Anyone may develop multiple sclerosis. More than two to three times as many women as men develop multiple sclerosis and this gender difference has been increasing over the past 50 years. Multiple sclerosis occurs in most ethnic groups, including African-Americans, Asians and Hispanics/Latinos, but is most common in Caucasians of northern European ancestry.

Approximately 400,000 individuals have been diagnosed with multiple sclerosis in the United States and as many as 2.5 million worldwide, with an estimated 10,000 new cases diagnosed in the United States annually. Since the Centers for Disease Control and Prevention (CDC) does not require U.S. physicians to report new cases, and because symptoms can be completely invisible, the prevalence of MS in the U.S. can only be estimated.

Diagnosing MS can be a challenging process. In early MS, symptoms may be non-specific and suggestive of several disorders of the nervous system. Early symptoms that come and go may be ignored. While no single laboratory test is yet available to prove or rule out MS, magnetic resonance imaging (MRI) is a great help in reaching a definitive diagnosis. Diagnostic criteria that incorporate MRI findings have been developed and revised by experts in the field and have helped providers make an accurate and timely diagnosis.

Multiple sclerosis symptoms occur when the immune-system produces inflammation within the central nervous system. The inflammatory attack damages myelin, (the protective insulation surrounding nerve fibers), oligodendrocytes (cells that make central nervous system myelin) and sometimes the underlying nerve fiber. The damage caused by inflammation can produce symptoms that resolve over weeks to months or symptoms that are permanent.

Progression is the accumulation of lasting symptoms over time. This can happen as a result of relapses, when a symptom doesn’t entirely go away when the flare-up has ended. But progression can also happen independently of relapse. In this case, a symptom often comes on slowly, getting more noticeable as time goes on.

Worsening of a symptom you have previously experienced doesn’t necessarily signal a relapse, pseudo-relapse, or disease progression. Sometimes, other health factors contribute, or several symptoms have a synergistic effect, each making the other worse. For example, lack of sleep, poor nutrition, or stress can contribute to chronic fatigue. Fatigue can contribute to cognitive dysfunction and worsen emotional symptoms, such as depression. When these problems persist more than a day with no other apparent health factors as the cause, or if you experience new or severe symptoms, contact your doctor.

The prognosis (or future outlook) for an individual with MS depends upon the type of MS they have, and the severity and frequency of relapses and/or progression.

In the broadest terms, those diagnosed with progressive MS may expect to experience a steady worsening of symptoms – frequently affecting mobility. However, the rate of that progression varies widely. One study followed people with progressive MS over several decades and noted that at 25 years after diagnosis, a quarter of the participants were still able to walk.

For those with relapsing MS, the prognosis is equally variable. Within 25 years, the majority will transition to the secondary progressive form of the disease, but that does not necessarily equate to developing severe disability. Often, they will not require a wheelchair or other mobility aid any earlier than their peers who do not have MS.

In some cases, the course of MS during the first five years may provide a clue to the progression of the disease during the next 10 years. Recent studies indicate that 90 percent of patients with minimal disability at five years after onset were still walking without an assistive device after 15 years.

There are steps a person can take to fight back against the disease, prevent relapses, and delay progression. These include beginning treatment as early as possible and adhering to their medication schedule, managing their sleep and stress effectively, eating well, staying active, and going tobacco-free.

No two cases of multiple sclerosis are exactly the same. Each person will have a different set of symptoms, and the timing and severity of relapses, as well as disease progression, will differ from person to person. However, doctors and researchers do use certain terms to characterize the nature of a person’s condition.

To better develop appropriate management plans, multiple sclerosis has typically been divided into classifications, or types. At diagnosis, a person is most likely to be classified as having one of the following:

Clinically-Isolated Syndrome (CIS) – A first and single neurological episode of inflammation or demyelination in the central nervous system lasting at least 24 hours, considered to be probable multiple sclerosis.

Primary-Progressive (PPMS) – in PPMS, the progression of neurological dysfunction and/or disability is present from the onset of multiple sclerosis, without any distinct relapses or remissions. Temporary, minor improvements may be experienced, but are not common.

Relapsing MS (RMS) – This form of multiple sclerosis is, by far, the most common form of the disease. RMS is defined by clearly identifiable attacks lasting days or weeks, with periods between relapses being stable and absent of disease progression. After an attack, many people experience a full recovery, but some will experience residual loss in mental or physical function upon recovery. RMS was previously known as Relapsing-Remitting MS, or RRMS.

Those diagnosed with RMS may eventually transition to a fourth category:

Secondary-Progressive (SPMS) – Begins with an RMS classification that becomes consistently progressive and includes more frequent relapses with minor remission. Loss of physical and mental function are accumulated without recovery between attacks.

