Multiple sclerosis

Multiple sclerosis is a nervous system disease that affects the brain and spinal cord caused by an inflammatory demyelinating condition.

Myelin is a fatty membrane that acts like the covering of an electrical cable and allows nerves to transmit their impulses rapidly. In multiple sclerosis, demyelination (loss of myelin) prevents nerves from conducting electrical impulses to the brain and from the brain to the peripheral nervous system efficiently.

Currently, multiple sclerosis is considered to be differentiated from other conditions that were previously thought to be part of the disease: neuromyelitis optica (NMO) and myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD).

It usually appears between 20 and 40 years of age and affects more women than men.

The causes of multiple sclerosis are unknown.

The causes of the symptoms manifested by individuals are myelin inflammation due to autoimmune causes, meaning that the body's defenses for some reason attack its own myelin, associated with nerve degeneration that causes progressive worsening if treatment is not initiated.

Multiple sclerosis appears to have genetic components (since it affects some races more than others) that interact with some environmental substance that triggers the immune response.

Some of these substances that are considered to potentially trigger the disease are:

• Vitamin D.
• Cigarette smoke.
• Sun exposure.
• Obesity.
• Viruses such as Epstein-Barr and human herpes virus 6.
• Salt consumption.
• Changes in intestinal microbiota (bacteria) apparently related to diet.

Multiple sclerosis can be classified as follows:

• Relapsing-remitting form: Occurs in 90% of cases. Affects women more frequently. It is characterized by episodes of neurological manifestations (may be one symptom or several different ones) that recur over time and may leave sequelae. Life expectancy is similar to that of the general population.

  Episodes last at least 24 hours and occur every 30 days or more.

• Primary progressive form: Occurs in 10% of cases. Affects men and women equally, almost always over 40 years of age. Patients have a progressive form from the beginning. Symptoms present progressively over at least one year and are mainly:

  • Spastic paraparesis.
  • Cerebellar or brainstem syndrome.
  • Sensory symptoms.
  • Optic neuropathy.

There may be a wide variety of other symptoms including fatigue, depression and mental changes, which makes this form easy to confuse with many other diseases.

• Secondary progressive form: At 10 years, 50% of those with the relapsing-remitting type progress to a form of progressive neurological deterioration.
• Acute multiple sclerosis.
• Diffuse cerebral sclerosis.

There are other forms with very aggressive onset that tend to worsen much more rapidly.

Factors associated with worse prognosis include:

• Disease onset before 10 years of age or after 50 years of age.
• Progressive course from the beginning.
• Onset with motor and cerebellar symptoms.
• Early recurrence after the first episode.

It typically presents with repeated episodes of illness and disease-free intervals.

Symptoms depend on which part of the central nervous system has been affected.

The main symptoms that appear during flares are:

• Vision
  • Double vision (diplopia)
  • Involuntary eye movement (nystagmus)
  • Blurred vision (optic neuritis)
• Speech
  • Difficulty speaking (dysarthria)
• Neurological symptoms
  • Depression
  • Vertigo and dizziness
  • Hand tremor
  • Tingling sensation
• Throat
  • Difficulty swallowing (dysphagia)
• Musculoskeletal
  • Weakness
  • Spasms
  • Fatigue
  • Loss of coordination (ataxia)
• Intestinal
  • Diarrhea
  • Incontinence
• Urinary
  • Urinary incontinence
  • Increased urinary frequency

There is no single test to diagnose multiple sclerosis.

When a person presents symptoms, the main examinations requested to determine the diagnosis of this disease are:

• Cerebrospinal fluid CSF study.
• Magnetic resonance imaging MRI.
• Optical coherence tomography.
• Evoked potentials.

The diagnostic criteria to determine that someone suffers from multiple sclerosis are observations made in magnetic resonance imaging MRI studies:

• Dissemination in time DIT: refers to the determination of demyelinating lesions in two magnetic resonance imaging scans taken at different times.
• Dissemination in space DIS: refers to the observation of two or more lesions in different areas of the central nervous system.

To determine these disseminations, the patient's symptoms are taken into account and other possible diseases such as tumors and other degenerative diseases are ruled out.

Multiple sclerosis treatment primarily aims to:

• Improve relapse symptoms.
• Stop disease progression.
• Improve lesions that cause sequelae.

There is no treatment that completely achieves the first objective, stopping disease progression.

There are two types of treatment in multiple sclerosis:

1. Relapse treatment

   • Corticosteroids: the most commonly used is methylprednisolone.
   • Plasmapheresis: usually performed every 48 hours. It is an invasive procedure in which blood is extracted from the person, plasma is separated and replaced with another fluid that is mixed with the other blood components and reintroduced into the body.

2. Disease-modifying drug treatment

   The most commonly used medications are:

   • Interferons
   • Glatiramer acetate
   • Natalizumab
   • Fingolimod
   • Teriflunomide
   • Dimethyl fumarate
   • Alemtuzumab
   • Cladribine

   These medications can reduce the number of relapses in some patients, but do not guarantee disease arrest. The medications are more effective for the relapsing-remitting form.

3. Other treatments

   To improve symptoms associated with multiple sclerosis such as depression, pain, fatigue, urinary problems, etc., there are a large number of medications (analgesics, anti-inflammatories, antidepressants, etc.) and therapies, with rehabilitation and family support for the affected person being among the most important.

   Hematopoietic stem cell transplantation is a management option in people with very severe disease.

   Recently, medications are being developed to counteract very common problems in people with multiple sclerosis such as spasticity, fatigue and gait disorders with good results.