Refresh


home
news
forum
articles
Purchase









Email Airbrains


M S    A N D    Y O U

Back to MSlinks
GLOSSARY
Acetylcholine - One of the chemicals in the body that is used by nerves to communicate with each other.

ACTH - Abbreviation for adrenocorticotrophic hormone; used for short term treatment of an acute exacerbation
(attack), no value as a long term treatment of MS.  
- A substance produced by the brain that regulates the production of steroids by the adrenal gland. This material can be produced artificially and is sometimes recommended by physicians to manage flare-ups of multiple sclerosis.

Acuity, Visual - Clarity of vision. Visual acuity is expressed as a fraction of normal vision. 20/400 means an eye that sees at 20 feet what an average eye sees at 400 feet.

Anesthesia - Loss of feeling (pain and touch perception) over part or all of the body.

Anoxia  - is a condition in which there is not enough oxygen for tissue oxygenation.

Anterior Horn  (Spinal Cord) - In the gray matter of the spinal cord, it contains motor neurons. The posterior horn (top) contains  sensory neurons.

Anterior Horn  - They command Skeletal muscles to perform the quick or the repetitive movements. They are the final target of all neural activity. Plaques or demyelination anywhere in the CNS must affect their function. ex: unstable gait, or incoordinate fingers.

Anterior Horn Cell   (Anterior Horn Neuron) -;A motor neuron in the anterior horn gray matter. These cells innervate muscle fibres directly  to produce movement of body parts. 

Antibodies - Substances produced by cells in response to stimullating agents such as viruses or bacteria, they are tailor made for a particular antigen.  
- Proteins produced by special cells in the immune system that attack germs, parasites, and other foreign substances in the body.  
- Complex glycoprotein produced in response to the presence of an antigen that has a destructive influence on the antigen which stimulated its formation, thus producing immunity.

Anti-inflammatory Drugs - Over-the-counter and prescription medications that are sometimes recommended to decrease inflammation. Aspirin and ibuprofen are types of over-the-counter anti-inflammatory medications.

Antigen - A molecular protein substance such as a virus, antigens stimulate an "immune response".  
- Any substance that triggers the immune system to produce an antibody; generally refers to infectious or toxic substances.

Aphasia - Loss of speech expression or comprehension.

Aspiration - Inhaling food particles or fluids into the lungs.

Asymmetry - Not the same on the two sides of the body.

Ataxia  - The inability to maintain balance, while walking. The failure of muscular coordination.    
- Poorly coordinated gait or limb movements.
- A reeling, wide-based gait. 

Atrophy - Loss of substance. Often refers to loss of bulk in a muscle that is used little or not at all.
Atrophy, Optic -  Pallor and loss of blood vessels on the optic nerve head as is seen through the ophthalmoscope. This is caused by loss of myelin or of optic nerve fibers and blood vessels in the optic nerve. 

Autoimmune disease - A process in which the body's immune system causes illness by attacking elements, such as particular cells or materials, that are normal and essential for health. The immune system is the body's defense system against abnormal substances (such as viruses or bacteria) in the body. In autoimmune disorders, the body's defense system attacks substances that are needed by (versus harmful to) the body

TOP.

B-Cell - A blood cell that makes proteins known as"immunoglobulins."  
- A type of white blood cell that matures into antibody producing cells when exposed to specific stimuli. 

Babinski's Sign -  When the sole of the foot is scratched, the big toe goes up instead of down. This is an indication that there is a lesion between the motor cortex on the opposite side of the brain the lower spinal cord. This is a sign of (plaque or lesion)  Pyramidal Tract Disease. 

Baclofen - A prescription medication for individuals with multiple sclerosis that is recommended for spasticity of muscles. Baclofen is an anti-spasticity agent that is believed to interfere with spinal cord activity that produces abnormal tone in the legs and arms. 

