Multiple Sclerosis Glossary

This area will feature some of the most mentioned terms and their definitions pertaining to Neurology and Multiple Sclerosis. Please check back for additions often.

 | A | B | C | D | E | F | G | H | I | L | M | N | O | P | R | S | T | V | W |

| A |
Antibody
Any of various substances existing in the blood or developed following immunization which counteract bacterial or viral poisons or destroy bacteria in the system.

Antigen
Any substance that stimulates a response from the immune system.

Astrocyte
Large cell found in the white and gray matter of the central nervous system. These cells provide structural support for the nervous system, are part of the blood-brain barrier, and are involved in repairing nerve tissues.

Ataxia
Failure of muscular coordination, irregularity of muscular action.

Auto-immune disorder
Disorder occurring when the body reacts against its own components, as if they were foreign, by developing antibodies against them. Such a reaction can induce a pathological condition.

Axon
It is through these that the impulses are transmitted to other nerve cells or to parts of the body directly stimulated by nerves (i.e. muscles, organs). In the nervous system, the axon is covered by a myelin sheath, and together they form the nerve fiber. Many thousands of these fibers, bundled together, form the anatomical structure known as a nerve.

| B |
Blood/brain barrier
Membrane that controls the passage of substances from the blood into the central nervous system.

| C |
Central nervous system
That part of the nervous system consisting of the brain and spinal cord.

Cerebrospinal fluid
The fluid found in the ventricles (pockets) of the brain, and around the spinal cord.

Cerebrum
The main portion of the brain, occupying the upper part of the cranial cavity. Divided into two hemispheres joined by the corpus callosum, an arched mass of white matter, it forms the largest part of the human central nervous system.

Cytokine
A soluble factor (protein) that transmits messages between cells, thus acting as an intercellular mediator by binding to specific receptors on target cells. Cytokines include lymphokines, monokines, interleukins and interferons.

| D |
Demyelination
Destruction of the myelin in the nervous tissue. Demyelination ultimately results in nervous system scars, called plaques, which interrupt communication between the neurons.

Diplopia
Double vision (two images of a single object).

DNA
Abbreviation for deoxyribonucleic acid - the very long molecule that winds up to form a chromosome and that contains the complete code for the automatic construction of the body.

| E |
Experimental allergic encephalomyelitis (EAE)
Chronic brain and spinal cord disease similar to multiple sclerosis which is induced by injecting myelin basic protein into laboratory animals.

Epidemiology
The study of diseases present in a population at a specific time.

| F |
Fibroblast
A connective tissue cell.

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| G |
Gadolinium
A chemical compound administered to patients during MRI scans. It serves to distinguish new lesions from old.

Genetic engineering
The process by which a gene (parts of the nucleus of the cell that carry information) is extracted and implanted into a different cell. The purpose of which is for the new cell to produce large, pure quantities of the substance coded by the genetic material.

Glycoprotein
Proteins that contain sugars.

Glycosylation
One of the most important modifications that occurs in mammalian cell production of interferons and ensures that the molecule produced functions correctly. It involves the addition of chains of sugar molecules to the amino acid chain, producing a carbohydrate structure similar to that found in natural interferon beta.

| H |
Human Leucocyte Antigens (HLAs)
Also known as the "Major Histocompatibility Complex", HLAs are groups of distinct molecules found on the surface of most of the cells of the body which serve essentially to recognize "self" and "non-self". The exact type of these molecules is inherited, and, therefore, each human being has his or her own distinct combination of these molecules.

| I |
Immunoglobulin G (IgG)
An antibody-containing substance produced by human plasma cells in plaques of a diseased central nervous system. Levels of IgG are increased in the cerebrospinal fluid of most MS patients.

Interferons
A class of proteins secreted by many cells and which seem to be part of the body's natural defense against viral infection. Interferons can belong to three different categories: alpha (produced by white cells), beta (of fibroblastic origin) and gamma (originating from lymphocytes). Each type of interferon has clearly differentiated biochemical effects.

| L |
Lesion
An area of injury or damage, for example, in the case of multiple sclerosis, a patch of demyelination in the brain or spinal cord.

Leucocyte
White blood cell.

