Regional structural impairments outside lesions are associated with verbal short-term memory deficits in chronic subcortical stroke

Abstract

Background and PurposeWe aimed to explore the neural mechanisms of verbal short-term memory (VSTM) impairment in subcortical stroke by evaluating the contributions of lesion and remote grey matter volume (GMV) reduction.ResultsThere was no significant correlation between lesions and VSTM. In stroke patients with left lesions, GMV reductions in the right middle frontal gyrus and in the left inferior frontal gyrus were positively correlated with VSTM impairment. In patients with right lesions, GMV reduction in the right dorsal posterior cingulate cortex was positively correlated with VSTM impairment.Materials and MethodsNinety-seven patients with chronic subcortical ischemic stroke and seventy-nine healthy controls underwent VSTM and structural MRI examinations. Voxel-based lesion symptom mapping was used to identify correlations between lesions and VSTM. Voxel-wise comparisons were used to identify brain regions with significant GMV reduction in patients with left and right lesions. These regions were used in correlation analyses between GMV and VSTM in each patient subgroup.ConclusionsThese findings suggest that VSTM impairment in subcortical stroke is associated with secondary regional structural damage in non-lesion regions, rather than with the lesion itself. Moreover, different neural substrates may underlie VSTM impairment in stroke patients with left and right lesions.

Structural covariance in subcortical stroke patients measured by automated MRI-based volumetry

“…Accordingly, the volumetric loss of the infratentorial regions may result from the Wallerian degeneration of the distal parts in the nervous systems following the injury of proximal axon or cell body (Yu et al, 2009). These results were in line with previous studies that reported the structural damage in remote regions in subcortical stroke, which was caused by axonal degeneration secondary to the occurrence of stroke lesions (Diao et al, 2017a, Diao et al, 2017b). However, volumetric alterations of infratentorial regions were rarely reported in patients with subcortical stroke.…”

“…In addition, the ratio of additional anatomical connections to missing connections was inverse in CI_L and CI_R groups, with more additional connections in CI_L groups and more missing connections in CI_R group. A previous study reported the right-sided stroke patients presented different cortical gray matter changes compared with left-sided ones (Diao et al, 2017a, Diao et al, 2017b), which also revealed a lesion-side effect, although they did not involve the volumetric changes of subcortical structures. This may also ascribe to the fact that right-handed patients with a left-dominant hemisphere stroke have less ability on daily life basis than those with lesions in the right hemisphere, which leading to faster degeneration of these regions in CI_L patients, as well as, the synergy volume alteration between the regions were more significant.…”

“…For instance, the functional magnetic resonance imaging (MRI) demonstrated altered activation within the motor network and in other functional network and their interaction between the functional networks after subcortical stroke (Wang et al, 2014). The brain morphometric studies based on structural MRI revealed multiregional gray matter volume changes in subcortical stroke patients, not only in brain regions adjacent to stroke lesions but also in the areas remote to lesions during recovery (Anderson et al, 2002; Zhang et al, 2014; Diao et al, 2017a, Diao et al, 2017b). However, the existing morphometric studies mostly focus on cortical gray matter structural changes, and the structural alterations of subcortical regions and infratentorial regions are rarely studied.…”

“…Furthermore, a multitude of neuroimaging studies have shown that the cerebral hemispheric asymmetry (Chiu and Damasio, 1980; LeMay, 1986; Corballis, 2014) may result in different structural reorganization following stroke in the homologous region of the left and right hemispheres, and the lesion-side effect has been found in gray matter volume changes in subcortical stroke patients (Diao et al, 2017a, Diao et al, 2017b). In this case, the analyses in our study were further refined according to the side of the lesions, as it would be also interesting to investigate whether patients with lesions in the left and right hemispheres exhibit similar or different patterns in brain structural damage and volumetric structural covariance.…”

Regional Shape Abnormalities in Thalamus and Verbal Memory Impairment After Subcortical Infarction

“…Our SVR-LSM analysis did not reveal any significant associations between lesion location and verbal memory impairment, which is consistent with previous findings. 38 These results suggest that the lesion itself may not be the critical neural mechanism for verbal memory impairment in the early phase of subcortical stroke in the area of the MCA. We found a significant positive correlation between the change rate of the left-thalamus volume and that of immediate recall, but not that of long-delay recall, in the left-hemisphere stroke patients within 12 weeks after onset.…”