Basal Ganglia - Are a group of functionally related nuclei, located bilaterally in the interior of the inferior aspect of the cerebrum, the midbrain and the diencephalon. They are the largest nuclei of the brain and play an important role in planning and coordinating motor movements and posture.  
- Exert their influence over networks that link the motor cortex to other cortical areas. They behave as a variable filter ensurring smooth muscle movements. 

Blood-Brain-Barrier - A semi-permeable cell layer (the interior wall) of blood vessels in the Central Nervous System (CNS). It prevents large molecules, immune cells, and all potentially damaging substances and foreign organisms (e.g. viruses) from passing out of the blood stream and into the CNS (brain and spinal cord). A break in the blood-brain-barrier may underlie the disease process in MS.  

Brainstem - That portion of the brain that connects the two cerebral hemispheres with the spinal cord. It has three major divisions: Midbrain, Pons and Medulla. This is the oldest part of the brain, where most involuntary functions are controlled from.  
- The area of nerve cells and nerve fibers at the base of the brain still within the skull that connects to the spinal cord.  
- The medulla oblongata, pons and midbrain constitute the brainstem. It connects the spinal cord's axons to the remainder of the brain and is responsible for many essential functions. All but two of the 12 cranial nerves, enter or exit the brain through the brainstem.  

Brainstem auditory evoked response (BAER) - A painless, diagnostic test in which electrical impulses from the base of the brain are recorded in response to repeated clicks during electroencephalography.

TOP 

CAT (or CT) scan - A diagnostic, computerized imaging system that uses X rays to determine the density of different spots in the body. By producing a picture of the densities at thousands of spots in the brain, a CT scan discloses normal and abnormal structures. 

CD4 - A specific, genetically determined type of T-cell, that is thought to play a primary role in MS & EAE. It is also known as "a helper T-cell". 

Cell - The body is made up almost entirely of many different kinds of cells. Each cell has a discrete inner core called the nucleus, surrounded by  cytoplasm, and is encased in a membrane separating it from other cells.  

Cellular Immunology -  One of the body's immune systems. 

Cell Membrane - The thin layer made of proteins, fats and carbohydrates, which form the capsule of a cell, and is its outside "skin".

Central nervous system - The part of the nervous system covered by the meninges. It includes the brain, spinal cord, and optic nerves.  

Centrocecal scotoma - A blind spot that interferes with central vision.
--------------------------------------------------------------------------------
Cerebellum - A part of the brain located above the brainstem, its chief function concerns balance and coordination of movements.
- Because cerebellar disease is only discernnible as complex motor dysfunction. It has no direct connection to any specific movement. ex: posture imbalance; changes the speed and  the cadence of speech; willed movements resemble tremor; and abnormalities of eye movements. The cerebellum has no ability to learn; hence once damaged, it will continue to malfunction.
--------------------------------------------------------------------------------
CEREBELLAR FUNCTION DISORDERS:

- The severity of symptoms  seems to depend on the amount of tissue destroyed and not on where the damage is. Among the most characteristic signs of cerebellar damage are the following:  

1) Asthenia  - This refers to a lack of muscular strength, either during voluntary muscle contraction or in holding posture.

2) Fatigability - Muscles on the same side as where cerebellar damage has occurred tire more easily and have slower than normal contraction and relaxtion times, leading to slowed movements.

3) Hypotonia - The muscles feel flabby and offer less resistance to passive displacement. This may be from lack of response to spinal tract input.

4) Ataxia - Literally "difficulty measuring" this term refers to failure to stop a motion at the intended point with overshoot occurring. Prediction would seem to be faulty here. This term indicates incoordination of muscular activity involving tremor, failure of progression, and failure accurately to perform rapid alternating movements such as tapping a finger. A swaying, unsteady and wide based gait is often the most obvious sign.
--------------------------------------------------------------------------------
Cerebrospinal Fluid (CSF) - The fluid surrounding the brain and the spinal cord.  

Cerebrum - Forms the great bulk of the brain and consists of two hemispheres which occupy the entire vault of the cranium and are incompletly seperated from each other by a deep median cleft, the longitudinal cerebral fissure.  

