Lateral SpinoThalamic Tract - A Sensory Nerve Tract in the Anterior-Lateral (Front-Side) portion of the Spinal Cord. Interruption of the LST, results in loss of Pain and Temperature sensations below the level of the lesion, on the Opposite Side of the body. #01 (View: Image)
Lesion - Any damage to tissue structure or function. A Scar is a Lesion. So is Cancer, a MS Plaque, a Stomach Ulcer or a Pimple. On T1 MRI scans, old lesions register as *Black Holes* - HypoIntense (less tissue) areas. While new inflammatory lesions are seen on T2 scans as, *Bright Spots* - HyperIntense (higher fluid content) areas.
- MS lesions on conventional MRIs T2, first appear as small, ovid shaped, focal bright spots having discrete borders. Cerebral lesions are usually located centrally, near the MidLine, asymmetrically arrayed, deep within the White Matter, and close to a blood vessel (Venule) that is near CerebroSpinal Fluid (Ventricles, or Spinal Cord). #01
Leukocytes - Any of the blood cells that are colorless, lack Hemoglobin, and contain a Nucleus (also called White Blood Corpuscle).
L'hermitte's Sign - An electrical sensation (Shock, Lightning Bolt) that some MSers experience, when flexing the neck, tilting, or lowering the head towards the chest. It begins at the base of the skull, runs down the Spine and into the limbs, before exiting through the hands or feet. #02, #25
- L'hermitte's Sign is thought to stem from injury (ie: compression, distortion, inflammation, radiation, metabolic or toxic aberrations) of the Cervical Dorsal Columns.
- After injury, the damaged Dorsal Column Axons or cell bodies have increased MechanoSensitivity, producing Ectopic Action Potentials that occur with greatest frequency during Cervical flexion (i.e., a maneuver that can alter Spinal Cord length by 2 cm).
- L'hermitte's Sign occurs in 33% of MSers and was the presenting symptom in 16%. (Also See: Tic-Douloureux)
Ligand - A Molecule or Ion that can bind another Molecule.
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. #01
Lymphocytes - A variety of White Blood Cells (Leukocytes), which are part of the body's Cellular Immune System. #09
- White Blood Cells play a large role in the Immune System, by responding to Antigens and triggering reactions in other cells. #27
(Also See: Lymphocytes)
- Are produced by Bone Marrow Stem Cells and depending on their site of subsequent maturation, they develop into either: B or T-Cells. #30
B-Cells - are responsible for Humoral Immune Responses, they produce ImmunoGlobulins (AntiBodies) to fight ExtraCellular infections (Bacteria, Fungus, etc.).
- T-Cells - are responsible for Cell-Mediated Immune Responses (Cellular Immunology) including both effector and regulatory cells. Helper T-Cells prime both AntiBody-mediated and Cell-mediated effectors for the attack, while Suppressors await the signal to change, slow, or end the assult.
Natural Killer Cells (NK) - recognize classes of cells and destroy tumor cells on contact, without needing a costimulator signal.
- CytoToxic T-Cells (CD8+) - handle the destruction of host cells, which have become infected by Viruses or other IntraCellular Pathogens. #22, #30
Helper T-Cells (CD4+) - heighten the production of AntiBodies by B-Cells and regulate the activities of all effector cells. A functional subclass of T-Cells that helps to generate CD8+ Cells and cooperate with B-Cells in the production of AntiBody-mediated responses.
- CD4+ Cells only recognize Antigens that are presented in association with MHC Class II molecules. #30
Suppressor T-Cells - supress B-Cell activity and seem to be in short supply during a MS attack (exacerbation). #28
- A functionally defined population of T-Cells, which reduce the Immune Responses of other T-Cells or B-Cells, or switch the response onto a different pathway. #28
Macrophage - Develop from Monocytes, a Phagocyte Cell that helps initiate and is involved in all stages of Immune Responses. It recognizes and can digest (Phagocytize) all foreign Antigens (ie. Bacteria, Viruses) and Cell Debris. Macrophages are also an integral part of DeMyelination and participate in tissue repairs.
- In the CNS, they are called Microglia Cells, and Kupffer Cells in the Liver, where they Phagocytize Bacteria, other Pathogens, and old red blood cells. #25, #27
Macrophage-Activating Factor (MAF) - Actually several Cytokines, including Interferon, released by activated T-Cells, which together induce activation of Macrophages, making them more efficient in Phagocytosis and CytoToxicity.
