
Glossary
Adherence: refers to how closely a person follows a prescribed treatment regimen. It includes their willingness to start treatment and their ability to take medications exactly as directed by their healthcare team.
Analgesics: a class of medications that relieve pain.
Antibody: a protein produced by a type of white blood cell in the immune system. Antibodies are released into the bloodstream in response to a foreign invader (known as an antigen), such as a bacterium, virus, parasite, or transplanted organ. An antibody then neutralizes the antigen by binding specifically to it.
Autoimmune disease: an improper immune response of the body against substances and tissues normally present in the body (i.e., the body attacks its own self). In MS, the immune system has an irregular response to the myelin (the protective sheath surrounding the nerve fibers) in the central nervous system. Cells of the immune system destroy the myelin.
Autoinjector: a device that contains a cartridge of medicine, a needle and usually a needle cover. An injection is delivered with a push of a button—this automatically inserts the needle, injects a single dose of the medicine.
Axon (nerve fiber): a long, slender extension of a nerve cell (neuron) that conducts electrical impulses away from the neuron's cell body. Many of these are bundled together to create the structure of a nerve. The movement of electrical impulses along the axon of a nerve cell is how messages are passed throughout the body.

Blood-brain barrier: a division that provides protection for the central nervous system (CNS [brain and spinal cord]) from the rest of the body. In MS, the blood-brain barrier can be weakened by lesions, allowing more damaging immune cells to enter the CNS.
Corticosteroids (or “steroids”): a class of medications used to provide relief for inflamed areas of the body to lessen swelling, redness, itching and allergic reactions. Corticosteroids are often used for a number of conditions, including autoimmune diseases.
Demyelination: the destructive removal of myelin (protective sheath covering a nerve cell axon). Demyelination is the major underlying factor responsible for the symptoms of MS. The patches of demyelination within the central nervous systems are known as lesions.
Disease-modifying drugs (or treatments, medication, therapy): a class of medications that work to change or alter the course of a disease, rather than just treat the symptoms of the disease.
Expanded disability status scale (EDSS): an assessment tool comprised of a group of tests that measure the functionality of different body systems. An EDSS score is calculated based on a person’s testing in seven functional areas. These scores fall within a clinical rating scale and range from 0 to 10, with higher numbers indicating more severe impairment and disability.
Exacerbation (relapse, attack, or flare-up): the appearance of new MS symptoms or the worsening of old symptoms. To be a true exacerbation, the attack must last at least 24 hours and be separated from the previous attack by at least 30 days. Most exacerbations last from a few days to several weeks or even months.
Immunological: of or related to the immune system.
Lesion (plaque): an area of the central nervous system that is inflamed due to demyelination (loss of myelin) of the nerve cell axon. Modern technologies such as MRI (magnetic resonance imaging) scans can produce images of the brain and spinal cord showing the distribution of the lesions.
Mammalian cells: cells or cell lines from mammals.
Macrobiotics: a theory or way of living that promotes well-being and longevity, usually by means of a diet (macrobiotic diet) consisting chiefly of whole grains and beans.
Myelin: an insulating and protective fatty protein which covers nerve cell axons (the long extension of a neuron) responsible for the smooth and fast conduction of nerve impulses throughout the central nervous system. In MS the myelin is attacked, causing the transmission of nerve impulses to be either slowed or blocked, affecting certain cognitive and physical abilities and skills.
Optic neuritis: a vision disorder characterized by inflammation of the optic nerve, causing loss of vision (partial or complete), sudden blurred or "foggy" vision, and/or pain when moving the affected eye. Optic neuritis is one of the most common symptoms of MS, and usually occurs at the first presentation of the disease.
Relapse (exacerbation, attack, or flare-up): the appearance of new MS symptoms or the worsening of old symptoms. To be a true relapse, the attack must last at least 24 hours and be separated from the previous attack by at least 30 days. Most relapses last from a few days to several weeks or even months.
Relapse rate: refers to how often someone suffers relapses. This is an important measure in MS treatment clinical trials.
Spasticity (spasms): a condition in which certain muscles are continuously contracted, causing stiffness or tightness.
Stem cells: a type of cell found in most organisms that form the basis of most cells as they grow and divide into specialized functions. They are now commonly studied for treatment of many different diseases and conditions because they have the potential to develop into many different, specialized cell types and can serve as an internal repair system. Researchers have shown that stem cells can replace damaged cells causing disease.
Subcutaneous injection: the administration of medication (or other medicinal substance such as insulin or vaccines) into the subcutaneous layer of fat that exists between the outside skin layers (dermis and epidermis) and the muscle layer.
T cell (T lymphocyte): a type of white blood cell of key importance to the immune system. T cells survey the body for foreign invaders (such as bacteria and viruses) and destroy them through a targeted approach. In MS, T cells become improperly activated, causing a misdirected attack against the body’s own myelin.