Hippocampal alterations in children with temporal lobe epilepsy with or without a history of febrile convulsions: evaluations with MR volumetry and proton MR spectroscopy.
OBJECTIVE
The causal effect of early febrile convulsions (FC) on later-onset temporal lobe epilepsy (TLE) remains unclear. In this study, we sought to examine the hippocampal alterations in epileptic children with or without FC history by using MR spectroscopy and volumetry.


METHODS
Fifty-five children ranging in age from 18 months to 15 years were enrolled in this study. Subjects were divided into three groups: the control group without either TLE or history of FC (n = 16), the TLE group with early history of FC (TLE + FC; n = 22), and the TLE group without FC history (n = 17). Measurement of hippocampal volume (HV) was performed on thin section T1-weighted images acquired with a 3D gradient echo MR image and normalized by the intracranial volume. Each individual subject had two measures of lateralization; one gives the smaller side of HV and the other the contralateral larger side of HV, assuming that the side with smaller HV is the possible primary site of seizure focus and the contralateral larger HV the secondary or normal site. Single-voxel proton MR spectroscopy of the hippocampi was performed, with metabolic ratio n-acetylaspartate (NAA)/choline (Cho) + creatine plus phosphocreatine (Cr) calculated and grouped separately as were with volumetry.


RESULTS
The overall mean HV for the control group was 2.61 +/- 0.21 cm(3) at an average intracranial volume of 965 +/- 241 cm(3), and the asymmetry index for hippocampal volume was (2.32 +/- 1.58)%. The overall mean HV was 2.30 +/- 0.33 cm(3) for TLE + FC group and 2.34 +/- 0.33 cm(3) for TLE group. Mean HV differed significantly for the three groups (P < .01). When the small and large sides were analyzed separately, significant differences were found between control and TLE as well as between control and TLE + FC for the smaller side (P < .05), whereas for the larger side significant differences were found only between control and TLE + FC. In MR spectroscopic measurements, the mean NAA/(Cr + Cho) of bilateral hippocampi was 0.77 +/- 0.06 for control group, 0.62 +/- 0.12 for TLE + FC group, and 0.66 +/- 0.11 for TLE group. In terms of statistically significant difference between groups, spectroscopic results were similar to volumetric measurements, except that there was no significant interaction effect between groups and measures of asymmetrical indices (P = .272).


CONCLUSIONS
Children with TLE and early history of FC tend to have lower hippocampal volumes and NAA/(Cr + Cho) ratios than do TLE children without FC history. The TLE + FC group seems to have increased vulnerability of the contralateral hippocampus as compared with TLE group. MR volumetry and spectroscopy are equally capable of showing the trends of hippocampal alternations in children with TLE with or without FC history.
Wu
Wen-Chau
WC
Department of Radiology, Tri-Service General Hospital and National Defense Medical Center, Taipei, Taiwan, Republic of China.
Huang
Chao-Ching
CC
Chung
Hsiao-Wen
HW
Liou
Michelle
M
Hsueh
Chun-Jen
CJ
Lee
Chang-Shin
CS
Wu
Ming-Long
ML
Chen
Cheng-Yu
CY
D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D004833:Epilepsy, Temporal Lobe / Q000150:complications*; D005260:Female; D006624:Hippocampus / Q000473:pathology*; D006801:Humans; D007223:Infant; D008279:Magnetic Resonance Imaging; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D003294:Seizures, Febrile / Q000150:complications*