Glossary

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A

Autoimmune: when the body’s immune, or defense, system mistakenly attacks its own tissue

Axon: the long, threadlike part of a neuron, or nerve cell, along which nerve signals are conducted

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B

Black box warning: a category of safety warnings required by the United States Food and Drug Administration (FDA) designed to highlight special problems, particularly those that are serious, and to give health care professionals a clear understanding of a potential medical complication associated with a drug

Blood-brain barrier: a protective network of blood vessels and cells that filters blood flowing to the brain

Brain atrophy: a loss of neurons and the connections between them. This loss of tissue can cause the brain to reduce in size

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C

Central nervous system (CNS): a term used to describe the brain and the spinal cord; the part of the body affected by multiple sclerosis

Cerebrospinal fluid (CSF): a clear fluid that circulates in the space surrounding the brain and spinal cord

Chemotherapy: a disease treatment that uses chemicals to destroy harmful cells and tissue

Class I clinical study: a prospective, randomized, controlled, blinded clinical trial conducted in a representative group of people who meet stringent inclusion criteria

Clinically isolated syndrome (CIS): a first neurologic episode that lasts at least 24 hours and is caused by inflammation/demyelination in 1 or more sites in the central nervous system

Cognitive difficulties: a term used to describe memory loss, difficulty concentrating, or difficulty solving problems

Compliance: the degree of constancy and accuracy with which a patient follows a prescribed regimen

Crossed over: a term used to describe patients who started in one group in a study (for example, the placebo group) and then moved to another group in the same study (for example, the treatment group)

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D

Demyelination: a degenerative process that erodes away the myelin sheath that normally protects nerve fibers. Demyelination exposes these fibers and appears to cause problems in nerve impulse conduction that may affect many physical systems

Double blind: a strict method of conducting a clinical trial that helps reduce the possibility of bias (unfair influence). In this type of trial, health care providers and participants are “blinded,” meaning neither group knows what drug regimen each participant is receiving

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E

Endpoint: a category of data used to compare the outcome in different arms of a clinical trial

Evoked potentials: tests that measure electrical activity in the central nervous system

Expanded Disability Status Scale (EDSS): a measurement that assesses a person’s mobility on a scale of 0 to 10 (with 0 indicating normal mobility)

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G

Gadolinium (Gd): a dye that allows magnetic resonance imaging to show areas of active inflammation

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I

Immediate postinjection reaction (IPIR): a reaction occurring immediately after an injection, which may include chest tightness or pain with a fluttery or rapid heartbeat and/or trouble breathing

Immune system: one of the most complex biological systems, made up of an advanced network of cells, tissues, and organs that work together to provide your body with a natural system of defenses

Immunomodulator: a chemical agent that modifies the immune response or the functioning of the immune, or defense, system (as by the stimulation of antibody formation)

Immunosuppressant: an agent capable of suppressing immune responses

Inflammation: the body’s response to physical insult or injury resulting in increased blood flow with swelling, tenderness, redness, and/or heat

Injection site reaction (ISR): a reaction occurring at the site of an injection, which often includes pain, redness, inflammation, lumps/welts, and/or itching

Interferon: a naturally occurring protein that interferes with the ability of viruses to reproduce. Interferon therapies used to treat multiple sclerosis are made from synthetic forms of interferon

Intramuscular (IM) injection: an injection with a long needle given deep into the muscle tissue

Intravenous (IV) infusion: a series of fluids or drugs that are given directly into a vein over an extended period of time

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L

Lesion: in multiple sclerosis, a damaged area in the brain or spinal cord caused by demyelination (also called plaque or sclerosis)

Lipoatrophy: a permanent indentation under the skin due to loss of fatty tissue

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M

Magnetic resonance imaging (MRI): a diagnostic procedure employing a special scanner to obtain detailed images of a specific area of the body, such as the brain or spinal cord

Malignancies: a term for diseases in which abnormal cells divide without control and can invade nearby tissues. Malignant cells can also spread to other parts of the body through the blood and lymph systems. Also called cancer

McDonald criteria: the most current set of standards for diagnosing multiple sclerosis, the McDonald criteria have largely replaced the Poser criteria in 2001 and were updated in 2005. The McDonald criteria incorporated more recent clinical advances and improvements in imaging technology to allow for earlier diagnosis and treatment of MS

MHC Class II modulator: a treatment for relapsing-remitting multiple sclerosis that is presumed to change the way the immune, or defense, system responds by working on inflammatory cells outside and inside the central nervous system

Monoclonal antibody (MAb): a laboratory-produced substance that can locate and bind to cells anywhere in the body

Monofocal episode: in clinically isolated syndrome, an episode that consists of a single neurologic sign or symptom—for example, an attack of optic neuritis—that is caused by a single lesion

Multicenter: a clinical trial that takes place at more than 1 medical center or clinic. Potential benefits include a larger number of participants, geographic variety, inclusion of various ethnic groups, and the ability to compare results among different medical centers—all of which help remove bias from the study

