There are four common tests used to help diagnose MS, although there is no definitive test available that can deliver this diagnosis. The medical team, commonly a neurologist will start by ruling out other conditions that could be causing your symptoms, for example, Lyme disease. Typically, MRI, Spinal Fluid Test, Evoked Potentials and a Neurological Exam are the tests used to determine a diagnosis of Multiple Sclerosis. It is in combination, with a heavy reliance on the neurological exam, that a diagnosis can be made. As you can imagine, with a disease as complex as MS, no two people presenting the same, this is a difficult process and the length of time to diagnosis can vary greatly from person to person.

Magnetic Resonance Imaging (MRI)
Magnetic Resonance Imaging (MRI) uses magnetized fields to look at different parts of your body, and in the case of MS, typically your brain and spine. There are open and closed MRI machines, with open machines used for people who tend to have claustrophobia. There is also a contrast dye injected part way through the imaging process, which is used to help show enhancing lesions, or “active” lesions. A brain MRI usually takes about an hour; a spine can be somewhat shorter depending on how much of the spine is being imaged.

While the MRI is a useful tool in assisting the neurologist with a diagnosis, it is important to note that this is a picture of your brain/spine at that moment in time. It is understood that the lesions are constantly changing, but it is one of the more commonly used diagnosis, as well as maintenance tools used by your medical team to assess how you are doing over time. Be sure to ask your doctor to review your results and images with you so that you can become familiar with what they are seeing, where lesions are located in your body, and how they might affect your function.

Spinal Fluid Test (Lumbar Puncture)
A lumbar puncture, or spinal tap, is done in the lower region of your back. A needle is inserted between two lumbar vertebrae to remove a sample of your spinal, or cerebrospinal fluid (CSF). This fluid surrounds your brain and spinal cord to protect them from injury. In MS, when your body is attacking itself, there will be a higher evidence of certain proteins in this spinal fluid. If your CSF doesn’t have these proteins, you still can be diagnosed with MS. 5%-10% of people never show signs of these proteins in their spinal fluid. Realize that these proteins can be present in other inflammatory conditions as well, so a positive result doesn’t automatically mean MS. It is just one of the four diagnostic tools used to complete the total picture for the medical team.
Evoked Potentials
In Multiple Sclerosis, an inflammatory process happens where your body starts attacking itself, damaging nerves in the process. These nerves are attempting to send signals to some part of your body, so when they get injured those signals may slow down, get confused or stop altogether. The Evoked Potentials tests measure the electrical activity in different parts of your brain that may be difficult for you or your medical team to quantify, yet you know through symptoms are going on. These tests involve light, touch and sound.

  • Visual Evoked Potentials (VEP): You sit in front of a screen and watch an alternating checkerboard pattern
  • Sensory Evoked Potentials (SEP) You get short electrical pulses on your arms and/or legs
  • Brainstem Auditory Evoked Potentials (BAEP) You hear a series of clicks in each ear

To do all three of these tests takes about two hours. You will have wires placed in strategic locations around your scalp. As in the MRI and other diagnosis tools, while the evoked potentials can certainly help quantify damage to nerves, they don’t necessarily tell the doctor whether MS is the cause or not. These results will be used in conjunction with all other tests he is performing to gather a total picture.

Neurological Exam
In Multiple Sclerosis, an inflammatory process happens where your body starts attacking itself, damaging nerves in the process. During the neurological exam, the neurologist will be assessing subjective and objective verification of the disease. Symptoms you describe during your discussion with the neurologist would be considered as subjective evidence of MS. Objective signs could be irregular eye movement, stiffness in your arms or legs (spasticity), arm or leg weakness, slow or fast limb reflexes; anything that shows interference with nerve conduction. The neurologist may check your walking to look for pace and balance issues. They may conduct short forms of cognitive assessments to first establish a baseline on your cognitive abilities and then to continue to track how you are doing over time. These usually include memory, recall, processing time, following instructions, etc.

