How is multiple sclerosis diagnosed?

There is no single diagnostic test that is proof-positive for multiple sclerosis (MS). There is a set of accepted criteria for MS diagnosis, but even this system is imperfect. Since diagnosing MS can be very difficult, it must be done by a neurologist who specializes in treating MS. As many as 10 percent of people diagnosed with multiple sclerosis actually have some other condition that mimics MS.

Examples of other conditions that masquerade as MS include inflammation in the blood vessels, multiple strokes, vitamin deficiency, and brain infection. Sometimes stress-related disorders can lead to a misdiagnosis of MS.

An accurate diagnosis of MS is based on your medical history and neurological examination using tests of nervous system function. Much depends on the skill of the doctor in asking the right questions to uncover information and to properly evaluate the signs and symptoms of a malfunctioning nervous system.

In addition to a thorough medical history and neurological examination, a variety of specialized procedures are helpful — although not always necessary — in accurately diagnosing MS. These include imaging techniques such as magnetic resonance imaging (MRI), spinal taps (examination of the cerebrospinal fluid that runs through the spinal column), evoked potentials (electrical tests to determine if MS affects nerve pathways), and laboratory analysis of blood samples.

What are the accepted criteria for a diagnosis of multiple sclerosis?

  • Onset usually between 10 and 60 years of age
  • Symptoms and signs indicating lesions of central nervous system white matter
  • Evidence of two or more lesions upon examination by MRI scan (see below)
  • Objective evidence of central nervous system disease on neurological examination
  • A course following one of two patterns: two or more episodes lasting at least 24 hours and occurring at least one month apart, or a progressive course of signs and symptoms over at least six months
  • No other explanation for the symptoms

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