The Impacts of Tumor and Tumor Associated Epilepsy on Subcortical Brain Structures and Long Distance Connectivity in Patients With Low Grade Glioma

Abstract

Low grade gliomas in cerebral cortex often cause symptoms related to higher cerebral functions such as attention, memory and executive function before treatment is initiated. Interestingly, focal tumors residing in one cortical region can lead to a diverse range of symptoms, indicating that the impact of a tumor is extended to multiple brain regions. We hypothesize that the presence of focal glioma in the cerebral cortex leads to alterations of distant subcortical areas and essential white matter tracts. In this study, we analyzed diffusion tensor imaging scans in glioma patients to study the effect of glioma on subcortical gray matter nuclei and long-distance connectivity. We found that the caudate nucleus, putamen and thalamus were affected by cortical glioma, displaying both volumetric and diffusion alterations. The cerebellar cortex contralateral to the tumor side also showed significant volume decrease. Additionally, tractography of the cortico-striatal and cortico-thalamic projections shows similar diffusion alterations. Tumor associated epilepsy might be an important contributing factor to the found alterations. Our findings indeed confirm concurrent structural and connectivity abrasions of brain areas distant from brain tumor, and provide insights into the pathogenesis of diverse neurological symptoms in glioma patients.

Restructuring of contralateral gray matter volume associated with cognition in patients with unilateral temporal lobe glioma before and after surgery

“…Indeed, structural changes in the regions distant from brain tumor have also been confirmed by some studies (Almairac et al, ; Bouwen et al, ). These structural changes have been correlated with cognition decline (Bouwen et al, ), though cognitive functions are not always caused by the alternation in the brain, sometimes the cognitive function recovers over time (Voytek et al, ), which may be attributed to the brain plasticity. Therefore, by exploring the structural alterations contributing to the integrity of cognitive function, may help to improve the preoperative plan and may result in the development of more rational strategie7s to facilitate neurorehabilitation of patients with glioma.…”

“…Some studies have suggested that localized tumors can affect the function of distant part of the brain (Liu et al, 2019;Park, Kim, Kim, Kim, & Shim, 2015;Zhang et al, 2016). Indeed, structural changes in the regions distant from brain tumor have also been confirmed by some studies (Almairac et al, 2018;Bouwen et al, 2018). These structural changes have been correlated with cognition decline (Bouwen et al, 2018), though cognitive functions are not always caused by the alternation in the brain, sometimes the cognitive function recovers over time (Voytek et al, 2010), which may be attributed to the brain plasticity.…”

“…Therefore, the present study was initiated to investigate the alteration in contralateral GM volume before and after surgery, and the relationship between the alterations in contralateral GM volume with cognitive function in unilateral temporal lobe glioma patients. We hypothesized that contralateral GM volume compensates for damaged glioma and the compensatory brain structure may be a structural basis of cognitive function compensation (Almairac et al, ; Bouwen et al, ; Duffau, ; Duffau, ).…”

“…And the VBM method does not favor a particular structure but can assess anatomical differences across the whole brain (Matsuda, 2016). This method has been successfully used to detect structural changes of cerebral GM and WM in patients with Alzheimer's disease, acute focal cerebral infarction and depression (Ashburner & Friston, 2000;Dang et al, 2013;Liu et al, 2014;Matsuda, 2016). Furthermore, Almairac et al found that patients with unilateral insular low-grade glioma exhibited noticeable increase in GM volume only in the contralateral insular lobe (Almairac et al, 2018), indicating a plastic compensatory mechanism in the distant brain regions.…”

“…We hypothesized that contralateral GM volume compensates for damaged glioma and the compensatory brain structure may be a structural basis of cognitive function compensation (Almairac et al, 2018;Bouwen et al, 2018;Duffau, 2005;Duffau, 2006…”