What Is MS?

MS can be a misunderstood disease.

Multiple sclerosis (MS) is a disease that affects the brain and spinal cord. It's thought to be an autoimmune disease . This means that, instead of defending the body against harmful invaders like viruses or bacteria, the immune system does the exact opposite. It attacks the body.

In the case of MS, the central nervous system is where most of the damage is done. Your brain contains nerve cells called neurons , which are covered by a tissue called a myelin sheath that protects and insulates them. The myelin also helps the neurons send electrical impulses to and from the brain, telling the body what to do.

In MS, the immune system eats away at the myelin sheath. There can be so much damage that the neurons can be frayed or even broken. When this happens, the neurons can't help electrical impulses travel where they are supposed to go. So your body can't function the way it's supposed to, and this causes the different symptoms of MS, such as vision problems and difficulty with muscle movement, coordination and balance.

Common multiple sclerosis symptoms include:

• Bladder and bowel problems
• Cognitive difficulties
• Depression
• Fatigue
• Muscle rigidity or stiffness
• Weakness or poor coordination
• Numbness and tingling
• Pain in arms and legs
• Visual disturbances

There are several different types of MS.

TYSABRI is approved to treat relapsing MS.

Of the nearly 400,000^* Americans living with MS, the most common diagnosis is for relapsing-remitting MS (RRMS). Altogether, there are 4 different types of MS:

• Relapsing-remitting MS (RRMS)
• Secondary-progressive MS (SPMS)
• Primary-progressive MS (PPMS)
• Progressive-relapsing MS (PRMS)

Note: TYSABRI is only indicated for RRMS and PRMS.

^*According to the National MS Society.