Correlation Between MRI Findings and Disability in Multiple Sclerosis
Brex PA, Ciccarelli O, O’Riordan JI, et al. NEJM. 2002;346:158–164
Prior to this study, it was well recognized that in patients who develop isolated syndromes suggestive of MS, such as optic neuritis or brainstem or spinal cord syndromes, the presence of T2-weighted lesions on MRI of the brain increases the likelihood of developing MS. However, the correlation between these T2 lesions and long-term disability was unknown prior to this prospective study.
To determine the relation between early lesion volume, changes in volume, and long-term disability in patients with isolated syndromes that are clinically suggestive of MS.
Prospective cohort study of patients presenting between 1984 and 1987.
71 patients in a serial MRI study of patients with isolated syndromes were reassessed after a mean of 14.1 years. Disability was measured with the use of Kurtzke’s Expanded Disability Status Scale (EDSS; possible range, 0 to 10, with a higher score indicating a greater degree of diability).
MRI data were available for assessments at base line and at 5, 10, and 14 years. Imaging was performed on a 0.5-T scanner at baseline and 5 years and on a 1.5-T scanner at 10 and 14 years.
Outcomes assessed include degree of disability and changes in MRI findings.
- Clinically definite MS developed in 44 out of 50 patients (88%) with abnormal results on MRI at presentation and in 4 of 21 patients (19%) with normal results on MRI.
- The median EDSS score at follow-up for those with MS was 3.25 (range, 0 to 10); 31% had an EDSS score of 6 or more (including three patients whose deaths were due to MS).
- Patients with worse clinical outcomes had larger numbers and volumes of lesions on MRI at baseline and larger increases in lesion volume over time.
- The EDSS score at 14 years correlated moderately with lesion volume on MRI at 5 years (r = 0.60) and with the increase in lesion volume over the first 5 years (r = 0.61).
This study showed that the EDSS score at 14 years correlated significantly with lesion volumes on MRI at all of the earlier time points, indicating that the lesion volume at any time contributes to the development of later disability. This study is an important natural history study. It is unlikely that a similar study could be done now given the wide array of disease modifying treatments (DMTs) which reduce MRI lesions over time. The study suggests that the number of lesions and the lesion volume on MRI in patients with early MS are moderately predictive of long-term disability. Given only moderate correlation, the authors point out that MRI lesion volume alone should not be used as the sole determinant when deciding about DMTs. However, this data help support the trend toward early use of DMT in patients with lesion accumulation/expansion, suggestive of MS. One important weaknesses of this study is the change in MRI technology over time. However, authors note that the degree of volume change seen in lesions was large enough to not be missed significantly on earlier scans. Overall, this study suggests that lesion volume on MRI is of prognostic value in assessing the risk of future disability.