The relationship between hippocampal volumes and nonverbal memory in patients with medial temporal lobe epilepsy

•Hippocampus, amygdala, and entorhinal cortex (EC) are the important structure for memory.•We assessed the quantitative confirmation of amygdala, and EC by volumetric MRI.•Memory was evaluated through the Clinical Memory Scale (CMS).•We prove that nonverbal memory was correlated with the status of the right hippocampus.

SummaryObjectiveTo explore the involvement of medial temporal lobe structures such as the hippocampus, amygdala, and entorhinal cortex (EC) in memory consolidation by volumetric magnetic resonance imaging (MRI).MethodsSixty-two consecutive patients with medial temporal lobe epilepsy (MMTLE) were assessed using the Clinical Memory Scale (CMS) and MRI to measure the volumes of the hippocampus, amygdala, and EC. Participants were grouped according to MRI findings into 3 groups: left MRI-positive (abnormal hippocampal formation on the left side; n = 17), right MRI-positive (abnormal hippocampal formation on the left side; n = 9), and MRI-negative (normal hippocampal formation; n = 36). One-way analysis of variance (ANOVA) was used to assess group differences for all volumetric data (Z scores or asymmetry indexes (AI)), memory scale scores, and clinical parameters. Post hoc analyses were done with Fisher's least significant difference (LSD) tests. AI = 100 × (L-R)/(L + R). “L” and “R” refer to the left and right volumes of each structure, respectively.ResultsThe nonsense graphical recognition tests and the facial memory tests were significantly different between the three groups. Post hoc analyses showed that the right MRI-positive group performed significantly worse than the MRI-negative group on nonsense graphical recognition tests (P = 0.008) and the left MRI-positive group had significantly lower scores than the MRI-negative group on facial memory tests (P = 0.023).ConclusionsNonverbal memory was correlated with the status of the right hippocampus.