Multiple Sclerosis Glossary: 52 Terms You Should Know

Knowing the proper terminology for MS-related concepts can help you communicate more effectively with your care team and others in the MS community.

The moment someone is diagnosed with multiple sclerosis (MS) is usually a major turning point in their life. Newly diagnosed people will find themselves learning a whole new vocabulary, including many words, phrases, and abbreviations that our science teachers never included in the class curriculum.

Navigating this complex disease can feel overwhelming. It can be a lot to understand the medical terminology and jargon associated with it. Learning common MS terms and definitions is essential to communicating effectively with healthcare providers and better managing MS symptoms.

We’re covering the most common MS-related lingo, acronyms, slang, and official medical terminology so that you can discuss this condition with your healthcare professional with confidence, and connect with others in the MS community who “speak” the same language.

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AFO (Ankle-foot orthosis)

A type of brace worn to help with foot drop, a common issue (see “foot drop” entry below) in MS. The AFO helps support muscles in the ankle and foot and makes walking easier.

Atrophy

The loss of muscle mass due to lack of use. This can occur in people who have difficulty with mobility and physical activity.

Autoimmune disease

A condition in which the body’s immune system mistakenly attacks its own healthy tissues and organs. In MS, which is widely believed to be an autoimmune disease, this attack occurs in the central nervous system, mainly attacking the myelin, the cells that produce it, and the nerves it covers.

Axon

An essential part of a neuron (nerve cell) that conducts electrical impulses and carries messages to other parts of the body. Its tail-like structure is covered in myelin (see “myelin” entry below).

B-cell

A type of white blood cell in the immune system that produces antibodies to fight foreign invaders like bacteria and viruses. B-cells contribute to the inflammation and damage seen in people with MS, as the antibodies they produce mistakenly attack and damage the myelin coating that protects nerve fibers in the CNS.

Clinically isolated syndrome (CIS)

A single episode of demyelination that leads to neurological symptoms, which can be the first signs of MS.

Cog fog

Slang used to describe the cognitive difficulties (like concentration and information processing) and general brain fog that some people with MS experience.

Central nervous system (CNS)

The central nervous system comprises the brain and spinal cord, which send and receive nerve impulses throughout the body to produce sensation and muscle movement. These are the areas affected by MS.

Crap gap

Slang for the period between when a person’s last infusion of their disease-modifying therapy (DMT) has worn off and when their next infusion is scheduled. During this gap, the crappy symptoms often seem to return.

CT scan

A CT (computed tomography) scan, also known as a CAT scan, is an imaging test that uses a series of X-rays to create detailed cross-sectional images of tissues, blood vessels, and bones. This test may help with MS diagnosis and symptoms.

Degenerative disease

A condition, such as MS, in which tissues or organs in the body deteriorate over time.

Diplopia

Another term for double vision, this is a common vision-related symptom of MS caused by inflammation or other damage to the nerves that control eye movement.

Disease-modifying therapies (DMTs)

Medications that can slow the progression of MS and reduce the frequency of relapses, but don’t cure the disease or directly address symptoms. A variety of DMTs are available, including oral therapies, injectables, and infusions.

Demyelination

The damage or loss of the protective myelin around axons in the CNS. (See “myelin” entry below.)

Dx

A medical abbreviation for the word “diagnosis.” Often used as a shorthand in writing when the topic of diagnosis arises.

Dysarthria

The medical term for difficulty speaking clearly. If the nerves that send signals to the muscles used in speech or respiration are affected by MS, a person may slur their words, or have difficulty controlling their volume or pacing of speech.

Dysphagia

The medical term for difficulty swallowing, which can be a symptom of MS as well as other conditions that affect the muscles and nerves involved in swallowing.

EDSS

This is an abbreviation for the Expanded Disability Status Scale, a measure commonly used to assess the severity of disability in people with MS. It uses a scale of 1 to 10 and helps track the progression of mobility and other MS-related issues over time.

Flare

Also known as a relapse or exacerbation, a flare (or flare-up) is a sudden worsening of symptoms or the onset of new symptoms caused by inflammation in the CNS. These can range from mild to severe and can last from a few days to several weeks.

Foot drop

Foot drop (sometimes called drop foot), is a common symptom of MS in which the front part of the foot is difficult to lift while walking due to weakness.

Gait

A person’s manner of walking. This can be affected by MS-related symptoms such as weakness, spasticity, or balance problems.

Hallway pinball

Slang to describe the way a person with MS may navigate narrow spaces like hallways, often by leaning on walls and corners for balance while walking, similar to the movement of a ball in a pinball machine.

HSCT

HSCT is an abbreviation for hematopoietic stem cell transplantation, an experimental and higher-risk treatment option for aggressive forms of MS. The procedure involves destroying the immune system and then rebuilding it with stem cells.

Infusion

The process of administering medications (including DMTs) or fluids through a needle or catheter, often intravenously. This process can take several hours and is usually done in a hospital or infusion center, but sometimes can be done at home.

Interferon beta

A component of certain types of DMTs for MS that work by reducing certain proteins produced by T cells and B cells. These drugs are typically injected.

