The path to a diagnosis of multiple sclerosis (MS) can be long and uncertain. For some people, years may elapse between experiencing the first symptoms and receiving a definitive MS diagnosis.

For many people, waiting to see whether the disease flares or progresses after a first episode is an unfortunate aspect of the diagnosis process. A health care provider may initially suspect a person has other conditions — or they may even provide a misdiagnosis. Some people have multiple chronic conditions, making it difficult for neurologists to identify which one is causing MS-like damage.

How Is MS Diagnosed?

MS can be difficult to diagnose. There is no single test that conclusively proves MS. Instead, there are three main criteria, all of which must be present to diagnose the condition:

• Evidence of damage in at least two separate parts of the central nervous system (CNS), which includes the brain, spinal cord, and optic nerves
• Evidence that the CNS damage happened at different times
• Every other possible condition has been ruled out

Some people may be diagnosed with clinically isolated syndrome if they have exhibited symptoms of MS and have damage (also called a lesion), visible through scans, in only one area of their CNS. Those who have a lesion but no MS symptoms may be diagnosed with radiologically isolated syndrome. People diagnosed with clinically isolated syndrome but not MS may be regularly checked for new lesions. They may even be treated with disease-modifying therapy to prevent progression.

About 85 percent of individuals diagnosed with MS are initially diagnosed with relapsing-remitting MS, while the remaining 15 percent are diagnosed with primary progressive MS.

Diagnostic Tests

Some tests can provide proof of damage caused by MS, and others can rule out other conditions.

Medical History

Your doctor will take a thorough history, asking about:

• Symptoms over time
• Family medical history
• Birthplace
• Possible exposures to toxins or infections

A clear picture may emerge from the medical history that will help a doctor assess risk factors that may strengthen the suspicion of MS or rule out other conditions.

Neurological Examination

Your doctor will carefully examine your eyes and reflexes for signs of nerve damage. They’ll ask you to move your arms and legs in specific ways to test for weakness or lack of coordination. The doctor also will test for loss of sensation by touching various parts of your body with a vibrating tuning fork, or sharp or dull items. The neurological exam provides an objective assessment of signs and symptoms that may suggest MS or another condition.

Magnetic Resonance Imaging

Magnetic resonance imaging (MRI) is one of the most valuable tools used in studying MS, and it’s a reliable source of criteria to diagnose MS. MRI uses a strong magnetic field and radio waves to measure the relative water content in the tissues of the CNS. Some types of MRI incorporate an intravenous injection of gadolinium. MRI scans provide the most detailed view of the CNS available with a noninvasive approach.

Undergoing a brain MRI should be painless, but the machine can be very loud. Wear earplugs to protect against ear damage. Be sure to report any metal content in your body — pacemaker devices, vagal nerve stimulators, orthopedic hardware, shrapnel — to the doctor so they can ensure your safety during the procedure.

MRI scans can show the location, extent, and number of lesions on the brain, spinal cord, and optic nerves. Some types of MRI can differentiate between current inflammation, newer, growing lesions, and older sections of permanent damage. MRI can reveal “silent” damage to the CNS that is not causing symptoms.

Most MS diagnoses are based in part on MRI results over time. After a diagnosis of MS is made, most people continue to receive regular scans to track whether (or how quickly) the disease is progressing.

Evoked Potential Test

An evoked potential (EP) test is sometimes conducted as part of the diagnosis process for MS. EP measures electrical activity in the brain in response to specific stimuli.

During an EP test, wires are placed on certain areas of the scalp. The doctor or nurse will then provide stimuli such as light, sound, or physical sensations as the test records brain activity, checking for areas where electrical conduction is slower due to demyelination. EP tests are usually painless.

EP tests can help confirm MS by revealing the extent and location of lesions that do not produce symptoms and may not be detectable by other tests.

Cerebrospinal Fluid Analysis

The CNS is bathed in a liquid called cerebrospinal fluid (CSF). The CSF cushions and protects the brain and spinal cord, circulates nutrients, and removes waste from the CNS. CSF analysis is a useful tool in diagnosing many neurological conditions.

CSF is collected via lumbar puncture, also called a spinal tap. During the procedure, you will be asked to lie on your side with your knees pulled up to your chest to create space between vertebrae. The doctor or nurse will clean an area over the spine in your lower back and insert a hollow needle between two vertebrae into the spinal canal, the space where the spinal cord is located. They will draw out a small amount of CSF, then bandage the puncture site.

A lumbar puncture can be painful. Some people have headaches or backaches after the procedure. You may need to lie down for a while after the lumbar puncture and avoid strenuous activities for the rest of the day.

In most people with MS, CSF analysis will show evidence of elevated levels of IgG antibodies and proteins called oligoclonal bands. In some people with MS, another type of protein created by the breakdown of myelin is also present. Finding these substances indicates an autoimmune disease but is not specifically conclusive for MS.

Ruling Out Other Conditions

Dozens of other conditions can produce MS-like symptoms, and a doctor must rule all of them out to make an accurate diagnosis of MS. The process of ruling out similar conditions is referred to as differential diagnosis. To list just a few, conditions that resemble MS may include:

• Brain tumors
• Nutritional deficiencies
• Demyelinating diseases of the brain or spinal cord such as Guillain-Barré syndrome
• Infections such as Lyme disease, syphilis, and HIV
• Other autoimmune disorders such as lupus or Sjögren’s syndrome
• Inherited conditions such as mitochondrial disease and leukodystrophies

Your neurologist may be able to rule out many of these conditions quickly based on your medical and family history or simple blood tests. Other disorders may require time and repeated tests before they can be confirmed or ruled out. The presence of other diseases in addition to MS may complicate the differential diagnosis and may eventually result in multiple diagnoses.

What Is the Prognosis for MS?

Survival rates for those with MS are improving over time. On average, the lifespan of a person with MS is about seven years shorter than that of other people. Having comorbidities (other health conditions at the same time) such as depression, diabetes, and/or heart disease may increase the risk for death in someone with MS.

There is no cure for MS, but it can be treated. In recent years, the U.S. Food and Drug Administration has approved more than 16 treatment options for MS based on clinical evidence that they can reduce the number and intensity of MS flares and slow the progress of the disease.

MS Condition Guide

• Multiple Sclerosis (MS) — An Overview
• Multiple Sclerosis Types
• Causes of Multiple Sclerosis
• Symptoms of Multiple Sclerosis
• Treatments for Multiple Sclerosis