MOGlossary

We developed the MOGlossary to help the MOGAD Community understand the new and often confusing jargon they often hear from their medical professionals and in reading educational materials presented to them.

Each of these terms is linked to other pages on The MOG Project website and provides on-demand popups on pages where the terms are used.

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Acute - The severe and sudden onset of a disease process.
Acute Disseminated Encephalomyelitis (ADEM) - An initial and brief autoimmune attack that causes widespread inflammation and damage to the brain, spinal cord, and optic nerve, typically in children. This initial attack establishes the basis for diagnosis. The MOG antibody is detectable in a percentage of Acute Disseminated Encephalomyelitis (ADEM) patients.
Acute Disseminated Encephalomyelitis with Optic Neuritis (ADEM/ON) - Single event acute disseminated encephalomyelitis (ADEM) that is followed by recurrent optic neuritis. (Refer to Acute Disseminated Encephalomyelitis (ADEM) and optic neuritis)
Acute Treatment - A type of treatment that is intended to stop an ongoing attack.
Antibody - A protective protein produced by your immune system that attaches to antigens (foreign substances), such as bacteria and toxins, and removes them from your body. In myelin oligodendrocyte glycoproten antibody disease (MOGAD), the body incorrectly produces an antibody that targets myelin oligodendrocyte glycoprotein, a component of the myelin sheath in the central nervous system.
Aseptic Meningitis, drug-induced - Inflammation of the brain and spinal cord membranes. In myelin oligodendrocyte glycoproten antibody disease (MOGAD), may be a serious drug-induced side effect caused by intravenous immunoglobulin (IVIG) treatment.
Aspirate - The unintentional inhaling of food or fluid to the lungs, potentially leading to more serious problems (e.g., pneumonia or lung infections).
Assay -
A laboratory test used to:
- Measure the presence or amount of a specific substance: in a sample, such as blood, urine, or tissue.
- Determine the potency or activity: of a drug or other substance.
- Analyze the purity: of a chemical compound.
- Identify and quantify: biomarkers related to a disease or condition.
Autoimmune - A disease in which the immune system incorrectly targets and attacks an individual's own healthy cells.
Autoimmune Encephalitis (AE) - Encephalitis caused by an immune attack on the brain (as opposed to viral encephalitis). Refer to encephalitis.
azathioprine (Imuran, AZT) - Brand names include Imuran and AZT. A therapeutic drug that suppresses the immune system often prescribed in certain autoimmune conditions. For myelin oligodendrocyte glycoprotein antibody disease (MOGAD), this medication is used to suppress the immune system to reduce disease activity.

Banding (MS Hug) - A symptom of central nervous system disorders caused by inflammation of the spinal cord (such as from MOGAD, NMOSD, and Multiple Sclerosis) in which one feels chest pain, rib pain or a tight uncomfortable band around the chest. It can be felt anywhere between the neck and the waist and may feel so tight around the chest that it's painful to breathe. It is also known as girdling or MS hug.
Bilateral - Refers to disease or attack on two sides.
Biomarker - A substance detectable by testing (e.g., blood sample or spinal fluid) that is indicative of a disease or infection.
Blood Brain Barrier (BBB) - Central nervous system blood vessels that regulate the movement of ions, molecules, and cells between the blood and the brain to allow passage of critical molecules required for neural function to enter, but restrict passage of pathogens and other potentially damaging molecules. Currently, it is not believed that the MOG antibody destroys or causes degredation of the blood brain barrier.
Brainstem - A structure in the brain that connects the cerebrum to the spinal cord and cerebellum, responsible for regulating many involuntary functions in the body (e.g., heartbeat and breathing).

