Hippocampal volume in childhood complex partial seizures

Seizure control does not predict hippocampal subfield volume change in children with focal drug-resistant epilepsy

Background and purpose

Recurrent seizures have been reported to induce neuronal loss in the hippocampus. It is unclear whether seizure control influences hippocampal volume. The aims of this study were to determine if there was a change in total or subfield hippocampal volume over time in children with focal drug-resistant epilepsy, and whether seizure control influenced total or subfield hippocampal volumes.

Methods

Using FreeSurfer’s automated segmentation of brain magnetic resonance imaging scans, we calculated the total and subfield (including CA1, CA3, CA4, subiculum, presubiculum, parasubiculum, molecular layer and dentate gyrus) hippocampal volumes of children with non-lesional focal epilepsy. Seizure frequency and hippocampal volumes were assessed at baseline and follow-up. Patients were classified into those who were seizure free or have improvement in seizures (group 1) and those with no improvement in seizures (group 2) at follow-up.

Results

Thirty-seven patients were included, with mean age 10.31 ± 3.68 years at baseline. The interval between the two magnetic resonance imaging scans was 2.59 ± 1.25 years. There was no significant difference in the total and subfield hippocampal volumes for the whole cohort at follow-up compared to baseline (all P > 0.002). Seizure control of the two groups did not predict total or subfield hippocampal volume, after controlling for baseline volume, age, severity of seizure frequency at baseline and time interval between the magnetic resonance imaging scans (all P > 0.002).

Conclusion

We have found that total and subfield hippocampal volumes did not change, and seizure control did not predict hippocampal volumes at follow-up in children with drug-resistant epilepsy.

Preclinical evidence of ghrelin as a therapeutic target in epilepsy

Ghrelin, an orexigenic peptide synthesized by endocrine cells of the gastric mucosa, plays a major role in inhibiting seizures. However, the underlying mechanism of ghrelin's anticonvulsant action is still unclear. Nowadays, there are considerable evidences showing that ghrelin is implicated in various neurophysiological processes, including learning and memory, neuroprotection, neurogenesis, and inflammatory effects. In this review, we will summarize the effects of ghrelin on epilepsy. It may provide a comprehensive picture of the role of ghrelin in epilepsy.

Multivariate analyses applied to fetal, neonatal and pediatric MRI of neurodevelopmental disorders

Multivariate analysis (MVA) is a class of statistical and pattern recognition methods that involve the processing of data that contains multiple measurements per sample. MVA can be used to address a wide variety of medical neuroimaging-related challenges including identifying variables associated with a measure of clinical importance (i.e. patient outcome), creating diagnostic tests, assisting in characterizing developmental disorders, understanding disease etiology, development and progression, assisting in treatment monitoring and much more. Compared to adults, imaging of developing immature brains has attracted less attention from MVA researchers. However, remarkable MVA research growth has occurred in recent years. This paper presents the results of a systematic review of the literature focusing on MVA technologies applied to neurodevelopmental disorders in fetal, neonatal and pediatric magnetic resonance imaging (MRI) of the brain. The goal of this manuscript is to provide a concise review of the state of the scientific literature on studies employing brain MRI and MVA in a pre-adult population. Neurological developmental disorders addressed in the MVA research contained in this review include autism spectrum disorder, attention deficit hyperactivity disorder, epilepsy, schizophrenia and more. While the results of this review demonstrate considerable interest from the scientific community in applications of MVA technologies in pediatric/neonatal/fetal brain MRI, the field is still young and considerable research growth remains ahead of us.

Volumetric changes in hippocampal subregions and their relation to memory in pediatric nonlesional localization-related epilepsy

OBJECTIVE

Developmental differences in structure and function have been reported along the hippocampal subregions. The aims of this study were to determine if there were volumetric differences in hippocampal head (HH), body (HB), tail (HT), and total hippocampus (TotH)) in children with nonlesional localization-related epilepsy relative to controls, and the relation between hippocampal subregions with episodic memory and clinical parameters.

METHODS

Forty-eight children with nonlesional localization-related epilepsy, consisting of 29 left-sided and 19 right-sided epilepsy, and 27 healthy controls were recruited. All patients and controls underwent volumetric T1-weighted imaging, and verbal and nonverbal memory testing. The volume of hippocampal subregions was compared between patients and controls. The associations between left hippocampal subregions with verbal memory; right hippocampal subregions with nonverbal memory; and hippocampal subregions with age, age at seizure onset, and seizure frequency were assessed.