Mast Cells - Develop from Basophil Cells (PolyMorphoNuclear Leukocytes), they reside in tissues, regulating Vascular Permeability (Blood-Brain Barrier) and Smooth Muscles. They possess IgE receptors, participating in immediate hypersensitivity reactions by degranulation (Release) of Heparin, Serotonin, Histamine, and other VasoActive Amines.
Microglia - (See: Glia Cells - Microglia)
Monoclonal AntiBodies - Are laboratory-produced AntiBodies, which can be programmed to react against a specific Antigen, in order to suppress the Immune Response. #28
Monocyte Cells - Develop from Stem Cells, are effective Antigen Presenting Cells, and patrol the bloodstream, searching for Antigens. In time, Monocytes migrate into tissue and develop into Macrophages. #30
Multiple Sclerosis - Is a Chronic Neurologic Disease of the Central Nervous System (CNS), occurring only in humans. MS is classified as both, a DeMyelinating and an Axonal Disease.
(See: Multiple Sclerosis as a Neuronal Disease)
- Although increasing evidence points to an AutoImmune aspect, no single Antigen or Immune System Dysfunction has been identified, so the cause of MS remains unknown.
(See: Multiple Sclerosis - The range of MS disease patterns, stages, and symptoms, with explanations of today's standard diagnostic tests.)
Myelin - A fatty (Lipid) substance forming a multi-layered sheath around some Nerve Fibers (Axons) in the Central, Autonomic and Peripheral Nervous Systems. Within the CNS, Myelin is formed by Oligodendeocytes and consists of their Cell Membranes (CytoPlasmic Extensions), which wrap themselves around Axons. (View Image)
- This Myelin Sheath covers and insulates sections (InterNodes) of CNS Axons, thereby reducing the electrical Capacitance between a Neuron's negatively charged Axonal Membrane (InterNodal Axolemma) and the surrounding positively charged ExtraCellular Fluid.
- Myelin greatly increases the conducting velocity of an Action Potential; while expending much less energy than an UnMyelinated Axon would require, to send an identical Action Potential, along the same distance. #01, #25
Myelin Basic Protein (MBP) - One of the components of Myelin, which may be increased in the CerebroSpinal Fluid of some - but not all MSers - following a DeMyelinating episode.
- MBP is positively charged and gets in between the Myelin BiLayers to link up the negatively-charged Lipids and glue the Myelin Sheath together. #25
- 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. #28
- A Virus which causes disease in Mucous Tissue such as the Throat, Mouth, or Lung. ex: (Influenza) See: Virus #09
Necrosis - Is tissue decomposition resulting from the loss of its Blood and Oxygen supply, Burns, or other severe injuries. It can also be caused by some medications, commonly used to treat MS.
- Necrosis of the skin occurs after a subcutaneous injection, when the body is intolerant of the medication. Necrosis of the Hip and Shoulder Joints are caused by the Long-Term use of Steroids. #07
Nerve Fibers (Axons) - Are long, sparsely branched Processes, having non-changing diameters that extend from a Neuron's Cell Body and connect another Neuron's Axon, Dendrite, or Cell Body and/or bodily organs that compose their Neural Network. #25
- A bundle of Nerve Fibers (Axons). The Fibers are either:
- Afferent - leading towards the higher Brain (CNS) and serving in the Perception of Sensory stimuli of the Skin, Joints, Muscles, and Inner Organs;
- Efferent - leading away from the higher Brain and Mediating contractions and relaxations of Muscles or Organs. #28
Neurologic Disease - Any disorder of the Nervous System. There are many different neurologic diseases, among which is Multiple Sclerosis. #25
- An individual Nerve Cell and the key data-processing cell of the Nervous System. Each has a Nucleus within a Cell Body and one or more Processes (Extensions) called Dendrites and Axons. #25, #28
NeuroTransmitters - Are chemicals (Small Molecules or Hormones), stored in small Synaptic Vessicles clustered at the tip of the Axon (terminal buttons).