Circumduction - A pattern of moving the legs in which the person swings the upper leg widely at the hip. It is usually caused by partial paralysis or spasticity of the limb. 

Clonus - Rapidly alternating contraction and relaxation of a muscle. Ankle clonus is the most common form of clonus. The spasms in the calf muscle makes the foot and leg bounce up and down. It is a sign of spasticity.  

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. 

Complement - A substance in serum that combines with antigen antibody compound. Symbol C'. 

Computed tomography - See CAT scan.

Coordination - An organized working together of muscles and groups of muscles aimed at bringing about a purposeful movement, such as walking or standing. 

Corpus Callosum - Is a thick band of more than 200 million myelinated transverse nerve fibers, which is the only connection between the two hemispheres of the cerebrum. It lies at the bottom of the longitudinal cerebral fissure.   
- The underside forms the roof of the two lateral ventricles.  

Cortex - Is the outer layer of any organ. 

Cortex, Cerebral - The outer layer of nerve cells that covers the entire surface of the cerebral hemispheres. Thinking and other complex neuronal activity occur in the cerebral cortex.  
- A 2.5 to 4.0 mm. thick layer of neurons containing gray matter. 

Cortex, Association - The cortex immediately adjacent to and closely connected to the primary sensory cortex. Association cortex gives form and meaning to raw sensory messages received at the primary sensory cortex thru widespread connections to many parts of both sides of the brain. 

Corticotropin - See ACTH.

Cortisone - A steroid hormone recommended to some people with multiple sclerosis to reduce acute inflammations in the nervous system. Cortisone carries significant risks. 

Cytokines - are proteins (usually glycoproteins) of relatively low molecular mass and often consisting of just a single chain. They regulate all the important biological processes - cell growth, cell activation, inflammation, immunity, tissue repair, fibrosis and morphogenesis. Although cytokins are considered to be a family, this is a functional rather than a structural concept; these proteins are not all chemically related. (Ex. Interferons and Interleukins).

TOP 

Dantrolene sodium (Dantrium) - An antispasticity medication. 

Deep tendon reflexes - The involuntary jerks that are normally produced at certain spots on a limb when the tendons are tapped with a hammer. 

Decompostion of Movement - inability to sequence properly fine, coordinated acts.    

Decubitus - An ulcer (sore) of the skin resulting from pressure and lack of movement, such as occurs when a person is mostly in a bed or a wheelchair. The ulcers occur most frequently in areas where the bone lies directly under the skin, such as the elbow, hip, or tailbone.  

Dementia - A generally profound and 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. 

Demyelination - Loss of the myelin sheath that normally covers a nerve or an axon.  
- The destruction or removal of the myelin covering nerve tissue.  
- The stripping off of the myelin lining of nerve fibers by a disease process. Multiple sclerosis is a demyelinating disease. Other factors, however, can also cause demyelination. 

Dendrite - The part of a neuron that carries impulses towards the cell body.  

Disability - 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. 

Disseminated - Scattered or distributed (multiple).  

Dysarthia - Problems with the clarity or rhythm of speech.  
- Poorly articulated speech resulting from dysfunction of the muscles controlling speech. The content and meaning of the spoken words remain normal.  

Dysdiadockokinesia - Inability to perform rapid alternating movements.

Dyesthesia - Distorted or unpleasant sensations experienced by a person when the skin is touched. 

Dysmetria - Inability to control range of movements.  
- A disturbance of coordination, caused by lesions in the cerebellum. A tendency to over- or under estimate the extent of motion needed to place an arm or leg in a certain position. 

Dyspepsia - Indigestion, a feeling of being over stuffed.  

Dysphagia - Difficulty in swallowing. It is a neurological or neuromuscular symptom which may result in aspiration (food or saliva enters the airway), slow swallowing (possibly leading to inadequate nutrittion), or both.  

Dysphonia - Disorders of voice quality (including poor pitch control, hoarsness, breathiness, and hypernasality) caused by spasticity, weakness, and incoordination of muscles in the throat and mouth.

