People who have radiologically isolated syndrome (RIS) don’t have any symptoms normally associated with multiple sclerosis (MS). They don’t feel fatigued, experience shaky limbs, or have vision problems. By all appearances, they don’t seem to have an autoimmune condition at all — until you look at magnetic resonance imaging (MRI) scans of their brain.

Radiologically isolated syndrome is a condition in which a person develops MS-like lesions on their brain or spinal cord but experiences none of the disease’s other symptoms. Here, we will compare and contrast RIS and MS, including their symptoms and causes, and their respective treatments.

What Is Radiologically Isolated Syndrome?

Radiologically isolated syndrome is intuitively named. Its symptoms can only be found on (are “isolated” to) radiological scans. Despite showing no outward symptoms, people with RIS have white matter lesions (areas of abnormal myelination) on their brain, spinal cord, or both.

RIS brain scan images tend to be very similar to those produced by people with multiple sclerosis because MS is a demyelinating disease. It causes a person’s immune system to attack and strip nerves of their protective coating, called the myelin sheath.

In MS, this demyelination depletes the nerves’ ability to transmit signals, causing the physical symptoms of the disease. In RIS, on the other hand, the appearance of white matter lesions does not correlate to the expression of symptoms. In fact, a diagnosis of RIS can only be made if the person does not have MS symptoms or any other neurological, infectious, toxic, vascular, or pharmacological (drug-based) problems that could cause lesions.

There is some debate in the medical community about whether RIS is an official diagnosis or just an earlier stage of MS. The condition is more common among people who have relatives with multiple sclerosis. However, the majority of people with RIS will not go on to develop MS.

What Is Multiple Sclerosis?

Multiple sclerosis is an autoimmune disease that targets the central nervous system (CNS). In people with MS, the immune system mistakenly attacks the nerves. Over time, these attacks lead to nerve deterioration and demyelination, which hinder the brain’s ability to communicate messages to the body. Miscommunication causes a variety of physical effects and results in the symptoms of MS.

Symptoms of RIS and MS

By definition, people with radiologically isolated syndrome have no physical symptoms. The only indications of their diagnosis are the white matter lesions found on their brain scans.

Multiple sclerosis, on the other hand, can cause a wide variety of symptoms. No two people with the disease have the exact same experience. Some might report several symptoms; others might have one or two mild complaints. That said, there are a few effects that are more common than others. For example, a full 80 percent of those with MS experience fatigue.

As one MyMSTeam member described, MS fatigue is more than a bout of tiredness. “Being tired from a hard day's work or not enough sleep is not like MS fatigue,” they explained. “You can’t really recover from it with a good nap.”

According to the National Multiple Sclerosis Society, more than half of people with MS also report problems with higher brain functions such as learning or remembering new information, accurately perceiving immediate environments, and organizing or problem-solving. In addition, just under 50 percent of people with MS experience chronic pain.

Other common symptoms of MS include abnormal sensations (like numbness or tingling), spasticity (involuntary tightening of the muscles), difficulty walking, vision problems, and bladder and bowel issues. Less common symptoms of MS include tremors, speech issues, breathing problems, seizures, and hearing loss.

Causes of RIS and MS

Experts believe that the causes of RIS and MS may very well be the same. While there is still plenty of research to be done on the matter, some neuroscience researchers believe that radiologically isolated syndrome is a preliminary form of multiple sclerosis.

Past research demonstrates that an RIS diagnosis can eventually turn into MS. One study found that within five years of their first MRI scan, two-thirds of participants with RIS had developed new lesions and one-third experienced clinically isolated syndrome (CIS). CIS refers to an episode of neurological symptoms lasting at least 24 hours that is caused by myelin loss in the CNS. Roughly 1 in 10 participants eventually developed primary-progressive MS (PPMS).

Where a person’s lesions appear seems to be a predictor of whether their RIS will turn into MS. A 2011 study found that 84 percent of people with RIS and cervical cord lesions ultimately developed MS, compared to only 7 percent of those who didn’t have these spinal cord lesions.

This research indicates that although MS isn’t an inevitable outcome of RIS, it isn’t an uncommon one, either. Because a person has a higher risk of developing MS and RIS when they have a close relative with the condition, researchers believe that genetic factors may be involved in the development of these diseases.