- When a Nerve Impulse arrives for transmission to the next Neuron, they cross the Synapse enabling message transmission to another Neuron or the Stimulation of an Effector Cell (Muscle or Gland). (View: Image)
- When a NeuroTransmitter is received, it either Excites (Depolarizes) or Inhibits (Hyperpolarizes) the PostSynaptic Neuron. More than 100 organic molecules are thought to act as NeuroTransmitters.
- Some examples are: Acetylcholine, NorEpinephrine, GABA, Serotonin, and Dopamine, although each acts in different responses. Some are Excitory, such as Acetylcholine, Serotonin, NorEpinephrine, and Dopamine. Some are associated with Relaxation, such as Dopamine and Serotonin.
Neutrophils - A Phagocyte member of Leukocyte Cells, they are the Adaptive Immune System's first line of defense against Bacterial infections. After leaving nearby Blood Vessels, these cells follow chemicals produced by Bacteria in a cut or scratch and proceed to locate and eliminate the invader.
Nodes Of Ranvier - Are the only gaps between Myelin sections (InterNodes) along Myelinated Axons, where Sodium (Na+) and Potassium (K+) can be exchanged (Saltatory Conduction); hence, continuing the Nerve signal's rapid transmission, to its target. They are crucial electrical refresher sites, where Action Potentials are restored. (View: Image) #20
Nuclear Magnetic Resonance (MRI, MR, NMR) - A diagnostic test that uses the magnetic properties of different substances in a Magnetic Field to produce images of the Brain, Spinal Cord, and other soft tissues of the Body. A MRI shows areas of Sclerosis (Lesion, Plaque), when they are larger than 2mm (Macroscopic Lesions).
- Scans can NOT show Microscopic Lesions, as they are too small for current imaging resolutions; but are included in your Lesion Load and Atrophy totals. These early smaller lesions are better documented, by Evoked Potential Tests, which are equally valid in meeting a Laboratory Supported Definite Multiple Sclerosis diagnosis.
- While this is the only test in which some Multiple Sclerosis Lesions can be seen, it cannot be regarded as conclusive; because, all lesions do not register on MRI scans and many other diseases can produce identical MRI images.
- MRI shows the size, quantity and distribution of Lesions larger than 2mm, and together with supporting evidence from your other diagnostic tests, Medical History, and Neurological Examination, may be a positive finding that confirms the MS diagnosis.
- It also provides an objective measure (Para-Clinical Evidence) of MS lesion activity in the Brain and Spinal Cord; however, Conventional MRI (T1 and T2 images) are NonSpecific (unknown cause) and have little relation to MS progression or Disability.
Magnetization Transfer and Proton MR Spectroscopy are two imaging techniques that better correlate with MS activity. They are not yet widely used, but newer more specific imaging protocols are presently being formulated. #25
- Abnormal MRI scans are found in
- 96% with a definite diagnosis of MS
- 70% with a diagnosis of probable MS
- 30 - 50% with a diagnosis of possible MS
- MRI Criteria for diagnosing MS
- At least 3 Lesions and two of the following:
- Lesions abutting the Lateral Ventricles
- Lesions with diameters greater than 5mm
- Lesions present in the Posterior Fossa (InfraTentorial)
Nocturia - Inability to hold urine while sleeping, resulting in bedwetting and/or disrupted sleep, due to repeated bathroom trips.
(See: Neurogenic Bladder, Urgency with Hesitancy)
Nystagmus - A back and forth twitching Eye movement (Rhythmical jerking movements), with the fast component maximal, towards the side of the Cerebellar Lesion. Characterized by rapid, involuntary Eye movements, in the horizontal or occasionally, the vertical direction. #12, #25, #28
(Also See: Oscillopsia; InterNuclear Ophthalmoplegia; Afferent Pupillary Defect; Optic Neuritis; Retrobulbar Neuritis)
Oligodendrocyte - (See: Glia Cells - Oligodendrocyte)
Optic Atrophy - Degeneration of the Optic Nerve, due to DeMyelination and loss of Blood Vessels on the Optic Nerve Head, seen as pallor through the Ophthalmoscope. #01, #25
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. #25
Optic Neuritis - Is inflammation of the Optic Nerve (behind the Eye, aka RetroBulbar Neuritis). Acute Optic Neuritis causes (Rapidly Progressive Acuity Loss, Decreased Color Perception and Contrast Sensitivity (Dyschromatopsia), Central Visual Field Loss (Central Scotoma), Afferent Pupillary Defect, Blurred Vision, and Transient or Permanent Loss of Vision).
