Glossary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

A

AFO: See Ankle-foot orthosis.
Afferent pupillary defect: (Also called Marcus Gunn pupil) Abnormal reflex response to light that is a sign of nerve fiber damage (such as due to optic neuritis).
Analgesic: A substance that relieves pain.
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Ankle-foot orthosis (AFO): A brace, usually plastic, that is worn on the lower leg and foot to support the ankle and correct foot drop. By holding the foot and ankle in the correct position, the AFO promotes correct heel-toe walking. (See Foot drop.)
Antibody: A variety of 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 triggers the immune system to produce an antibody; generally refers to foreign proteins (infectious or toxic substances). See Antibody.
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Assistive devices: Any tools designed and/or adapted to help a person perform a particular task, e.g., cane, walker, shower chair.
Ataxia: Lack of coordination and unsteadiness that result from the brain's failure to regulate the body's posture and the strength and direction of limb movements. Most often caused by disease activity in the cerebellum or its connections with other parts of the brain.
Atrophy: A wasting or decrease in size of a part of the body because of disease or lack of use.
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Attack: See Exacerbation.
Autoimmune disease: Process in which the body's immune system causes illness by mistakenly attacking healthy cells, organs, or tissues. Multiple sclerosis is believed to be an autoimmune disease, along with systemic lupus, rheumatoid arthritis, scleroderma, and many others. The precise origin and an understanding of how these diseases occur are not yet well known.
Autonomic nervous system: 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.
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Axon: Impulses are transmitted to other nerve cells or parts of the body (i.e., muscles, organs) through axons. 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 the nerve.

B

Babinski reflex: Neurological sign in MS in which stroking the outside sole of the foot with a painful stimulus causes an extensor (upward) movement of the big toe rather than the normal flexor (downward) movement of the toe.
Bell's palsy: Paralysis of the facial nerve, which can occur as a consequence of MS, viral infection, or other infections. It has acute onset and can be transient or permanent.
Benign Multiple Sclerosis: Form of relapsing-remitting multiple sclerosis with minimal disability after 10-15 years of disease. Patients with benign MS account for approximately 10 percent of the MS patient population.
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Blood-brain barrier (BBB): Semi-permeable cell layer around blood vessels in the brain and spinal cord that prevents large molecules, cells, and potentially damaging substances and disease-causing organisms (e.g., viruses) from passing out of the blood stream into the central nervous system (brain and spinal cord).
Brain stem: Part of the central nervous system that houses the nerve centers of the head as well as the centers for respiration and heart control and through which all impulses to and from the periphery of the brain pass. It extends from the base of the brain to the spinal cord.
Brainstem auditory evoked potentials (BAEPs): Test in which the brain's electrical activity in response to auditory stimuli (e.g., clicking sounds) is recorded by an electroencephalograph (EEG) and analyzed by computer. Demyelination results in a slowing of response time. This test is sometimes useful in the diagnosis of MS because it can confirm the presence of a suspected lesion or identify the presence of a lesion that has produced no symptoms. BAEPs have been shown to be less useful in the diagnosis of MS than either visual or somatosensory evoked potential tests.
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C

