How is multiple sclerosis diagnosed?

Diana Meeks
Diana Meeks on behalf of Sigma Nursing
Family Practitioner

Unfortunately, there is no definite way to test for multiple sclerosis (MS). Oftentimes, patients undergo multiple tests and appointments before a diagnosis. Doctors must first conclude that your symptoms are not the result of some other condition or disease. Then, they check for damage in more than one section of the nervous system and determine if this damage took place at least 30 days apart before diagnosing MS. Common procedures include:

  • blood and spinal fluid tests to make sure your symptoms are not the result of an infection;
  • MRIs that provide pictures of your organs that doctors can use to look for myelin damage;
  • evoked potential tests that send electrical signals through your body to see if the signal travels as planned or becomes altered.

Diagnosing multiple sclerosis (MS) involves several tests and a lot of discussions with several types of health care professionals. There are no symptoms, physical findings or tests that alone can definitively show that a person has MS. Instead, doctors use several strategies, including a medical history, neurologic exam, tests such as visual evoked potentials (VEPs) and spinal taps and imaging tests such as magnetic resonance imaging (MRI), to make a diagnosis.

For a diagnosis of MS, a health care professional must:

  • discover evidence of damage in at least two separate areas of the central nervous system (CNS), including the brain, spinal cord and optic nerves AND
  • find evidence that the damages occurred at least one month apart AND
  • be able to rule out all other possible diagnoses

Early diagnosis of MS is important because a new generation of treatments introduced in the 1990s can reduce the frequency and severity of MS attacks. In fact, research has prompted health care professionals to change the diagnostic criteria to treat more cases of MS as early as possible.

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The diagnosis of multiple sclerosis (MS) is a clinical one as there is not a diagnostic test to verify or exclude the diagnosis. This can be frustrating for people in whom the diagnosis is initially ambiguous. Classically, a diagnosis of MS is made based on clinical attacks disseminated in time and space, with the caveat that an alternative explanation for the neurological symptoms is not found. Magnetic resonance imaging (MRI) is often supportive of the diagnosis, and the McDonald criteria (last revised in 2010) allow the diagnosis to be made in a person who has had one clinical attack and MRI findings suggestive of MS. Supporting tests may include a spinal tap or visual evoked potentials.

Dr. Louis Rosner

Neurologists analyze information in two stages. First they discern where the problem is. Then they must consider what all the causes of disease are in that location. When several locations are involved, the list of possible diagnoses narrows.

To diagnose multiple sclerosis, the neurological evaluation must satisfy two clinical criteria: first, a course of attacks and remissions, and second, findings (either from the neurological examination or the patient's history) that suggest lesions in at least two of the main sites of the central nervous system - spinal cord, brain stem-cerebellum, optic nerve, or cerebrum.

The success of a diagnosis is, of course, highly dependent on the doctor's skill in observing and soliciting an accurate description of history and symptoms. The history begins with the present illness - when and how did it start? It's important to discuss each symptom - if it disappeared and when, if it still persists, if symptoms vary during the day, if it's constant or intermittent, what provides relief, if it's affected by heat from exercise or a hot bath, and so on. Then the patient's past history must be carefully reviewed, taking in any illnesses, injuries, operations, allergies, medications, pregnancies, or alcohol or drug abuse. The neurologist might also take a history from a parent, husband, wife, or other close family member. The family history will include serious medical problems, causes of death, and any other neurological disorders in parents, brothers, sisters, and children. The visit to the neurologist, including the history taking and neurological examination can take up to two hours. (It should be remembered that the neurologist may also suspect a stroke, a tumor, an adverse reaction to medication, or some other problem.)

Multiple Sclerosis

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Multiple Sclerosis

Too often, multiple sclerosis is thought of only as "the crippler of young adults." But in fact, 75 percent of all people with MS will never need a wheelchair. In Multiple Sclerosis, Dr. Louis J....

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.