Central Nervous System (CNS) - Nerve tissue that resides in and composes the brain, spinal cord, and optic nerve
Central Sensitization Syndrome - A state in which the central nervous system amplifies the senses (i.e., touch, smell, taste, hearing, and sight). May include sensitivity to bright lights, loud noises, strong smells, rough textures, or pressure on the body.
Cerebral coritcal encephalitis (CCE) - A rare clinical phenotype of MOGAD, which usually begins with seizures, headaches, and fever. Sometimes there is only one-sided cerebral cortical inflammation without any white matter inflammation. MOGAD patients who experience this phenotype are often misdiagnosed with viral encephalitis, stroke or infection.
Cerebrospinal Fluid (CSF) - A clear, colorless liquid found throughout the cavities of the central nervous system that helps protect the brain and spinal cord by acting like a cushion against sudden impact or injury, and provides a medium for the transport of nutrients and the removal of waste products for proper functioning.
Chronic Relapsing Inflammatory Optic Neuropathy (CRION) - A disease where the optic nerve is the target of two or more demyelinating attacks separated by at least 30 days, resulting in visual deficits and may or may not be accompanied by pain on eye movement. CRION patients may or may not be MOG antibody positive.
Clinical Trial - Research studies performed using people as subjects that are aimed at evaluating a medical, surgical, or behavioral intervention to determine to what degree a new treatment (e.g., drugs or medical devices) is safe and effective for general populations.
Clinically Isolated Syndrome (CIS) - A condition in which a single non-encephalopathic demyelinating attack results in damage and neurological symptoms based on the location of the brain that became damaged. In the case of multiple sclerosis (MS), if the attack meets criteria for MS by McDonald criteria, then it is determined to be MS. If it does not meet this MS criteria, then it remains CIS. However, many MOGAD patients with their first attack could technically meet criteria for MS, but a trained neuroimmunologist would generally know the difference.
CT Scan - Known as a computerized tomography scan. It combines a series of X-ray images taken from different angles around the body using computer processing to create cross-sectional images of the bones, blood vessels, and soft tissues inside the body.

Delirium - A serious change in mental abilities resulting in confused thinking and a lack of awareness of someone's surroundings. This disorder usually comes on fast — within hours or a few days. May be a symptom of MOGAD from disease process in the brain.
Demyelination - The process in which the protective coating of nerve tissue (i.e. myelin) becomes damaged or breaks down, causing nerve impulses to slow or halt that results in neurological problems.
Diplopia - The medical term for double vision.
Drop Foot / Leg - Caused by weakness or paralysis of the muscles involved in lifting the front part of the foot. This causes the toes to drag along the ground while walking.
Drug-Induced Aseptic Meningitis - see Aseptic Meningitis (Drug-Induced)
Dysesthesia - Chronic pain triggered by inflammation or damage of the spinal cord that includes sensations such as burning, electric shock, or a general tightening around the body. It generally occurs in the legs, feet, arms, and hands, but it can affect any part of the body. This symptom is caused by an active or previous MOGAD attack in the spinal cord.
Dysphasia - Difficulty or inability to speak or interpret speech due to disease or damage to the brain.
Dystonia - A neurological movement disorder characterized by involuntary muscle contractions that cause slow repetitive movements or abnormal postures that can sometimes be painful. This symptom is caused by an active or previous MOGAD attack in particular areas of the brain.

EEG (Electroencephalography) - A test that measures electrical activity in the brain using small, metal discs (electrodes) attached to the scalp. Brain cells communicate via electrial impulses and are active all the time, even during sleep. The activity shows as waving lines on an EEG recording. It is used to find changes in brain activity and is important in detecting seizures.
EMG (Electromyography) - A diagnostic procedure to assess the health of muscles and the nerve cells that control them (motor neurons). It can reveal nerve dysfunction, muscle dysfunction, or problems with nerve-to-muscle signal transmission. Sometimes ordered when a patient has symptoms such as tingling, numbness, or muscle weakness.
Encephalitis - A disease in which inflammation of brain tissue caused by an infection or an autoimmune response results in swelling and damage. When caused by an autoimmune disease, sometimes called Autoimmune Encephalitis.
Encephalopathy - Refers to an alteration in consciousness (e.g., stupor, lethargy, delirium, confusion) or behavioral change unexplained by fever, systemic illness or postictal symptoms.
Eosinophils - A type of white blood cell that plays a role in the immune system by helping fight infections and boost inflammation in the body. in MOGAD, these levels in your blood may be monitored depending on your doctor and the medication you are taking.
Evoked Potential Tests - Tests used to measure the electrical activity in certain areas of the brain and spinal cord. The test records how quickly and completely the nerve signals reach the brain. These tests may be given as a diagnostic tool for neurological disorders.

