Dados do Trabalho

Título

Bilateral, unilateral and absent hippocampal atrophy exhibit different graph theory patterns in temporal lobe epilepsy

Resumo

Introduction: Although temporal lobe epilepsy (TLE) with unilateral hippocampal atrophy (HA) has been extensively investigated, fewer studies evaluated the impact of bilateral HA and the absence of HA on the efficiency of brain connectivity and networks.
Objectives: To investigate brain connectivity and network properties with graph theory methods in TLE patients according to the laterality of HA (RIGHT-HA, LEFT-HA, BILATERAL-HA, NEGATIVE-HA).
Materials and Methods: We analyzed 216 3T MRI resting-state images of TLE patients followed at the University of Campinas (median age: 48 y.o.; 122 women): 92 with LEFT-HA, 70 with RIGHT-HA, 25 with BILATERAL-HA and 29 NEGATIVE-TLE. Groups were paired with healthy controls in terms of age (p>0.05) and sex (p>0.05). We used the CONN connectivity toolbox/MATLAB 2019 to preprocess and extract graph theory measures (global efficiency (G-eff), average path length (PATH), degree/cost (DEGREE), betweenness centrality (BC), local efficiency (L-eff) and clustering coefficient (CC), after a whole-brain analysis. We considered a cost of 0.15 (including only the 15% more statistically significant results) and reported p-values<0.05.
Results: The LEFT-HA and RIGHT-HA presented a trend to higher measures of global connectivity (G-Con), local connectivity (L-Con), and centrality in the brain (higher G-eff, DEGREE, BC, L-eff, CC and lower PATH) and a trend to lower G-Con, L-Con and centrality in the cerebellum. The LEFT-HA and RIGHT-HA presented higher DEGREE in the ipsilateral hippocampus and higher L-eff /CC in the contralateral hippocampus. The NEGATIVE-TLE group showed a trend to lower G-eff and higher average PATH, DEGREE and CC in the brain. The BILATERAL-HA presented a trend to higher L-eff /CC in the brain.
Conclusion: All groups presented a trend of higher local connectivity to the detriment of the G-eff. While the unilateral groups showed higher connectivity levels in the brain (with higher ipsilateral hippocampal G-Con and probable compensatory higher contralateral hippocampal L-Con) and disconnection in the cerebellum, the NEGATIVE-TLE presented concordantly higher L-Con and lower G-Con both in the brain and cerebellum. BILATERAL-HA did not exhibit any other specific patterns. Overall, cerebral G-eff is reduced in all TLE groups, regardless of the presence of HA. The presence of unilateral HA adds specific dysfunction in bilateral hemispheric connectivity, which may yield poor performance of the global brain connectivity.