TOP

EAE (Experimental Allergic Encephalomyelitis) - A disease induced in lab animals that is similar to what is seen in humans with MS. 

Edema - Swelling in the brain or elsewhere caused by the abnormal accumulation of fluid. 

Emboli - are small particles that occlude the circulation of smaller blood vessels. 

Electroencephalography - A painless, diagnostic technique that amplifies and records electrical activity in the brain. 

Embolization - is the process of occlusion by emboli.  

Encephalitis - Inflalmmation of the brain, sometimes called "sleeping sickness" caused by viruses and other microscopic organisms.  

Epidemiology - The science concerned with the cause, frequency and distribution of an infectious process or a physiological state in a human community.  

Etiology - The 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. 

Evoked potentials - Electrical signals recorded from the central nervous system that appear in response to repetitive stimuli, such as a clicking noise, flashing light, or electrical shock. Evoked potentials rely on electroencephalography to record responses. 

Exacerbation - An increase in the severity of symptoms. Exacerbations of MS usually involve an increase in definite symptoms, lasting weeks or months. During the attack, numerous individual symptoms may come and go in succession. Acute attacks are usually followed by complete or partial remission - the abatement or diminution of symptoms.  
- A worsening or flare-up of neurologic signs and symptoms (such as numbness, weakness or lost vision), usually associated with inflammation and demyelination in the brain or spinal cord. The opposite of exacerbation is remittance.  
- The appearance of new symptoms or the aggravation of old ones, lasting at least 24 hours. 

Fasciculus, Medial Longitudinal - A nerve fiber tract in the brainstem that helps to control horizontal eye movements. The (MLF) coordinates the two eyes, when they look to the left or to the right. A lesion in the MLF interrups that coordination so that the eyes do not turn in precisely the same direction at exactly the same time. Thereby producing two images in the brain of the same scene - double vision.  

Fecal incontinence - Loss of control of bowel movements. 

Flare-up - See exacerbation. 

Focal deficits - Impaired strength or sensation over part of the body. 

Footdrop - Impaired or absent voluntary dorsiflexion of the foot.  
- The normal heel-toe pattern of walking (gait) is disturbed, causing the toes to touch the ground before the heel, resulting in the person tripping and losing balance.  

Frontal Lobes - The largest lobes of the Cerebrum. The anterior (front) part of each of the cerebral hemispheres, is the control centers for learning, behavior, judgement, and personality. The back part of the frontal lobe is the motor cortex which controls voluntary movement.

TOP  

Gadolinium - A chemical compound which can be administered to a person, having MRI imaging done, to enhance the distinction between new lesions and old lesions. 

Gait ataxia - Broad-based, staggering patterns of walking caused by poor coordination of the limbs. 

Gamma Globulin - Blood proteins that carry antibody activity. White blood cells in MS plaques make gamma globulins that may be found in the spinal fluid. Increased percentage of gamma gloublin, and presence of oligoclonal gamma globulin bands are characteristic of the spinal fluid in MS.  
- A protein fraction of the blood serum which contains many different kinds of antibodies.  
- A family of antibodies that is increased in the spinal fluid of many, but not all, people with multiple sclerosis. 

Gene - The biological unit of heredity. Genes determine the structure and function of all proteins in the body. In turn, these proteins govern body shape and function. 

Genetic Determinant - Pertaining to heredity, ie, HL-A antigen.  

Girdle sensations - The sensation of feeling a tight band around one's trunk that is sometimes experienced by people with multiple sclerosis. 

Glands - A collection of cells specialized to secrete materials unrelated to their ordinary needs. For instance, the salivary gland is a collection of cells that secrete saliva. Those cells have no use for the product, which aids digestion in the mouth and stomach.

--------------------------------------------------------------------------------

Glial - scars are produced by enlargement of the fibrils of astrocytes (a type of glia) that normally support the nerve cells and their nerve fibers. When a portion of the nervous system is damaged, these fibers enlarge and replace the damaged area. This process is referred to as Gliosis.  