- Optic Neuritis (ON) most often includes Pain, with Eye movement, in or behind the Eye when Vision deteriorates. ON episodes often reappear, each reaching a peak within days, and recovery takes from 5 weeks to six months - with or without any particular treatment.
See: CorticoSteroids In Optic Neuritis
- An ON attack is often an invisible (subclinical) event, symptoms are either not noticed, or simply dismissed. Fortunately, subsequent Visual Evoked Potential (VEP) testing always registers this prior damage, as slowed response times. This finding can be used to fullfill MS's diagnostic requirement of a previous attack (Time Dissemination), or involvement of a second (Space Criterion) CNS Functional System.
- Optic Neuritis is very common in many, but not all MSers and usually occurs in only one Eye at a time. It is one of the first diagnosable signs that you may have Multiple Sclerosis. Although acute Optic Neuritis is very upsetting and scary, ON is considered a good indication, of having a milder MS course, when it is the presenting symptom. #25
- When the inflammation involves the first part of the Nerve and can be seen at the Optic Disk, usually during the course of an Eye Examination, it is called Optic Papillitis. This may cause colors to appear washed-out or faded and bright lights generally make seeing difficult, even when there are good color contrasts.
- Wearing yellow tinted sunglasses or adding a light photo-ray tint to your eyeglass prescription, greatly reduces the glare of bright lights and the feeling of Dizziness.
(Also See: Diplopia, Afferent Pupillary Defect, Retrobulbar Neuritis, Nystagmus, Oscillopsia, Dyschromatopsia, InterNuclear Ophthalmoplegia, & Diagnosing MS)
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. #01
Oscillopsia - Continuous, Involuntary, and Chaotic Eye movements that result in a Visual Disturbance in which objects appear to be Jumping or Bouncing. (Also See: Nystagmus) #28
- A mechanical appliance such as a Leg brace
or Shoe inserts that are specially designed to Control, Correct, or Compensate for impaired limb function. #28
- Inability to move a part of the body. #28
Paraparesis - A weakness but not total paralysis of the lower extremities (legs). #28
- Partial or incomplete paralysis of a part
of the body. #28
Paresthesias - (Gr.- para = abnormal, aisthesis = sensation) Sensations of Burning, Prickling, Creeping on the Skin, or "Pins-and-Needles" that develop with damage to a Pain Pathway (Nerve or Axon). Which may or may not be associated with any physical findings on Neurological Examination. #25
- Lesions or damage in the Dorsal Columns (Spinal Cord) often register as tingling and numbness, due to irritation of Sensory Nerve fibers, as they die. These sensations range from merely annoying to severe pain. In some cases, even the light touch of clothing, can be painful.
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. #28
(Also See: L'hermitte's Sign, Trigeminal Neuralgia)
Peptides - Short strings (groups) of Amino Acids, which Immune Cells (Leukocytes) use to identify Cells, as belonging to Self or Antigen.
Nervous System - All the Nerves and Nerve Cells outside the Central Nervous System. #01
PeriVentricular Region - The area surrounding the four fluid-filled cavities (Ventricles) within the Brain. MS plaques are commonly found within this region. #28
Phagocyte - A PolyMorphoNuclear Leukocyte that consumes cellular debris and invading MicroOrganisms. Neutrophils, Dendrites, and Macrophages are Phagocytes or eating cells (phago = "eating", cyte = "cell").
- These APCs present Antigens on their cell surfaces that are the chemical remains (Peptide) of the Organism. Antigens presented in this way activate specific responses and destroy the invading Organism. #30
Phagocytosis - The engulfment, digestion, and subsequent processing of debris or a MicroOrganism by Antigen Presenting Cells. #30 (Also See: Phagocytosis)
PhosphoLipids - Are fatty substances that are a major component of Myelin. #27
Pituitary Gland - (often called the master gland) is located in a small bony cavity at the base of the Brain, it has two Lobes: the Anterior and Posterior Lobes.