JC virus

The JC (John Cunningham) virus is super common, affecting 70–90% of people worldwide. It can remain inactive in the body for years without causing any harm. However, it can reactivate in individuals who take certain DMTs, causing a serious brain infection known as progressive multifocal leukoencephalopathy (PML).

Jelly legs

Slang used to describe a lack of stability in the legs, often due to MS-related muscle weakness or spasticity.

Lesion

A spot in the central nervous system, seen on CT and MRI scans, that’s been damaged by MS-related inflammation and demyelination. Lesions are also sometimes called plaques.

Myelin

A protective coating that surrounds axons in the CNS. In people with MS, the immune system mistakenly attacks and damages this coating, causing a range of symptoms and complications.

Mobility device

Any device that helps people with mobility issues move around more easily, including wheelchairs, walkers, and canes.

MS hug

An MS symptom that causes a feeling of tightness, pressure, or pain around the chest or torso. Sometimes called the MS girdle or the MS corset.

MRI (magnetic resonance imaging)

A diagnostic imaging test that uses a powerful magnetic field, radio waves, and a computer to produce detailed images of the brain, spinal cord, and other parts of the body. It’s often used to diagnose MS and monitor its progression.

Neuro

Often used as slang for “neurologist,” which is a doctor who specializes in treating conditions that affect the nervous system, including MS. You’ll probably see this doctor at least a couple of times a year.

Nystagmus

A common but treatable MS symptom when the eye moves up and down, side to side, or in circles involuntarily. This can cause vision problems (including problems with depth perception) as well as dizziness, and difficulty with balance. It can often be treated with medications.

Optic neuritis

An inflammation of the optic nerve, which connects the eye to the brain. This can cause eye pain and vision problems, including double vision, blurriness, blindness, or loss of color vision. This is often one of the first symptoms that leads to an MS diagnosis. Vision usually returns after treatment.

PML (Progressive multifocal leukoencephalopathy)

A rare and potentially life threatening viral infection of the CNS. People with weakened immune systems, including those with MS who take certain medications, and who also test positive for JC virus antibodies, are at a higher risk of developing PML.

Primary progressive MS (PPMS)

A type of MS that gradually worsens over time, without periods of remission, and often without significant relapses.

Pseudobulbar affect

A condition that can occur in MS and is characterized by uncontrollable episodes of laughing or crying. This is often in response to emotions that are not particularly strong or even consistent with those behaviors.

Pseudo-flare

A temporary worsening of MS symptoms that is not caused by new MS-related inflammation, but rather by external factors such as stress, illness, or heat exposure.

Relapsing-remitting MS (RRMS)

The most common form of MS affects about 85% of people diagnosed with the disease. It’s characterized by flare-ups or relapses of symptoms, followed by periods of remission with fewer to no symptoms.

Sclerosis

This word, right in the name of our disease, is a general term that refers to the hardening or scarring of damaged tissue, including the nerve fibers affected in MS. These areas of scarring are also called lesions or plaques.

Secondary progressive MS (SPMS)

A type of MS that begins as RRMS but eventually progresses to a steady worsening of symptoms over time.

Spasticity

A symptom characterized by involuntary muscle contractions, stiffness, and tightness, which can cause pain and difficulty with movement.

Spinal tap

A diagnostic test, medically known as a lumbar puncture, in which a needle is inserted into the spinal canal to collect a sample of cerebrospinal fluid (CSF) for analysis. This can help diagnose MS and other neurological conditions.

Steroids

Specifically, corticosteroids are medications used to reduce inflammation in the body. In MS, they are often used to treat acute relapses or exacerbations. These are not the same as anabolic steroids used by bodybuilders to bulk up muscles.

T-cells

T-cells are a type of white blood cell that play a key role in the immune system’s attack in MS. Once activated, they release a variety of molecules that lead to inflammation and nerve damage.

Uhthoff’s sign

A medical term for the worsening of MS symptoms that can occur when the body becomes overheated. This can happen due to exercise, exposure to hot weather, or even taking a hot shower. The phenomenon is named after Wilhelm Uhthoff, a German ophthalmologist who first described it in 1890.

Vertigo

A type of dizziness where it feels like you (or the room) are spinning or whirling. It can be a symptom of MS when lesions in the brainstem or cerebellum affect balance and spatial orientation.

Wooden legs

Slang used by people with MS to describe a feeling of stiffness or heaviness in the legs, which can make walking difficult.

White matter

White matter is a type of brain tissue made up of nerve fibers heavily protected by myelin, a fatty substance that helps messages travel quickly and efficiently between different parts of the brain and spinal cord. In MS, the white matter is often damaged by the immune system’s attack on the myelin, leading to a variety of symptoms.

WBCs

An abbreviation for white blood cells, also known as lymphocytes, which boost immunity by helping to fight off infections and foreign invaders. When your doctor orders a WBC count, she’s asking for a blood test that measures the number of white blood cells in a certain volume of your blood. In people with MS, the WBC count may be elevated during a relapse or exacerbation.

Zingers

Slang to describe the sharp, shooting pains that can occur in various parts of the body, particularly the head and spine. Officially known as Lhermitte’s sign, it’s thought to be caused by damage to the myelin coating that protects nerve fibers.