Abstracts

RATIONALE: The piriform cortex (PC) is one of the most sensitive brain areas to become damaged by prolonged seizure activity in experimental models. Little is, however, known about the appearance and severity of the PC damage in humans with TLE. Here we investigated the occurrence of the PC damage and its coappearance with the hippocampal damage in patients with chronic TLE by using quantitative MR volumetry.
METHODS: 38 adults (21 females, 17 males) with chronic TLE and 23 age-matched controls (12 females, 11 males) were included in the study. All underwent a high-resolution MR imaging at 1.5 T, including a tilted T1-weighted 3D-dataset subsequently reformatted to the bi-comissural line. A method to assess the volume of the region including the piriform cortex and the cortical amygdaloid nuclei (PCA) with a standard work console was designed by using landmarks defined by the analysis of Nissl-stained histologic sections from 23 age and sex matched autopsy controls. Ten controls were used to assess the intra- and inter-observer variability (6% and 8%, respectively). Differences in the normalized PCA volumes and asymmetry ratios between the study groups (controls, TLE patients with focus on the left or right) were determined with non-parametric tests using Bonferroni adjustment.
RESULTS: Normalized control volumes were 530[plusminus]59mm3 (422-644) [mean[plusminus]SD (range)] for the right and 512[plusminus]60mm3 (406-610) for the left PCA. In controls, there was no right-left asymmetry. In right TLE patients, the mean right PCA volume was 15% smaller than in left TLE patients (p[lt]0.005) and 18% smaller than in controls (p[lt]0.0005). In left TLE patients, the mean left PCA volume was 16% smaller than in the right TLE patients (p[lt]0.0005) and 17% smaller than in controls (p[lt]0.0005). In both TLE patient groups the asymmetry ratio of the PCA was significantly different compared to controls indicating that PCA volumes were smaller ipsilaterally than contralaterally. Patients with hippocampal volumes at least 2 standard deviations below the control mean had a mean ipsilateral PCA volume that was 18% smaller than in patients without hippocampal damage (p[lt]0.005).
CONCLUSIONS: The results indicate that the PCA is an area extensively damaged in chronic TLE patients, particularly in those with hippocampal atrophy.
[Supported by: Portuguese Science and Technology Foundation (BD 18498/98), Kuopio University Hospital EVO Grant, The Vaajasalo Foundation, The Sigrid Juselius Foundation, and Academy of Finland.]