CAT scan: See Computerized axial tomography.
Catheter: Hollow, flexible tube, made of plastic or rubber, which can be inserted through the urinary opening into the bladder to drain excess urine that cannot be excreted normally.
Central Nervous System (CNS): Collective term for the brain, spinal cord and optic nerve.
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Cerebellum: Part of the brain situated above the brainstem that controls balance and coordination of movement.
Cerebrospinal fluid (CSF): Watery, colorless, clear fluid found in the ventricles (pockets) of the brain, and surrounding the spinal cord and brain. 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. See Lumbar puncture.
Cerebrum: 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.
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Chronic: Of long duration, not acute; a term often used to describe a disease that shows gradual worsening.
Clinical finding: Observation made during a medical examination indicating change or impairment in a physical or mental function.
: Formal test of a medical procedure or pharmaceutical agent.
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Cognition: High-level functions carried out by the human brain, including comprehension and use of speech, visual perception and construction, calculation ability, attention (information processing), memory, and executive functions such as planning, problem solving, and self-monitoring.
Cognitive impairment: Changes in cognitive function caused by trauma or disease process. Some degree of cognitive impairment occurs in approximately 50-60 percent of people with MS, with memory, information processing, and executive functions being the most commonly affected functions.See Cognition.
Cognitive rehabilitation: Techniques designed to improve the functioning of individuals whose cognition is impaired because of physical trauma or disease. Rehabilitation strategies are designed to improve the impaired function via repetitive drills or practice, or to compensate impaired functions that are not likely to improve. Cognitive rehabilitation is provided by psychologists and neuropsychologists, speech/language pathologists, and occupational therapists. While these three types of specialists use different assessment tools and treatment strategies, they share the common goal of improving the individual's ability to function as independently and safely as possible in the home and work environment.
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Combined (bladder) dysfunction: Type of neurogenic bladder dysfunction in MS (also called detrusor-external sphincter dyssynergia — DESD). Simultaneous contractions of the bladder's detrusor muscle and external sphincter cause urine to be trapped in the bladder, resulting in symptoms of urinary urgency, hesitancy, dribbling, and incontinence.
Computerized axial tomography (CAT scan): Non-invasive diagnostic radiology technique for examining soft tissues of the body. A computer integrates X-ray scanned "slices" of the organ being examined into a cross-sectional picture.
Condom catheter: Tube connected to a thin, flexible sheath that is worn over the penis to allow drainage of urine into a collection system; can be used to manage male urinary incontinence.
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Constipation: Condition in which bowel movements happen less frequently than is normal for the particular individual, or the stool is small, hard, and difficult or painful to pass.
Contraction: Shortening of muscle fibers that result in the movement of a joint.
Contracture: Permanent shortening of the muscles and tendons adjacent to a joint, which can result from severe, untreated spasticity and interferes with normal movement around the affected joint. If left untreated, the affected joint can become frozen in a fixed position.
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Corticosteroids: Natural steroid hormones or man-made drugs used to suppress inflammation.
Cranial nerves: Nerves that carry sensory, motor, or parasympathetic fibers to the face and neck. Included among this group of twelve nerves are the optic nerve (vision), trigeminal nerve (sensation along the face) oculomotor nerve (eye movement), facial nerve, auditory nerve and vagus nerve (pharynx and vocal cords). Evaluation of cranial nerve function is part of the standard neurological exam.
Cystoscopy: Diagnostic procedure in which a special viewing device called a cystoscope is inserted into the urethra (a tubular structure that drains urine from the bladder) to examine the inside of the urinary bladder.
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Cytokine: Intercellular messenger cells.

D

DNA: Abbreviation for deoxyribonucleic acid a long molecule that forms a chromosome and that contains the complete code for cell and body development.
Deep tendon reflexes: Involuntary contractions of the muscle that are normally produced when the tendons are tapped with a hammer leading to limb movement. Reflexes are tested as part of the standard neurological exam.
Dementia: Progressive loss of intellectual function, sometimes associated with personality change, that results from loss of brain substance, and is sufficient to interfere with a person's normal, functional activities.
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Demyelination: Destruction of the myelin in the central nervous system that results in interruptions of communication between neurons. Regions of demyelination are called plaques.
Detrusor muscle: Muscle of the urinary bladder that contracts and causes the bladder to empty.
Detrusor-external sphincter dyssynergia (DESD): See Combined (Bladder) dysfunction.
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Diplopia: Double vision, or the simultaneous awareness of two images of the same object that results from a failure of the two eyes to work in a coordinated fashion.
Disability: As defined by the World Health Organization, a disability (resulting from an impairment) is a restriction or lack of ability to perform an activity in the manner or within the range considered normal for a human being.
Disease modifying Drugs (DMD): These therapies include beta interferons, glatiramer acetate and immunosuppressants (mitoxantrone). Disease modifying therapies are essential to modify the course of MS. They are currently the most effective way of controlling the course of MS.
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Double-blind clinical study: A study in which none of the participants, including the subjects, examining doctors, attending nurses, or any other research staff, know who is taking the test drug and who is taking a control or placebo agent.
Dysmetria: Disturbance of coordination, caused by lesions in the cerebellum. 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 neurological or neuromuscular symptom that may result in aspiration (whereby food or saliva enters the airway), slow swallowing (possibly resulting in inadequate nutrition), or both.
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Dysphonia: Disorders of voice quality (including poor pitch control, hoarseness, breathiness, and hypernasality) caused by spasticity, weakness, and lack of coordination of muscles in the mouth and throat.
Dyspnea: Air starvation with pained breathing. It occurs normally from physical exertion, and abnormally either from impaired respiration, emotional distress, or a breakdown in nerve responses.

