Citation

Leh SE, Schroeder C, Chen JK, Chakrvarty MM, Park MT, Cheung B, Petrides M, Huntgeburth SC, Gosselin N, Hock C, Ptito A. J. Neurotrauma 2016; 34(7): 1402-1411.

Affiliation

Montreal Neurological Institute, Cognitive Neuroscience Unit, Montreal, Quebec, Canada ; alain.ptito@mcgill.ca.

Copyright

(Copyright © 2016, Mary Ann Liebert Publishers)

DOI

10.1089/neu.2016.4591

PMID

27786023

Abstract

Mild traumatic brain injury (mTBI) affects a large number of individuals and diffusion tensor imaging (DTI) can be used to investigate microstructural integrity of brain tissue after mTBI. However, results have varied considerably between studies and gray matter (GM) integrity has been largely neglected in these investigations. Given impaired working memory processing after mTBI and its possible association with Alzheimer's disease, we investigated hippocampal integrity and parcellated this structure into five subregions: subiculum, cornu ammonis (CA) 1, CA 2 / 3, CA 4 / dentate gyrus, and stratum radiatum / lacunosum moleculare (SRLM). We also employed shape analysis of bilateral hippocampi to explore whether morphological changes had occurred due to the traumatic injury and conducted neuropsychological memory tests. The sample comprised 15 subjects with mTBI (18 55 years, 9 female) and 13 age and sex matched healthy control subjects (19 57 years, 9 female). Voxel wise analyses showed significantly increased mean diffusivity (MD) in patients compared to controls in the right hippocampus and three of its five subregions (family-wise error [FWE] corrected p < 0.05). Additionally, results from probabilistic tractography indicated impaired CA 1 connectivity after mTBI (Benjamini-Hochberg false discovery rate [FDR] corrected p < 0.05). Shape of bilateral hippocampi did not significantly differ between groups (Benjamini-Hochberg FDR corrected p > 0.05). Subjects with mTBI reported more symptoms and performed worse in a non-standard verbal working memory task. Based on these preliminary findings, we were able to demonstrate altered diffusivity of hippocampal subregions following mTBI, indicating impaired GM microstructural integrity. These differences highlight the potential of diffusion imaging for investigation of subtle, yet relevant changes in GM microstructure not detected otherwise following mTBI.

Language: en