Glossary


Multiple sclerosis is a complex condition.


Much of the material on this website may be new for readers, and as such, an expansive glossary has been created to help define technical terms and concepts. The goal of this glossary is to enhance the understanding of MS and MS-related topics.

A

ATROPHY

The decrease in the volume of brain or muscle tissue often associated with MS.

AUTOIMMUNE DISEASE

When the body’s own immune system attacks its own tissue, it is known as an autoimmune disease. MS is believed to be an autoimmune disease.

AXON

The nerve fibre that extends out from the nerve cell and conducts impulses to other nerve cells or muscles.

B

BACTERIA

Microorganisms that are the basis of fermentation and infectious diseases.

BBB (Blood brain barrier)

A protective barrier that lines the blood vessels and is the gatekeeper between the blood and brain tissue that carefully filters which molecules can enter the brain, optic nerves and spinal cord of the central nervous system (CNS).

B-CELL

A type of lymphocyte (white blood cell) manufactured in the bone marrow that produces antibodies to fight against “foreign invaders” (such as bacteria or viruses) within the body and help to regulate other immune cells.

C

CENTRAL NERVOUS SYSTEM (CNS)

The part of the nervous system that includes the brain and spinal cord.

CIS (Clinically isolated syndrome)

Prior to a diagnosis of MS, CIS is a single attack (or the appearance of one or more symptoms characteristic of MS), with a very high risk of developing MS, when no other diseases or causes for symptoms are apparent.

COGNITION

The process of knowing in the broadest sense, including perception, memory and judgment.

COGNITIVE IMPAIRMENT

Changes in mental function caused by trauma or disease process. Some degree of cognitive impairment occurs in approximately 50% to 60% of people with MS.

CORTICOSTEROID

A type of steroid that works by reducing inflammation in the central nervous system (CNS).

D

DEMYELINATION

Damage to the protective covering of the nerves (myelin) of the central nervous system (CNS), causing interruptions in the flow of nerve impulses in the CNS.

DIAGNOSIS

The process of discovering or identifying a diseased condition by means of a medical examination, laboratory test or other.

DIPLOPIA

Double vision resulting from lesions in the brain stem, a part of the nervous system between the brain and cervical spinal cord.

DIS (Dissemination in space)

Evidence of damage to at least two different areas of the central nervous system.

DIT (Dissemination in time)

Evidence of an episode of damage in the central nervous system at different time points.

DYSARTHRIA

A condition in which the muscles used for speech are weak and there is difficulty controlling them. Dysarthria is often characterized by slurred or slow speech that can be difficult to understand.

DYSESTHESIA

Type of pain that is experienced as a burning, aching, or “pins and needles” type of sensation under the skin. In some cases these sensations may occur with no touch at all.

E

EVOKED POTENTIALS

A test that measures the electrical activity of the brain in response to stimulation of specific sensory nerve pathways.

EDSS (Expanded Disability Status Scale)

The EDSS is a clinical rating scale based on the judgement of a trained examiner, ranging from 0 to 10 in half-point increments. It is used to assess mental and physical ability, focusing on areas such as visual, sensory and bowel and bladder function.  

CLICK HERE to see what the EDSS scale looks like

F

FLARE-UP

A sudden appearance or worsening of the symptoms of a disease or condition.

G

GAIT

A particular way or manner of moving on foot – whether it be walking, jogging, skipping or running.

I

IMMUNE-MEDIATED DISEASE

A disease in which components of the immune system (T-cells, antibodies and others) are responsible for the disease either directly or indirectly.

IMMUNE SYSTEM

A collection of cells, tissues and molecules that act as the body’s defense against disease-producing agents (pathogens) such as viruses and bacteria.

INFLAMMATION

A protective response that involves immune cells, blood vessels and molecular mediators that aims to eliminate the initial cause of cell injury and to initiate tissue repair.

INTERFERON

A family of naturally occurring proteins that are made and secreted by cells of the immune system (white blood cells, for example). Three classes of interferons have been identified: alpha, beta and gamma.

J

JCV (JC virus)

The JC virus was named after John Cunningham, in whom it was first diagnosed in 1971. A common infection completely unrelated to MS, people are thought to be exposed to it sometime during childhood. Although some can be infected by the virus it is normally kept under control by the immune system, causing no signs or symptoms. In some individuals, the immune system is weakened and the body is less able to fight an infection. In these instances, the virus can reactivate and cause potentially fatal inflammation and damage to the brain known as progressive multifocal leukoencephalopathy (PML).

If you have any questions or concerns about the JC virus or PML, contact your physician for more information.

L

LASSITUDE

Sometimes referred to as “MS fatigue,” this type of fatigue is unique to people with MS and may happen because of nerve damage. More severe than regular fatigue, it tends to come on suddenly, can be aggravated by heat and humidity and may worsen as the day progresses.

LESION

An abnormal area seen on MRI that may represent inflammation, demyelination and/or axonal damage. A lesion (or plaque) that can vary from a few millimeters to a few centimeters in diameter generally contains inflammatory cells and other cells that contribute to brain inflammation and damage.

