A
Autoimmune
In autoimmune diseases, the immune system mistakenly attacks healthy tissues in the body. This can cause inflammation and damage to the affected tissues.1
Axon
A long, slender part of a nerve cell [neuron] that carries messages. In multiple sclerosis [MS], axons may be damaged by the disease process. This damage can lead to loss of function.1
C
Central nervous system [CNS]
The brain, spinal cord, and nerves of the eye [optic nerves]. MS is a disease of the CNS.1
Cerebrospinal fluid [CSF]
A clear fluid that surrounds and cushions the brain and spinal cord.1
Corticosteroids
A group of drugs that are used to reduce inflammation in people with MS. Also known as “steroids.”1
D
Demyelination
The loss of myelin, a fatty material that coats and protects nerve fibers. Demyelination disrupts the flow of information within the nervous system. It can lead to brain and nerve symptoms in people with MS.1
Diplopia
The medical term for double vision that only occurs when both eyes are open, which can happen in people with MS.1,2
Disease-modifying therapies
Known as DMTs, these are drugs used to treat relapsing forms of MS. They reduce the number of relapses as well as the severity and number of new areas of damage in the brain. They do not generally improve everyday symptoms or heal damage that has already occured.3
E
Epstein-Barr virus [EBV]
A virus that is best known for causing mononucleosis (mono). It has also been linked to MS.4
F
Fatigue
A feeling of tiredness or exhaustion that is not relieved by rest. Fatigue is common in people with MS.5
Foot drop
Difficulty lifting the front part of the foot due to weakness or paralysis. Muscle weakness and tightness from MS can cause this problem.6,7
L
Lesion
A patch of damage or inflammation. In people with MS, lesions occur in the brain, spinal cord, and optic nerves.8
Lhermitte’s sign
An electric shock-like feeling that runs down your back and sometimes in your arms, legs, and belly when you flex your neck. It is caused by irritation of the nerve roots in your upper spine. About 16 in 100 people with MS get this, but it is not specific to MS.1,9
Lumbar puncture
Also called a spinal tap. A procedure used to collect cerebrospinal fluid [CSF] that is usually done in a clinic or hospital. In a lumbar puncture, your doctor inserts a needle into your lower back and removes CSF. The CSF is then sent to the lab to be analyzed. This procedure can be used to help diagnose conditions such as MS.1
M
Myelin
A fatty material that coats and protects nerve fibers in the brain and spinal cord. Myelin is damaged in MS, leading to disruptions in nerve signals.1
N
Neurologist
A doctor who specializes in diagnosing and treating disorders of the brain and nervous system.10
Nystagmus
Uncontrolled movement of the eyes that can make it hard to see. In people with nystagmus, a part of the brain that controls eye movements does not work properly. It can affect both eyes or just one eye. Nystagmus can be caused by several conditions, including MS.1,11
O
Oligoclonal bands [O-bands]
Proteins found in the cerebrospinal fluid [CSF]. They are thought to be biomarkers, or indicators, of inflammatory diseases of the CNS like MS. O-bands can be used to help diagnose MS. However, not everyone with MS has O-bands, and those with O-bands do not always have MS.12
Optic nerves
The large nerves, one in each eye, that carry visual information from the eyes to the brain. This area of the CNS is commonly affected in people with MS.
Optic neuritis
Inflammation of the optic nerve. This can cause visual problems such as blurred vision, vision loss, or decreased color vision.1
P
Paresthesia
An abnormal prickling or tingling sensation that is sometimes felt in the hands, feet, or face. Nerve damage from MS may cause this symptom.1
Primary-progressive MS [PPMS)]
A type of MS that causes a gradual worsening of symptoms. With PPMS, you do not have relapses or go through periods of remission [a pause in the progression of symptoms].1
Progressive-relapsing MS [PRMS]
A progressive course of MS with acute relapses that happen as the disease progresses.1
R
Relapse
A period, often days, when new neurologic symptoms develop in people with MS. Also known as a flare-up.
Relapsing-remitting MS [RRMS]
RRMS causes periods of remission followed by relapses. The majority of people with MS have RRMS.1
Remission
A period in which MS symptoms are stable (or absent) for a while.
S
Secondary-progressive MS [SPMS]
A type of MS that initially follows the relapsing-remitting MS [RRMS] pattern but in which the condition continues to progress between relapses.1
Spasticity
A common MS symptom in which muscles get stiff and rigid.1,13
T
Trigeminal neuralgia
A sudden, sharp facial pain often triggered by a light touch or movement. It is caused by damage to the trigeminal nerve that can be caused by MS.1,14
U
Uhthoff’s phenomenon
A temporary worsening of MS symptoms caused by heat. Symptoms that can worsen include fatigue, weakness, blurred vision, problems with balance, and numbness or tingling.15
V
Vertigo
A feeling that you or the world around you is spinning. It can be caused by a number of conditions, including MS. Vertigo may also lead to nausea and vomiting.1