E

EDSS: Expanded Disability Status Scale. A scale used to measure the level of disability in MS and its changes in the course of the disease.
Edema: Localized or systemic condition in which the body tissues contain an excessive amount of fluid.
Electroencephalography (EEG): Diagnostic procedure that records, via electrodes attached to various areas of the person's head, electrical activity generated by brain cells.
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Electromyography (EMG): Diagnostic procedure that records muscle electrical potentials through a needle or small plate electrodes. The test can also measure the ability of peripheral nerves to conduct impulses.
Epidemiology: The study of diseases present in a community at a specific time.
Etiology: Study of all factors that may be involved in the development of a disease, including the patient's susceptibility, the nature of the disease-causing agent, and the way in which the person's body is invaded by the agent.
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Evoked potentials (EPs): Recordings of the nervous system's electrical response to the stimulation of specific sensory pathways (e.g., 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.
Exacerbation: In MS, the appearance of new symptoms or the aggravation of old ones, lasting at least twenty-four hours (synonymous with attack, relapse, flare-up, or worsening); usually associated with inflammation and demyelination in the brain and/or spinal cord.

F

Failure to empty (bladder): Type of neurogenic bladder dysfunction in MS resulting from demyelination in the voiding reflex center of the spinal cord. The bladder tends to over fill and become flaccid, resulting in symptoms of urinary urgency, hesitancy, and incontinence.
Failure to store (bladder): Type of neurogenic bladder dysfunction in MS resulting from demyelination of the pathways between the spinal cord and brain. Typically seen in a small, spastic bladder, storage failure can cause symptoms of urinary urgency, frequency, incontinence, and nocturia.
Fibroblast: Connective tissue cell.
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Finger-to-nose test: 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 neurological exam.
Flare-up: See Exacerbation
Foley catheter: See Indwelling catheter.
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Foot drop: Condition of weakness in the muscles of the leg, caused by poor nerve conduction, which interferes with a person's ability to extend the ankle and walk with a normal pattern. The toes touch the ground before the heel, causing the person to trip or lose balance.
Frontal lobes: Largest lobes of the brain. The anterior (front) part of each of the cerebral hemispheres that make up the cerebrum. The back part of the frontal lobe is the motor cortex, which controls voluntary movement; the area of the frontal lobe that is further forward is concerned with learning, behavior, judgment, and personality.

G

Gadolinium: Contrast medium injected prior to MRI scans. It passes through breaches in the blood-brain barrier and is therefore used to highlight new and active lesions. The usage of gadolinium greatly enhances the sensitivity of T1-weighted MRI.
Ganglia (singular: ganglion): Colonies of autonomic or sensory neurons (cell bodies) outside the brain and spinal cord acting to control local functions or transmit information to the CNS.
Glycosylation: A modification of protein that occurs in mammalian cell production that involves the addition of chains of sugar molecules to the amino acid chain, producing a carbohydrate structure similar to that found in natural proteins, such as interferon beta.
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H

Handicap: As defined by the World Health Organization, a handicap is a disadvantage, resulting from an impairment or a disability that interferes with a person's efforts to fulfill a role that is normal for that person. Handicap is therefore a social concept, representing the social and environmental consequences of a person's impairments and disabilities.
Heel-knee-shin test: Test of coordination in which the person is asked, with eyes closed, to place one heel on the opposite knee and slide it up and down the shin.
Helper T-lymphocytes: White blood cells that are a major contributor to the immune system's inflammatory response against myelin.
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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.

