Radiologically Isolated Syndrome (RIS)
Overview
The availability of magnetic resonance imaging (MRI) has led to an increase in the detection of abnormal brain findings even in cases when there are no outward symptoms. When these findings are similar to what is seen in patients with multiple sclerosis (MS), but the patient is not experiencing any of the typical physical or neurological symptoms associated with MS, this is known as radiologically isolated syndrome (RIS).
Although there is a strong association between RIS and MS, being diagnosed with RIS does not mean a patient will always be diagnosed with MS.
MS is a disease of the central nervous system (brain, spinal cord and optic nerve). This disorder causes destruction of the coating (myelin) that surrounds and protects nerve fibers (axons). As a result, the damage disrupts the normal flow of messages (nerve impulses) from the central nervous system (CNS), causing a reduction or loss of body function. In many cases, the nerve fibers (axons) are also destroyed.
Symptoms
Patients with RIS generally do not experience symptoms (asymptomatic).
Causes and Risk Factors
When followed over a two year period, one third of patients with RIS develop a neurological event and are diagnosed with MS, one third develop a new finding on MRI without any symptoms, and one third show no change.
Since the risk of multiple sclerosis is significantly higher when a parent has been diagnosed with the disease, genetic factors may play a role. The unusual relationship between a person's geographic location during childhood and the risk of multiple sclerosis later in life suggests that there may be environmental factors at work in the disease.
Diagnosis
Diagnosis of RIS often occurs during diagnosis of another unrelated condition, such as migraine headaches or trauma to the area.
After a brain abnormality is observed on an MRI, the physician will typically take a detailed medical history and perform a neurological examination. Because RIS is often asymptomatic, accurately diagnosing the condition can be difficult. Newer imaging methods that allow the medical team to see if blood vessels are running through the lesions, a distinguishing feature of multiple sclerosis, can help in making a more accurate diagnosis.
The patient's medical team may also order a lumbar puncture, also known as a spinal tap, and cerebrospinal fluid analysis, as well as nerve function tests. Blood tests may be performed to rule out other conditions that have similar symptoms.
Patients diagnosed with RIS will have routine checkups to see if their condition is progressing toward multiple sclerosis.
Treatment
There is no cure for RIS and depending on the patient's history, MRI results and condition, observation may be the only treatment necessary.
If the physician observes changes in the patient's MRIs that more closely resemble multiple sclerosis over time, medications may be used in an effort to slow the progression of the condition and reduce the damage it may cause.
Other medications may address specific symptoms such as:
- Depression
- Muscle spasms
- Need for frequent urination
- Erectile dysfunction
Choosing the right medication requires careful consideration of the risks and benefits, along with close collaboration with an experienced neurologist with experience in treating the disease, such as those in the Multiple Sclerosis Center at the Cedars-Sinai's Department of Neurology.
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