Researchers believe that MS, in particular, is caused by a combination of environmental and genetic factors. While the root causes of MS are not yet certain, doctors do have a clear understanding of how and why MS symptoms occur. The physical effects associated with MS start occurring as a result of immune system dysfunction. Over time, repeated immune attacks inflame the nerves, lead to degeneration of the protective myelin sheath, and can cause permanent scarring (sclerosis). Lesions, scarring, and demyelination prevent the CNS from transmitting messages as quickly or effectively as it usually would — which ultimately results in physical symptoms.

Diagnosing Radiologically Isolated Syndrome and Multiple Sclerosis

Although many of the methods and tests used to identify RIS and MS overlap, the diagnostic process is notably easier for multiple sclerosis.

Because MS comes with clear — even characteristic — symptoms, doctors can typically make a diagnosis of multiple sclerosis by evaluating a person’s medical history and physical symptoms. They may confirm their conclusions via a brain imaging scan such as MRI, which will identify any brain or spinal cord lesions. Evoked potential tests — which assess how well the CNS responds to stimuli such as visual patterns or electrical impulses — can also be used to gauge whether your nerves are transmitting information at a normal baseline speed.

If a person’s symptoms are unusual or unclear, the doctor may run a panel of blood tests or perform a spinal tap (lumbar puncture) to take a sample of cerebrospinal fluid. A spinal tap isn’t a test for MS, in particular. Instead, physicians use it to rule out infections or other conditions that can cause MS-like symptoms.

Diagnosing RIS can be challenging because the disease is outwardly invisible. Doctors can’t use a person’s clinical symptoms or medical history to make a diagnosis because people with RIS usually don’t have any physical issues or past neurological abnormalities to consider.

In fact, RIS is often discovered when a person with no history of neurological troubles undergoes evaluation after experiencing head trauma or common symptoms like headaches and dizziness.

That said, once doctors realize that the lesions are there, they can take steps to clarify their diagnosis. Because there are no physical signs of RIS, physicians usually need to rely more on magnetic resonance imaging tests. There’s currently a great deal of debate over the diagnostic criteria for RIS in the medical community. Neurologists often need to find very specific signs within imaging scans — such as the presence of blood vessels running through white matter lesions, a sign of MS — to confirm or rule out RIS.

As with MS, a doctor may also draw blood or order a spinal tap to rule out other infections or conditions.

Treatments for RIS and MS

Given that RIS is asymptomatic, treatments for the condition are relatively limited. Generally, doctors will keep an eye out for any signs that a person’s RIS may be transitioning to MS. If such signs appear, they may prescribe MS medications to slow the disease’s progress.

This strategy is consistent with all treatments for MS. Because there is no cure for MS, doctors typically focus on limiting disease progression and shortening relapse periods. There are two primary categories of MS treatments: acute, which can address immediate relapse symptoms, and progression modification, which can slow long-term deterioration.

Acute Treatments for MS

There are several acute treatments for multiple sclerosis, including medications and plasma exchange.

Corticosteroid Medications

For acute treatments, your doctor may recommend a corticosteroid to reduce nerve inflammation. These medications can be taken in a tablet form, as with oral prednisone, or intravenously with Solu-Medrol (methylprednisolone).

Plasma Exchange

If your symptoms are particularly severe or don’t respond to steroids, your physician might suggest undergoing plasma exchange (plasmapheresis). During this procedure, your blood cells are separated from your plasma — the liquid portion of your blood — then remixed with a protein solution and returned to your body. Because plasma often includes defensive proteins, removing and replacing it can help limit the immediate severity of a person’s autoimmune attacks.

Beta Interferons

Beta interferons, which are injected medications, take a similar tack by introducing synthetic interferon proteins into a person’s system. Your body normally produces interferons to reduce inflammation. Beta interferons like Avonex (interferon beta 1a) accomplish the same purpose but are developed in a lab. This treatment can provide short-term relief during relapses.

Progression Modification Treatments for MS

Embarking on an aggressive treatment course soon after a diagnosis of MS may help you limit the long-term severity of your MS symptoms, reduce relapse frequency, and slow lesion formation. However, intensive early treatment can come with significant side effects, so you will need to talk with your doctor about what to expect from your care plan.

Currently, Ocrevus (ocrelizumab) is the only disease-modifying therapy (DMT) approved by the U.S. Food and Drug Administration (FDA) for primary progressive MS. This drug can also help those with relapsing-remitting MS (RRMS), though it is not the only option. Other drugs used to treat RRMS include Lemtrada (alemtuzumab) and Tysabri (natalizumab).

Follow up with your doctor to decide which treatment course is best for you.

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