Multiple Sclerosis

  • Reviewed by Andrew E. Budson, MD, Contributor; Editorial Advisory Board Member, Harvard Health Publishing

Multiple sclerosis (MS) is a disease that affects nerve cells’ protective sheath (myelin) in the brain and spinal cord, and it can affect the nerve cells (also known as neurons) as well. The damage disrupts or slows nerve signals.

MS can cause a variety of symptoms including impaired vision, mobility problems, cognitive impairment, muscle pain, and fatigue. Symptoms can come and go. Periods when symptoms suddenly worsen are called relapses (they are also referred to as attacks or flare-ups). They alternate with periods when symptoms improve (remissions). 

MS can become debilitating. There is no cure for MS, but many medications and treatments can help manage relapses, ease symptoms, and slow the disease’s progression.

MS affects more women than men. A family history of MS also raises a person’s risk.


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What is multiple sclerosis?

Multiple sclerosis is a disease of the central nervous system in which the body’s own immune system attacks the myelin insulation surrounding nerve cells in the brain and spinal cord.

Myelin helps to insulate the neurons and allows rapid transmission of nerve impulses. In individuals with MS, the myelin becomes damaged, disrupting or slowing nerve signals. Sometimes the myelin grows back and no permanent damage occurs, although the neurons themselves may be damaged when areas of scarring occur along the nerves. Once the nerves are damaged, the neurologic dysfunction is generally irreversible.

This damage leads to various problems, such as double or blurred vision, cognitive impairment, mobility issues, muscle pain, fatigue, numbness, and loss of coordination.

What are the different types of multiple sclerosis?

There are four types of multiple sclerosis:

Relapsing-remitting MS. This type of MS, in which symptoms come and go, is the most common. Relapses can last for days to weeks. They are followed by remissions, which can last weeks, months, or even years. During remissions, many people with MS feel close to normal.

Secondary progressive MS. About half of people with relapsing-remitting MS eventually enter a secondary phase during which brain and spinal cord damage gradually but steadily gets worse. As a result, symptoms also gradually worsen.

Primary progressive MS. In people with this type of MS, symptoms worsen gradually and continuously from the start, without periods of relapse and remission.

Progressive relapsing MS. This is the least common type of MS in which symptoms steadily worsen from the start, but with periods of relapse and remission.

What are multiple sclerosis symptoms?

MS symptoms usually appear before age 40. The severity and duration of symptoms varies. Some people may be symptom-free most of their lives, while others have severe, persistent, and/or progressive symptoms.

Although there are many possible symptoms of MS, most people only experience a few of them. Common MS signs and symptoms include:

  • Blurred or double vision (this is often the first sign of MS)
  • Slurred speech 
  • Cognitive impairment
  • Vertigo and dizziness
  • Clumsiness, especially on one side 
  • Loss of coordination 
  • Unsteady gait 
  • Muscle pain or weakness
  • Fatigue (physical and mental)
  • Hand trembling 
  • Facial problems including numbness, weakness, or pain 
  • Bladder control problems or the inability to empty the bladder
  • Tingling, numbness, or a feeling of constriction in the arms, legs, trunk, or face         
  • Weakness or a heavy feeling in the arms or legs 
  • Seizures (affecting about 2% of people with MS)
  • Sexual dysfunction (loss of libido, vaginal dryness, erectile dysfunction)

Multiple sclerosis treatments

There is no cure for MS, but treatment can help to manage flare-ups, slow the worsening of the disease, and ease symptoms.

Managing flare-ups. Corticosteroid drugs are the primary treatment for reducing the duration of flare-ups. They are often given intravenously (by IV). Plasma exchange, also known as plasmapheresis, may be recommended for flare-ups that do not improve rapidly with corticosteroid treatment. Plasma exchange is a procedure in which the portion of the blood without cells (plasma) is removed and replaced with plasma from a blood donor or with a plasma substitute. Plasma exchange is thought to work because harmful antibodies and other proteins are removed from the person’s body.

Disease-modifying therapy. Some medications act on the immune system to help slow disease progression.

  • Beta interferons. These drugs slow the worsening of nervous system damage by dampening the inflammation that damages myelin and nerve cells. They also reduce the frequency, duration, and severity of flare ups. These drugs are given by injection into the muscle or just under the skin.  
  • Glatiramer acetate (Copaxone). This drug blocks damage to myelin and may reduce the frequency of relapses. Some physicians recommend it when beta interferons cannot be used, is no longer effective, or is not well tolerated.
  • Monoclonal antibodies. These drugs work by partly inhibiting the body’s immune system, which reduces the frequency of attacks.
  • Nrf2 activators. These drugs decrease inflammation and prevent nerve damage that can cause symptoms.
  • Immunomodulators. These drugs decrease the activity of immune cells that may damage myelin and nerve cells.

Easing symptoms. Other medications can treat specific symptoms caused by MS, such as fatigue, muscle spasms, bladder dysfunction, depression, and seizures.

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