I

Immune system: Complex system of various types of cells that protects the body against disease-producing organisms and other foreign invaders.
Immunity: Ability to resist infection and to heal. The process may involve acquired immunity, (the ability to learn and remember a specific infectious agent), or innate immunity (the genetically programmed system of responses that attack, digest, remove, and initiate inflammation and tissue healing).
Immunocompetent cells: White blood cells (B- and T-lymphocytes and others) that defend against invading agents in the body.
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Immunoglobulin G (IgG): An antibody produced by human plasma cells. It is also found in plaques of a diseased central nervous system. Levels of IgG are increased in the cerebrospinal fluid of most MS patients.
Immunosuppression: In MS, 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 cyclosporin, methotrexate, and azathioprine.
Impairment: As defined by the World Health Organization, an impairment is any loss or abnormality of psychological, physiological, or anatomical structure or function. It represents a deviation from the person's usual biomedical state. An impairment is thus any loss of function directly resulting from injury or disease.
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Incidence: Number of new cases of a disease in a specified population over a defined period of time.
Incontinence: Also called spontaneous voiding; the inability to retain control of urine or bowel movements.
Indwelling catheter: Type of catheter (see Catheter) that remains in the bladder on a temporary or permanent basis. It is used only when intermittent catheterization is not possible or is medically contraindicated.
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Inflammation: The immunologic response of body tissue to injury, characterized by mobilization of white blood cells and antibodies, swelling, and fluid accumulation.
Intention tremor: Rhythmic shaking that occurs in the course of a purposeful movement, such as reaching to pick something up or bringing an outstretched finger to touch one's nose.
Interferon: Group of immune system proteins — alpha, beta, and gamma — that are produced by different cells in the body. All three have antiviral effects, but act in different ways to control the activity of the immune system. Only interferon beta, a carbohydrate-bearing protein produced by fibroblasts (cells found in skin and connective tissues) has conclusively been shown to be effective in treating MS. Commercially available interferon beta include interferon beta-1a (Rebif^® and Avonex^® ) and interferon beta-1b (Betaseron^®).
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Interferon beta-1a: Interferon beta that is very similar to that produced naturally by the human body. It is obtained in the laboratory via a biotechnological process: the interferon beta gene is inserted into laboratory-grown mammalian cells, which then produce the protein.
Interferon beta-1b: Interferon beta that is slightly different from the one produced naturally by the human body. It is obtained in the laboratory via a biotechnological process: the interferon beta gene is inserted into bacteria, which then produce the protein. Interferon beta-1b has a slightly different amino acid structure and lacks the glycosylated moiety that is found in natural interferon beta.
Intermittent self-catheterization (ISC): Procedure in which the person periodically inserts a catheter into the urinary opening to drain urine from the bladder. ISC is used in the management of bladder dysfunction to drain urine that remains after voiding, prevent bladder distention, prevent kidney damage, and restore bladder function.
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Internuclear ophthalmoplegia: Disturbance of coordinated eye movements in which the eye turned outward to look toward the side develops nystagmus (rapid, involuntary movements) while the other eye simultaneously fails to turn completely inward. This neurological sign, of which the person is usually unaware, can be detected during the neurological exam.
Intramuscular Injection: Injected into the muscle.
Intrathecal space: Space surrounding the brain and spinal cord that contains cerebrospinal fluid.
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Intravenous: Within a vein; often used in the context of an injection into the vein of a medication dissolved in a liquid.

J

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K

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L

L'Hermitte's sign: 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.
Lesion: See Plaque.
Lesion load: Total volume of brain tissue affected by the MS disease process (as seen on MRI T2-weighted scans).
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Leukeocyte: White blood cell.
Leukocytosis: Having abnormally high numbers of white blood cells, usually the result of a non-viral infection.
Leukopenia: Having abnormally low numbers of white blood cells.
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Limbic system: System in the brain, generally considered to mediate emotions and primitive response (eating, drinking, etc).
Lumbar Puncture: Diagnostic procedure that uses a needle to penetrate the spinal canal at the level of third-fourth or fourth-fifth lumbar vertebrae to remove cerebrospinal fluid for analysis. This procedure is used to examine the cerebrospinal fluid for changes in composition that are characteristic of MS (e.g., elevated white cell count, elevated protein content, the presence of oligoclonal bands).
Lumbar Region: The lower back composed of five segments of the spinal chord and column between the sacrum (tail bone) and thoracic (chest) regions.
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Lymphocyte: Specialized cells of the immune system, which recognize antigens and subsequently release substances which activate other cells, or directly destroy the antigen. Lymphocytes are divided into two main groups: T-lymphocytes and B-lymphocytes.

