Multiple sclerosis (MS)
What is it?
Multiple sclerosis is a demyelinating and neurodegenerative inflammatory disease of the central nervous system, i.e. the brain, spinal cord and optic nerve. In particular, it is a demyelinating disease, as it affects myelin, i.e. the shell of the axons in the central nervous system. In multiple sclerosis, myelin is lost, resulting in impulse conduction from the brain to the periphery and from the periphery to the brain being disrupted, thus causing various manifestations and symptoms of the disease. It is also called plaque sclerosis because the areas where myelin loss occurs are localised (plaques) and appear as areas of scar tissue (sclerosis). These areas tend to develop at different times and in different areas of the brain, spinal cord and optic nerve during the course of the disease, which is why it is called 'multiple sclerosis'. Multiple sclerosis is a disease that usually occurs in young adults, between the ages of 20 and 40, but is less common in those under the age of 10 or over the age of 60. Women are more often affected than men, with a ratio between 3:1 and 2:1.
Caucasian populations are more susceptible to the disease than African and Oriental populations. There is also a geographical gradient in the risk of developing multiple sclerosis: the disease occurs more frequently as one moves away from tropical climates towards temperate climates (i.e. it occurs more frequently as one moves closer to the Earth's poles). Multiple sclerosis is neither contagious nor hereditary, as there is no single mutated gene that is passed from parent to offspring. However, there is a genetic predisposition, which means there is an increased risk of developing the disease in a family where there are already other people with the same disease.
The cause of the disease is not yet known, but there is active and ongoing research aimed at identifying it. According to current knowledge, multiple sclerosis is caused by the interaction of at least three factors: genetic predisposition, environmental factors and disimmune phenomena. Myelin damage is caused by an abnormal response of the immune system of the affected person, which normally protects the body against microorganisms (bacteria and viruses) by recognising the different parts of the body, including myelin, as its own and therefore not attacking them. This autoimmune process can be caused by an environmental factor (such as a virus) in people with a genetic predisposition to MS. The course of multiple sclerosis is highly variable.
In some cases after the first episode there can be a free interval of even many years, while in others there is immediately another relapse (poussée or exacerbation) with new symptoms or resurgence of symptoms already manifested. The course of the disease can be of different types:
- multiple sclerosis with relapses and remissions: that is, there are unpredictable relapses (attacks or exacerbations) with a variable duration of days or months and with partial or total recovery (remission);
- secondary progressive multiple sclerosis: patients who began with a form of relapses and remissions then present, during the course of the disease, a gradual and progressive worsening of disability with or without superimposed relapses;
- primary progressive multiple sclerosis: form of multiple sclerosis in which there is a gradual and progressive worsening of disability since the onset of the disease.
85% of patients initially present a disease with a course of relapses and remissions and 80-90% of them enter a secondary phase within 20-25 years, the other 15% present a progressive course from the beginning with or without superimposed disease relapses.
Which are the symptoms?
Multiple sclerosis is a very variable disease, with symptoms depending on which areas of the nervous system are affected. Some symptoms are very common, others are rare, and most patients experience more than one symptom during the course of the disease. Motor disorders: may be mild, causing weakness and motor disturbances in one or more limbs (paresis), or may be severe with a complete loss of strength in one or more limbs with inability to move them (plegia). In addition to strength deficits, there may be an increase in muscle tone as indicated by increased resistance to passive movements (spasticity).
- Sensory disturbances: these can be subjective symptoms such as crawling, tingling, skin induction, burning sensations, or objective symptoms such as reduced tactile, pain or temperature sensitivity; there can be pain resulting from muscle contractures or postural changes as well as episodic pain, i.e. stabbing pain in certain areas of the body such as the face (trigeminal neuralgia) or electrical shock along the spine and lower extremities. i.e. stabbing pain in certain areas of the body such as the face (trigeminal neuralgia), or a sensation of electrical shock along the spine and lower extremities when the head is tilted (Lhermitte's sign).
- Visual disturbances: partial or complete blurring of vision, often accompanied by pain when the eyeball moves (optic neuritis); double vision, or diplopia.
- Balance disorders: dizziness, often together with nausea and vomiting, difficulty in maintaining an upright posture and walking, often accompanied by involuntary, rhythmic eyeball movements observed by the neurologist during examination (nystagmus).