GLIAL CELLS - outnumber neurons by about five to one in the nervous system. They have processes but do not form or conduct nerve impulses. They possess the capacity to divide throughout life. The following are included as types of glial cells and their assigned functions:  

1) Astrocyte Cells - are of two types, depending on number and degree of branching of their processes. Fibrous astrocytes have fewer and less branched processes; protoplasmic (Mossy) astrocytes have more and highly branched processes. Both types of cells are believed to be the major force creating cohesion of the central nervous tissue. In other words, they hold things together and maintain the structural relationship of the cells and their vascular supply.
- Seem to be responsible for the scars or plaques that form on nerve fibers stripped of myelin. These Astrocyte-caused scars may prevent oligodendrocytes from repairing damaged myelin.   

2) Oligodendrocyte Cells - are myelin forming cells of the CNS. Each internode of CNS myelin is the product of a single oligodendrocyte.
- Manufactures and repairs myelin.  

3) Ependymal Cells - act as an epithelial lining for the cavities within the CNS - ventricles of the brain and central canal of the spinal cord. Very small amounts of cerebrospinal fluid are formed by secretion by these cells, and they form a part of the choroid plexuses of the brain, wherein the vast bulk of cerebrospinal fluid is formed by filtration and secretion from the blood vessels composing the plexuses. 

4) Microglia Cells - are sometimes called brain macrophages. They seem to migrate into nerve tissue from the bloodstream, perhaps being derived from blood cells called monocytes. They come to lie around both neurons and injury or inflammation in the CNS. They then become mobile and phagocytic and assume a role in cleaning up the traumatized area. They are the only mesodermally derived cells of the nervous system.

5) Satellite Cells - are formed in peripheral ganglia and serve to support the cell bodies of neurons in those ganglia.  

6) - Schwann Cells - are peripheral in location and are involved in peripheral myelin formation and in the formation of the neurilemma.  

--------------------------------------------------------------------------------

Glucocorticoid Hormones - Steroid hormones that are produced by the adrenal glands in response to stimulation by adrenocorticotropic hormone (ACTH) from the pituitary gland. These hormones, are artifically increased to serve as an anti-inflammation treatment for acute exacerbations of MS, and Optic Neuritis. 

Gray Matter - Portions of the CNS where nerve cell bodies are concentrated. Cortex is gray matter. So are the anterior and posterior horns of the spinal cord and more. 

Hemianopsia - One-sided visual field loss. 

Hemiparesis - Sensory loss or weakness of the face, arm and leg on one side of the body.  

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

Histocompatibility Genes - Are a category of DNA genes called, class II major histocompatibility complex genes. They create the antigens by which the immune system recognizes itself.  

Human Lymphocyte Antigene (HLA) - One of the histocompatibility genes used to determine if donor organs are compatible.  
- Antigen responsible for rejection of tissue transplants and correlated with specific diseases, including MS. 
- Antigens that, when combined with antigenic peptides, cause T-cells to launch an attack.   

Human T-cell Lymphotropic Virus type 1 (HTLV-1) - A retrovirus currently being studied that operates in human T-cells and causes a disease called Tropical Spastic Paraphesis.

Hypoxia - Indicates a severe oxygen shortage in tissue. 

TOP

Immunity - Security against any particular disease or poison, ie, gamma globulin. 

Immunoglobulin - A term for the various types of antibodies produced by the immune system.  

Immunosuppression - Any form of treatment or drug, which slows or inhibits the body's usual immune responses. Some examples used to treat MS are:  Cyclosporin, Methotrexate, and Azathioprine.   

Impairment - Any loss or abnormality of psychological, physiological, or anatomical structure or function. It is a deviation from the person's usual biomedical state. An impairment is thus any loss of function directly resulting from injury or disease. 

Impotence - Poor or absent erection of the penis.  

Incidence - The number of new cases of a disease in a specified population over a defined time period. 

Incontinence - The inability to hold urine or stool until urination or defecation is intended.  

