Dynamic volumetric changes of hippocampal subfields in clinically isolated syndrome patients: A 2-year MRI study.

BACKGROUND

Different subregional patterns of hippocampal involvement have been observed in diverse multiple sclerosis (MS) phenotypes.

OBJECTIVE

To evaluate the occurrence of regional hippocampal variations in clinically isolated syndrome (CIS) patients, their relationships with focal white matter (WM) lesions, and their prognostic implications.

METHODS

Brain dual-echo and three-dimensional (3D) T1-weighted scans were acquired from 14 healthy controls and 36 CIS patients within 2 months from clinical onset and after 3, 12, and 24 months. Radial distance distribution was assessed using 3D parametric surface mesh models. A cognitive screening was also performed.

RESULTS

Patients showed clusters of reduced radial distance in the Cornu Ammonis 1 from month 3, progressively extending to the subiculum, negatively correlated with ipsilateral T2 and T1 lesion volume. Increased radial distance appeared in the right dentate gyrus after 3 ( < 0.05), 12, and 24 ( < 0.001) months, and in the left one after 3 and 24 months ( < 0.001), positively correlated with lesional measures. Hippocampal volume variations were more pronounced in patients converting to MS after 24 months and did not correlate with cognitive performance.

CONCLUSION

Regional hippocampal changes occur in CIS, are more pronounced in patients converting to MS, and are modulated by focal WM lesions.