| Objective:According to the definition of the International League Against Epilepsy, idiopathic generalized epilepsy with generalized tonic-clonic seizures only (IGE-GTCS) is characterized by no neuroradiological signs. However, one volumetric MRI study demonstrated 4 out of 41 patients with IGE-GTCS had hippocampus atrophy [volume> 2 Standard deviation (SD)below mean] Another study which manually assessed the volumes of hippocampus reported that the hippocampus was normal in patients with IGE-GTCS. Very few studies have focused on this. On the other hand, generalized seizures are more likely to impair cognitive functions than focal seizures among various seizure types. No study about the cognition of the patients with IGE-GTCS has been found. To our knowledgement, hippocampus and amygdala were correlated with cognitive function. The study aimed to investigate volumetric abnormalities of the hippocampus and amygdala, as well as the relations among volume, cognitive function, and clinical characteristics in patients with IGE-GTCS.Method:The participants included thirty patients with IGE-GTCS (15 males and 15 females) and 32 age, gender, and education matched healthy controls (15 males and 17 females). The patients were recruited from the Epilepsy Clinic of the Department of Neurology, First Affiliated Hospital of DaLian Medical University. The imagines were acquired on a 1.5 T GE Signa MR scanner. A three-dimensional fast spoiled gradient-recalled sequence (3D-FSPGR) was used for acquisition of sagittal T1-weighted images. After that, the images were processed on a Unix workstation (Silicon Graphics, Mountain View, CA, USA) with the software package Dr View 5.0. Hippocampus and amygdala were manually traced on consecutive coronal 1-mm-thick slices, from anterior to posterior, with the corresponding sagittal and axial planes simultaneously presented as references. Volumes of hippocampus and amygdala were calculated by the software automatically. Wechsler Adult Intelligence Scale-Revised in China (WAIS-RC) was administered to each participant on the same day of magnetic resonance imaging (MRI) scan by the same psychologist who was blind to the diagnosis of the participant. WAIS-RC provided scores for all its 11 subsets, as well as a verbal intelligence quotient (VIQ), a performance intelligence quotient (PIQ), and a full scale intelligence quotient (FSIQ). Kaufman factor scores were obtained by summing subset scores that loaded the individual factors:verbal comprehension (VC), perceptual organization (PO), freedom from distractibility (FD). Group differences for age, education, cognitive tests were assessed using independent-samples T test, and the sex distribution was evaluated with theχ2 test. Statistical differences in the regional volume measures were analyzed using repeated measures multivariate analysis of covariance (MANCOVA). Pearson's partial correlation coefficients were calculated to examine the relationships between hippocampal volumes and clinical variables, hippocampal volumes and cognitive scores, amygdala volumes and cognitive scores, and between cognitive scores and clinical variables. The significance level was set at p<0.05.Result:In patients, the mean volume of the left hippocampus was 3.43 (0.09) cm3, the right was 3.60 (0.10) cm3, the mean volume of the left amygdala was 1.14 (0.04) cm3, the right was 1.11 (0.04) cm3. In controls, the mean volume of the left hippocampus was 3.68 (0.06) cm3, the right was 3.79 (0.07) cm3, the mean volume of the left amygdala was 1.17 (0.04) cm3, the right was 1.20 (0.34) cm3.Compared with controls, patients with IGE-GTCS had significantly decreased volumes in bilateral hippocampus (p<0.001) and a significant left-smaller-than-right volumetric asymmetry of hippocampus (p=0.007). There was no significant difference in amygdala volume between patients and controls. The patients had significantly low scores in all subsets of WAIS-RC. The left hippocampus was significantly positively correlated with arithmetic (r=0.37, p<0.05), block-design (r=0.42. p=0.02); the right hippocampus was significantly positively correlated with arithmetic. (r=0.48, p=0.009), picture completion (r=0.43, p=0.02), block design (r=0.43, p=0.02), PO (r=0.27, p=0.04), PIQ (r=0,39, p=0.03), and FSIQ (r=0.37, p<0.05). Multiple significant negative correlations were revealed between the total number or frequency of seizures and cognitive measures.Conclusion:1. Patients with IGE-GTCS had significant volume reductions in bilateral hippocampus compared with normal controls, and that of the left seemed more severely affected than the right.2. Patients with IGE-GTCS performed significantly worse on all the WAIS-RC's measures; the total number of seizures and seizure frequency were significantly negatively associated with multiple cognitive measures.3. Volume reductions of the hippocampus were also correlated with some aspects of cognitive impairment. |
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