Lymphocyte
Specialized cells of the immune system which recognize antigens and subsequently release either antibodies or other substances which activate other cells, or directly destroy the antigen. Lymphocytes are divided into two main groups: T-lymphocytes and B-lymphocytes.

| M |
Macrophage
Large white blood cells which have an important role in defending the body against invasion by bacteria.

Magnetic Resonance Imaging (MRI)
High resolution scanner that allows exact imaging of the brain, and can reveal the characteristic plaques of multiple sclerosis.

Multiple Sclerosis
An auto-immune disease of the central nervous system, mainly affecting young adults, whose origin is unknown. It damages nerve fiber insulation (myelin) in a random and patchy manner, causing a wide range of neurological defects. It is characterized clinically by symptoms that typically abate spontaneously in the early years of the disease but often get gradually worse in later years.

Benign Multiple Sclerosis
It is characterized by complete recovery from isolated attacks or exacerbations. Patients with benign MS do not become disabled and account for 10% of the MS patient population.

Relapsing-Remitting Multiple Sclerosis (RRMS)
It is characterized by the unpredictable occurrence of new symptoms or the worsening of old symptoms (relapses or exacerbations). RRMS is a common form of MS and accounts for approximately 40% of the patient population.

Primary Progressive Multiple Sclerosis (PPMS)
It is characterized by the occurrence of relapses that steadily worsen symptoms and leading to death. This form of multiple sclerosis accounts for 10% of the patient population

Secondary Progressive Multiple Sclerosis (SPMS)
It is characterized by isolated attacks, like RRMS, but recovery is incomplete and disability progresses between exacerbations. Patients with SPMS will eventually become moderately or severely disabled. SPMS patients account for 40% of the patient population.

Myelin
The myelin sheath, which surrounds axons of some nerve cells, consists of concentric layers of myelin, a phospholipidic protein. A complex natural electrical insulator, myelin serves to speed up the conduction of electrochemical messages between the central nervous system and the rest of the body.

Myelin basic protein (MBP)
MBP is a major component of myelin. When damage to the myelin occurs (as in MS), MBP can often be found in abnormally high levels in the patient's cerebrospinal fluid. When injected into laboratory animals, MPB induces experimental allergic encephalomyelitis, a chronic spinal cord disease similar to MS.

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| N |
NK (natural killer) cell
NK cells comprise a minor fraction of the antigen recognizing cells of normal blood cells. They are directly cytotoxic to other cells.

Neuron
Any of the conducting cells of the nervous system.

Nystagmus
Succession of involuntary rhythmic oscillations of the eyeballs, composed of an alternation between slow and rapid movements.

| O |
Oligodendrocytes
Cells of the central nervous system that produce and maintain myelin.

Optic neuritis
An inflammatory disorder of the optic nerve that usually occurs in only one eye and causes visual loss and sometimes blindness. It is generally temporary.

| P |
Paresthesias
An abnormal sensation such as prickling, burning, pins and needles.

Plaques
Areas of inflammation and demyelination typical of multiple sclerosis. The loss of myelin in plaques disrupts or blocks nerve signals.

Pathogenesis
Mode of development of a disease.

Protein
Molecule made of a chain of amino acids.

| R |
Receptor
A protein found on the surface of a cell. It allows the latter to identify antigens.

Recombinant
Pertaining to any substance produced by genetic engineering.

Retrobulbular neuritis
An inflammatory disorder of the optic nerve that is usually temporary. It causes rapid loss of vision and may cause pain upon moving the eyes.

| S |
Spasticity
Involuntary muscle contractions leading to spasms and stiffness or rigidity. In multiple sclerosis, spasticity primarily affects the lower limbs.

| T |
T-cell lymphocytes
T-cell lymphocytes act as the maestro of the immune system by regulating the different functions of all the cells that make up the immune system. They themselves also play a major role in the destruction of viruses that invade the body. They develop in the thymus during embryonic life.

Transverse myelitis
An acute spinal cord disorder which causes sudden low back pain, muscle weakness and abnormal sensory sensations in the lower extremities. Transverse myelitis often remits spontaneously, however, severe or long-lasting cases can lead to permanent disability.

| V |
Vermal region (of the brain)
A narrow strip of tissue that connects the two hemispheres of the cerebellum

| W |
White matter
Nerve fibers that are the site of MS lesions and underlie the gray matter of the brain and spinal cord.

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