(MS), according to new research. Cortical lesions also may be an early marker of future disability accumulation.
In the study, patients who had developed secondary progressive MS after 20 years of follow-up had approximately 7 cortical lesions at baseline. This number was significantly higher than the baseline number of cortical lesions in patients with clinically isolated syndrome (CIS), relapsing-remitting MS, or primary progressive MS at 20 years.
“Our study represented a clear indication that the assessment, presence, and high number of cortical lesions at diagnosis is one of the tools at the disposal of the neurologist for the early identification of patients with more serious disease course,” said Gian Marco Schiavi, MD, a neurology resident at the University of Verona, Italy, during the presentation of his research.
The study was presented October 14 at the annual meeting of the European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS).
Accumulation of disability
Previous research has indicated that cortical lesions play a role in the accumulation of disability in MS and the conversion to secondary progressive MS. Other observations suggest that the number of cortical lesions after 30 years of follow-up explains more than 40% of the difference in disability between patients with secondary progressive MS.
The current investigators sought to understand whether cortical lesions at diagnosis could predict a patient’s risk for development of secondary progressive MS and risk for disability accumulation. They included 220 patients with MS and approximately 20 years of follow-up in their study.
At the time of diagnosis, all participants underwent 1.5-T MRI with double inversion recovery. Participants also presented for periodic MRI and clinical evaluations.
The researchers used analysis of variance to compare the baseline number of cortical lesions between patients with CIS, relapsing-remitting MS, secondary progressive MS, and primary progressive MS at 20 years. They also performed a multivariable regression analysis to predict patients’ final scores on the Expanded Disability Status Scale (EDSS). Variables included participants’ demographic, clinical, and radiological characteristics.
Lesions and disease progression
At baseline (the time of diagnosis), 162 patients had relapsing-remitting MS, 45 had CIS, and 12 had primary progressive MS. In all, 106 patients had no cortical lesions, 47 had 3 or fewer cortical lesions, and 67 had more than 3 cortical lesions.
At 20 years, 12 patients still had CIS, 152 had relapsing-remitting MS, and 44 had developed secondary progressive MS.
The mean number of cortical lesions at diagnosis was 6.6 in patients with secondary progressive MS at 20 years, which was significantly higher than the mean 1.3 cortical lesions in the other patients (P < .001).
In addition, post-hoc analysis showed that the median number of cortical lesions was significantly higher in patients with secondary progressive MS (6), compared with those with CIS (0; P < .001), relapsing-remitting MS (0; P < .001), and primary progressive MS (4.5; P = .013). Patients with primary progressive MS had a higher number of cortical lesions than patients with CIS and those with relapsing-remitting MS (P = .001).
The investigators also examined disability at 20 years. At that timepoint, mean EDSS score was 1.5 in patients with no cortical lesions, 3.0 in patients with 1 to 3 cortical lesions at baseline, and 6.0 in patients with more than 3 cortical lesions.
In a regression analysis, the number of cortical lesions and EDSS at diagnosis were the best predictors of long-term disability (P < .001). These factors explained about 57% of the variance in EDSS score after 20 years.