Glossary of Terms


Glossary of Terms Related to Multiple Sclerosis

Acute: Having rapid onset, usually with recovery; not chronic or long-lasting.

Antibody: Protein produced by certain cells of the immune system, which is produced in response to bacteria, viruses and other types of foreign antigens.

Antigen: Any substance that triggers the immune system to produce an antibody; generally refers to infections or toxic substances.

Ataxia: The incoordination and unsteadiness that results from the brain's failure to regulate the body's posture and the strength and direction of limb movements. Ataxia is most often caused by disease activity in the cerebellum.

Autoimmune disease: A process in which the body's immune system causes illness by mistakenly attacking healthy cells, organs or tissues in the body that are essential for good health. Multiple sclerosis is believed to be an autoimmune disease, along with systemic lupus erythematosus, rheumatoid arthritis, scleroderma and many others. The precise origin and pathophysiologic processes of these diseases are unknown.

Autonomic nervous system: The part of the nervous system that regulates involuntary vital functions, including the activity of the cardiac (heart) muscle, smooth muscles (e.g., of the gut) and glands. The autonomic nervous system has two divisions: the sympathetic nervous
system accelerates heart rate, constricts blood vessels and raises blood pressure; the parasympathetic nervous system slows heart rate, increases intestinal and gland activity,
and relaxes sphincter muscles.

Bell's palsy: A paralysis of the facial nerve (usually on one side of the face), which can occur
as a consequence of MS, viral infection or other infections. It has acute onset and can
be transient or permanent.

Central nervous system: The part of the nervous system that includes the brain, optic nerves and spinal cord. The nerves that leave the spinal cord and go to the rest of the body make up the peripheral nervous system.

Cerebrospinal fluid (CSF): A watery, colorless, clear fluid that bathes and protects the brain and spinal cord. The composition of this fluid can be altered by a variety of diseases. Certain changes in CSF that are characteristic of MS can be detected with a lumbar puncture (spinal tap), a test sometimes used to help make the MS diagnosis.

Chronic: Of long duration, not acute; a term often used to describe a disease that shows
gradual worsening.

Clinically isolated syndrome (CIS): A first neurological event that is suggestive of demyelination, accompanied by multiple, clinically "silent" (asymptomatic) lesions on MRI that are typical of MS. Individuals with this syndrome are at high risk for developing clinically definite MS.

Demyelination: A loss of myelin in the white matter of the central nervous system.

Dysesthesia: Distorted or unpleasant sensations experienced by a person when the skin is touched, that are typically caused by abnormalities in the sensory pathways in the brain and spinal cord.

Dysmetria: A disturbance of coordination, caused by lesions in the cerebellum. A tendency to over- or underestimate the extent of motion needed to place an arm or leg in a certain position as, for example, in overreaching for an object.

Dysphagia: Difficulty in swallowing. It is a neurologic or neuromuscular symptom that may result in aspiration (whereby food or saliva enters the airway), slow swallowing (possibly resulting in inadequate nutrition) or both.

Evoked potentials (EPs): EPs are recordings of the nervous system's electrical response to the stimulation of specific sensory pathways (eg., visual, auditory, general sensory). In tests of evoked potentials, a person's recorded responses are displayed on an oscilloscope and analyzed on a computer that allows comparison with normal response times. Demyelination results in a slowing of response time. EPs can demonstrate lesions along specific nerve pathways whether or not the lesions are producing symptoms, thus making this test useful in confirming the diagnosis of MS. Visual EPs are considered the most useful in MS.

Finger-to-nose test: As a test of dysmetria and intention tremor, the person is asked, with eyes closed, to touch the tip of the nose with the tip of the index finger. This test is part of the standard neurologic exam.

Hemiparesis: Weakness of one side of the body, including one arm and one leg.

Hemiplegia: Paralysis of one side of the body, including one arm and one leg.

Immunosuppression: In MS, a form of treatment that slows or inhibits the body's natural
immune responses, including those directed against the body's own tissues. Examples
of immunosuppressive treatments in MS include mitoxantrone, cyclosporine, methotrexate
and azathioprine.

Lhermitte's sign: An abnormal sensation of electricity or "pins and needles" going down the spine into the arms and legs that occurs when the neck is bent forward so that the chin touches the chest.

Myelin: A soft, white coating of nerve fibers in the central nervous system, which may be found in higher than normal concentrations in the cerebrospinal fluid of individuals with MS and other diseases that damage myelin.

Myelogram: An x-ray procedure by which the spinal canal and the spinal cord can be visualized. It is performed in conjunction with a lumbar puncture and injection of a special x-ray contrast material into the spinal cord.

Nervous system: Includes all of the neural structures in the body: the central nervous system consists of the brain, spinal cord and optic nerves; the peripheral nervous system consists of the nerve roots, nerve plexi, and nerves throughout the body.

Neurologist: Physician who specializes in the diagnosis and treatment of conditions related to the nervous system.

Oscillopsia: Continuous, involuntary and chaotic eye movements that result in a visual disturbance in which objects appear to be jumping or bouncing.

Paraparesis: A weakness but not total paralysis of the lower extremities/legs.

Plaque: An area of inflamed or demyelinated central nervous system tissue. A plaque, or lesion, which can vary from a few millimeters to a few centimeters in diameter, generally contains inflammatory cells and other cells that are important in brain inflammation.

Stance ataxia: An inability to stand upright due to disturbed coordination of the involved muscles, which results in swaying and a tendency to fall in one or another direction.

Trigeminal neuralgia: Lightning-like, acute pain in the face caused by demyelination of
nerve fibers at the site where the sensory (trigeminal) nerve root for that part of the face
enters the brainstem.

Vertigo: A dizzying sensation of the environment spinning, often accompanied by nausea
and vomiting.

White matter: The part of the brain that contains myelinated nerve fibers, and therefore appears white, in contrast to the cortex of the brain, which contains nerve cell bodies and appears gray.

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