# Gray Matter Volumetry and Cognitive Functioning in Pediatric Posterior Fossa Tumor Survivors

## TL;DR

This study finds that children who survived posterior fossa brain tumors show reduced gray matter volume and lower cognitive abilities, especially if they received radiation therapy.

## Contribution

The study identifies specific brain regions affected by radiation therapy and links reduced gray matter volume to impaired working memory in tumor survivors.

## Key findings

- Survivors with radiation therapy had reduced gray matter volume in the thalami and diencephalon.
- Lower gray matter volume was associated with poorer working memory performance in survivors.
- Craniospinal radiation caused the most pronounced gray matter volume deviations.

## Abstract

Children who survive a posterior fossa tumor often require radiation therapy, which can be lifesaving but may also damage developing brain tissue. This treatment, along with the tumor and other therapies, can affect cognitive abilities such as memory, language, and attention. This study investigated whether survivors show differences in gray matter volumes and how these differences relate to cognitive abilities. By comparing anatomical magnetic resonance images and cognitive test scores from survivors with and without radiation therapy to controls, we identified specific brain regions with lower gray matter volume, particularly in survivors who received radiation therapy. Survivors also showed lower cognitive ability, and lower gray matter volume was related to lower working memory. These findings highlight the long-term impact of a brain tumor and its treatment on survivors and may help guide future clinical strategies to improve long-term outcomes.

Background/Objectives: Posterior fossa tumors (PFTs) often require radiotherapy which may damage both cortical and subcortical brain tissue. We examined voxel-based and region-based gray matter volume (GMV) alterations and explored their relation to cognitive functioning. Methods: Using T1-weighted MR imaging, intelligence scores from the Wechsler Adult Intelligence Scale-IV (WAIS-IV), and domain scores for language, learning, and memory, complex attention and cognitive flexibility were investigated in 18 of 21 assessed PFT survivors and 21 matched controls. GMV was quantified with voxel-based and region-based volumetry, compared among groups (controls versus survivors, irradiated versus non-irradiated survivors), and correlated with cognitive performance. Results: Survivors showed reduced GMV in two voxel-based clusters, located in the left occipital fusiform area and the left pallidum. Region-based analyses showed lower GMV in survivors located in subcortical areas, while higher GMV was observed in the left inferior temporal region. Survivors who received craniospinal radiation exhibited reductions in GMV in bilateral thalami, right ventral diencephalon, and central corpus callosum, and higher GMV in the bilateral middle temporal regions. Compared to controls, survivors scored lower for all cognitive domains, except for complex attention and cognitive flexibility. Amongst survivors, the GMV of the bilateral thalami and right ventral diencephalon correlated positively with working memory. Conclusions: Overall, PFT survivors demonstrated both alterations in GMV and cognitive functioning, with the most pronounced GMV deviations found in those treated with craniospinal radiation. Reduced GMV was associated with poorer cognitive performance.