasm.
Muscle biopsy. It consists in taking and analyzing a small sample of muscle tissue belonging to the patient under observation. The microscope vision of the muscle fibers allows us to see if an inflammation is in progress or not inside the cells.
It is considered, for its high reliability, the definitive examination.
INSTRUMENTAL EXAMINATIONS
The possible instrumental tests are:
- Electromyogram. It is used to measure the electrical activity of the muscles. It is not invasive at all.
- Nuclear magnetic resonance (NMR). It is usually used not so much to recognize a myositis, but to identify the best place to perform the biopsy. It is not an invasive exam
- X-ray radiography. It is used when, from the physical examination, the possibility emerges that at the origin of the symptoms there is an ossifying myositis. The test uses harmful ionizing radiation.
- Computed Axial Tomography (CT). It is useful when infectious myositis is suspected. This test also uses ionizing radiation.
Treatment
To establish the most adequate therapy, it is essential to clarify the precise causes of origin of myositis. In fact, successfully treating a myositis without knowing its etiological origin is very unlikely.
Therapeutic approaches are based on pharmacological treatments supported by simple behavioral countermeasures.
TREATMENT OF IDIOPATHIC INFLAMMATORY MYOPATHIES
Polymyositis and dermatomyositis: the pharmacological choice, for these two idiopathic forms of myositis, is very wide. It usually begins with the administration of corticosteroids (for example, prednisone); if these do not work, we switch to immunosuppressive drugs (for example, methotrexate or azathioprine) and intravenous injection of immunoglobulins.
The first effects of the treatment begin to be seen after one or two months from the beginning of the treatment and the results are generally satisfactory.
Inclusion Body Myositis: Pharmacological treatments are the same as for polymyositis and dermatomyositis. However, the results are far less satisfying. Most patients with this form of myositis tend to worsen their health over the years.
- Prednisone
- Methylprednisolone
- Topical (mild forms)
- Systemic (severe forms)
- Methotrexate
- Azathioprine
- Cyclosporine
- Rituximab
- Mycophenolate mofetil
- Cyclophosphamide
- Systemic
- Intravenous
TREATMENT OF INFECTIOUS MYOSITIS
When myositis is infectious, it is advisable to rest and take analgesic (pain relieving) and anti-inflammatory drugs. However, alongside these general treatments, the patient also needs specific care for the infectious agent that caused the myositis. .
Some examples: in cases of Trichinella infection, the patient must take mebendazole or albendazole, because only in this way can he "kill" the parasite; in cases of bacterial infection, it is essential to administer antibiotics to eliminate the bacterium.
Mild infections can fade in 4-7 days; severe ones can take up to 3 weeks to heal.
TREATMENT OF MYOSITES ASSOCIATED WITH OTHER PATHOLOGIES
When myositis is due to other pathologies, the most appropriate therapy must be set to resolve both the muscle inflammation and the disease that gives rise to everything. Limiting yourself to just treating myositis would only offer temporary benefits, since, sooner or later, the symptoms would reappear.
In light of this, treatments vary from case to case. For example, if systemic lupus erythematosus is the "origin c", one should opt for immunosuppressive drugs; if, on the other hand, there is lung cancer, anticancer drugs should be administered.
TREATMENT OF OXFICATING MYOSITIS
Usually, in cases of ossifying myositis, it is necessary to wait for the bone mass to disappear on its own. This occurs within a few months. If this does not happen (rare case), surgery is done for removal.
TREATMENT OF DRUG INDUCED MYOSITIS
In drug-induced myositis, the interruption of the drug therapy responsible for the disorder is sufficient to resolve the muscle inflammation. However, it still takes several weeks, if not months, to appreciate its effects.
Prognosis and prevention
For an individual affected by myositis, the prognosis depends first of all on the triggering cause and, secondly, on when and how to intervene with the treatments.
THE LESS SERIOUS FORMS
Ossifying and drug-induced myositis always have a positive prognosis, as long as the causes are correctly interpreted and the right therapeutic countermeasures are implemented.
For infectious myositis, the matter is more complicated and requires special considerations: an early diagnosis of the disorder and timely treatment ensure that the prognosis becomes positive; conversely, a late or incorrect diagnosis and inappropriate treatment make the prognosis negative.
This second possibility is a rare event (so much so that infectious myositis has been included among the less severe forms), but sometimes possible.
THE MOST SERIOUS FORMS
The forms of myositis with a potentially negative prognosis include idiopathic inflammatory myopathies and myositis associated with other pathologies. These can have serious complications and it is not certain that the therapy is always effective, even when it is drastic (as in the case of a tumor).
Infectious myositis not adequately treated and caused by dangerous viruses and microorganisms, such as the AIDS virus, should be considered serious.
PREVENTION
Preventing certain forms of myositis is possible. That's how:
- Get the flu shot annually (recommended for people with a weak immune system)
- Cook the meat well (the trichinella parasite is found in raw meat)
- Do not use drugs, specifically injectable ones, and use condoms correctly in case of occasional intercourse
- Keep the skin clean
- Do not take medications recklessly, especially those associated with myositis
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