- The Anterior Pituitary is Glandular. A stalk links the Pituitary to the HypoThalamus, which controls release of Pituitary Hormones. The Posterior Pituitary is used to store Hormones until they are needed. (Also See: GlucoCorticoid Hormones
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. Some people respond to the placebo or sham treatment simply because they are convinced that they have been given the real treatment, and may even have a real physical reaction to the placebo. #25
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 (Spasticity) in the Brain or Spinal Cord. #28
- A Steroid drug related chemically and therapeutically to the Steroid Hormones normally made in the the Adrenal Glands. Prednisone and other Steroid medications carry significant Long-Term Risks. #25
- 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. #20
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. #01 (View Image)
Prevalence - The number of all new and old cases of a disease in a defined population at a particular point in time. #28
Primary/Progressive MS - A clinical course of MS characterized from the beginning by progressive Disability, with no plateaus or remissions or an occasional plateau and very short-lived, minor improvements. #28
Progressive/Relapsing MS - A rare type of MS that shows disease progression (increased Disability) from onset, but with clear, acute relapses, with or without full recovery after each relapse. #29, #28
Prospective Memory - The ability to remember an event or commitment planned for the future. Thus, a person who agrees to meet or call someone at a given time on the following day, must be able to remember the appointment when the time comes. Both Prospective and Recent Memory are frequently major Cognitive problems for MSers. #28
Proteins - A group of complex organic compounds, composed of Amino Acids, with defined three-dimensional structures (encoded in DNA) that controls its particular function. Proteins are responsible for all reactions and activities of Cells. #01
Pseudo-Exacerbation - A temporary aggravation of disease symptoms, resulting from an elevation in body temperature or other stressor (ex. an infection, fatigue, heat, or constipation), that disappears once the stressor is removed. A pseudo-exacerbation involves only pre-existing symptoms (flare-up), rather than new disease activity or progression. #28
Pyramidal Tract (CorticoSpinal) - One of the major Motor Tracts from the Brain to the Spinal Cord. The Pyramidal System is specialized for making discrete movements, its Axons fibers form the Pyramids of the Medulla Oblongata. It originates in the Cortex of the Frontal Lobe. #01
- It communicates directly with Motor Neurons in the Spinal Cord, to activate Fine Motor Control: ex: tying shoelaces, writing, etc.
- It orchestrates the Motor Response and helps to Specify Body Posture at all levels of the Spinal Cord.
- It Adjusts Muscle Tone to counter the changing centers of gravity
- Plaque here causes the symptoms of Spasticity: Muscle Tightness, Ankle Clonus, Flexor Spasms, Exhaustion, Loss Of Muscle Power, and Paralysis #02
Quadriplegia - The paralysis of both arms and both legs. #28
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). MSers with MS-related memory impairment typically experience the greatest difficulity remembering these types of things from the recent past. #28
Reflex - An 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; or Absent Reflexes can be indicative of Neurological damage, including MS, and are therefore tested during the standard Neurological Exam.
- An unconscious muscle tightening that is mediated by Anterior Horn Neurons, in the Spinal Cord. Increased muscle tone (tightness, spasticity) is normally an early finding in Multiple Sclerosis. #01, #28
Relapsing/Remitting MS - A clinical phase having distinct relapses (also called acute attacks or exacerbations), with either full recovery (no disability), or partial recovery and lasting disability. There is no visible disease progression (worsening) between attacks; but *stable* periods, span and mask, the continuing subclinical disease process.
