Normal-appearing white matter structural integrity in incidentally discovered low-grade gliomas: a single institution study.

Abstract

Incidentally discovered low-grade gliomas (iLGGs) are poorly reported in the literature and little is still known about their effects on white-matter structure. In this study, we investigated whether iLLG growth in either hemisphere could affect main white-matter association tracts and cortico-spinal tract. We retrospectively analyzed white-matter integrity in a group of 18 patients with iLGG having a mostly preserved cognitive status [1]. We identified two groups of patients, 13 having iLGG in left hemisphere (LH) and five in right hemisphere (RH) and maximum lesion overlap in inferior frontal gyrus and in medial frontal areas, respectively. A group of healthy controls (N.=20) was included. We carried out a univariate analysis of variance to inspect potential effect of interaction between hemisphere harboring the lesion (i.e., LH or RH) and hemisphere taken into account on number of streamlines and fractional anisotropy (FA) of reconstructed white-matter tracts. The sole significant interaction concerned left arcuate fasciculus, with patients with iLGG in LH having a lower number of streamlines than healthy controls; interaction involving FA was not significant for any of the fascicles. Lack of any other significant findings indicates overall preserved white matter. iLGG size and growth pattern could explain why white-matter status did not markedly differ with respect to the healthy controls. Findings therefore support evidence that iLGGs represent the earlier phase in natural history of LGGs and are discussed in a clinical perspective and in support to safe early surgery.