medwireNews: Researchers believe that, when diagnosing multiple sclerosis (MS), lesions in the symptomatic region should not be excluded, as stated in the McDonald dissemination in space (DIS) criteria.
They found that including any lesion in the symptomatic region increased the sensitivity for diagnosing MS in a sample of 30 patients with a clinically isolated syndrome without comprising specificity.
“The Magnetic Resonance Imaging in Multiple Sclerosis Group has recently recommended revisions to the MRI [magnetic resonance imaging] criteria for DIS to include lesions in the symptomatic region”, notes the team, led by Wallace Brownlee (UCL Institute of Neurology, London, UK).
“This study provides evidence to support that recommendation.”
The researchers applied the McDonald 2010 DIS criteria to baseline MRI scans for 30 individuals aged an average of 31 years with brainstem/cerebellar or spinal cord syndrome and compared the results with those for two modified DIS criteria. The first allowed the inclusion of asymptomatic lesions in the symptomatic region in DIS, while the second allowed the inclusion of any lesion.
MRI showed the presence of at least one T2 hyperintense lesion in the symptomatic region in 77% of patients, 37% of whom had two or more.
All of the DIS criteria had good sensitivity and specificity, but the two modified criteria were more sensitive and more accurate than the McDonald 2010 criteria.
The sensitivity, specificity and accuracy were 73%, 73% and 73%, respectively, for the McDonald 2010 criteria. This compared with corresponding percentages of 80%, 73% and 77% when asymptomatic lesions were included and 87%, 73% and 80% when any lesion in the symptomatic region was included.
The researchers report in Neurology that they would favour modified DIS criteria that included any lesion in the symptomatic region, rather than just asymptomatic ones, “first because the sensitivity was higher and second because the criteria would be easier to apply in a clinical setting.”
The use of DIS criteria, combined with dissemination over a 3-month follow-up period, improved the time it took to diagnose MS.
Based on clinical evidence alone, MS was diagnosed within a mean of 24.9 months, but using McDonald 2010 criteria this was reduced to 8.9 months. Using the modified DIS criteria allowed MS to be diagnosed sooner, but not significantly so, at 6.7 months when asymptomatic lesions were included and 4.8 months with the inclusion of any lesion.
Commenting on the findings in a related editorial, Aaron Miller (Icahn School of Medicine at Mount Sinai, New York, USA) and Daniel Pelletier (University of Southern California, Los Angeles, USA) stress: “Making a diagnosis of MS earlier is advantageous, but being correct is critical.”
They therefore highlight the point made by Brownlee and team that “care should be taken to exclude conditions that mimic MS” and as such the data apply only to patients with clinically isolated syndrome.
By Lucy Piper
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