M

MRI T1 weighted scans: See Magnetic resonance imaging.
MRI T2 weighted scans: See Magnetic resonance imaging.
Macrophage: Large white blood cells, which have an important role in defending the body against invasion by bacteria.
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Magnetic resonance imaging (MRI): Imaging technique based on detection of the response of water molecules to strong magnetic fields. It produces visual images of different body parts without the use of X-rays and can therefore be performed repeatedly. MRI allows the neurologist to identify MS lesions in the brain and spinal cord, at different stages of their development. T1 scans and T2 scans refer to the different scanning sequences to help distinguish tissue features.
Marcus Gunn pupil: See Afferent pupillary defect.
Monoclonal antibodies: Antibodies, which can be programmed to react against a specific antigen in order to suppress the immune response.
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Motor neurons: Nerve cells of the brain and spinal cord that enable movement of various parts of the body.
Motor point block: See Nerve block.
Multiple sclerosis: Presumed autoimmune disease of the central nervous system, mainly affecting young adults, whose origin is unknown. It damages myelin (nerve fiber insulation) 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.
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Muscle tone: Characteristic of a muscle brought about by the constant flow of nerve stimuli to that muscle, which describes its resistance to stretching. Abnormal muscle tone can be defined as: hypertonus (increased muscle tone, as in spasticity); hypotonus (reduced muscle tone; flaccid paralysis); atony (loss of muscle tone). Muscle tone is evaluated as part of the standard neurological exam in MS.
Myalgia: Tenderness or pain of the muscles themselves.
Myelin: Soft, white coating composed of lipids (fats) and protein, surrounding nerve fibers in the central nervous system. 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.
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Myelin basic protein (MBP): Major protein component of myelin. May be a target of immune attack of myelin in multiple sclerosis.
Myelitis: Inflammatory disease of the spinal cord. In transverse myelitis, the inflammation spreads across the tissue of the spinal cord, resulting in a loss of its normal function to transmit nerve impulses up and down, as though the spinal cord had been severed partially or completely.
Myelogram: 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 canal.
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Myelosuppresion: Reduced ability of bone marrow cells to produce red and white blood cells, generally due to drugs used for cancer, but can occur as a manifestation of diseases such as hematologic (blood cell) malignancies.

N

NK (natural killer) cell: Comprise a minor fraction of the antigen recognizing cells of normal blood cells. They are directly cytotoxic (lethal) to other cells.
Necrosis: Death of tissue or cells.
Nerve: Bundle of axons (nerve fibers). The fibers are either afferent (leading toward the brain and serving in the perception of sensory stimuli of the skin, joints, muscles, and inner organs) or efferent (leading away from the brain and mediating contractions of muscles).
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Nerve block: Procedure used to anesthetize a nerve and relieve otherwise intractable spasticity, including painful flexor spasms. An injection of phenol into the affected nerve interferes with the function of that nerve for up to three months, potentially increasing a person's comfort and mobility.
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.
Neuralgia: Pain, sometimes severe, that manifests along the length of a nerve and arises within the nerve itself, not in the tissue from which the sensation seems to arise.
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Neurasthenia: Tiredness or exhaustion, often in excess of what would seem appropriate from purely physical causes.
Neuritis: Nerve inflammation, usually with direct nerve damage, part of a degenerative process.
Neurogenic: Related to activity of the nervous system, as in "neurogenic bladder."
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Neurogenic bladder: Bladder dysfunction associated with neurologic malfunction in the spinal cord and characterized by a failure to empty, failure to store, or a combination of the two. Symptoms that result from these three types of dysfunction include urinary urgency, frequency, hesitancy, nocturia, and incontinence.
Neuron: The basic nerve cell of the nervous system. A neuron consists of a nucleus within a cell body and one or more processes (extensions) called dendrites and axons. Neurons generate electrical impulses and communicate information throughout the nervous system.
Neuropathies: Disease of the peripheral nerves.
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Neuropsychologist: Psychologist with specialized training in the evaluation of cognitive functions. Neuropsychologists use a number of standardized tests to evaluate specific cognitive functions and identify areas of cognitive impairment. They also provide remediation for individuals with MS-related cognitive impairment. See Cognition and Cognitive impairment.
Nocturia: The need to urinate during the night.
Nystagmus: Rapid, involuntary movements of the eyes in the horizontal or, occasionally, the vertical direction.
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O

