What is multiple sclerosis?
Multiple sclerosis (MS) is a chronic, progressive autoimmune condition that affects the central nervous system. MS occurs when the immune system attacks the myelin that protects the nerve fibers in the spinal cord and brain. This is known as demyelination, and it causes communication difficulty between the nerves and the brain. Eventually it can result in damage to the nerves.
The cause of multiple sclerosis is currently unknown. It’s thought that genetic and environmental factors can play a role. There’s currently no cure for MS, though there are treatments that can reduce symptoms.
Multiple sclerosis can be difficult to diagnosis; there is no single test that can diagnose it. Instead, a diagnosis typically requires multiple tests to rule out other conditions with similar symptoms. After your doctor conducts a physical examination, they’ll likely order several different tests if they suspect you may have MS.
Blood tests are likely the first test that your doctor will order. Blood tests can’t currently result in a firm diagnosis of MS, but they can rule out other conditions. These conditions include:
All of these disorders can be diagnosed with bloodwork alone. Blood tests can also reveal abnormal results. This can lead toward diagnoses such as cancer or a vitamin B-12 deficiency.
Magnetic resonance imaging
Magnetic resonance imaging (MRI) is one of the most-used tools when it comes to diagnosing MS. MRIs use radio waves and magnetic fields to evaluate the relative water content in tissues of the body. They can detect normal and abnormal tissues and can spot irregularities.
MRIs offer detailed and sensitive images of the brain and spinal cord. It is much less invasive than X-rays or CT scans, which both use radiation.
Doctors will be looking for two things when they order an MRI with a suspected diagnosis of MS. The first is that they’ll check for any other abnormalities that could rule out MS and point to a different diagnosis, such as a brain tumor. They’ll also look for evidence of demyelination.
The layer of myelin that protects the nerve fibers is fatty and repels water when it’s undamaged. If the myelin has been damaged, however, this fat content is reduced or stripped away entirely and no longer repels water. The area will hold more water as a result, which can be detected by MRIs.
To diagnose MS, doctors must find evidence of demyelination. In addition to ruling out other potential conditions, an MRI can provide solid evidence that demyelination has occurred.
Before you go in for your MRI, remove all jewelry. If you have any metal on your clothes (including zippers or bra hooks), you’ll be asked to change into a hospital gown. You’ll lie still inside the MRI machine (which is open on both ends) for the duration of the procedure, which takes between 45 minutes and 1 hour. Let your doctor and technician know ahead of time if you have:
- metallic implants
- implanted drug infusions
- artificial heart valves
- history of diabetes
- any other conditions that you think could be relevant
Lumbar puncture, also called a spinal tap, is sometimes used in the process of diagnosing MS. This procedure will remove a sample of the cerebrospinal fluid (CSF) for testing. Lumbar punctures are considered invasive. During the procedure, a needle is inserted into the lower back, between vertebrae, and into the spinal canal. This hollow needle will collect the sample of CSF for testing.
A spinal tap typically takes about 30 minutes, and you will be given a local anesthetic. The patient is typically asked to lay on their side with their spine curved. After the area has been cleaned and a local anesthetic has been administered, a doctor will inject the hollow needle into the spinal canal to withdraw one to two tablespoons of CSF. Usually, there is no special preparation. You may be asked to stop taking blood thinners.
Doctors who order lumbar punctures during the process of an MS diagnosis will use the test to rule out conditions with similar symptoms. They will also look for signs of MS, specifically:
- elevated levels of antibodies called IgG antibodies
- proteins called oligoclonal bands
- an unusually high amount of white blood cells
The number of white blood cells in the spinal fluid of people with MS can be up to seven times higher than normal. However, these abnormal immune responses can also be caused by other conditions.
It’s also estimated that 5 to 10 percent of people with MS do not show any abnormalities in their CSF.
Evoked potential test
Evoked potential (EP) tests measure the electrical activity in the brain that occurs in response to stimulation, such as sound, touch, or sight. Each type of stimuli will evoke minute electrical signals, which can be measured by the electrodes placed on the scalp to monitor activity in certain areas of the brain. There are three types of EP tests. The visual evoked response (VER or VEP) is the one most commonly used to diagnose MS.
When doctors order an EP test, they’re going to look for impaired transmission that is present along the optic nerve pathways. This typically happens fairly early in most MS patients.
No preparation is necessary to take an EP test. During the test, you’ll sit in front of a screen that has an alternating checkerboard pattern on it. You may be asked to cover one eye at a time. It does require active concentration, but it’s safe and noninvasive. If you wear glasses, ask your doctor ahead of time if you should bring them.
New tests under development
Medical knowledge is always advancing. As technology and our knowledge of MS moves forward, doctors may find new tests to make the MS diagnosis process an easier one.
A blood test is currently being developed that will be able to detect biomarkers that are associated with MS. While this test likely won’t be able to diagnose MS on its own, it can help doctors evaluate risk factors and make diagnosis just a little easier.
What is the outlook for MS?
Currently, it’s difficult to diagnose MS. Using a number of tests to rule out other conditions is the only way to arrive at a diagnosis. In some cases, doctors may be able to diagnose people with a physical examination, a look at their medical history, and an MRI. Other people may need to go through all of the tests above in order to arrive at a diagnosis.
If you’re experiencing symptoms that resemble MS, make an appointment with your doctor. The sooner you get diagnosed, the sooner you can get treatment, which can help to alleviate troublesome symptoms.