Flare - Refer to Relapse.
Focal Siezure - A focal seizure involves one part of the body and affected persons do not lose consciousness (See Seizures)

gabapentin (Neurontin) - An anticonvulsant medication that is used to treat a variety of nervous system-related conditions. For myelin oligodendrocyte glycoprotein antibody disease (MOGAD), this is sometimes given to reduce tremors, spasms, seizures, neuropathy pain, and other possible uses.
Grand Mal Siezure - Causes a sudden loss of consciousness and violent muscle contractions called tonic (stiffening) and clonic (twitching or jerking) muscle acitivity. It is caused by abnormal electrical activity throughout the brain. Usually followed by a period where patient is postictal. May be a symptom of MOGAD from disease process in the brain or a medication side effect.

Hemianopia - Sometimes called hemianopsia, it is defined as 50% partial blindness or a loss of sight in half of your visual field. In relation to MOGAD, it is caused by inflammation or lesions damaging the part of the brain that sends signals to the optic nerve rather than damage to the optic nerve itself.
Hemiparesis - Muscle weakness on one side of the body caused by a nervous system disruption in the brain or spinal cord. in MOGAD, it is caused by demyelination interrupting the signals to muscles resulting in loss of function.
Hypoesthesia (Loss of Sensation / Tingling) - Total or partial loss of sensation in a part of your body known as Hypoesthesia. Sometimes accompanied by a pins-and-needles tingling.

Immunoglobulin (IVIG / SCIG) - A human blood donor product made up of immunoglobulins (IgG and IgM antibodies) derived from plasma that can be administered intravenously (IVIG) or subcutaneously (SCIG). For myelin oligodendrocyte glycoprotein antibody disease (MOGAD), it is used as an immunomodulator to reduce disease activity. Sometimes used for acute attacks or as an ongoing preventative treatment.
Immunologist - A doctor or scientist who specializes in immune system disorders.
Immunomodulator - A substance that affects the function of the immune system, either stimulating or suppressing its activity
Immunomodulator - Drugs that modify the activity of the immune system in a beneficial way. In reference to myelin oligodendrocyte glycoproten antibody disease (MOGAD), decreases disease activity.
Incontinence - A condition where the muscles or nerves of the bladder (urinary incontinence) or bowel (fecal incontinence) are unable to control or hold its contents.
Inflammation - A process of the immune system that involves chemicals released by immune cells (i.e. white blood cells) inducing localized heat, swelling, redness, and pain to an area that occurs when tissue becomes damaged or infected from a pathogen, and usually results in the desctruction and removal of the pathogen and/or healing to the tissue. In the case of myelin oligodendrocyte glycoprotein antibody disease (MOGAD), inflammation is the result of the incorrect targeting of the myelin oligodendrocyte glycoprotein (MOG) by the immune system, resulting in damage to myelin sheaths.
Infusion - A method of putting fluids, including drugs, into the bloodstream. In reference to myelin oligodendrocyte glycoproten antibody disease (MOGAD), typically given intravenously (IV) or subcutaneously (SC).
Interleukin-6 inhibitor (IL-6 inhibitor) - Immunosuppressive agents that inhibit the action of interleukins. Interleukins are a group of cytokines (secreted proteins in response to infection) synthesized by white blood cells (lymphocytes, monocytes, and macrophages).They play a key role in the regulation of the immune system. Studies have shown that in MOGAD these medications can disrupt the action of the MOG Antibody on the myelin in the central nervous system to help prevent future attacks.
Intravenous (IV) - A way of giving a drug or other substance through a needle or tube inserted into a vein.

Lesion - In relation to MOGAD, an area of damage or scarring in the central nervous system. It is caused by inflammation that results from the immune system attacking the myelin sheath around nerves. Lesions can be found on the brain, spine, or optic nerves.
Lethargy - A general state of fatigue that involves a lack of energy and motivation for physical and mental tasks. May be a symptom of MOGAD or a medication side effect.
Longitudinally extensive transverse myelitis (LETM) - A neurological condition characterized by by a contiguous inflammatory lesion of the spinal cord. LETM is often associated with the autoimmune central nervous system disease neuromyeltis optica (NMO) and MOGAD but rarely with Multiple Sclerosis (MS).
LP (Lumber Puncture) - A procedure that involves inserting a needle into the spinal canal to collect spinal fluid, typically for diagnostic purposes. Often used during diagnosis of neurological conditions. Otherwise known as a spinal tap.
Lymphocytes - Cells that circulate in your blood that are part of the immune system. In MOGAD, they are often monitored when taking preventative medications for MOGAD that deplete B-cells which are a type of lymphocyte.

