Multiple Sclerosis: What Kind of Disease It Is and How It Develops

The diagnosis of "multiple sclerosis" sounds frightening, although it has an understandable mechanism behind it: the body's own immune system damages the sheaths of nerve fibers. Below is what kind of disease it is, why it is called autoimmune, and how it develops.

Multiple Sclerosis: What Kind of Disease It Is

This is a disease of the central nervous system — the brain and spinal cord. The English name is multiple sclerosis, abbreviated MS; in Russian, the abbreviation RS has become established. Multiple sclerosis is the most common autoimmune disease of the CNS: in 2020, about 2.8 million people worldwide had it.

The name is more precise than it seems: "multiple sclerosis" is short for multiple cerebrospinal sclerosis, that is, multiple glial scars (scleroses, or plaques) in the white matter of the brain and spinal cord. The disease was first described in 1868 by the French neurologist Jean-Martin Charcot.

Autoimmune Mechanism: What Happens to the Nervous System

A nerve fiber is covered with myelin — an insulating sheath that helps the signal travel quickly. In MS, the immune system mistakenly attacks myelin itself, and messages between the brain and body slow down or are blocked — hence the symptoms.

The exact cause is unknown; impaired immune regulation, genetics, and environmental factors are suspected. The risk is higher at ages 20–50, in women (two to three times more often), with a family history, smoking (approximately twofold), and after Epstein–Barr virus infection. Little sun exposure and low vitamin D levels are also discussed.

Types of Course and Stages of Multiple Sclerosis

The form of the disease is determined by how it changes over time.

• Relapsing-remitting — the most common: exacerbations alternate with recovery, when there are few or no symptoms; over time it often transitions to secondary progressive.
• Secondary progressive — symptoms are constantly present and slowly increase.
• Primary progressive — deterioration from the very beginning, without periods of recovery; it occurs less often than the others.
• Clinically isolated syndrome — a single episode of symptoms lasting at least 24 hours; it may be an early sign of MS, but not in everyone.

How MS Is Diagnosed

There is no single test that confirms the diagnosis. The neurologist asks about complaints and performs an examination: checks reflexes, strength, sensation, coordination, vision, and balance. Next, MRI of the brain and spinal cord, blood tests to rule out other causes, and a lumbar puncture — collection of cerebrospinal fluid — may be possible. Sensors on the skin show how quickly a signal from the eyes or ears reaches the brain. The McDonald criteria are used to formalize the diagnosis.

Prognosis and When to See a Neurologist

The disease is incurable, but treatment slows progression and relieves symptoms. Life expectancy is on average several years shorter than in the general population, while most people with MS live to old age. Statistically favorable factors are female sex, young age, a relapsing course, and rare exacerbations at the onset. In relapsing forms, some persistent neurological problems often remain, especially as the disease progresses; in progressive forms, body functions slowly deteriorate.

See a neurologist for unexplained fatigue, blurred vision or eye pain, numbness and tingling, unsteadiness, muscle spasms and stiffness, frequent urination, or memory lapses. Such signs by themselves do not mean MS, but they require evaluation.

Having MS by itself is not a reason to call an ambulance. Call 103 or 112 if sudden weakness or numbness appears in one arm, vision is lost or blurred, or balance and coordination are impaired: such signs may be a manifestation of stroke.

This material is for reference: it explains the mechanism of the disease but does not replace a doctor's consultation — only a specialist can assess your symptoms and examinations.

This content is for reference and does not replace a doctor's consultation. Medical disclaimer