Inflammation - A tissue's immunological response to injury, characterized by mobilization of white blood cells and antibodies, swelling, and fluid accumulation. 

Interferon - An interfering protein that neutralizes virus. It is produced by the body's cells in response to foreign nucleic acid, such as viruses. It protects uninfected cells.  
- A protein substance that is produced naturally in the body by the natural killer cells of the immune system in response to a variety of foreign substances, such as viruses and bacteria.  
- These proteins are antiviral cytokins and are also potent immune regulators and growth factors.
- Interferons fall into three groups:
Alpha is produced by Leukocytes in response to viruses or nucleic acids;
Beta is produced by fibrobasts in response to viruses or nucleic acids;
Gamma is produced by Lymphocytes (both T and LGL) in response to immune stimuli. It is produced by activated T-cells and natural killer cells. A degree of immune activation leads to the production of Gamma, an increase in antigen presenting cell function (APC), activates macrophages in general, and probably enhances their capacity to act as APCs. 

Interleukins (IL-1 to IL-15) - are molecules mainly made by leucocytes, and which mostly act on leucocytes. The main targets for interleukin action vary from T and B cells to fibroblasts and endothelium.  

Ischemia - Is an insufficient blood supply to an organ or tissue. 

Lateral Spinothalamic Tract - A tract in the anterior-lateral portion of the spinal cord. Interruption of the (LST) results in loss of pain and temperature sensation below the level of the interruption on the opposite side of the of the body. 

Lesion - Any abnormal damage to tissue structure or function. A scar is a lesion. So is cancer, a MS plaque, a stomach ulcer or a pimple. 

Lhermitte's sign - An electrical sensation that runs down the spine and into the limbs that some people with multiple sclerosis experience when they flex their necks, such as when tilting their heads.

Lobe (Of The Brain) - A major division of the cerebral hemisphere. Each cerebral hemisphere is divided into: frontal lobe, parietal lobe, occipital lobe, temporal lobe, and limbic lobe. 

Lymphocytes - A variety of white blood cells which are part of the immune systems of the body. 
- White blood cells play a large role in the immune system, by responding to antigens and triggering reactions in other cells.  
- Are produced by bone marrow stem cells and depending on their site of subsequent maturation, they develop into either:

B-Cells, which are responsible for humoral immune responses - used to fight bacterial infections;
T-Cells, which are responsible for cell-mediated immune responses - used to fight virual infections.  
Helper T-cells, heighten the production of antibodies by B-cells;
Suppressor T-cells, supress B-cell activity and seem to be in short supply during a MS exacerbation. 

TOP

Macrophage - A scavenger cell involved in demyelination.  
- Cells that have the ability to recognize and ingest all foreign antigens through rcceptors on the surface of their cell membranes.  
- A white blood cell with scavenger characteristics that has the ability to ingest and destroy foreign substances such as bacteria and cell debris. 

Medulla - The lowest major segment of the brainstem. 

Microemboli - Refers to any small emboli that predominantly occlude the microcirculation.  

Monoclonal Antibodies - Are laboratory-produced antibodies, which can be programmed to react againsta specific antigen in order to suppress the immune response. 

MR or MRI - See nuclear magnetic resonance. 

Myelin - Fatty substance which forms a sheath around some nerve fibers in the CNS and the peripheral nervous system. Myelin is formed by Oligodendeocyte cells and consists largely of their cell membranes, which wrap themselves around the nerve axons.  
- The fatty insulation of nerve fibers that is damaged in multiple sclerosis. Myelin covers and insulates the body's nerves in the brain in what is called the myelin sheath.  

Myelin basic protein - One of the components of myelin, and of spinal fluid that is increased in the spinal fluid of some, but not all, people with multiple sclerosis.  

Myelitis - An inflammatory disease of the spinal cord. In transverse myelitis, the inflammation spreads across 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. 