- Relapsing forms of MS are the most common beginning types, comprising 85% of the total. However, 50% of cases will have progression within 10 - 15 years, and an additional 40% within 25 years of onset; as the disease evolves, into the Secondary/Progressive phase. #29
Remission - A decrease in the severity or number of MS symptoms and signs, or their temporary disappearance. The opposite of remission is exacerbation. #25, #28
Remote Memory - The ability to remember people or events from the distant past. MSers tend to experience few if any problems with their remote memory. #28
ReMyelination - The repair or replacement of damaged Myelin, which usually occurs spontaneously in the early course of MS, but is a very slow process. Early MS damage (Lesion) is repaired (ReMyelinated) by Oligodendrocytes extending new cytoplamic extensions that spiral around (rewrap) Axons, to form new Myelin sections (InterNodes). #28
Reticular Formation - A vital part of the Autonomic Nervous System, which is scattered like a cloud throughout most of the length of the BrainStem. These nuclei receive Nerves innervating the Face and play an important role in Arousing and Maintaining Consciousness. Visual, or Acoustical Stimuli, and Mental Activities can stimulate this system to maintain Attention and Alertness. #01
Retrobulbar Neuritis - Inflammation of the second part of the Optic Nerve (behind the Eye), which cannot be seen by an Eye Examination. It is one of the most common beginning symptoms of Multiple Sclerosis; but can also occur as an isolated Neurological Lesion incident, with full recovery of Vision and no further progression to Clinically Definite MS. (Also See: Optic Neuritis)
- A type of Virus named for its ability to convert RNA to DNA and thus use Genetic material to make the proteins it needs to survive and reproduce itself, causing several diseases in the process. #27
Romberg's Sign - Loss of Position Sense indicated by, the inability to remain immobile (without swaying), while standing with Feet together and Eyes closed. (Also See: Babinski's Sign)
Romberg Test - An examination by a physician during which your positional sense of balance is tested. It entails you standing with feet together, arms outstretched in front, and eyes open, and then closed. #25, #26
Scanning Speech - Un-natural Speech characterized by Staccato-like Articulation, that sounds clipped because the person unintentionally pauses between syllables and skips some of their sounds. #28
Sclerosis - Hardening of tissue. In MS, sclerosis is the body's replacement of lost Myelin, around CNS Axons with scar tissue. Early Lesions are usually ReMyelinated and functions restored. However, if Astrocytes make Sclerosis (Gliosis), Myelin can NOT be repaired and the damage is permanent. #28
Secondary/Progressive MS - A clinical course of MS which initially is Relapsing/Remitting and then becomes progressive at a variable rate, possibly with an occasional relapse and minor remission. #28
- MS that begins with a pattern of clear-cut relapses and recovery, but becomes steadily progressive over time with continued worsening between occasional acute attacks. #29 (Also See:Types of MS)
Segment, Spinal Cord - One defined portion of the Spinal Cord, which are - Eight Cervical Segments (Neck & Upper Extremities); Twelve Thoracic Segments (Chest); Five Lumbar Segments (Lower Trunk & Lower Extremities); and Five Sacral Segments (Buttocks, Bowel, Bladder and Sexual Function). #01
Sensory - Receptor mechanisms monitoring changes in both external and internal environment and convey this data to the CNS.
- Such as: Pain, Smell, Taste, Temperature, Vision, Hearing, Touch, and ProprioCeption (Acceleration and Position In Space). This awareness enables the coordination and quick implementation of survival reactions. (View: Image)
Sensory Cortex - The network of Neurons located along the Cerebral Parietal Lobe's surface.
Sensory Input - Stimuli that the Nervous System receives from the external or internal environment: includes Pressure, Taste, Odor, Sound, Light, and Blood pH.
Sensory Neurons - The Cell-Bodies of Axons carrying signals from receptors that transmit information about the environment, to processing centers in the Brain and Spinal Cord. Spinal Cord Neurons processing messages from peripheral receptors are sometimes called Afferent Neurons, InterNeurons, or Lower Motor Neurons.
Sensory Pathways (Afferent) - Axons carrying information from organs and tissues to Cortical control centers (Thalamus, Parietal Lobe). #28 (View: Upper, Lower)
Sequela - A condition following or caused by a previous disease; an after effect of illness. #09
Sign, Neurologic - An objective physical problem or abnormality identified by a doctor during the Neurological Examination. Neurological signs may differ significantly from the symptoms reported by the patient, because they are identifiable only with specific tests and may cause no noticeable symptoms. #28
- Any evidence of malfunction perceived by a physican. #01
(Also See: Babinski's Sign And Romberg's Sign)
SomatoSensory Evoked Potentials - A painless test which records nerve message transmission times within the Brain, in response to repeated electrical shocks, applied to a Peripheral Nerve. Slower response times are typically present in early MS, especially the Nerves of the legs and feet.
- Normally, the Brain's reaction to such stimuli is almost instantaneous. DeMyelination or a Lesion in the Nerve Pathway causes a delay, so reception time will be significantly slower than normal. #25 (Also See: Evoked Potentials)
Spasticity - CNS damage caused by Multiple Sclerosis, prevents Nerve messages from reaching the Brain's higher control area (Cerebellum); thus it is unable to inhibit the reflex orders (Muscle Contracting) initiated in the Spinal Cord.
