What Is Multiple Sclerosis?

The central nervous system (CNS) is the primary processing center of the body, encompassing the brain and spinal cord. It is responsible for everything from what you think to how you move. Multiple sclerosis (MS) affects the CNS, disrupting the way nerve signals communicate in the brain, as well as between the body and the brain, leading to a range of symptoms that vary from person to person.

“Symptoms of MS will depend on what parts of the nervous system are affected and to what degree,” says Vijayshree Yadav, MBBS, a neurologist and professor of neurology at the Oregon Health & Science University in Portland, OR.

According to the National Multiple Sclerosis Society, almost one million people in the United States have received a diagnosis of MS. If you or a loved one is among them, understanding the symptoms, complications, and treatments for multiple sclerosis can help you better manage your health.

What Does Multiple Sclerosis Do to the Body?

The central nervous system controls numerous essential functions in the body, including movement, vision, thinking, bowel and bladder control, and sensation. It does this by sending electrical signals along nerve fibers throughout the body; these fibers are surrounded by a protective substance called myelin.

In multiple sclerosis, inflammation occurs in the body because the immune system mistakenly attacks healthy tissue, leading to a loss of function, Dr. Yadav says. This inflammation damages myelin and can also injure the nerve fibers themselves, disrupting the way nerve signals fire.

“Everything we do is controlled by the CNS, so when there’s damage and nerve cells are disrupted, it can lead to a range of issues, from vision problems to difficulty balancing to brain fog,” explains Dr. Yadav. “One of the most challenging aspects of MS is that these symptoms can change over time, sometimes even from one day to the next.”

What Are the Early Signs of Multiple Sclerosis?

Just as MS symptoms can be different from one person to the next, early indications of the condition also vary from person to person, according to Amy Laitinen, M.D., a neurologist and director of multiple sclerosis and neuroimmunology at Marcus Neuroscience Institute, part of Baptist Health South Florida in Boca Raton.

Early signs can include:

• Balance and coordination issues
• Bladder or bowel changes such as sudden urgency or increased frequency
• Emotional changes, including depression and anxiety
• Muscle weakness, particularly on one side
• Numbness and tingling in the arms, legs, or face
• Significant fatigue
• Vision issues like pain with eye movement, double vision, or blurriness

In early stages of the disease, symptoms may be more subtle, but as MS progresses, says Dr. Laitinen, symptoms could become more intense or last longer. “Because early MS symptoms can be mild, it makes it challenging to identify MS early,” she adds. “This can be exacerbated by mistaking these signs for other medical conditions or physical issues.”

For example, symptoms like fatigue, anxiety, or short-term memory struggles might be chalked up to stress or sleep difficulties. For older adults, symptoms like bladder dysfunction, muscle weakness, or impaired balance could be mistaken for the natural effects of aging.

What Are the Most Common Multiple Sclerosis Symptoms?

The exact symptoms someone with multiple sclerosis experiences depend on which areas of their nervous system have been affected and how much damage occurs, says Dr. Yadav. It’s also possible to have MS with no symptoms at all.

Still, some symptoms are more prevalent than others, including symptoms related to mobility, vision, cognition, and bladder and/or bowel control. Let’s take a closer look at each.

Movement and Mobility Symptoms

The inflammation occurring with multiple sclerosis can attack the pathway of nerves that control muscle movement, says Misbah Azeem, M.D., a neurologist who specializes in treating MS at National Jewish Health in Denver, CO. This creates noticeable changes in walking and mobility, as well as coordination and balance. You may notice that multiple sclerosis is affecting your mobility as it relates to:

• Coordination issues
• Foot drop
• Leg weakness and heaviness
• Muscle spasms
• Muscle stiffness (also called spasticity)
• Numbness in the legs and feet
• Unsteady movements

“Mobility can also be affected due to other symptoms of MS, such as fatigue, pain, and vision problems,” says Dr. Azeem. Together, these symptoms help explain why difficulty walking affects up to 80% of people with the disease. If your mobility limitations are affecting your quality of life, talk with your care team about using a mobility aid to manage MS.

Vision Symptoms

Difficulty with vision is one of the most common complaints for people with multiple sclerosis, says Dr. Azeem. Vision symptoms can be caused by inflammation of the nerve connecting the eye to the brain or by damage to the pathways that control eye movement, and can lead to challenges like:

• Diplopia. Also known as double vision, this symptom is prompted by damage to the brainstem nerves that coordinate eye movements.
• Nystagmus. This refers to involuntary, rapid eye movements that are uncontrolled and may lead to dizziness or vertigo.
• Optic neuritis. Inflammation of the optic nerve usually affects one eye in people with MS and may cause pain with eye movement, a central blind spot, or differences in color perception.

