New and enlarging white matter lesions adjacent to the ventricle system and thalamic atrophy are independently associated with lateral ventricular enlargement in multiple sclerosis

Objective To investigate the association between new or enlarging T2-weighted ( w ) white matter (WM) lesions adjacent to the ventricle wall, deep grey matter (DGM) atrophy and lateral ventricular enlargement in multiple sclerosis (MS). Methods Patients derived from the Genetic Multiple Sclerosis Associations study. Lateral ventricles and DGM were segmented fully automated at baseline and 5 years follow-up using Automatic Lateral Ventricle delineation (ALVIN) and Multiple Automatically Generated Templates brain segmentation algorithm (MAgeT), respectively. T2w and T1w lesions were manually segmented. To investigate the association between lesion distance to the ventricle wall and the lateral ventricle volume, we parcellated the WM into concentric periventricular bands using FMRIB Software Library. Associations between clinical and MRI parameters were assessed in generalized linear models using generalized estimating equations for repeated measures. Results We studied 127 MS patients. Lateral ventricles enlarged on average by 2.4%/year. Patients with new/enlarging T2w WM lesions between baseline and follow-up at 5 years had accelerated lateral ventricular enlargement compared with patients without ( p = 0.004). This was true in a multivariable analysis adjusted for age, gender, and whole brain atrophy. When looking at the T2w lesions in different periventricular bands, we found the strongest association between new/enlarging T2w lesions and lateral ventricle enlargement for WM lesions adjacent to the ventricle system ( p < 0.001). Moreover, and indepedent of new/enlarging WM lesions, DGM atrophy was associated with ventricular enlargement. In a multivariable analysis, this was driven by thalamic atrophy ( p < 0.001). Conclusion New/enlarging T2w lesions adjacent to the ventricle system and thalamic atrophy are independently associated with lateral ventricular enlargement in MS.