Occupational therapist (OT): Assess functioning in activities of everyday living, including dressing, bathing, grooming, meal preparation, writing, and driving, which are essential for independent living. In making treatment recommendations, the OT addresses (1) fatigue management, (2) upper body strength, movement, and coordination, (3) adaptations to the home and work environment, including both structural changes and specialized equipment for particular activities, and (4) compensatory strategies for impairments in thinking, sensation, or vision.
Oligoclonal bands: Diagnostic sign indicating abnormal levels of certain antibodies in the cerebrospinal fluid; seen in approximately 90 percent of people with multiple sclerosis, but not specific to MS.
Oligodendrocyte: Type of cell in the central nervous system that is responsible for making and supporting myelin.
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Ophthalmoscope: Instrument designed for examination of the interior of the eye.
Optic atrophy: Wasting of the optic disc that results from partial or complete degeneration of optic nerve fibers and is associated with a loss of visual acuity.
Optic disc: Spot on the surface of the retina where cells of the retina converge to form the optic nerve; the only part of the retina that is insensitive to light ("blind spot").
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Optic neuritis: Inflammation or demyelination of the optic (visual) nerve with temporary or permanent impairment of vision and associated with pain during the acute phase.
Orthosis: Also called orthotic; a mechanical appliance such as a leg brace or splint that is specially designed to control, correct, or compensate for impaired limb function.
Orthotic: Also called orthosis; a mechanical appliance such as a leg brace or splint that is specially designed to control, correct, or compensate for impaired limb function.
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Oscillopsia: Continuous, involuntary, and chaotic eye movements that result in a visual disturbance in which objects appear to be jumping or bouncing.
Osteoporosis: Decalcification of the bones. It is possible for it to develop due to lack of mobility experienced by wheelchair-bound individuals.

P

Paralysis: Inability to move a part of the body.
Paraparesis: A weakness but not total paralysis of both lower extremities (legs).
Paraplegia: Paralysis of both lower extremities (legs).
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Parasympathetic Nervous System: Division of the autonomic nervous system that controls normal digestive, reproductive, cardiopulmonary, and vascular functions and stimulates most secretions. This subsystem works as a direct antagonist to the sympathetic division, and functions are balanced by their interaction.
Paresis: Partial or incomplete paralysis of a part of the body.
Paresthesia: Spontaneously occurring sensation of burning, prickling, tingling, or creeping on the skin that may or may not be associated with any physical findings on neurological examination.
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Paroxysmal symptom: Any one of several symptoms that have sudden onset, apparently in response to some kind of movement or sensory stimulation, last for a few moments, and then subside. Paroxysmal symptoms tend to occur frequently in those individuals who have them, and follow a similar pattern from one episode to the next. Examples include acute episodes of trigeminal neuralgia (sharp facial pain), tonic seizures (intense spasm of limb or limbs on one side of the body), dysarthria (slurred speech often accompanied by loss of balance and coordination), and various paresthesias (sensory disturbances ranging from tingling to severe pain).
Pathogenesis: Mode of development of a disease.
Physical therapist (PT): Individual trained to evaluate and improve movement and function of the body, with particular attention to physical mobility, balance, posture, fatigue, and pain. A physical therapy program typically involves (1) educating the person with MS about the physical problems caused by the disease, (2) designing an individualized exercise program to address the problems, and (3) enhancing mobility and energy conservation through the use of a variety of mobility aids and adaptive equipment.
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Placebo: Inactive, non-drug compound designed to look just like the test drug. It is administered to control group subjects in double-blind clinical trials (in which neither the researchers nor the subjects know who is getting the drug and who is getting the placebo) as a means of assessing the benefits and liabilities of the test drug taken by experimental group subjects.
Placebo effect: Apparently beneficial result of therapy that occurs because of the patient's expectation that the therapy will help.
Plantar reflex: Reflex response obtained by applying a painful stimulus along the outer border of the sole of the foot from the heel to the little toe. The normal flexor response is a bunching and downward movement of the toes. An upward movement of the big toe is called an extensor response, or Babinski reflex, which is a sensitive indicator of disease in the brain or spinal cord.
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Plaque: An area of inflamed or demyelinated central nervous system tissue.
Position sense: Ability to tell, with one's eyes closed, where fingers and toes are in space. Position sense is evaluated during the standard neurological exam in MS.
Postural tremor: Rhythmic shaking that occurs when the muscles are tensed to hold an object or stay in a given position.
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Power grading: Measurement of muscle strength used to evaluate weakness or paralysis. Power is tested as part of the standard neurological exam in MS.
Prevalence: Number of all new and old cases of a disease in a defined population at a particular point in time.
Primary progressive MS (PPMS): Clinical course of MS characterized from the beginning by progressive disease, with no plateaus or remissions, or an occasional plateau and very short-lived, minor improvements.
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Prognosis: Prediction of the future course of the disease.
Progression of disability: Progressive accumulation over time of irreversible neurologic deficits and abnormalities, occurring either as a result of incomplete recovery of relapses, or between relapses.
Pseudo-bulbar affect: Condition in which episodes of laughing and/or crying occur for no apparent reason. The person's actual mood may be unrelated to the emotion being expressed. This condition is thought to be caused by lesions in the part of the brain involved in emotional feeling and expression.
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Pseudo-exacerbation: Temporary aggravation of disease symptoms, resulting from an elevation in body temperature or other stressor (e.g., fever, severe fatigue), that disappears once the stressor is removed. A pseudo-exacerbation involves symptom flare-up rather than new disease activity or progression.