These symptoms can affect balance and coordination, says Dr. Azeem. Because of that, it’s essential to work with an ophthalmologist on treatment, as well as a physical therapist who can help you adjust to changes in vision, he adds.

Cognitive and Emotional Symptoms

Multiple sclerosis can bring emotional challenges as well as physical ones. Per the National Multiple Sclerosis Society, emotional distress may be caused by dealing with an unpredictable disease that progresses over time; in addition, the nerve damage caused by MS can affect parts of the brain related to emotional regulation.

Multiple sclerosis is also known to prompt a faster rate of brain atrophy, which refers to the brain shrinking in size, something that occurs naturally with age but is accelerated in people with multiple sclerosis, according to Dr. Azeem. The result is that people with the disease may take longer to process information, formulate a response, or focus on a task at hand.

Bladder, Bowel, and Sexual Symptoms

Nerve signals in the CNS extend to the pelvic organs as well, which may lead to issues with bladder, bowel, and sexual function. For example, Multiple Sclerosis and Related Disorders notes that over 43% of people with MS reported concurrent bladder, bowel, and sexual symptoms. These can include:

• Constipation or diarrhea
• Decreased genital sensation
• Difficulty emptying the bladder completely
• Erectile dysfunction
• Frequent urination
• Loss of bladder or bowel control
• Reduced libido
• Urinary or bowel urgency
• Vaginal dryness

Having symptoms like these may raise anxiety levels and be stressful, says Dr. Yadav. Because of that, it’s important to address these with an MS team, even if it feels embarrassing to talk about.

What Causes Multiple Sclerosis?

There is no single known cause of multiple sclerosis, but there are some well-established risk factors that can combine to increase the odds of developing the condition. These include age (MS is most often diagnosed between ages 20 and 40, although it can begin later in life as well); sex (women are more likely than men to develop MS); genetic susceptibility; previous infection with Epstein-Barr virus (EBV); geographic location (MS is more common in areas farthest from the equator); smoking; and early-life obesity.

Having another autoimmune condition like thyroid disease, inflammatory bowel disease, or type 1 diabetes also raises your risk of developing MS.

“It’s important to note that you can have all of these risk factors and still not develop MS,” says Dr. Yadav. “There’s a great deal we still don’t know about why MS occurs.”

What Triggers an MS Flare-Up or Relapse?

Factors that contribute to the development of multiple sclerosis are not always the same as factors that can worsen symptoms or cause new symptoms in someone who already has the disease, known as a flare-up or relapse.

A true MS relapse occurs when new or worsening symptoms caused by inflammatory activity in the central nervous system last at least 24 hours and cannot be explained by fever or an active infection, says Dr. Azeem. Factors that can worsen MS symptoms include:

• Exhaustion and poor sleep. Fatigue can make existing symptoms more difficult to manage and can also affect emotional well-being.
• Heat and fever. Hot weather, hot showers, strenuous exercise, or a fever can temporarily intensify symptoms such as weakness, fatigue, and blurred vision.
• Infections. Urinary tract infections, respiratory infections, and other illnesses can temporarily worsen existing symptoms.
• Stress. Some people notice that symptoms become more troublesome during stressful periods. Stress may affect sleep, fatigue, and emotional health.

“Anyone experiencing new symptoms or a significant change in existing symptoms should contact their doctor,” says Dr. Yadav. New medication or a change in dosing may be necessary to reduce inflammation and prevent symptoms from worsening.

Is Multiple Sclerosis Hereditary?

While MS can run in families, it’s not directly inherited in the way some other genetic disorders are, says Dr. Laitinen, noting that more than 200 genes are associated with the risk of developing multiple sclerosis, although the estimated odds of MS in a first-degree family member are just 4%, which is much lower than many other inherited conditions.

That means genetic testing cannot reliably predict whether an otherwise healthy person will develop MS, and it also means that family history is a risk factor, not a guarantee of getting MS.

What Are the Different Types of Multiple Sclerosis?

There are four types of MS, and a neurologist will determine which one is present as a way to tailor treatment.

Clinically Isolated Syndrome (CIS)

This refers to a first episode of neurologic symptoms that last at least 24 hours and are caused by inflammation or damage to the central nervous system. Symptoms may include vision problems, numbness, weakness, or difficulties with balance and coordination. CIS resembles an MS relapse but does not necessarily mean a person has MS. Some people experience only one episode and never develop MS, while others may develop MS later.

