Multiple sclerosis (MS) is a disease that affects the central nervous system, which controls the way we think, learn, move and feel. While there have been great advances in treating the condition, limiting the damage it can cause depends on how early it is discovered. Knowing the first signs of multiple sclerosis can help you or a loved one get care sooner.

What is multiple sclerosis?

"Multiple sclerosis is considered an autoimmune inflammatory disease," says Dr. Abdul R. Alchaki, a neurologist and multiple sclerosis specialist at Houston Methodist. "The body's immune system, specifically certain types of white blood cells, mistakenly attacks and damages the myelin sheath, the protective covering that surrounds nerve fibers in the central nervous system."

The name multiple sclerosis refers to the scar tissue, or lesions, that result from the immune system's attack on myelin, the protective sheath that coats nerve fibers. People with this condition have multiple lesions that can occur on the optic nerve, in the brain or the spinal cord, according to Dr. Alchaki.

Dr. Alchaki says that MS manifests uniquely in every individual, with no two patients experiencing identical symptoms or disease progression. The variability of the condition depends on several factors, including the timing of diagnosis and the initiation of treatment. The impact of MS can range from episodic symptoms that may remit to more persistent symptoms that could last a lifetime.

Multiple sclerosis symptoms

"The scarring caused by MS is as distinct as a fingerprint, varying from one person to another," Dr. Alchaki says. "This means the unique pattern of their lesions influences the diversity of symptoms each individual may encounter."

The symptoms of MS are determined by the locations within the central nervous system where lesions of inflamed tissue develop:

Lesions on the optic nerve

"When lesions occur on the optic nerve, people get a condition called optic neuritis," Dr. Alchaki says. "This can make their vision in one eye become less clear or blurry, and it might hurt to move their eye from side to side."

Spinal cord lesions

"People with lesions in their spinal cord might have symptoms such as weakness: resulting in challenges with walking, difficulty with hand coordination, maybe a loss of sensation or numbness in the hands or feet," Dr. Alchaki says. "Additionally, bowel or bladder control problems are common — for instance, many people with MS face chronic constipation and the need to urinate more urgently and frequently than others."

Lesions in the brain

"When MS affects the brain, people may experience challenges with concentration, multitasking and memory," Dr. Alchaki says. "If the disease impacts the cerebellum, which is a part of the brain that regulates coordination and balance, they might struggle with maintaining balance or experience tremors."

While each person will confront different challenges with MS symptoms, the symptoms that are seen most include blurry vision, numbness, and fatigue.

The first signs of multiple sclerosis can be vague

Relapsing Remitting MS, the most common MS disease course, is generally divided into different stages, according to Dr. Alchaki. The first stage, the preclinical phase or silent phase, is characterized by subtle signs that individuals might notice but not immediately link to MS due to their vague nature.

"During this early stage, which can last three to five years, symptoms aren't typically specific and may manifest as changes in mood, such as depression, anxiety or fatigue," Dr. Alchaki says. "These early signs might not prompt an immediate consultation with a neurologist or lead to a brain MRI. However, if someone undergoes an MRI for another reason, like a car accident, MS lesions could be visible, even though specific MS symptoms aren't yet pronounced."

The next phase is known as clinically isolated syndrome (CIS), which marks the onset of more recognizable symptoms of MS.

"In the CIS phase, individuals may experience their first notable MS symptoms, such as optic neuritis or vision loss, or sensory changes like numbness, or weakness possibly affecting only one side of the body or from the chest or waist down," Dr. Alchaki says. "These symptoms are more aligned with classic signs of MS and often lead to further investigation and diagnosis."

Most people with MS will experience their first distinct symptoms in their 20s or 30s, according to Dr. Alchaki. Some may experience minor, unexplained symptoms sporadically for years before receiving a diagnosis in their 40s and 50s. The condition can also occur in children, although less than 5% of people with MS have their first symptoms before age 16, according to the National Multiple Sclerosis Society.

The journey to MS diagnosis

For people with MS, getting a diagnosis may not be straightforward. Dr. Alchaki says that in the preclinical phase, people may notice some of the trademark symptoms but may get treated for targeted symptoms without knowing the underlying cause.

"There are multiple studies that show that people in the preclinical phase will utilize the health system very often," Dr. Alchaki says. "Very often they see multiple physicians, multiple subspecialists before they get a diagnosis of MS. They see their primary care doctor for fatigue, maybe a psychiatrist for mood changes, urologist for bladder dysfunction or a gastroenterologist for chronic constipation."

People may also delay getting care because of the nature of MS itself — that it's most often a relapsing-remitting condition. Most people with MS experience periods of having symptoms, called relapses, that are followed by periods where symptoms improve, called remission. (Hence, the name Relapsing Remitting MS.)

"Symptoms can vary widely among individuals, but many people experience a return to their normal health state after early relapses," Dr. Alchaki says. "For example, someone might have a period of blurred vision in the right eye that persists for a few weeks, but just as they're about to visit their eye doctor, the vision improves. The improvement might lead them to cancel the doctor's appointment, thinking they're no longer in need of medical attention. It's after these initial relapses, when symptoms temporarily improve, that individuals might delay seeking medical advice, contributing to delays in diagnosis that can span several years."

Over time, if a person with MS remains untreated, Dr. Alchaki says they will experience more frequent relapses, and their condition tends to deteriorate due to the progressive loss of nerve function. Unlike earlier stages where recovery to a pre-relapse state might occur, in later stages, full recovery during remission periods becomes less likely. For example, someone who initially had temporary blurred vision in the right eye might find such blurriness becomes a persistent issue after subsequent relapses. Often, only when these symptoms become more constant and noticeable do individuals start to seek medical attention.

Treatments for MS have improved

The earliest description of MS goes back to the fourteenth century, but it wasn't until the twentieth century that a proven therapy that could change the course of the disease was available. In 1993, the Food and Drug Administration approved the first medication, interferon beta-1b (IFNbeta-1b).

While revolutionary at that time, Dr. Alchaki says that the treatment available to patients diagnosed in the 1990s, 2000s and early 2010s were limited in their efficacy, preventing relapses in only about 30% to 35% of cases. This limitation placed these patients at a higher risk of disability. Since 2011, developments in MS medications have surged.

"Today, we have about 24 MS medications and the vast majority of these medications, more than 50%, were approved after 2017," Dr. Alchaki says. "Some of the medications we have right now can prevent new MS lesions from forming with 95% to 99% accuracy."

The problem, according to Dr. Alchaki, is that while these emerging medications can help prevent new symptoms from developing, they can't reverse the disease. That's why getting care soon after noticing the first signs of MS is so crucial for treatment and outcomes.

"If you catch the disease early, and you start a good medication, people can do very well for the rest of their life," Dr. Alchaki says. "Caught later, there's not much that can be done to reverse the damage caused by the lesions."