- Muscle groups normally work together, when one is flexed, its opposing muscle is relaxed. MS disrupts this communication causing muscles to needlessly stay tight or contracted. This increased muscle tone is called Spasticity. Increased Muscle Tone - Tightness or Stiff Muscles, usually around a Joint. #04
- Increased resistance to movement. It refers to the stiffness that can occur in a Limb, usually in the Leg. Spasticity often accompanies Weakness, but it is possible to have Spasticity without Weakness and to have Weakness without Spasticity. #25
- Spasticity tends to occur most frequently in a specific group of muscles that are responsible for maintaining our upright posture, referred to as Anti-Gravity or Postural Muscles. These include the Calf (Gastrocnemius), Thigh (Quadriceps), Buttock (Gluteus Maximus), Groin (Adductor) and occasionally the Back (Erector Spinae) Muscles. #06
Spinal Cord - is the communication link between the Brain and the Peripheral Nervous System (PNS) inferior to the head; it integrates incoming Nerve impulses and produces responses through Reflex mechanisms. (View: Function, Structure)
- The cord extends from the Foramen Magnum to the level of the 2nd Lumbar Vertebra. It is composed of Cervical, Thoracic, Lumbar, and Sacral Segments, which are named according to the area of the Vertebra Column from which their Nerves enter and exit.
- Thirty-one pairs of Spinal Nerves exit the Spinal Cord and pass out of the vertebral column through the InterVertebra Foramia.
Nerves to the extremities enter and leave through:
- In cross section, the Spinal Cord consists of a central Gray portion and a peripherial White portion. The White Matter consists of Nerve Tracts, and the Gray Matter consists of Nerve Cell Bodies and Dendrites. An Anterior median Fissue and a Posterior median Sulcus are deep clefts partially separating the two halves of the Cord. #11
The Cervical Enlargement - in the inferior Cervical region corresponds to the location at which Nerves that supply the upper limbs enter or exit the cord
The LumboSacral Enlargement - in the inferior Thoracic and superior Lumbar regions is the site at which the Nerves that supply the lower limbs enter or exit
Suppressor T-Lymphocytes - White Blood Cells (Lymphocytes) which inhibit or stop certain Immune activity, and which may be in short supply during a MS exacerbation. #28
Synapse - The specialized junction between Neurons, there is no anatomical continuity between them. Instead, the gap is crossed by, NeuroTransmitters.
- They diffuse across the Synapse completing the connection, from the end branch of a PreSynaptic Axon, to the Dendrite, Cell Body, or Axon of a PostSynaptic Neuron. #20, #25
T-Cell - A type of white blood cell (Leukocyte), whose activities are influenced by their development in the Thymus Gland. #25
- Are responsible for Cell-Mediated Immune Responses - used to fight virual infections. (See: Lymphocytes) #22
- A white blood cell (Lymphocyte) that dominates the Cellular Immune response to an Antigen. #27
Tandem Gait - A test of balance and coordination which involves alternately placing the Heel of one Foot directly in front of the Toes of the other Foot. #28
Thalamus - Most Sensory Input initially projects to the Thalamus where Afferent Neurons synapse with Thalamic Neurons, which send projections from the Thalamus to the Cerebral Cortex. The Thalamus also has other functions, such as influencing Mood and General Body Movements that are associated with Strong Emotions such as Fear or Rage. #11
Thymus - A small Gland in the Chest above the Heart. The Thymus influences the behavior of White Blood Cells and other elements of the body's Immune System. #25
- A level or strength of a substance such as
AntiBodies in Serum. #09
Tolerance - The T-Cell's inability or diminished sensitivity to an Antigen.
- A bundle of Axons traveling together. In most cases, the Origin and Destination of Axons in a Tract are quite similar. #01
Transverse Myelitis - Inflammation in the Spinal Cord interfering with Nerve function below the level of the inflammation. (Also See: MS Hug) #25
- An acute attack of inflammatory DeMyelination that involves a section of the Spinal Cord. Paralysis and Numbness are experienced in the Legs and Trunk below the level of the inflammation. (Also See: Spinal Cord Segment) #28
Tremor - Either with Intention or Sustention indicates Cerebellar damage (Muscle InCoordination). Intentional Tremor becomes more shaky, in direct correlation to your increased concentration to reach, grasp, or do something. #02
Trigeminal Neuralgia (Tic-Douloureux) - Pain in the Face that comes on abruptly that sometimes develops with Multiple Sclerosis. Lightening-like, acute pain in the face caused by DeMyelination of Nerve Fibers, where the Trigeminal Nerve's Sensory Root, for that part of the Face enters the BrainStem.