Again, we can’t stress enough, that because there is no one test that can diagnose Multiple Sclerosis, it is the total picture of results of tests, combined with symptoms reported by you, and the experience of your neurologist that will be able to definitively deliver a MS diagnosis. Some happen quickly. Others take time. Patience, trying not to stress over the process, finding a good support system to help you through what you are experiencing, advocating and educating yourself, are all critical components to this journey. Please know that at the MSAV, we are always here to help however we can. Feel free to use the information in the contact us section to get ahold of us for any information and support we might be able to provide.

Timely and accurate diagnosis

There are many possible causes of neurological symptoms. When MS is considered as a potential diagnosis, other causes must be excluded — through the tools and tests outlined below — before an MS diagnosis is considered definitive. While this process of exclusion may be very rapid for some individuals, it can take a much longer time — with repeat testing — for others. Making the diagnosis of MS as quickly and accurately as possible is important for several reasons:

  • People who are living with frightening and uncomfortable symptoms want and need to know the reason for their discomfort. Getting the diagnosis allows them to begin the adjustment process and relieves them of worries about other diseases such as cancer.
  • Since we now know that permanent neurologic damage can occur even in the earliest stages of MS, it is important to confirm the diagnosis so that the appropriate treatment(s) can be initiated as early in the disease process as possible.


At this time, there are no symptoms, physical findings or laboratory tests that can, by themselves, determine if a person has MS. Several strategies are used to determine if a person meets the long-established criteria for a diagnosis of MS, and to rule out other possible causes of whatever symptoms the person is experiencing. These strategies include a careful medical history, a neurologic exam and various tests including magnetic resonance imaging (MRI), evoked potentials (EP) and spinal fluid analysis.

Criteria for a diagnosis of MS

In order to make a diagnosis of MS, the physician must find evidence of damage in at least two separate areas of the central nervous system (CNS), which includes the brain, spinal cord and optic nerves AND find evidence that the damage occurred at least one month apart AND rule out all other possible diagnoses

The Revised McDonald Criteria, published In 2010 by the International Panel on the Diagnosis of Multiple Sclerosis, include specific guidelines for using MRI, visual evoked potentials (VEP) and cerebrospinal fluid analysis to speed the diagnostic process. These tests can be used to look for a second area of damage in a person who has experienced only one attack (also called a relapse or an exacerbation) of MS-like symptoms — referred to as clinically-isolated syndrome (CIS). A person with CIS may or may not go on to develop MS.

Tools for making a diagnosis

The physician performs a variety of tests to evaluate mental, emotional and language functions, movement and coordination, balance, vision, and the other four senses. In many instances, the person’s medical history and neurologic exam provide enough evidence to meet the diagnostic criteria. While there is no definitive blood test for MS, blood tests can rule out other conditions that cause symptoms similar to those of MS, including Lyme disease, a group of diseases known as collagen-vascular diseases, certain rare hereditary disorders, and AIDS. Other tests (described below) are used to confirm the MS diagnosis or provide additional evidence if it’s necessary.

Magnetic Resonance Imaging (MRI)

Diagnostic tool that currently offers the most sensitive non-invasive way of imaging the brain, spinal cord or other areas of the body.

Cerebrospinal Fluid (CSF)

A clear, colorless liquid that bathes the brain and spinal cord. Certain changes in the CSF indicate an abnormal immune response within the central nervous system, which can help diagnose MS and other diseases.

Evoked Potentials (EP)

Tests that measure the electrical activity of the brain in response to stimulation of specific sensory nerve pathways; able to detect the slowing of electrical conduction caused by demyelination.

Other conditions cause demyelination

Although MS is the most common, other conditions can damage myelin in the CNS, including viral infections, side effects from high exposure to certain toxic materials, severe vitamin B12 deficiency, autoimmune conditions that lead to inflammation of blood vessels (the “collagen-vascular diseases”), and some rare hereditary disorders.

Demyelination of the peripheral nervous system (the nerves outside the brain and spinal cord) occurs in Guillain-Barré Syndrome. After some injuries, the myelin sheath in the peripheral nervous system regenerates, bringing recovery of function.

Some demyelinating conditions are self-limiting, while others may be progressive. Careful (and sometimes repetitive) examinations may be needed to establish an exact diagnosis among the possible causes of neurologic symptoms.