Q

Quad cane: Cane that has a broad base on four short "feet," which provide extra stability.
Quadriplegia: Paralysis of both arms and both legs.

R

Rebiject, Rebiject II: Rebiject and Rebiject II are autoinjection devices for use only with Rebif. Rebiject II is the latest generation of this technology, designed to help make injections easier to manage.
Recent memory: The ability to remember events, conversations, content of reading material or television programs from a short time ago, i.e., an hour or two ago or last night. People with MS-related memory impairment typically experience greatest difficulty remembering these types of things in the recent past.
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Recombinant: Produced by a biotechnological process in the laboratory.
Reflex: Involuntary response of the nervous system to a stimulus, such as the stretch reflex, which is elicited by tapping a tendon with a reflex hammer, resulting in a contraction. Increased, diminished, or absent reflexes can be indicative of neurologic damage, including MS, and are therefore tested as part of the standard neurological exam.
Relapse: See Exacerbation.
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Relapsing-remitting MS (RRMS): Clinical course of MS that is characterized by the occurrence of new symptoms or the worsening of old symptoms (relapses or exacerbations). Symptoms may evolve over several days or weeks and then fully or partially disappear. The pattern of attacks is unpredictable even in the same person. RRMS accounts for approximately 40% of the patient population with MS at any given time.
Remission: Lessening in the severity of symptoms or a "return" to the level of health equal (or similar) to the one experience prior to the last attack.
Remote memory: Ability to remember people or events from the distant past.
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Remyelination: Repair of damaged myelin. Some myelin repair may occur spontaneously in MS but is usually a very slow and uncontrollable process.
Residual urine: Urine that remains in the bladder following urination.
Retrobulbar neuritis: See Optic neuritis.
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Romberg's sign: Inability to maintain balance in a standing position with feet and legs drawn together and eyes closed.

S

SGOT (serum glutamic oxaloacetic transaminase) and SGPT (serum glutamic pyruvic transaminase): Liver enzyme test that identify levels which are normally only present in minute quantities in the blood, they become elevated under a variety of circumstances, including hepatitis and in association with medication use.
Sclerosis: Hardening of tissue. In MS, sclerosis is the body's replacement of lost myelin around CNS nerve cells with scar tissue.
Scotoma: Gap or blind spot in the visual field.
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Secondary progressive MS (SPMS): Clinical course of MS that initially is relapsing-remitting and then becomes progressive at a variable rate. With SPMS, neurological symptoms tend to worsen progressively. At first, there may still be some relapses and then relapses stop completely and a slow but steady progression of disability takes place.
Sensory: Related to bodily sensations such as pain, smell, taste, temperature, vision, hearing, acceleration, and position in space.
Somatosensory evoked potential: Test that measures the brain's electrical activity in response to repeated (mild) electrical stimulation of different parts of the body. Demyelination results in a slowing of response time. This test is useful in the diagnosis of MS because it can confirm the presence of a suspected lesion (area of demyelination) or identify the presence of a lesion that has produced no symptoms.
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Spasm: Symptom of spasticity in which the legs and/or arms straighten or flex (bend) suddenly into a stiff, extended position. These spasms, which typically last for several seconds to minutes, occur most commonly in bed at night, but may occur with attempted movement. They can be extensor or flexor.
Spasticity: Increased muscle tone associated with involuntary muscle contractions, spasms and stiffness. In multiple sclerosis, spasticity is most prominent in the lower limbs.
Speech/language pathologist: Specializes in the diagnosis and treatment of speech and swallowing disorders. A person with MS may be referred to a speech/language pathologist for help with either one or both of these problems. Because of their expertise with speech and language difficulties, these specialists also provide cognitive remediation for individuals with cognitive impairment.
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Sphincter: Circular band of muscle fibers that tightens or closes a natural opening of the body, such as the external anal sphincter, which closes the anus, and the internal and external urinary sphincters, which close the urinary canal.
Spinal tap: See Lumbar puncture.
Spontaneous voiding: See Incontinence.
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Subcutaneous Injection: Injected just under the skin.
Suppressor T-lymphocytes: White blood cells that act as part of the immune system.
Sympathetic: Part of the nervous system that is in charge of involuntary body functions such as our heart, organs and glands. The sympathetic nervous system originates in the spinal cord.
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Symptom: Subjectively perceived problem or complaint reported by the patient. In multiple sclerosis, common symptoms include visual problems, fatigue, sensory changes, weakness or paralysis of limbs, tremor, lack of coordination, poor balance, bladder or bowel changes, and psychological changes.
Symptomatic Drugs: Medicines that help alleviate some of the symptoms seen in MS (fatigue, pain, urinary dysfunction, spasms, etc.).