MOG-EM - Inflammation of the active tissues of the brain caused by an autoimmune response due to the presence of the MOG Antibody.
Monofocal episode - A single neurologic sign or symptom that is caused by a single area of attack. Neurological signs or symptoms vary based on location of attack.
Monophasic - A disease characterized by only one phase or attack.
MRI (Magnetic Resonance Imaging) - A noninvasive imaging technique that uses strong magnetic fields to produce images of nearly any structure of the body. For MOGAD, it is typically used with and without contrast to identify disease activity in the central nervous system.
Multifocal episode - More than one sign or symptom caused by multiple areas of attack. Neurological signs or symptoms vary based on location of attack.
Multiphasic - A disease characterized by two or more phases or attacks.
Multiphasic Disseminated Encephalomyelitis (MDEM) - Autoimmune Encephalitis caused by MOG.
Multiple Sclerosis (MS) - An autoimmune disease that attacks healthy cells in the myelin, the protective sheath that surrounds nerves in the central nervous system (CNS) leading to neurological symptoms originating from the brain, spinal cord, and/or optic nerve.
mycophenolate mofetil (CellCept, MMF) - CellCept is the brand name for Mycophenolate Mofetil (also sometimes referred to as MMF). It is an immunosuppressant medication often prescribed for some autoimmune conditions. For myelin oligodendrocyte glycoprotein antibody disease (MOGAD), this medication is used to suppress the immune system to reduce disease activity.
myelin - An insulating layer, or sheath that forms around nerves, including those in the brain and spinal cord. It is made up of protein and fatty substances. This myelin sheath allows electrical impulses to transmit quickly and efficiently along the nerve cells. If myelin is damaged, these impulses slow down.
Myelin Oligodendrocyte Glycoprotein (MOG) - A type of protein involved in cell adhesion. Present throughout myelin sheaths.
Myelin Oligodendrocyte Glycoprotein Antibody Disease (MOGAD) -
Often referred to as MOGAD, Anti-MOG, MOG Ab+, MOG Antibody Disease, MOG Associated Antibody Disease, MOG positive disease
Myelin Oligodendrocyte Glycoprotein Immunoglobulin G (MOG-IgG) - Refers to the presence of immunoglobulin G (IgG) antibodies in the blood that are specifically targeted against myelin oligodendrocyte glycoprotein (MOG), a protein found in the central nervous system

Neuroimmune - A term that refers to the components of the immune system that acts in and affects the central nervous system.
Neuromyelitis Optica Spectrum Disorder (NMOSD) - A disorder of the central nervous system that primarily affects the nerves of the eye and the spinal cord. Also known as Neuromyelitis Optica (NMO) or Devic's Disease
Neuropathy - Damage or dysfunction of one or more nerves that typically results in numbness, tingling, muscle weakness and pain in the affected area.
Neutrophils - A type of white blood cell that helps your immune system fight infections and heal injuries. in MOGAD, these levels in your blood may be monitored depending on your doctor and the medication you are taking.
Nystagmus - A rapid, involuntary movement of the eyes. Can be horizontal, vertical, or even circular movement.

Oligoclonal bands - A type of protein found in the cerebral spinal fluid that is an indicator of inflammation. It is often an indication in multiple sclerosis, and is sometimes found in MOGAD and NMOSD..
Ophthalmologist - A board-certified medical doctor that specializes in diseases and disorders of the eye.
Optic Nerve - The cranial nerves that relay messages from your eyes to your brain to create visual images. These nerves extend from the retina in the back of the eyes to the part of the brain that processes what we see. In myelin oligodendrocyte glycoproten antibody disease (MOGAD), they may be the target of inflammation or lesions, sometimes causing visual disruption or blindness.
Optic Neuritis (ON) - Inflammation of the optic nerve that may be classified as unilateral (affecting one eye) or bilateral (affecting both eyes) that may result in vision changes, vision loss, and/or pain with eye movement.
Optical Coherence Tomography (OCT) - A noninvasive imaging technology used to obtain high resolution cross-sectional images of the retina. The layers within the retina can be differentiated and retinal thickness can be measured to aid in the early detection and diagnosis of retinal diseases and conditions such as damage causd by optic neuritis in MOGAD.