- Coordination disorders: unsteadiness and staggering when walking, which becomes unsteady and wobbly, with widening of the support (ataxia); movements lose smoothness and become unsteady and wobbly when executed with the appearance of tremor (for example, putting a glass to the mouth); speech may also lose smoothness and rhythm and become mumbled. Fatigue, i.e. early fatigue in the activities of daily life, feeling of exhaustion, feeling a loss of physical and mental energy.
- Cognitive disorders: impaired memory, attention and concentration deficits, reduced speed of information processing, reduced fluency.
- Neuropsychological disorders: fatigue, mood swings and depression.
- Sphincter disorders: bladder disorders with frequent and urgent urination or difficulty emptying the bladder or urinary incontinence; intestinal disorders with constipation or less frequently fecal incontinence.
- Sexual disorders: in men, erectile dysfunction up to impotence, and in women, reduced libido and sensitivity of the genitals.
How is it diagnosed?
The diagnosis of multiple sclerosis is mainly clinical, namely based on the presentation of at least two episodes of neurological deficits occurring at different times and indicating that at least two different areas of the central nervous system are affected (dissemination in space and time), after excluding other possible differential diagnoses. The diagnosis is therefore based on the anamnesis (clinical history) and neurological examination (to check for abnormalities caused by central nervous system lesions). However, the neurologist resorts to some tests and paraclinical methods that are fundamental to the diagnosis of the disease, as they can greatly increase the accuracy of the diagnosis and anticipate it. These include nuclear magnetic resonance imaging, which can detect areas of demyelination in the brain, spinal cord and/or optic nerve and, through the use of a contrast agent (gadolinium), reveal active lesions, i.e. the most recent lesions.
The cerebrospinal fluid (the fluid surrounding the brain and spinal cord) is then examined by means of a lumbar puncture, which reveals the state of inflammation in the nervous system and, in particular, makes it possible to check for the presence of certain antibodies called "oligoclonal bands". In addition, auditory, visual, somatosensory and motor evoked potentials make it possible to detect conduction defects in the auditory, visual, haptic and motor sensory pathways respectively. With these tests, it is possible, even at the onset of the first symptoms of the disease, to predict the progression to multiple sclerosis with more than 95% probability in the presence of multiple lesions on magnetic resonance imaging of the brain and/or spinal cord, together with oligoclonal bands in the cerebrospinal fluid. Evoked potentials have less diagnostic value, but are useful for confirming central nervous system disorders even in the absence of symptoms in the motor or sensory pathway under investigation.
How is it treated?
The treatment of multiple sclerosis has three different objectives. The first is to use therapy to alter the course of the disease. Its aim is to limit the inflammatory activity underlying the clinical relapses of the disease and the new lesions visible on MRI, and to prevent the long-term consequences of multiple sclerosis, such as the accumulation of abnormalities, disease progression and neurodegenerative processes. In recent years, the availability of immunomodulatory, immunosuppressive and biological therapies has radically changed the therapeutic approach to the treatment of multiple sclerosis. These therapies should be started as early as possible in the early stages of the disease.
The following drugs are currently approved for the treatment of multiple sclerosis: interferon beta 1a and 1b, glatiramer acetate, teriflunomide, dimethyl fumarate, cladribine, natalizumab, fingolimod, ozanimod, siponimod, ponesimod, alemtuzumab, oxalizumab and ofatumumab. Each of these drugs has specific criteria for prescribing. The large number of approved therapies increasingly makes it possible to tailor the therapy to the needs of the individual patient in terms of efficacy, safety aspects and the patient's own preferences. The second goal of multiple sclerosis treatment relates to rapid recovery from clinical relapses.
Steroid therapy, usually intravenous for 3-5 days, is the standard treatment for the acute phase of inflammatory disease, i.e. clinical relapses of the disease. Such treatment can promote a more rapid functional recovery and protect against the occurrence of more severe abnormalities in the first weeks after treatment. In cases of inadequate response and poor recovery from steroid therapy, plasmapheresis (3 to 5 sessions) or intravenous administration of immunoglobulins may be useful. The third aim of multiple sclerosis treatment is to relief the clinical symptoms associated with the disease, such as spasticity, pain, fatigue, and cognitive impairment, through a combination of appropriate symptomatic drug therapy and rehabilitation strategies (both motor and cognitive).
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