Generality
ADEM, also known as acute disseminated encephalomyelitis, is a neurological disorder characterized by inflammation of the brain and spinal cord and a process of demyelination of the nerves of the central nervous system and, sometimes, of the peripheral nervous system.
Most likely, ADEM is an autoimmune condition.
The typical symptoms of ADEM consist of: nausea, vomiting, visual difficulties, confusion, drowsiness, weakness in the limbs, difficulty in swallowing, a tendency to fall and convulsions.
At the most advanced and severe stages, ADEM can lead to coma.
For a correct diagnosis, the fundamental tests are: physical examination, medical history, magnetic resonance imaging of the brain and lumbar puncture.
Currently, the only treatments available to ADEM patients are: two pharmacological therapies, one based on corticosteroids and one based on immunosuppressants and anticancer drugs, and finally, plasmapheresis.
What is ADEM?
ADEM, or disseminated acute encephalomyelitis, is an autoimmune neurological disease characterized by an inflammatory process involving the brain and spinal cord and a demyelinating process of the nerves belonging to the central nervous system and, sometimes, of the nervous system peripheral .
Epidemiology
ADEM is a very rare disease; in fact, its incidence rate is equal to 8 cases per 1, 000, 000 people per year.
It can occur at any age, however statistical studies have shown that it mainly concerns children and adolescents (NB: subjects between the ages of 5 and 8 are by far the most interested).
ADEM affects males and females more or less equally.
Its mortality rate is 5%.
Causes
Autoimmune diseases are particular morbid conditions, characterized by an exaggerated and improper response of the immune system . In fact, in individuals with an autoimmune disease, the cellular and glycoprotein elements, which constitute the immune system, recognize some organs and / or tissues of the human body as foreign and, for this reason, they attack them; in other words, they act against the organs and / or tissues of the human body as they act against viral, bacterial or fungal agents.
The aggression that the immune system performs towards the body to be defended involves more or less damage or alteration of the organs and tissues involved.
In most circumstances, the precise mechanisms that lead an individual's immune system to turn against the organism to which it should protect, thus triggering an autoimmune disease, are unclear, if not unknown.
In the specific case of ADEM, it is known that the triggering / favoring factor is, very often, a previous viral or bacterial infection or, more rarely, a previous vaccination . ADEM following a viral or bacterial infection is called post-infectious ADEM (or post-infectious acute disseminated encephalomyelitis ); the ADEM following a vaccination, instead, takes the specific name of post-vaccine ADEM (or post-vaccinated acute disseminated encephalomyelitis ).
POST-INFECTIVE ADEM
Post-infectious ADEM affects between 50 and 75% of patients, hence most clinical cases.
Viruses considered to be possible triggers of ADEM include: influenza virus, Enterovirus, measles virus, varicella virus, mumps virus, rubella virus, Epstein Barr virus, the Cytomegalovirus, Herpes simplex virus, hepatitis A virus and Coxsackievirus.
As far as post-infectious bacterial ADEM is concerned, the bacteria that can potentially cause it are: Mycoplasma pneumoniae, beta-hemolytic streptococcus, bacteria of the genus Leptospira and Borrelia burgdorferi (bacterium responsible for Lyme disease ).
POST-VACCINIC ADEM
Post-vaccine ADEM affects only a few patients; it is therefore very rare.
Among the vaccinations from which this particular form of ADEM can derive, it stands out:
- The rabies vaccine (ie against rabies) of the Semple type, no longer in use;
- Vaccines for hepatitis B, pertussis, diphtheria, mumps, measles, rubella, pneumococcal pneumonia, varicella, Japanese encephalitis and poliomyelitis.
For the avoidance of bad interpretations, it should be emphasized that the aforementioned vaccines are implicated in the appearance of ADEM only on very rare occasions; to renounce it for fear of ADEM exposes the person concerned to surely higher risks for good health and life.
PATHOLOGICAL ANATOMY
From the observation of the organs of the central nervous system of patients with ADEM it emerged that the inflammatory lesions mainly involve the white subcortical and central substance of both cerebral hemispheres, of the cerebellum, of the brainstem and of the spinal cord .
Symptoms, signs and complications
Typically, the typical symptoms of post-infectious ADEM appear 1-3 weeks after the triggering infection and consist of:
- Temperature;
- Nausea;
- He retched;
- Confusion;
- Visual problems (eg: blurred vision or double vision);
- Drowsiness;
- Weakness in the arms and / or legs;
- Tendency to fall;
- Difficulty swallowing;
- Convulsions.
As for the classic symptoms of post-vaccine ADEM, they appear 1 to 3 months after the offending vaccination and consist of:
- Nausea;
- He retched;
- Visual difficulties (eg: blurred vision or double vision);
- Confusion;
- Drowsiness;
- Weakness in the arms and / or legs;
- Difficulty swallowing;
- Tendency to fall;
- Convulsions.
OTHER SYMPTOMS OF ADEM
In addition to the symptoms reported above, ADEM may be responsible for: hemiparesis, paraparesis and paralysis of the cranial nerves .
COMPLICATIONS
At the most advanced stages and without proper medical attention, ADEM can lead to coma .
Diagnosis
To achieve a correct diagnosis of ADEM, the following are fundamental:
- The objective examination ;
- The anamnesis . The news that it can provide is essential to understand if an ADEM is post-infectious or post-vaccine;
- Magnetic resonance imaging of the brain It allows to see the consequences of inflammatory processes on the white substance;
- Lumbar puncture with subsequent analysis of cerebrospinal fluid . This test makes it possible to distinguish ADEM from the most known and common multiple sclerosis, whose symptoms are largely overlapping.
Therapy
The availability of treatments for ADEM is really small, since, until now, investments aimed at finding adequate treatments and new therapeutic remedies have always been very limited.
Currently, the only treatments available to ADEM patients are: a drug therapy based on corticosteroids, a second drug therapy based on immunosuppressants and anticancer drugs and, finally, plasmapheresis .
CORTICOSTEROID THERAPY
Corticosteroids are powerful anti-inflammatories, or drugs that act against inflammation processes.
Their prolonged or reckless use can have serious repercussions on the health of the human organism and lead, for example, to the onset of: osteoporosis, diabetes, cataracts or obesity.
In the presence of ADEM, the use of corticosteroids is the first line treatment .
Initially, the therapy in question takes place intravenously and involves high pharmacological doses; among the most used corticosteroids in this phase are methylprednisolone and dexamethasone .
Therefore, after 3-6 weeks, drug administration becomes oral and involves low doses of prednisolone .
According to some statistical surveys, patients who use methylprednisolone would get superior benefits compared to patients using dexamethasone.
| Summary of possible therapies in case of ADEM | |
Corticosteroids |
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immunosuppressant |
|
Anti-cancer drugs |
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plasmapheresis | It allows to remove part of the immune cells responsible for the inflammatory state. |
Prognosis
According to various medical investigations, the prognosis in the case of ADEM:
- It is favorable in most cases (even more than 70% of patients), with a recovery of neurological functions that may be complete or semi-complete. Semi-complete means that there are still some disabilities, motor (eg: ataxia or hemiparesis) and / or cognitive impairment (eg short-term amnesia or loss of attention);
- It is highly unfavorable for at least 5%, a percentage that equates to the mortality rate.
It is a fact that the negativity of the prognosis in the case of ADEM depends, to a large extent, on the lack of treatment with corticosteroids .
As a final figure, it is noted that children with ADEM have greater hopes of enjoying a favorable prognosis than adults.