Multifocal episode: in clinically isolated syndrome, an episode that consists of more than 1 neurologic sign or symptom—for example, an attack of optic neuritis accompanied by weakness on 1 side—caused by lesions in more than 1 area of the central nervous system

Multiple sclerosis (MS): a disease that attacks the central nervous system. With MS, the immune, or defense, system creates swelling and causes damage to the nerve coating (called myelin) that protects the nerve fibers in the brain and spinal cord. This damage prevents nerve cells from communicating properly to relay signals to and from other parts of the body

Myelin: a soft, white coating that surrounds and protects nerve fibers in the central and peripheral nervous systems. Myelin also helps nerve fibers conduct electrical impulses

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N

Neurodegeneration: permanent damage or loss of nerve cells, including neurons and axons

Neurologist: a medical doctor (or physician) who specializes in conditions that affect the nervous system, such as multiple sclerosis, epilepsy, or Parkinson’s disease

Neuron: the basic nerve cell of the central nervous system

Neutralizing antibodies (NAbs): proteins produced by the body that may block (“neutralize”) the effectiveness of a drug therapy

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O

Oligoclonal bands: a series of distinct bands found in the immunoglobulin (a protein substance from immune cells) of the cerebrospinal fluid. The bands may be present in other conditions, but they are helpful in diagnosing multiple sclerosis if other symptoms are present

Open label: a method of conducting a clinical trial in which both the patients and doctors know what therapy the patient is taking

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P

Phase III trial: a trial to prove that a drug is effective in a large group of people. It may compare the drug with another drug or with placebo. Phase III trials are required for United States Food and Drug Administration (FDA) approval of a drug

Pivotal trial: a controlled trial to evaluate the safety and effectiveness of a drug in patients who have the disease or condition to be treated. These trials usually represent the most rigorous demonstration of the drug’s effectiveness and safety, and they are the basis for filing with the United States Food and Drug Administration (FDA) for approval to treat the disease

Placebo: an inactive substance that helps determine the effectiveness of a drug by giving researchers something to compare the active drug to

Placebo controlled: a study method that compares patients taking a drug with patients taking placebo

Poser criteria: a set of standards for the diagnosis of multiple sclerosis proposed in 1983, the Poser criteria were developed to reflect the advances of detection techniques (MRI scans and spinal taps) that helped neurologists to determine the existence of lesions and other evidence of MS. They established the basis for diagnosing MS until replaced by the McDonald criteria, published in 2001 and updated in 2005

Pregnancy category: a system devised by the United States Food and Drug Administration (FDA) for classifying risk associated with use of a drug during pregnancy. There are currently 5 pregnancy categories: A, B, C, D, and X. The FDA is considering a proposal to eliminate these categories in favor of a more detailed discussion of the risks and data. For information about pregnancy categories and available multiple sclerosis therapies, click here

Primary endpoint: the main goal of a clinical trial

Primary-progressive multiple sclerosis (PPMS): a less common form of multiple sclerosis than the relapsing-remitting form. PPMS makes up approximately 10% of all cases of MS and is characterized by a slow but nearly continuous worsening of disease

Progressive multifocal leukoencephalopathy (PML): an opportunistic viral infection of the brain that usually leads to death or severe disability

Progressive-relapsing multiple sclerosis (PRMS): the rarest form of multiple sclerosis, which affects approximately 5% of all diagnosed patients. People with PRMS may go through a steady worsening of their condition after being diagnosed. They may also experience clear, severe relapses with or without complete recovery

Prospective study: this type of “forward-looking” study is designed with a specific goal (or endpoint) in mind

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R

Randomized: a method of conducting a clinical trial in which participants are randomly chosen to take either 1 drug regimen or another. This method reduces the bias that can negatively affect the validity of medical research

Relapse: a worsening of multiple sclerosis symptoms or an appearance of new symptoms (also called attack, exacerbation, or flare-up)

Relapsing-remitting multiple sclerosis (RRMS): the most common form of multiple sclerosis, which affects approximately 85% of people newly diagnosed. RRMS is characterized by relapses that are usually followed by a partial or complete recovery

Retrospective study: a study that looks back in time for results that have already occurred in order to evaluate participants who have not been monitored under established criteria. This type of study is usually viewed as less reliable than a prospective study

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S

Sclerosis: hardening of tissue. In multiple sclerosis, sclerosis is the body’s replacement of lost myelin around central nervous system cells with scar tissue (also called lesion or plaque)

Secondary-progressive multiple sclerosis (SPMS): a stage of multiple sclerosis that may come after relapsing-remitting MS. People with SPMS may have occasional relapses, minor remissions, and/or plateaus. Late in the course of the disease, they may experience a progressive disability

Staggered enrollment: a term used to indicate that study participants joined over an extended period of time, not all at once

Subcutaneous injection: an injection with a short needle given into the fatty layer just under the skin

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T

T cell: one type of protective white blood cell that travels throughout the bloodstream looking for viruses, bacteria, fungal infections, and tumor cells. They play an important role in protecting your body

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