M

MAGNETIC RESONANCE IMAGING (MRI)

A diagnostic procedure that produces visual images of different body parts without the use of X-rays. An important diagnostic tool in MS, MRI makes it possible to visualize and count lesions in the white matter of the brain and spinal cord.

MCDONALD CRITERIA

When MS is considered as a potential diagnosis, an individual’s medical history and neurological exam are the mainstay. Neurologists use the McDonald criteria to diagnose MS. This requires evidence of two neurological events consistent with demyelination, where alternatives have been excluded and evidence of disease activity separated in both time (lesions that formed at different points in time) and space (lesions in at least two separate areas of the central nervous system).

MYELIN

A fatty protein that serves as a protective covering and insulation to the nerves that work like wires to carry messages to and from the central nervous system (CNS).

N

NEUROINFLAMMATION

Inflammation of nervous system tissue caused by an immune response to trauma, toxins or the invasion of disease-producing agents such as viruses or bacteria into the central nervous system (CNS).

NEUROLOGY

The branch of medicine concerned with the study and treatment of disorders of the nervous system.

NEURON

A specialized nerve cell transmitting nerve impulses.

NUMBNESS

A loss of sensation in the part of the body that interferes with the ability to use the affected body part. For example, a person with very numb feet may have difficulty walking. Numb hands may prevent writing, dressing or holding objects safely.

O

OLIGOCLONAL BANDS

Group of proteins called immunoglobulins. The presence of these proteins indicates inflammation of the central nervous system (CNS).

P

PARESTHESIAS

Tingling, burning or numbing sensation.

PLAQUE

Abnormal cluster of protein fragments that builds up between nerve cells.

PRIMARY PROGRESSIVE MS (PPMS)

A disease course characterized by steadily worsening neurologic function from the beginning, without relapses or remissions.

PROGRESSIVE -RELAPSING MS (PRMS)

A progressive course of MS from the onset with acute relapses occurring later in the disease course.

R

RELAPSE

In the absence of fever or infection, the appearance of new symptoms or the aggravation of old ones, lasting at least 24 hours and usually associated with inflammation and demyelination in the brain or spinal cord.

RELAPSING REMITTING MS (RRMS)

The most common disease course at the time of diagnosis, characterized by clearly defined attacks or worsening neurologic function (also called relapses or exacerbations), which are followed by periods of partial or complete recovery (remissions).

REMISSION

Reduction and stability in severity of one’s MS, or the disappearance of symptoms.

S

SECONDARY PROGRESSIVE MS (SPMS)

A disease course that follows relapsing-remitting MS (RRMS), in which the disease begins to progress more steadily, with or without relapses. Most people diagnosed with RRMS will transition to SPMS within 10-20 years.

SEIZURE

Episodes that are the result of abnormal electrical discharges in an injured or scarred area of the brain.

SEXUAL DYSFUNCTION

Difficulty experienced by an individual or a couple during any stage of a normal sexual activity, including physical pleasure, desire, preference, arousal or orgasm.

SPASM

A sudden, involuntary contraction of a muscle or group of muscles.

SPASTICITY

An unusual tightness or stiffness of the muscles occurring typically in the legs (calf or thigh), groin, buttocks, arms or hands. Mostly occurring in disorders of the central nervous system (CNS).

SPEECH DISORDERS

Problems that may include lack of precision in articulation, loss of conversational flow and difficulty with speaking rate, loudness or vocal quality.

SPINAL TAP

Also referred to as a lumbar puncture, it is a diagnostic medical procedure used to collect cerebrospinal fluid (CSF) to confirm or exclude conditions, and may be used in diagnosis of other conditions.

SUBCUTANEOUS INJECTION

Injection that is given under the skin. Because subcutaneous tissue has few blood vessels, drugs injected here have slow, sustained rates of absorption.

SYMPTOM

A departure from normal function or feeling that is noticed by a patient, reflecting the presence of an unusual state, or of a disease.

T

T-CELLS

Immune-system cells that have the ability to increase an immune response within the body, causing inflammation and damage in MS.

TINGLING

Abnormal sensations (such as a slight prickling or stinging sensation) that can occur anywhere in the body, but are often felt in fingers, hands, feet, arms or legs.

TREMOR

An involuntary muscle contraction and relaxation involving twitching movements of one or more body parts.

U

UHTHOFF’S PHENOMENON

Phenomenon that occurs because of damage to the optic nerve, which interferes with the transmission of signals between the eye and the brain. Symptoms include blurry or reduced vision.

V

VERTIGO

The sensation of spinning or rotating that may occur as the result of lesions in the brainstem areas that coordinate balance.

VIRUS

A microorganism that is smaller than a bacterium that cannot grow or reproduce apart from a living cell. A virus invades living cells and uses their chemical machinery to keep itself alive and to replicate itself.

 

For over 30 years, Biogen has been a leader in MS research and currently offers the broadest MS therapy portfolio to help people with relapsing forms of MS.