- Tic (sudden jerk) Douloureux (caused by pain) most commonly strikes inside and outside of the cheek, back across the face towards the ear, and the upper teeth. The AntiConvulsants [Tegretol® (Carbamazepine); Dilantin® (Phenytoin); Neurontin® (Gabapentin)] effectly relieve the pain of Trigeminal Neuralgia. #02, #25, #28
Tumor Necrosis Factor (TNF) - A Cytokine released by activated Macrophages, similar to LymphoToxin that activated T-Cells secrete. It enhances activation of T-Cells, and induces proliferation of T-Cells and B-Cells.
- TNF also attracts additional Macrophages and Granulocytes to the site. This prompts Macrophage and other Immune Cells, to release tissue-damaging, Oxygen-containing substances and ProstaGlandins to promote Inflammation. #30
Uhthoff's Syndrome - A metabolic by-product of exercise, or an increase in body temperature causes a Reversible Conduction Block in a DeMyelinated Optic Nerve, resulting in the temporary loss or blurriness of Vision.
- Uhthoff's Symptom (temporary Visual Loss with exercise), is an indication of previous Optic Neuritis damage and a major risk factor for the recurrence of Optic Neuritis and the further development of Multiple Sclerosis.
Urinary Retention - Involuntary accumulation of excessive Urine in the Bladder. #25
Uveitis - Inflammation within the middle layer of the Eye (the Uvea) between the Sclera and Retina, affecting any of the three parts of the Uvea:
- Uveites includes Retinal Venous Sheating, which represents active Periphlebitis (Sclerosis) that occurs in 10 - 20% of MSers, and symptoms range from mild to severe. Its complications are directly proportional to the extent and severity of the Ocular inflammation. They include: Glaucoma, Cataracts, Macular Edema, Retinal Detachment, and Vitreous Hemorrhages. #31
- The Iris - the colored part of the Eye
- The Ciliary Body - behind the Iris, which makes the fluid inside the Eye
- The Choroid - a Vascular lining beneath the Retina
Ventricles - The four cavities in the CNS that contain the Vascular membrane (Choroid Plexus) which secrete CerebroSpinal Fluid. There are two Lateral Ventricles (one in each Hemisphere), they connect with the Third Ventricle in the DienCephalon.
- In the MidBrain, the Cerebral Aqueduct connects with the Fourth Ventricle (located between the Pons, Cerebellum, and Medulla Oblongata). Which joins the Central Canal of the Spinal Cord and the SubArachnoid space which surrounds the Central Nervous System.
(Also See: Ventricular System)
Vertigo - A feeling of internal uneaseiness, confusion, or light-headedness (passing out). The term Dizzy is commonly confused with Vertigo (a sensation your surroundings are spinning).
- While the feeling that you are off-balance, vaguely out-of-sorts, and/or actually spinning (not your surroundings) is Dizziness. DeMyelination within the Cerebellum or its Nerve Pathways, may cause Dizziness. #25
(Also See: Vertigo/Dizziness)
Virus - A living agent, the smallest and simplest form of life, which depends on other living cells, in order to reproduce itself. The first known Virus was discovered in 1898. #09
Evoked Potentials (VEPs) - A diagnostic technique for recording electrical response times, in the CNS to repeated visual stimuli. This is a very sensitive way of detecting Optic Neuritis. #25
- Evoked Potential Tests are able to confirm the presence of a suspected Lesion, and can identify the presence of an unsuspected Lesion (Clinically Silent), which has produced no symptoms. They are extremely useful in diagnosing MS and VEPs are abnormal, in approximately 90% of MS cases. #28
Wallerian Degeneration - Is Axonal Degeneration without local Inflammation and before local DeMyelination that results from a distal injury to the same Axon. Wallerian Degeneration commonly occurs, sometime after a distant Axonal part has been severed.