Paralysis - The loss of the ability to move some or all of your body.
Pathogen - A microorganism that causes, or can cause, disease.
Petit Mal (Absence) Seizure - A brief, sudden lapse of consciousness. More common in children than adults. An absence seizure may present as one staring blankly into space for a few seconds followed by a quick return to a normal level of alertness. Absence seizures do not have a postictal period and are characterized by immediate resumption of prior activity. May be a symptom of MOGAD from disease process in the brain.
Pharmacodynamics - The study of what a drug does to the body, essentially examining the effects of drugs on living systems.
Pharmacokinetics -
The branch of pharmacology concerned with the movement of drugs within the body.
Phenotype - When used in reference to myelin oligodendrocyte glycoproten antibody disease (MOGAD), indicates the particular presentation or combination of symptoms an individual experiences based on the part of the central nervous system affected by MOGAD.
Photophobia (Light Sensitivity) - Eye discomfort in bright light.
Plasma Exchange (PLEX / Plasmapheresis) - A procedure in which a machine is used to separate the patient's plasma from the blood cells. The plasma is separated from the blood cells, the blood cells are mixed with a liquid to replace the plasma, then it is returned to the patient's body. For myelin oligodendrocyte glycoprotein antibody disease (MOGAD), this treatment is sometimes given to remove antibodies from the blood stream to reduce disease activity during an active attack. May be used as a preventative treatment when other treatment options fail.
Port - A small medical appliance that is surgically installed to provide access to a major vein. A catheter connects the port (under the skin) to the vein to draw blood and give treatments, including intravenous fluids, blood transfusions, or drugs.
Postictal - A period that begins when a seizure subsides and ends when the patient returns to baseline. It typically lasts between 5 and 30 minutes and is characterized by disorienting symptoms such as confusion, drowsiness, hypertension, headache, nausea, etc.
Pre-Medications (Pre-meds) - Medications taken before some treatments to prevent adverse reactions or side-effects.
Preventative - Refers to a medication or treatment that is administered to prevent future relapses (Also referred to as Preventative or Preventive Treatment).
Pseudo-Relapse - The recurrence of neurologic symptoms often due to an exacerbating factor or trigger such as heat or sickness. Pseudo-relapses can often be distinguished clinically from relapses by their fluctuance in severity and improvement over 24-48 hours. Pseudo-relapses will never show any new or worsening lesions on MRI.
Pulfrich Phenomenon (Pulfrich effect) - A neuro-ophthalmic observation in which two-dimensional (2-D) objects are perceived to be three-dimensional (3-D) due to slight discrepancies in signal transmission time between a set of eyes and the visual cortex. This has been noted in MOGAD.

Recurrent Optic Neuritis (RON) - A form of optic neuritis (ON) that can be recurrent.
Rehabilitation - The effort of restoring a person back to normal function through targeted treatment such as physical therapy.
Relapse - When you present to your doctor or hospital with new or worsening central nervous system symptoms. Generally, if your symptoms gradually worsen over 24-48 hours, there is heightened concern of a relapse. (Also referred to as a flare by the myelin oligodendrocyte glycoproten antibody disease (MOGAD) community).
rituximab (Rituxan) - The common brand for this drug is Rituxan. A therapeutic drug that suppresses the immune system often prescribed in certain autoimmune conditions. For myelin oligodendrocyte glycoprotein antibody disease (MOGAD), this medication is used to suppress the immune system to reduce disease activity.