Most people with multiple sclerosis can expect to experience relapses. A relapse is a relatively sudden (over hours or days) episode of new symptoms or worsening of existing multiple sclerosis symptoms. People call relapses by different names including an attack, a flare up, an episode, a blip or an exacerbation. People who experience relapses are also likely to experience pseudo-relapses. This is a temporary worsening of symptoms, lasting less than 24 hours, caused by something other than central nervous system inflammation. Common causes are heat intolerance, infection, and illness.

No. MS is not contagious or directly inherited. Studies do indicate that genetic factors and certain environmental factors may make certain individuals more susceptible to the disease.

Life expectancy for people with MS has increased over time. We believe this is due to treatment breakthroughs, improved healthcare and life style changes. Recent research however, indicates that people with MS may live an average of about seven years less than the general population because of disease complications or other medical conditions. Many of these complications are preventable or manageable. Attention to overall health and wellness can help reduce the risk of other medical conditions, such as heart disease and stroke, that can contribute to a shortened life expectancy. In some rare instances, there are cases of MS that progress rapidly from disease onset and can be fatal.

MS symptoms are variable and unpredictable. No two people have exactly the same symptoms, and each person’s symptoms can change or fluctuate over time. One person might experience only one or two of the possible symptoms while another person experiences many more.

As multiple sclerosis causes damage in the central nervous system, nearly any function can be adversely affected. However, the most common symptoms may include:

Cognitive difficulties
Many people with multiple sclerosis have problems with cognition. Symptoms may include: memory loss, attention and concentration issues, difficulty processing information, trouble planning and prioritizing, and verbal fluency issues (like word recall).

Vision problems
People with multiple sclerosis may experience problems with their eyes. This happens because the optic nerve can become inflamed, or other related nerves can be damaged, resulting in potential blurred vision, loss of normal color vision, blindness in one eye, a dark spot in the field of vision, double vision, and uncontrolled eye movements or “jumping vision.”

Fatigue
People with multiple sclerosis may become more easily worn out after physical activity than usual. In addition to experiencing physical fatigue from doing simple things, people with multiple sclerosis may also experience mental fatigue from depression.

Heat sensitivity
High temperatures make it harder than it already is for demyelinated nerve cells to conduct electrical signals. Because of this, many people with multiple sclerosis may experience a temporary worsening of symptoms when exposed to heat or dealing with a fever. Symptoms caused by heat are typically temporary and once the temperature cools, even by a small amount, the symptoms usually subside.

Bowel and bladder problems
Problems with your bowel and bladder can happen because multiple sclerosis lesions may block or delay nerve signals in parts of the central nervous system that control the bowel, bladder and urinary muscles. Symptoms of bladder dysfunction may include incontinence; having to urinate frequently, urgently, or at night (nocturia); and the inability to empty your bladder completely. When you have problems emptying your bladder, you are at a higher risk for contracting a urinary tract infection (UTI). Bowel problems may include constipation and diarrhea.

Sexual issues
The nerve damage caused by multiple sclerosis may lead to issues with sexual function. This means sexual response—including arousal and orgasm—can be directly affected. Men may experience difficulty achieving or maintaining an erection, and reduced sensation or difficulty achieving ejaculation. Women may experience reduced sensation, painfully heightened sensation, or vaginal dryness. Sexual issues may also stem from other multiple sclerosis symptoms such as fatigue or spasticity, as well as from psychological factors relating to self-esteem and mood changes.

Pain
People with multiple sclerosis may feel things like sharp stabbing facial pain. Burning, aching, and tingling “pins and needles” are also common around the body. Chronic back and musculoskeletal pain may be experienced as a result of walking problems and/or muscle spasticity. If you’re experiencing pain, it’s important to identify its source with the help of your doctor.

Motor problems
Because multiple sclerosis can damage the nerves in the spinal cord and brain, your muscles may become weak and ineffective. Stiff muscles and spasms, or sudden involuntary movements, also known as spasticity, are common. Trouble with walking is also common in people with multiple sclerosis. Experiencing some degree of tremor, or uncontrollable shaking, can also occur in various parts of the body.

While some people with MS must eventually use a wheelchair to maintain their independence, the possibility is less likely than you may think.

The course of MS can vary widely, and it is impossible to predict the nature, severity, or timing of progression in a given person. Some people with MS will have a more progressive disease course than others. Yet, history studies have indicated that, absent of any treatment, only about one-third of people with MS require a wheelchair or mobility aid after 20 years with MS.

Today, treatments are available to slow the progression of disability. Some people with MS respond quite well and may have no progression for many years. For others, the treatment may slow, but not stop the progression. With treatment, your chances of requiring a wheelchair can drastically shrink below that one-third mark. It is important to be active, and to work with your healthcare provider to obtain the most appropriate treatment. In doing so, you will keep disability at bay for as long as possible.

No. Moreover, the majority of people with MS do not become severely disabled. Two-thirds of people who have MS remain able to walk, though many will need an aid, such as a cane or crutches, and some will use a scooter or wheelchair because of fatigue, weakness, balance problems, or to assist with conserving energy.