It can be a challenge for doctors to diagnose multiple sclerosis (MS). There’s no single test that can prove you have it. And many conditions have symptoms that seem like those of MS.
A neurologist -- a doctor who specializes in treating the disease -- should be able to help. They’ll ask how you’re feeling and help you figure out if your symptoms mean you have MS or another problem.
What Do Doctors Look For?
MS can take some time and a number of tests to diagnose. It starts when you or your doctor notices certain signs or symptoms that could be MS. These might include:
- Numbness or tingling in the skin (typically, hands or feet)
- Unusual weakness in arms, legs, or fingers
- Slurred speech
- Stumbling or trouble walking
- Double vision or loss of color
- Flashing lights that others can’t see
- Eye pain that gets worse with movement
When you first notice these symptoms, especially if they are serious, your doctor might need to rule out other causes like stroke, tumor, or pressure on the spinal cord. If the symptoms last more than a couple of days, even if they go away on their own, it may be time to see a neurologist who specializes in MS to speed up diagnosis and start treatment.
If your doctors suspect MS, they will look for further symptoms and signs that suggest MS. To make a final MS diagnosis, they will use several tools to try and do three things:
- Rule out any other conditions that could cause your symptoms
- Find damage to at least two spots on your brain
- Prove the damage happened at different points in time
What Are the Tools for Diagnosis?
The doctor will start by asking you about your medical history and your symptoms. They’ll also do a few tests to see if your brain and spinal cord are working as they should. These include:
But older people or those with high blood pressure and diabetes also can have the same kinds of spots on a brain MRI. So the doctor will consider other info, including your symptoms, along with the scan results or the enhancement of lesions before they make a diagnosis.
Also, an MRI result that says things are normal doesn’t rule out MS. You could be one of a small number of people who have lesions in places the scan can’t show.
Lumbar puncture: This test, which you may also hear called a spinal tap, checks the fluid that runs through your spinal column. Doctors use it to look for high levels of proteins and other substances that are signs of the disease. It can help diagnose MS, but it, too, isn’t absolute proof.
Blood tests: They can’t diagnose MS, but the doctor will use them to look for substances in your blood that point to it. Most importantly, they can help your doctor rule out conditions that look like MS.
Eye exam: An eye exam could reveal problems that MS sometimes causes. Your doctor will test how well you can see detail far away, your field of vision, eye muscle strength, and pressure inside the eyeball, among other things. Possible MS-related conditions might include:
- Optic neuritis: Damage to the optic nerve that often causes pain as well as blind spots surrounded by areas of normal vision
- Nystagmus: Eyes move rhythmically back and forth or up and down without conscious effort. May be due to nerve damage, especially in the brainstem or cerebellum.
- Diplopia: Double vision that happens due to damage to the nerve pathways that control the eyes. It can be an early symptom of MS.
Evoked potential test: If you have unusual symptoms, your doctor may do this to check your nerve function. This test uses electrodes to measure electrical activity in areas of your brain triggered by touch, sound, or light. This might happen while you look at a pattern on a screen, listen to clicking sounds, or get electrical pulses on your body.
What Are the McDonald Criteria?
The McDonald criteria, named for neurologist Ian McDonald, are measures aimed at helping doctors diagnose MS more accurately and quickly. First published in 2001, they’ve been revised several times, according to the latest research.
To diagnose you with MS under these criteria, doctors need evidence that you have damage in more than one distinct part of your nervous system. You also need to have had symptoms typical of MS. These symptoms must have lasted at least 24 hours (not necessarily continuously), at a time when you had no fever or infection.
The evidence must show that this damage happened over time and corresponds to nerves involved in an MS attack. That could mean you’ve had two separate MS attacks at least 30 days apart. But you could be diagnosed after just one episode of symptoms, if an MRI shows you have MS lesions that occurred earlier in a certain area of your brain.
The McDonald criteria take into account:
- Your symptoms
- How many attacks you’ve had
- Results of imaging tests like MRI
- Findings of optical coherence tomography, which examines your retinas
- Results of other tests, like those done on your spinal fluid after a lumbar puncture
Other possible causes of your condition also need to have been ruled out.
After a Diagnosis
It may take a long time to figure out that you have MS. If you’ve been waiting years or months, the news might be a relief. Or it could be a huge shock. Either way, you’ll have concerns about what the disease means for your life and your family. That's completely understandable.
Talk with others -- your friends, your doctor, a support group, or a counselor -- about your feelings. Your health care team can help you decide the best ways to treat your disease and live with it day to day. MS affects everyone differently, so what works for one person with the condition may not be what’s best for you.