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Diagnosis of MS

 

MRI (Magnetic Resonance Imaging)

Much progress has been made over the past 20 years toward making a confirmed diagnosis of multiple sclerosis. Not that long ago, it could take well over a year to get a confirmation. Unfortunately, the disease could progress significantly before any treatment was initiated. Fortunately, as ways to diagnosis MS have made great strides, new therapies have been developed as well.

Several tests have been used over recent years to establish a diagnosis. Some of them, along with their restrictions:

  • X-rays difficult to see lesions, or any structural changes
  • EEG (electroencephalograph) not very reliable in a diagnosis, but can be useful in ruling out MS
  • CT scan (computed tomography) a big advancement over the X-ray, but still unable to detect small lesions
  • Spinal tap useful in detecting abnormalities in spinal fluid. However, some of the same abnormalities may appear in other central nervous system diseases
  • MRI (magnetic resonance imaging) by far, the most useful tool in making a confirmed diagnosis of MS

MRI Structure

Very simply, MRI allows a non-invasive look inside the body. Focused on a particular part of the body (in the case of MS, the brain and spinal cord) it provides the ability to see one wafer-thin "slice" at a time.

MRI example

As the patient lies inside what is essentially a large electromagnet, a highly intense magnetic field is created around the body. As the magnet spins, protons, neutrons and electrons inside the body respond in their unique ways to form an image that is able to detect even the smallest lesions, or areas of demyelination.

Magnetic resonance imaging is important in confirming a diagnosis of MS as well as understanding the dynamics of demyelinating plaque development. So much so, that doctors John W. Rose, Maria Houtchens, and Sharon Lynch report that abnormal MRI scans are found in:

  • 90% of patients with definite diagnosis of MS
  • 70% of patients with diagnosis of probable MS
  • 30% - 50% of patients with possible MS

However, as accurate as an MRI is in confirming a diagnosis of MS, other tests may be needed in a process of elimination to arrive at the appropriate conclusion.

Doctors Rose, Houtchens, and Lynch go on to say, "At present, there are no tests in which an abnormality is specific for MS. Nonetheless, clinical examinations and diagnostic testing, including MRI, lumbar puncture (spinal tap) and evoked potentials are very helpful." The following standard diagnostic criteria are commonly used:

Clinical (Attacks) Objective Lesions Additional requirements to make diagnosis
2 or more 2 or more -None; clinical evidence will suffice (additional evidence desirable but must be consistent with MS)
2 or more 1 -Dissemination in space by MRI
or
positive CSF (spinal tap) and 2 or more MRI lesions consistent with MS
or
further clinical attack involving different site
1 2 or more - Dissemination in time by MRI
or
second clinical attack
1(monosymptomatic) 1 -Dissemination in space by MRI
or
positive CSF (spinal tap) and 2 or more MRI lesions consistent with MS
AND
-Dissemination in time by MRI
or
second clinical attack
0 (progression from onset) 1 -Positive CSF (spinal tap)
AND
-Dissemination in space by MRI evidence of 9 or more T2 brain lesions
or
2 or more cord lesions
or
4-8 brain and 1 cord lesionor positive VEP (Visual Evoked Potentials) with 4-8 MRI lesions
or
positive VEP (Visual Evoked Potentials) with less than 4 brain lesions plus 1 cord lesion
AND
Dissemination in time by MRI or continued progression for 1 year


Mcdonald et al. Recommended Diagnostic criteria for MS. Ann Neurol 2001;50:121-127

Paraclinical Evidence in MS Diagnosis

(2001 The National Multiple Schlerosis Society)

What is a positive MRI?

3 out of 4 of the following:

  • 1 Gd-enhancing lesion or 9 T2 hypertense lesions if no Gd-enhancing lesion
  • 1 or more infratentorial lesions
  • 1 or more juxtacortical lesions
  • 3 or more periventricular lesions

Note: 1 cord lesion can substitute for 1 brain lesion

What Provides MRI Evidence of Dissemination in Time?

  • 1 Gd-enhancing lesion demonstrated in a scan done at least 3 months following onset of clinical attack at a site different from attack

or

  • In absence of Gd-enhancing lesions at a 3 month scan,follow up scan after an additional 3 months showing Gd-lesion or new T2 lesion

What is Positive CSF?

Oligoclonal IgG bands in CSF (and not serum) or elevated IgG index

What is Positive VEP?

Delayed but well-preserved wave form

As technology continues to evolve, it's a matter of when, not if the definitive diagnostic tool is developed. And, as research and development evolve, the goal of conquering MS will become reality.