Volumetric hippocampal changes in glioblastoma: a biomarker for neuroplasticity?

PURPOSE: The pleiotropic effect of gliomas on the development of cognitive disorders and structural brain changes has garnered increasing interest in recent years. While it is widely accepted that multimodal therapies for brain cancer can foster cognitive impairment, the direct effect of gliomas on critical cognitive areas before anti-tumor therapies is still controversial. In this study, we focused on the effect of IDH1 wild-type glioblastoma on the human hippocampus volume. METHODS: We carried out a case-control study using voxel-based morphometry assessment, analyzed with the Computational Anatomy Toolbox software. Glioblastoma diagnosis was performed according to the latest 2021 WHO classification. Due to stringent inclusion criteria, 15 patients affected by IDH1 wild type glioblastoma were included and compared to 19 age-matched controls. RESULTS: We observed a statistically significant increase in the absolute mean hippocampal volume (p = 0.017), as well as in the ipsilateral (compared to the lesion, p = 0.027) and the contralateral hippocampal volumes (p = 0.014) in the group of patients. When the data were normalized per total intracranial volume, we confirmed a statistically significant increase only in the contralateral hippocampal volume (p = 0.042). CONCLUSIONS: To the best of our knowledge, this is the first study to explore hippocampal volumetric changes in a cohort of adult patients affected by IDH1 wild-type glioblastoma, according to the latest WHO classification. We demonstrated an adaptive volumetric response of the hippocampus, which was more pronounced on the side contralateral to the lesion, suggesting substantial integrity and resilience of the medial temporal structures before the initiation of multimodal treatments.

Anti-Gad 65 encephalitis with rapidly progressive temporal atrophy reveals the involvement of the temporal lobe in the neuroanatomical basis of palilalia.

Palilalia is an acquired speech disorder characterized by the reiteration of words or sentences, historically divided in two main subtypes: "palilalie heterolalique" and "palilalie homolalique". In the former, the reiteration is characterized by rate increase and volume decrease, while in the latter these features remain unaltered. While the "heterolalique" subtype has been mainly observed in the context of basal ganglia diseases, the neuroanatomical basis of the "homolalique" subtype has never been completely clarified. Here we report the case of an 81 years-old woman who developed an extremely repetitive and perseverative language with "homolalique" subtype features and a rapidly progressive course with severe bitemporal atrophy, as a consequence of anti-glutamic acid decarboxylase 65 (GAD 65) antibodies encephalitis. To the best of our knowledge, this is the first report of palilalia in the context of anti-GAD 65 encephalitis. Through the support of voxel-based morphometry and hippocampal subfields analysis, this case study provides a fascinating way of understanding the networks responsible for palilalia, shedding some light on the critical role of temporal areas in the onset of this rare language disorder.

Predicting amyloid-PET status in a memory clinic: The role of the novel antero-posterior index and visual rating scales.

INTRODUCTION: Visual rating scales are increasingly utilized in clinical practice to assess atrophy in crucial brain regions among patients with cognitive disorders. However, their capacity to predict Alzheimer's disease (AD)-related pathology remains unexplored, particularly within a heterogeneous memory clinic population. This study aims to assess the accuracy of a novel visual rating assessment, the antero-posterior index (API) scale, in predicting amyloid-PET status. Furthermore, the study seeks to determine the optimal cohort-based cutoffs for the medial temporal atrophy (MTA) and parietal atrophy (PA) scales and to integrate the main visual rating scores into a predictive model. METHODS: We conducted a retrospective analysis of brain MRI and high-resolution TC scans from 153 patients with cognitive disorders who had undergone amyloid-PET assessments due to suspected AD pathology in a real-world memory clinic setting. RESULTS: The API scale (cutoff ≥1) exhibited the highest accuracy (AUC = 0.721) among the visual rating scales. The combination of the cohort-based MTA and PA threshold with the API yielded favorable accuracy (AUC = 0.787). Analyzing a cohort of MCI/Mild dementia patients below 75 years of age, the API scale and the predictive model improved their accuracy (AUC = 0.741 and 0.813, respectively), achieving excellent results in the early-onset population (AUC = 0.857 and 0.949, respectively). CONCLUSION: Our study emphasizes the significance of visual rating scales in predicting amyloid-PET positivity within a real-world memory clinic. Implementing the novel API scale, alongside our cohort-based MTA and PA thresholds, has the potential to substantially enhance diagnostic accuracy.