Contralesional macrostructural plasticity of the insular cortex in patients with glioma: A VBM study

Abstract

Objective: To assess the homotopic structural plasticity in case of unilateral damage of the insula.

Methods: To detect changes in gray matter volumes of the contralesional insula from structural MRIs, we used voxel-based morphometry (VBM) in a sample of 84 patients with a diffuse low-grade glioma invading the left insula (insL group; n = 47) or the right insula (insR group; n = 37).

Results: The region of interest-based VBM analysis highlighted a large cluster of voxels with gray matter volume increase in the contralesional insula in both patient groups (k = 2,214 voxels for insL and k = 879 voxels for insR, p < 0.05, family-wise error corrected) compared with 24 age-matched healthy controls. Gray matter volume was increased for the entire insula (t ₆₉ = 3.63, p = 0.0016 for insL; t ₅₉ = 3.54, p = 0.0024 for insR, Bonferroni corrected), whereas no significant changes were found in 2 control regions for both patient groups. Furthermore, an increase of 24.6% and 31.6% in the gray matter volume was observed in the insula-related VBM cluster for insL and insR patients, respectively, compared with healthy controls (t ₆₉ = 7.39, p = 2.59 × 10^-10 and t ₅₉ = 7.51, p = 3.61 × 10^-10).

Conclusions: The reported results demonstrate that slow-growing but massive lesion infiltration of the insula induces marked increase of gray matter volume in the contralateral one. Our findings give support for a homotopic reorganization that might be a physiologic basis for the high level of functional compensation observed in patients with glioma.