Secondary Degeneration of White Matter Tract following Basal Ganglia Infarction: A Longitudinal Diffusion Tensor Imaging Study

Introduction: We explored the relationship between secondary degeneration of white matter (WM) tracts and motor outcomes after left basal ganglia infarction and investigated alterations in the diffusion indices of WM tracts in distal areas.Methods: Clinical neurological evaluations were accomplished using the Fugl-Meyer scale (FMS). Then, the fractional anisotropy (FA) of the bilateral superior corona radiata (SCR), cerebral peduncle (CP), corticospinal tracts (CST), and corpus callosum (CC) were measured in all patients and control subjects.Results: Regional-based analysis revealed decreased FA values in the ipsilesional SCR, CP, and CST of the patients, compared to the control subjects at 5-time points. The relative FA (rFA) values of the SCR, CP, and CST decreased progressively with time, the lowest values recorded at 90 days before increasing slightly at 180 days after stroke. Compared to the contralateral areas, the FA values of the ipsilesional SCR and CST areas were significantly decreased (P=0.023), while those of the CP decreased at 180 days (P=0.008). Compared with the values at 7 days, the rFA values of the ipsilesional SCR and CP areas were significantly reduced at 14, 30, and 90 days, while those in the CST area were significantly reduced at 14, 90, and 180 days. The CP rFA value at 7 days correlated positively with the FM scores at 180 days (r=0.469, P=0.037).Conclusion: This study provides an objective, comprehensive, and automated protocol for detecting secondary degeneration of WM, which is important in understanding rehabilitation mechanisms after stroke.