Types of Multiple Sclerosis

Multiple sclerosis, or MS, is a chronic disorder of the central nervous system, which includes the brain and spinal cord. MS is considered to be an autoimmune disorder, meaning the body’s immune system mistakenly attacks healthy tissue. Doctors at NYU Langone are experts at identifying the different categories or types of multiple sclerosis.

In people with MS, the body’s immune system attacks the protective coating of nerves, called the myelin sheath, throughout the central nervous system. When myelin is damaged, scar tissue called sclerosis or lesions form at the site of the damage. This disrupts nerve impulses traveling to and from the brain and spinal cord. The resulting neurological symptoms vary depending on the amount of damage and which parts of the central nervous system are affected.

The condition can occur at any age, but it most commonly affects people between 15 and 60 years old. However, it can also affect children and teens. White women are most likely to be diagnosed with MS. No one knows what causes MS, though certain risk factors, such as genetics, environmental factors, and cigarette smoking have been identified.

Experts at NYU Langone’s Multiple Sclerosis Comprehensive Care Center recognize that no two people with MS have exactly the same symptoms. In addition, these symptoms can change or fluctuate over time.

Some people may have muscle tightness or spasticity, tremors, and fatigue, whereas others may have vision loss or paralysis, which may be temporary or permanent. MS can cause forgetfulness or difficulty concentrating as well as problems with bladder and bowel function.

People with MS may also experience difficulty with balance and coordination of movements. Some develop numbness, and others have itching or irregular sensations, such as a "pins and needles" feeling or burning pains in the arms and legs.

Although most of these main symptoms are the direct result of damage to the myelin in the central nervous system, secondary symptoms or complications can arise as a result. Bladder dysfunction, for example, may cause repeated urinary tract infections. Inactivity due to pain or fatigue may cause loss of muscle tone, decreased bone density, poor posture, or lack of trunk or “core” control.

Periods of active MS symptoms are called relapses or flare-ups. These can be followed by a period without symptoms, called remission.

The most common way to categorize MS is to track the course of the illness over time.

Clinically Isolated Syndrome

The first time you experience a neurological symptom or symptoms, this episode or “attack,” is described as clinically isolated syndrome. Symptoms, which may or may not recur, may include blurry vision, weakness, numbness, or difficulty with balance.

Depending on the results of testing, such as an MRI scan, doctors can determine if you are in the early stages of MS and likely to experience another attack. If symptoms recur, the condition is then referred to as relapsing-remitting MS.

NYU Langone physicians may discuss starting medication for multiple sclerosis after this first episode. Studies show that beginning medications early can prevent or prolong the next attack.

Relapsing–Remitting Multiple Sclerosis

People with relapsing–remitting MS have attacks that alternate with remission. When symptoms appear, it’s described as a relapse; remission occurs when they subside, with or without treatment.

Typically, symptoms develop over the course of days and then spontaneously improve over weeks or months. Usually, people recover well after a relapse; however, it’s not uncommon to experience residual symptoms, such as numbness. Relapses can occur at any time, even after years of remission.

This type of MS is the most common—approximately 85 percent of people with the disease are initially diagnosed with relapsing–remitting MS.

The severity of a person’s symptoms may change from day to day and even hour to hour. Each of these variations is not considered a relapse. Heat, fever, infection, fatigue, and stress can increase the severity of symptoms. A symptom must be new and persist for more than 24 hours in order for a relapse to occur.

Almost all of the treatments available have been studied in and approved for use in people with this type of MS. For this reason, it’s important that you are diagnosed with the correct type of MS. You and your neurologist should spend time together discussing your current symptoms, especially regarding when they began and how they’ve progressed over the years.

Secondary-Progressive Multiple Sclerosis

Anywhere from 10 to 20 years after the original diagnosis, a person with MS may be determined to have a form of the condition called secondary-progressive MS. At this point, the disease begins to progress more steadily, without alternating periods of relapse and remission.

People with secondary-progressive MS experience gradual changes in function with or without periods of stability. For example, they may notice that a year ago they could walk for 10 city blocks before needing a rest, but can now only walk 8 blocks.

The transition between relapsing–remitting MS and secondary-progressive MS may be difficult to detect. There are no tests available that can distinguish between these two stages of MS.

Primary-Progressive Multiple Sclerosis

People who are diagnosed with primary-progressive MS have symptoms that steadily worsen. They do not experience remission or flare-ups.

People with this type of MS, however, may experience temporary plateaus, during which symptoms do not progress. About 10 percent of people with MS are diagnosed with this form of the condition.