Purpose: To investigate the patterns of regional gray matter (GM) and white matter (WM) atrophy, WM microstructural tissue damage, and changes in patients with a clinically isolated syndrome (CIS) suggestive of multiple sclerosis at 2 years from clinical onset.
Materials and methods: Institutional review board approval and written informed consent from all patients were obtained. Neurologic assessment and conventional, diffusion-tensor, and volumetric brain MR imaging sequences were performed in 37 patients with CIS within 2 months of clinical onset, and after 3, 12, and 24 months. Fourteen healthy control subjects also were studied. Longitudinal GM and WM volume changes and WM microstructural abnormalities were assessed by using voxel-based morphometry (P < .001, uncorrected) and tract-based spatial statistics (P < .05, corrected).
Results: At 24 months, 33 of 37 (89%) patients had developed multiple sclerosis. At month 3, patients with CIS showed a transient volume increase in frontal, parietal, temporal, and cerebellar GM regions. At 12 months, patients with CIS developed atrophy of the thalami, caudate nuclei, cerebellum, and frontal, parietal, and temporal lobes. At 24 months GM volume of the frontal, temporal, and parietal cortical areas further decreased from that at 12 months. WM atrophy involved only a few WM regions at 2 months from clinical onset, with progressive involvement of additional WM tracts with time. A diffuse pattern of WM microstructural abnormalities was detected within 2 months of onset and had worsened at 24 months.
Conclusion: After an acute inflammatory event, dynamic modifications of regional GM and WM damage occur in patients with CIS, with a progressive evolution of WM damage from disease onset and a transient, early increase in GM volume, followed by GM atrophy. Neurodegenerative processes start early in patients with multiple sclerosis.