Myxovirus - A virus which causes disease in mucous tissue such as the throat, mouth, or lung.  ex: (Influenza) 

Necrosis - Is the death or decay of tissue in a part of the body which is the result of loss of blood supply, burning, and other severe injuries. 

Nerve fibers - Fibers that extend from the body of a nerve cell that transmit electrical pulses as part of the information handling in the nervous system.  
- A bundle of nerve fibers (axons). The fibers are either afferent - leading towards 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 and relaxsations of muscles or organs. 

Nerve Impulse - The electrochemical charge carried by an axon. 

Neuron - An individual nerve cell.  
- 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.  

Neurologic disease - Any disorder of the nervous system. There are many different neurologic diseases, among which is multiple sclerosis. 

Nuclear magnetic resonance (MRI, MR, NMR) - A diagnostic test that uses the properties of different substances in a magnetic field to produce images of the brain, spinal cord, and other parts of the body. 

Nystagumus - With the fast component maximal towards the side of the cerebellar lesion. 
- Rhythmical jerking movements of the eyes.  
- Rapid, involuntary movements of the eyes in the horizontal or, occasionally, the vertical direction. 

Oligoclonal bands - Accumulations in the spinal fluid of excessive amounts of limited classes of antibodies. 

Oligodendrocytes - Cells in the brain and in the spinal cord that produce the myelin sheath that insulates nerve fibers. (See: Glial Cells #2) 

Optic atrophy - Degeneration of the optic nerve. 

Optic neuritis - Inflammation of the optic nerve that causes transient or permanent loss of vision and is often associated with pain in the eye at the time vision deteriorates. Optic neuritis is common in many, but not all, people with multiple sclerosis. Often, optic neuritis is one of the first diagnosable signs that an individual may have multiple sclerosis. 

Optic nerve - The bundle of nerve fibers formed by the light sensitive retina of the eye that extends from the eye and connects to the brain. 

Organelle (Little Organ) - Particles within cells that are covered with their own membrane. Many different kinds of organelle occur within cells, each with a special function.  

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

Orthotic - A mechanical appliance such as a leg brace or shoe inserts that are specially designed to control, correct, or compensate for impaired limb function.  

TOP

Paralysis - Inability to move a part of the body.  

Paraparesis - A weakness but not total paralysis of the lower extremities (legs).  

Paresis - Partial or incomplete paralysis of a part of the body. 

Paresthesias - Sensations of "pins-and-needles" that develop with damage to a pain pathway.  
- A spontaneously occuring sensation of burning, prickling, or creeping on the skin that may or may not be associated with any physical findings on neurological examination.  

Paroxysmal Symptom - Any one of several symptoms which have a sudden onset, apparently in response to some kind of movement or sensory stimulation, last for a few moments, and then subside. They are thought to be caused by the short-circuiting of electrical impulses along demyelinated axons. 

Peripheral Nervous System - All the nerves and nerve cells outside the Central Nervous System.  

Periventricular Region - The area surrounding the four fluid-filled cavities within the brain. MS plaques are commonly found within this region.  

Phospholipids - Are fatty substances that are a major component of myelin. 

Placebo effect - The apparently beneficial result of a medication or other therapy that has no proven value or effect in the management of a medical problem. The apparent benefits occur because of an individual's expectation that the therapy will help.  

Plantar Reflex - A reflex response obtained by drawing a pointed object 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's Sign, which is a sensitive indicator of disease in the brain or spinal cord. 

Plaque - The demyelinating scarring of the axons. Which comprise the bulk of the White Matter in the Central Nervous System.

Prednisone - A steroid drug related chemically and therapeutically to the steroid hormones normally made in the adrenal glands. Prednisone and other steroid medications carry significant risks.

Pons - The portion of the brainstem just superior to the medulla oblongata, is about 2.5cm. in length. It contains the respiratory center, which controls the mechanism that permits outflow of air from the lungs. 

Posterior Column - Bundle of axons in the posterior part of the spinal cord. Interruption of this column on one side of the spinal cord causes loss of position sense below the level of the interruption on the same side of the body.  

Prevalence