Multiple sclerosis

GENERAL ASPECTS

What is multiple sclerosis?

Multiple Sclerosis is a demyelinating autoimmune disease that is diagnosed in Spain alone with 1,800 new cases each year. It affects an estimated 47,000 people, 700,000 in Europe and 2.5 million worldwide, although the number of patients with Multiple Sclerosis has doubled in the last 20 years.

The increase in prevalence can be attributed to improved diagnostic methods, but also to various environmental factors derived from changes in lifestyle habits, such as an increase in indoor activity (which implies a decrease in vitamin D levels), changes in diet, an increase in the obese population or the consumption of toxic substances such as tobacco.

It is more prevalent in women and the age of onset is usually between 20 and 40 years of age, although it can also occur in children and older people. It is a chronic disease and is the leading non-traumatic cause of disability in young adults. It is more common in women; 3 out of every 4 people with Multiple Sclerosis are women.

What types of multiple sclerosis are there?

1. Relapsing-remitting multiple sclerosis: This is the most common form of multiple sclerosis. It occurs in the form of outbreaks that last for days or weeks. The patient subsequently recovers progressively, although sequelae may remain.
2. Primarily progressive multiple sclerosis: 10% of people with multiple sclerosis present with an onset without flare-ups, with symptoms that worsen progressively, mainly with gait disturbance. It is more frequent in males.
3. Secondarily progressive multiple sclerosis: In some people with multiple sclerosis, the disease, which has started as a flare-up, evolves into a progressively worsening course.

With the appearance in recent years of effective treatments in progressive forms, a new classification is established that differentiates between Multiple Sclerosis with progression (if it presents progression of disability) or without progression. And between active Multiple Sclerosis (if it presents outbreaks or appearance of new lesions in resonance) or non-active Multiple Sclerosis.

Is it a hereditary disease?

No, although it is known that there is a genetic predisposition on which environmental factors act. In the case of having a parent with Multiple Sclerosis, the risk of developing the disease is around 2%, although the risk is higher if both the father and the mother have it and in monozygotic twins, where it reaches 20-30%. We know that this genetic predisposition is determined by multiple genes, the gene that shows the most consistent relationship being HLA class II (loci DRB1, DQA1, DQB1).

It is more frequent in white people. Northern European countries and the northern United States, for example, are areas of high incidence, but in recent decades, there has been a significant increase in cases in more southern areas such as Mediterranean Europe.

What are the environmental factors that may favor the development of Multiple Sclerosis?

Some of the main factors that have been linked to Multiple Sclerosis are:

1. Infections: Several viruses have been linked to the development of Multiple Sclerosis such as, for example, Epstein-Barr Virus (EBV), HHV-6 (human herpes virus type 6) or HERV (human endogenous retrovirus). It has also been associated with non-viral microorganisms such as chlamydia pneumoniae.
2. Vitamin D: The suspicion that low vitamin D levels may increase the risk of Multiple Sclerosis initially arises from the fact that it is a disease more prevalent in Nordic countries with fewer hours of sunlight. On the other hand, there is strong evidence that low vitamin D levels favor a pro-inflammatory state in the immune system.
3. The increase in childhood and adolescent obesity may also be behind the upward trend in the incidence and prevalence of Multiple Sclerosis.
4. Tobacco: Smoking, as well as passive exposure to tobacco smoke, is another environmental factor that can influence the development of Multiple Sclerosis. In addition, being a smoker is a risk factor for disability progression in people who have already developed the disease.
5. Diet: The abandonment of the Mediterranean diet and a greater weight of processed foods rich in saturated fats favor changes in the intestinal microbiota, which plays an important role in the balance of the immune system. Studies in mice find proinflammatory changes in the immune system if changes are made in the composition of the intestinal flora of patients with Multiple Sclerosis.

What are the symptoms?

