Anterior and posterior complexes: a step towards improving neurosonographic screening of midline and cortical anomalies.

OBJECTIVE: To describe the anatomical structures that form the anterior (AC) and posterior (PC) complexes of the fetal brain and to categorize their anomalies in fetuses with cerebral abnormalities. METHODS: We analyzed retrospectively volume datasets from 100 normal fetuses between 20 and 30 weeks' gestation. On the axial transventricular plane, our analysis of the AC included the interhemispheric fissure (IHF), the callosal sulcus (CS), the genu of the corpus callosum (CC), the cavum septi pellucidi (CSP) and the anterior horns (AH) of the lateral ventricles. The PC included the splenium of the CC, the medial wall of the lateral ventricles, the CS and the parieto-occipital fissure (POF). We then categorized AC/PC findings in 32 fetuses with agenesis of the septi pellucidi, schizencephaly, callosal dysgenesis, cortical malformation and hypoxic-ischemic brain injury. RESULTS: The structures forming the AC and PC were visible in 100% and 92%, respectively, of normal cases. In the AC, the CSP was square-shaped in 73% of cases and it was triangular in 27%; the AH was comma-shaped in 92% of cases and triangular in the remainder. In the PC, the splenium of the CC interrupted and bridged the midline and was delimited posteriorly by the CS and the IHF. The POF was visible posteriorly. We categorized AC and PC abnormalities according to the main deviation from normality in their anatomical structures. The AC was abnormal in 30/32 cases and the PC was abnormal in 16/32 cases. In the two cases with normal AC, the PC was abnormal. CONCLUSION: Normal appearance of AC and PC seems to be a strong indicator of fetal central nervous system normality. Morphological abnormalities in both complexes are robust markers of midline defects, but not exclusively so. The majority of fetuses with cortical malformations showed a defect in the AC.

[Quantitative volumetric analysis of the hippocampus, amygdala and entorhinal cortex: normative database for the adult Portuguese population]. / Análisis volumétrico mesiotemporal: valores normativos del hipocampo, la amígdala y el córtex entorrinal en la población adulta portuguesa.

INTRODUCTION: Atrophy of the hippocampus, amygdala and entorhinal cortex can be found in neurodegenerative diseases, head trauma and epilepsy and are expressed by means of volume reductions. The ability to detect these changes quantitatively depends on accurate comparisons with normative databases. AIM: To present standard magnetic resonance imaging (MRI) volumes of the mesio-temporal lobe structures and an objective statistical methodology for contrasting pathological states. SUBJECTS AND METHODS: Volumes of the right and left hippocampi, amygdalae and entorhinal cortex were measured from MRI in 34 right-handed healthy volunteers, aged 19-52 years. Data were normalized for the individual variation in total intracranial volume. Reproducibility was confirmed by intra/inter-observer tests. The statistical analyses included asymmetry comparisons, correlations between volumes and tests to assess the influence of age, gender and general morphometry (body mass index and height). For each volume, we further defined a normative interval by means of 99% confidence ellipses, accordingly to Hotteling's method. RESULTS: Right-left asymmetry in the volumes of the hippocampus and entorhinal cortex was a normal finding. Structures located in the right hemisphere were larger than the left by a small but statistically significant amount. No asymmetry was found in the amygdala. There was no correlation in-between these volumes. Gender differences were exclusively noted in the absolute amygdala volumes (male > female) but were eliminated by the normalization procedure. No effect of age or morphometry was seen in the absolute or normalized volumes (except for a milder correlation between hippocampal volumes and height). Confidence ellipses were built for every structure and provided a precise reading of the data. Particularly, it allowed for a clear distinction of pathological asymmetries and bilateral cases. CONCLUSION: These normative volumes serve as a reference for the assessment of pathologic groups within similar age-range. The use of a single graphic representation simplifies the clinical interpretation and enhances the precision of the results.

Apparent diffusion coefficient mapping of the hippocampus and the amygdala in pharmaco-resistant temporal lobe epilepsy.

BACKGROUND AND PURPOSE: The purpose of this study is to determine whether interictal apparent diffusion coefficients (ADC) provide a robust means for detecting amygdalo-hippocampal abnormalities in adult patients with localization-related chronic temporal lobe epilepsy (TLE) undergoing presurgical evaluation. METHODS: Fifty-five patients and 20 age-matched controls were studied with hippocampal and amygdala ADC maps (HADC and AMYADC), volumes (HCVOL, AMYVOL), T2 relaxometry (HCT2, AMYT2), and hippocampal N-acetylaspartate to choline and creatine/phosphocreatine ratios (HCSI). Mean values and 99% confidence ellipses were computed for the groups. Individual ADC mapping was compared with electroencephalography (EEG) data and further correlated with the quantitative MR measures and with the age at onset and duration of TLE. Moreover, we evaluated the association and the predictive value of HADC and AMYADC with respect to the surgical outcome in a subgroup of patients (n = 21) operated on the side of maximal EEG lateralization and with MR imaging criteria for hippocampal sclerosis, 71% of which became seizure-free. RESULTS: In controls, there was no relation between ADC values and age, sex, or right-left asymmetries. In TLE groups with right (n = 29) or left epileptogenic foci (n = 26), group comparisons showed that ADC mapping detected changes ipsilateral to the focus in the hippocampus (P < .01) and the amygdala (P < .05), accordingly with the volumes, T2 maps, and HCSI. Significant Pearson correlations (2-tailed) were obtained between ADC maps and the volume of the hippocampus (r = -0.64) and of the amygdala (r = -0.55; both P < .01), T2 (r = 0.70, r = 0.29; both P < .01), but not with HCSI. Individual ADC analysis showed ipsilateral pathology in 82% of cases (hippocampus) and 35% (amygdala) and included a moderate association between ipsilateral HADC and AMYADC (r = 0.54; P < .01). Bilateral abnormalities were found in 7% (hippocampus) and 5% (amygdala) of cases. Except for HCSI and the amygdala data, there were significant correlations between the asymmetry indices and the duration of epilepsy (HADC: r = 0.42; HCT2: r = 0.50; HCVOL: r = 0.35; all P < .01). Age at onset was associated only with ipsilateral HADC (r = 0.35; P < .01) and HCVOL and HCT2 (both P < .05). The association with postsurgical successes was characteristic of HADC (Fisher exact test, 2-tailed: P =.031; Spearman correlation: r(s) = -0.75; P = .0002), but not AMYADC. The predictive value regarding a favorable outcome was 0.87 (odds ratio 26; 95% confidence interval 2.33-38.86). As determined by regression models, both larger ipsilateral HADCs and asymmetry indices predicted surgical success. CONCLUSION: Interictal ADC mapping lateralizes efficiently the lesion side in accordance with the EEG data and might be used to study the differential regional aspects of mesio-temporal sclerosis. HADC--not AMYADC--maps discriminate favorably postoperative outcome and can be added to the multidisciplinary evaluation workout of pharmacoresistant TLE patients.