T

T-cell Lymphocytes: Or white blood cells. Regulate the different functions of all the cells that make up the immune system and they also play a major role in the destruction of viruses that invade the body. Develop in the bone marrow and mature in the thymus.
Tandem gait: Test of balance and coordination that involves alternately placing the heel of one foot directly against the toes of the other foot.
Tenotomy: Irreversible surgical procedure performed to cut severely contracted tendons attached to muscles that do not respond to any other type of spasticity control and are causing intractable pain and skin complications related to lack of physical movement.
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Tinnitis: Ringing in the ears.
Titration: Gradual stepping up of a dose of medicine. It allows the body to adjust and become used to the medicine's effects, thereby reducing the likelihood and severity of potential side effects that may occur at the beginning of a treatment.
Titubation: Form of tremor, resulting from demyelination in the cerebellum, that manifests itself primarily in the head and neck.
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Transcutaneous electric nerve stimulation (TENS): Nonaddictive and noninvasive method of pain control that applies electric impulses to nerve endings via electrodes that are attached to a stimulator by flexible wires and placed on the skin. The electric impulses block the transmission of pain signals to the brain.
Transverse myelitis: Acute attack of inflammatory demyelination that involves both sides of the spinal cord. The spinal cord loses its ability to transmit nerve impulses up and down. Paralysis and numbness are experienced in the legs and trunk below the level of the inflammation.
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.

U

Urethra: Duct or tube that drains the urinary bladder.
Urinary frequency: Requirement to void urine frequently.
Urinary hesitancy: Inability to void urine spontaneously even though the urge to do so is present.
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Urinary incontinence: See Incontinence.
Urinary sphincter: Muscle closing the urethra, which in a state of flaccid paralysis causes urinary incontinence and in a state of spastic paralysis results in an inability to urinate.
Urinary urgency: Inability to postpone urination once the need to void has been felt.
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Urologist: Physician who specializes in the branch of medicine (urology) concerned with the anatomy, physiology, disorders, and care of the male and female urinary tract, as well as the male genital tract.

V

Vertigo: Dizzying sensation of the environment spinning, often accompanied by nausea and vomiting.
Vibration sense: Ability to feel vibrations against various parts of the body. Vibration sense is tested (with a tuning fork) as part of the sensory portion of the neurological exam.
Visual acuity: Clarity of vision. Acuity is measured as a fraction of normal vision. 20/20 vision indicates an eye that sees at 20 feet what a normal eye should see at 20 feet; 20/400 vision indicates an eye that sees at 20 feet what a normal eye sees at 400 feet.
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Visual evoked potential: Test in which the brain's electrical activity in response to visual stimuli (e.g., a flashing checkerboard) is recorded by an electroencephalograph and analyzed by computer. Demyelination results in a slowing of response time. Because this test is able to confirm the presence of a suspected brain lesion (area of demyelination) as well as identify the presence of a lesion that has produced no symptoms, it is useful in diagnosing MS. VEPs are abnormal in approximately 90 percent of people with MS.

W

WBC (White Blood Cells): Including those of innate immunity, like basophils, neutrophils, eosinophils, monocytes, macrophages to name a few, and those of acquired immunity.
White matter: Region of the brain that is comprised almost entirely of myelinated nerve fibers giving it a white texture that underlies the gray matter (neuronal layer) of the brain.

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