The most common form of Multiple Sclerosis, Recurrent Remitting Multiple Sclerosis, is manifested by a first outbreak that may present with motor symptoms, gait or balance disturbance, optic nerve inflammation with loss of visual acuity and eye pain, or sensory disturbances in the form of tingling, cramping or neuropathic pain. To suspect a flare, symptoms must remain constant for at least 24 hours.

The most frequent initial symptom is altered sensation in 45% of cases, followed by motor weakness. Inflammation of the optic nerve, leading to loss of visual acuity, constitutes the initial outbreak in 20% of patients.

The outbreak usually lasts for days or weeks, with the patient progressively recovering until complete resolution or persistence of sequelae, depending on the severity.

In 10% of people with Multiple Sclerosis, the disease does not present in the form of outbreaks, but the symptoms progress from the onset and generally begin with a gait disturbance that gradually worsens. On many occasions, the patient comes to the neurologist after having consulted other specialists and it is not until a proper neurological examination and a brain and spinal cord resonance imaging is performed that the diagnosis is made. It is more common in men around 40 years of age.

People with Multiple Sclerosis may also present other symptoms independently of the outbreaks such as fatigue, cognitive problems, spasticity, pain, sexual dysfunction or urinary symptoms that should be addressed in the consultation because they can significantly affect the quality of life. It is necessary to establish the most appropriate diagnosis and treatment.

How is it diagnosed?

For the diagnosis it is essential to perform a brain MRI and, usually, also a spinal cord MRI, where demyelinating plaques, which are those areas where myelin inflammation is visible, can be observed. Depending on the location and morphology of the lesions, the neurologist will confirm whether the MRI findings meet the criteria for Multiple Sclerosis. The study is usually performed with contrast (gadolinium). L

Generally, the neurologist will perform more complementary tests to differentiate Multiple Sclerosis from other possible pathologies and ensure the diagnosis, such as a complete blood test, a study of visual, auditory and/or somatosensory evoked potentials and a lumbar puncture. A lumbar puncture is a common practice because it may be essential for diagnosis and, in addition, it provides information on the prognosis.

Do you have treatment?

Yes, at the present time we have multiple treatments that act on the immune system modifying the evolution of the disease. The drugs reduce the risk of new outbreaks, reduce the risk of new lesions appearing on MRI and improve the prognosis. Early diagnosis is important to start treatment at the right time and a follow-up by a specialist neurologist to choose the drug indicated in each case. Injectable, oral and intravenous infusion drugs are available. Each of them acts in a different way on the immune system and has a different level of efficacy and risks. The choice of treatment is a complex process and requires a personalized benefit-risk assessment for each person with Multiple Sclerosis.

Among the different drugs used to control the disease are interferons, glatiramer acetate, teriflunomide, dimethyl fumarate, cladribine, fingolimod, natalizumab, ocrelizumab, alentuzumab, sipnimod, etc.

There are multiple trials underway with different molecules, as well as the safety and efficacy of mesenchymal stem cell transplantation and autologous hematopoietic stem cell transplantation as a treatment for relapsing remitting multiple sclerosis.

In addition to immunomodulatory treatment, the neurologist may consider other treatments aimed at controlling symptoms such as spasticity, pain, fatigue or urinary symptoms.

Can lifestyle habits influence the evolution of the disease?

It is recommended to maintain adequate vitamin D levels, being necessary a control by the neurologist in case supplementation is required. In addition, it has been proven that obesity probably worsens the prognosis by generating a proinflammatory state.

Similarly, there are data on the negative influence of smoking on the risk of disease progression, and it is advisable to avoid alcohol consumption and maintain a Mediterranean diet rich in oily fish, fruits, vegetables and legumes, as well as low in saturated fatty acids. Physical activity and neurological rehabilitation are beneficial as they generate mechanisms that favor the reorganization of damaged neuronal networks, although it is advisable to be supervised by a specialist to avoid injuries and to carry out an appropriate exercise program.