Abstract
Aim: Insufficient correlation between the findings on conventional MRI and physical disability, the so-called clinical-radiological paradox, complicates the estimation of individual prognosis and therapeutic decisions in patients with MS. The primary goal of our work was to elucidate the role of spinal cord atrophy in the situation of the clinical-radiological paradox.
A secondary objective was to identify predictors of spinal cord volume in healthy individuals. Patients and methods: A total of 2,009 patients with relapsing-remitting and secondary progressive MS and 102 healthy volunteers underwent a 3T MRI examination of the brain and spinal cord with automatic volumetry.
Patients with Expanded Disability Status Scale (EDSS) = 3.5 of the same age, with the same disease duration and identical intracranial lesion volume. Moreover, we identified patients with an unusually high respectively low lesion volume and disproportionally low respectively severe physical disability.
In these groups representing the clinical-radiological paradox, we compared global and regional spinal cord and brain volumes by using parametric and nonparametric tests. We also evaluated the proportion of patients with brain and/or spinal cord atrophy identified by 2 standard deviations from normative values.
Results: 245 patients with EDSS = 3.5 only in the normalized spinal cord volume (P = 0.002) and normalized cerebral white matter volume (P = 0.028). Cerebral white matter was one of the predictors of spinal cord volume in healthy individuals.
Patients with unusually high lesion load and minimal physical disability had lower global and regional brain volumes, however, their normalized spinal cord volumes did not differ from those of non-paradox patients and from patients with a low lesion load and severe disability. The lowest non-normalized (absolute) spinal cord volumes were observed in patients with a low lesion load and severe disability.
Conclusion: Spinal cord volume may explain the discrepancy between intracranial lesion load and physical disability.