LAUSR

The hippocampus is known to remodel in pathologic conditions including epilepsy and Alzheimer’s disease. Literature investigating the effect of high-grade gliomas (HGGs) on the hippocampus following resection and adjuvant chemoradiation are limited; no study has evaluated these effects in tumors exclusively in the temporal lobe. A retrospective chart review was conducted on 30 patients with temporal HGGs who underwent craniotomy for resection with adjuvant RT and TMZ. Brainlab Elements was used to manually contour bilateral hippocampal gray matter volumes in the subgranular zone using T1-precontrast MRI sequences (1.5 mm thickness or less) pre-resection and at time of most recent follow up. These volumes were compared using a student’s t-test with significance set at p< 0.05. Average follow up time was 23.5 months from initial resection. Average pre-treatment hippocampal volumes in this temporal glioma cohort compared to healthy controls from prior studies were 2.93 vs 2.83 cm3 (right, p=0.31) and 2.78 vs 2.76 cm3 (left, p=0.39) respectively. Pre vs post resection right hippocampal volumes in patients with right sided lesions were 2.59 vs 1.75 cm3 (p=.002). Left hippocampal volumes in patients with left sided tumors were 2.99 vs 1.64 cm3 pre and post resection respectively(p=0.0009). No significant differences in hippocampal volumes contralateral to the tumor side were found following treatment (p=0.31 and 0.07 for right and left hippocampi respectively). Temporal gliomas are in close anatomic proximity to the hippocampi also may invade and/or disrupt local circuits which output to the hippocampi. Resection and chemoradiation are correlated with decreased hippocampal volumes ipsilateral to the primary locus of disease. Further characterization of hippocampal subregions, particularly the dentate gyrus, in addition to results of neuropsychiatric testing pre and post treatment are necessary to better elucidate the clinical implications of these morphologic changes and the putative functional networks which underlie them.