How is multiple sclerosis (MS) diagnosed?

Updated: Mar 27, 2019
  • Author: James A Wilson, MD, MSc, FRCPC; Chief Editor: James G Smirniotopoulos, MD  more...
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A diagnosis of MS is made on the basis of clinical findings by using supporting evidence from ancillary tests such as CSF examination for oligoclonal banding and MRI. [9, 10]

Clinically, MS has historically been diagnosed via the demonstration of white matter dysfunction disseminated in time and space. [11] With the advent of diagnostic laboratory investigations and imaging techniques, the Poser criteria were proposed to establish a degree of certainty of diagnosis in the absence of the 2 clinical attacks by using terms such as possible MS and probable MS. [12]

With increasing treatment options for MS and better imaging techniques, newer diagnostic criteria have been suggested that allow diagnosis after a single attack coupled with appropriate positive test results. These criteria have been coined the MacDonald criteria. [13]   [14]  Essentially, they allow for the second attack in time to be defined by a new lesion appearing on MRI. Also, the MacDonald criteria allow the dissemination in space to be established on the basis of either 9 typical white matter lesions on MRI or 1 enhancing lesion. If CSF studies show increased IgG values or oligoclonal banding, the presence of only 2 typical MRI lesions satisfy the dissemination-in-time criteria.

The new McDonald criteria include the following [9, 13, 14, 15] :

  • In a patient with a typical clinically isolated syndrome and fulfilment of clinical or MRI criteria for dissemination in space and no better explanation for the clinical presentation, demonstration of CSF-specific oligoclonal bands in the absence of other CSF findings atypical of multiple sclerosis allows a diagnosis to be made.
  • Symptomatic and asymptomatic MRI lesions can be considered in the determination of dissemination in space or time. MRI lesions in the optic nerve in a patient presenting with optic neuritis remain an exception and, owing to insufficient evidence, cannot be used in fulfilling the McDonald criteria. 
  • Cortical and juxtacortical lesions can be used in fulfilling MRI criteria for dissemination in space.
  • At the time of diagnosis, a provisional disease course should be specified (relapsing-remitting, primary progressive, or secondary progressive) and whether the course is active or not, and progressive or not based on the previous year's history. The phenotype should be periodically re-evaluated based on accumulated information.

With respect to the initial clinical presentation in MS, it may vary with the white matter tract involved, and it may include somatic sensory changes, optic neuritis, or weakness. After only a single attack, the diagnosis of MS is suggested if the first impairment is coupled with positive paraclinical test results, such as those on imaging or CSF studies. Furthermore, the attack must be compatible with the pattern of impairment found in patients with MS, which typically means that the duration of deficit is days to weeks. Worsening of vision due to optic neuritis and subsequent exercise is known as the Uhthoff phenomenon.

Stankiewicz et al correlated brain lesions and clinical status with 1.5T and 3T MRI in 32 patients with MS by use of MRI fluid-attenuated inversion-recovery (FLAIR) sequences, and the authors found that MRI at 3T may provide increased sensitivity and validity in assessment of MS brain lesions. The study showed that FLAIR lesion volume (FLLV) at 3T was higher than at 1.5T. While 3T FLLV correlated moderately and significantly, 1.5T FLLV correlated poorly. When controlling for age and depression, correlations between FLLV and cognitive measures were significant at 1.5T for the Judgment of Line Orientation Test, the Symbol Digit Modalities Test, and the California Verbal Learning Test Delayed Free Recall, but at 3T, correlations were significant and of greater magnitude. [16]

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