Seizure - A sudden, temporary disturbance in brain activity that causes changes in behavior, movement, sensation, or consciousness
Seizure - A sudden, uncontrolled electrical disturbance in the brain. It can cause changes in your behavior, movements or feelings, and in levels of consciousness. Types of seizures may include grand mal (clonic and tonic), petit mal (absence), focal, atonic, myoclonic or a combination. Seizures can be a symptom of MOGAD, including all subtypes of seizures.
Seropositive - A laboratory test result that shows the presence of a specific marker, usually an antibody, in the blood. For MOGAD, seropositive means that you have tested positive for the MOG antibody.
Spasm - A sudden involuntary muscular contraction or convulsive movement
Spinal Tap - A procedure that involves inserting a needle into the spinal canal to collect spinal fluid, typically for diagnostic purposes. Often used during diagnosis of neurological conditions. Otherwise known as a lumbar puncture.
Steroid Dependency - May occur for MOGAD patients when tapering to a lower dose of steroids causing recurrance of symptoms and may cause a relapse of new disease activity.
Steroids (Methylprednisolone, Prednisone, Prednisolone, Solumedrol, Dexamethasone) - A type of medication typically given intraveneously or orally. For myelin oligodendrocyte glycoprotein antibody disease (MOGAD) it is used as an immunosuppressant and anti-inflammatory to reduce disease activity and inflammation. In adults, it is sometimes used in high doses for acute attacks. In some adult patients, it may be used for 1-2 months after an acute attack to avoid a rapid onset of relapse. Higher doses (>10mg/day) are not recommended for an extended period of time but lower doses (<=10mg/day) may be used in some patients longer term. In children, it may be used after treatment of an acute attack, but it is not recommended long-term due to the profound effects of chronic steroids on a child's health. Use of oral prednisone as a maintenance therapy in relapsing pediatric MOGAD patients is discouraged due to side effects in developing children, and other therapies such as monthly immune globulin are suggested. (To understand relapsing during steroid tapering, see Steroid Dependency)
Stupor - A condition of greatly dulled or completely suspended sense or sensibility, a state of near-unconiousness or insensibility. May be a symptom of MOGAD from disease process in the brain.
Subcutaneous (SC) - A method of administering medication by injection under the skin.
Supplements - A substance that when consumed, improves nutritional deficiencies in an individual's diet (i.e. multivitamins).

Titer Test - A diagnostic test that determines whether a patient has been exposed to an antigen or not, as determined by titration of blood or cerebrospinal fluid. The MOGAD titer test is used to confirm a MOGAD diagnosis.
tocilizumab (Actemra) - An immunosuppressive drug that blocks the inflammatory protein IL-6. This may improve symptoms caused by inflammation. The common brand for this drug is Actemra. For myelin oligodendrocyte glycoprotein antibody disease (MOGAD), this medication is used to suppress the immune system to reduce disease activity. May be given intraveneously or by subcutaneous injection.
Transcutaneous Electrical Nerve Stimulation (TENS Device) - A device that delivers low electrical impulses through a person's skin. Used to treat some symptoms (such as neuropathy pain or bladder retention) of myelin oligodendrocyte glycoproten antibody disease (MOGAD).
Transverse Myelitis (TM) - A disorder caused by inflammation of the spinal cord. It is characterized by symptoms and signs of neurologic dysfunction in motor and sensory tracts on both sides of the spinal cord. The involvement of motor and sensory control pathways frequently produce altered sensation, weakness and sometimes urinary or bowel dysfunction. In relation to MOGAD, the inflammation is caused by the MOG Antibody.
Tremor - The involuntary slow or rapid shaking or rhythmic movement of a body part, typically the hands, head, legs, or vocal chords.

Uhthoff's Syndrome / Phenomenon (Heat Sensitivity) - A temporary worsening of neurological symptoms related to a demyelinating disorder such as MS, MOGAD or NMOSD when the body has prolonged exposure to excessive heat causing a rise in the body's core temperature (e.g., from hot weather, exercise, fever, saunas, or hot tubs).
Unilateral - Refers to disease or attack on a single side.

Vertebral segments - A spinal segment made up of two vertebrae attached together by ligaments, with a soft disc separating them. In MOGAD, the vertebrae segment region and number is used to describe the location of a lesion or inflammation caused by the disease process.
Vision Abnormalities / Blindness - Any alterations in your ability to see normally which may include blurred vision, cloudy vision, double vision, color change, seeing spots in your vision, or loss of vision. Vision changes may occur in one or both eyes. With MOGAD, vision changes are caused by optic neuritis.
Vision Field Test - A visual test that determines blind spots in your field of vision and their location by measuring the width of area you can see while focusing on a central point.