Relapsing-Remitting Multiple Sclerosis (RRMS)

This is the most common form of MS and is characterized by distinct episodes, called relapses, during which new neurological symptoms appear or existing symptoms worsen. These episodes may last days, weeks, or occasionally months and are followed by periods of remission, when symptoms improve partially or completely. RRMS symptoms vary widely and may include fatigue, vision disturbances, numbness, weakness, or balance difficulties.

Secondary-Progressive Multiple Sclerosis (SPMS)

Some people with RRMS eventually go on to develop this form, in which neurologic function gradually worsens over time. This progression may lead to increasing difficulties with walking, balance, coordination, fatigue, or other daily activities. The transition to SPMS can occur gradually, making it difficult to identify precisely when it begins.

Primary-Progressive Multiple Sclerosis (PPMS)

Also characterized by a gradual worsening of neurological symptoms and disability, PPMS shows progressive decline from the beginning of the disease, rather than distinct relapses followed by recovery periods. The rate of progression varies from person to person, and symptoms may worsen steadily or fluctuate over time.

Can Older Adults Develop Multiple Sclerosis?

The vast majority of people with MS are diagnosed between the ages of 18 and 50, but it’s possible for late-onset MS to occur after that point, according to Dr. Laitinen. A JAMA Neurology found that 5% of people with MS were diagnosed after 50. Much like symptom variability at any age, older adults can experience mild MS symptoms or have more intense and debilitating challenges. “However, as a person with MS gets older, some may experience general progression or worsening of their symptoms, manifesting as worsening bladder function or decreased walking endurance,” Dr. Laitinen notes.

How Is Multiple Sclerosis Diagnosed?

A thorough medical history and clinical examination will help identify areas of the nervous system that may be affected by MS, says Dr. Azeem. An MRI that shows images of the brain and spinal cord will be used to confirm these findings and identify where lesions along the central nervous system are located.

Typically, the next step is to perform a lumbar puncture (also known as a spinal tap) to test the spinal fluid for inflammation. If further confirmation of a diagnosis is needed, providers may choose to test the functioning of the optic nerves, Dr. Azeem adds.

“Symptoms over time will also be evaluated,” he says. “This can include problems with vision, fatigue, coordination, mobility, bowel and bladder function, and muscle weakness.” Monitoring which symptoms are present, how long they’ve been occurring, and how often they happen can help you and your provider keep an eye on any disease progression.

How Is Multiple Sclerosis Treated?

Treatment for MS usually involves medications and lifestyle changes that can have a meaningful effect on both the progression of the disease and everyday function.

Disease-Modifying Therapies

Disease-modifying therapies (also called DMTs) are long-term medications that calm an immune attack, which reduces relapses and new lesions, says Dr. Azeem. They work by altering how the immune system works, which reduces inflammation and slows MS progression. There are more than 20 different disease-modifying therapies for MS approved by the Food and Drug Administration (FDA), he adds.

Treatment for an MS Relapse

Treatments for relapses are meant to be used for a brief time as a way to speed recovery, Dr. Azeem says. A relapse is often treated with a short course of high-dose steroids that can alleviate symptoms and bring down inflammation.

Symptom Management

Although DMTs can slow disease progression and steroids can lessen symptoms during flares, neither is intended for managing specific symptoms, says Dr. Azeem. Instead, your provider will talk with you about individual treatments depending on which MS symptoms affect you most.

Common multiple sclerosis symptoms like fatigue may be managed by assessing secondary causes like sleep disorders, medication side effects, or other medical conditions that would cause fatigue like anemia or thyroid dysfunction.

Meanwhile, muscle stiffness and spasticity can be helped with exercises and stretches that can ease muscle tension. Medications like gabapentin (Neurontin), pregabalin (Lyrica), and baclofen (Lioresal) may help as well. Other medications like gabapentin or pregabalin may be prescribed for nerve pain and numbness, while muscle relaxants could be recommended for pain caused by muscle spasms.

Vision problems need to be evaluated by an ophthalmologist or a neuro-ophthalmologist to see if specialized lenses are required for visual correction or reduction of double vision.

What Is the Outlook for Someone With MS?

Thanks to DMTs and earlier diagnoses, people with MS typically have a near-normal life expectancy, says Dr. Yadav. Challenges with mobility can be supported through assistive devices or physical therapy, while cognitive changes may improve by working with an occupational or speech therapist.

To stay one step ahead of managing multiple sclerosis, follow your medication regimen, maintain healthy habits that keep body and mind strong overall, and stay in regular communication with your MS team.