Correlation of diffusion tensor imaging findings and episodic memory impairment in temporal lobe epilepsy

Abstract

Purpose: Our aim was to evaluate the utility of diffusion tensor imaging (DTI) in exploration of white matter tracts microstructure changes and clarify their relation to episodic memory in temporal lobe epilepsy (TLE). Materials and methods: DTI was performed on 30 (18 left, 12 right) TLE patients and 20 healthy controls. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were calculated for six fiber tracts; the parahippocampal cingulum (PHC), superior longitudinal fasciculus (SLF), inferior longitudinal fasciculus (ILF), fornix (FORX), uncinate fasciculus (UF) and corpus callosum (CC). Assessment for episodic memory (visual and verbal) was performed at least 48 h after the last seizure. Results: All TLE patients had episodic memory impairment. Left TLE patients demonstrated more verbal memory affection, whereas right TLE patients demonstrated more visual memory affection (p < 0.05). Abnormal DTI parameters (decreased FA and increased ADC) were detected in most of the white matter tracts (p < 0.001) compared to control group. In left TLE patients, there was significant correlation between DTI parameters of left (PHC, SLF, UF, FORX) and verbal memory. Whereas, in right TLE patient, we found significant correlation between DTI parameters of right ILF and visual memory. Conclusions: TLE patients had multiple micro-structural white matter tracts abnormalities and episodic memory impairment. Both are structurally and functionally related.

Keywords

• DTI
• Episodic memory
• Temporal lobe epilepsy