RESULTS

Patients with left-sided epilepsy had smaller left HH (p = 0.003) and HB (p = 0.012), right HB (p = 0.021) and HT (p = 0.015), and right TotH (p = 0.020) volumes. Those with right-sided epilepsy had smaller right HT (p = 0.018) volume. There were no statistically significant differences between verbal and nonverbal memory in left-sided and right-sided epilepsy relative to controls (all p > 0.025). In left-sided epilepsy, there was a significant association between left HH volume with verbal memory (β = 0.492, p = 0.001). There was no significant association between left and right hippocampal subregions with verbal and nonverbal memory, respectively, in right-sided epilepsy and controls (all p > 0.002). In left-sided and right-sided epilepsy, there was no significant association between hippocampal subregions with age, age at seizure onset, and seizure frequency (all p > 0.002).

SIGNIFICANCE

We have found hippocampal volume reduction, but did not identify a gradient in the severity of volume reduction along the hippocampal axis in children with localization-related epilepsy. Further study is needed to clarify if there are volumetric changes within the cornu ammonis subfields and dentate gyrus. A PowerPoint slide summarizing this article is available for download in the Supporting Information section here.

Hippocampal MR Volumetric Studies in Paediatric Patients with Epilepsy and Normal Controls

The aim of this study was to determine and compare the hippocampal volume in children with epilepsy and in children in a control group and to compare the mean of right and left hippocampal volume in control subjects. This study was carried out at University Sains Malaysia (USM) from January 2008 to June 2009. This is a cross sectional study of 40 children with epilepsy and 40 children in a control volunteer group. Serial MRI of brain and temporal lobe were performed using a Signa Horizon LX 1.0 Tesla system. Oblique coronal sections perpendicular to the axis of temporal lobe were done with 4 mm slice thickness and 1 mm gap. T1, T2, FLAIR and SPGR series were done. The whole hippocampal volume was measured. Volumetry was done manually by using Osirix workstation (v 3.5.1–64 bit). All slices were measured three times and the average volume was taken. Data were analyzed by paired t test and independent t test for univariate data. The mean hippocampal volume in the control group was 2.81 cm3 (SD=0.38) and 2.65 cm3 (SD=0.41) for right and left hippocampus respectively. The mean hippocampal volume in epilepsy patients was 2.47 cm3 (SD=0.52) and 2.39 cm3 (SD=0.44) for right and left respectively. The hippocampal volume in epileptic children was significantly smaller than normal control children in average volume (p=0.001) and both right (p=0.002) and left (p=0.007) individually. In the control group, the right hippocampus volume was much greater than the left (p<0.001). The data of this study provide a useful reference for the study of hippocampal volume in the Malay paediatric population. It is useful in doubtful cases to determine which side is affected and also serves as part of the study to establish the whole age-related hippocampal growth.

Deformation-based morphometry of prospective neurodevelopmental changes in new onset paediatric epilepsy

Epilepsy is a prevalent childhood neurological disorder, but there are few prospective quantitative magnetic resonance imaging studies examining patterns of brain development compared to healthy controls. Controlled prospective investigations initiated at or near epilepsy onset would best characterize the nature, timing and course of neuroimaging abnormalities in paediatric epilepsy. In this study, we report the results of a deformation-based morphometry technique to examine baseline and 2-year prospective neurodevelopmental brain changes in children with new and recent onset localization-related epilepsies (n = 24) and idiopathic generalized epilepsies (n = 20) compared to healthy controls (n = 36). Children with epilepsy demonstrated differences from controls in baseline grey and white matter volumes suggesting antecedent anomalies in brain development, as well as abnormal patterns of prospective brain development that involved not only slowed white matter expansion, but also abnormalities of cortical grey matter development involving both greater and lesser volume changes compared to controls. Furthermore, abnormal neurodevelopmental changes extended outside the cortex affecting several subcortical structures including thalamus, cerebellum, brainstem and pons. Finally, there were significant differences between the epilepsy syndromes (localization-related epilepsies and idiopathic generalized epilepsies) with the idiopathic generalized epilepsies group showing a more disrupted pattern of brain structure both at baseline and over the 2-year interval.

Brain development in children with new onset epilepsy: a prospective controlled cohort investigation

PURPOSE

To characterize prospective neurodevelopmental changes in brain structure in children with new and recent-onset epilepsy compared to healthy controls.

METHODS

Thirty-four healthy controls (mean age 12.9 years) and 38 children with new/recent-onset idiopathic epilepsy (mean age 12.9 years) underwent 1.5 T magnetic resonance imaging (MRI) at baseline and 2 years later. Prospective changes in total cerebral and lobar gray and white matter volumes were compared within and between groups.

RESULTS

Prospective changes in gray matter volume were comparable for the epilepsy and control groups, with significant (p < 0.0001) reduction in total cerebral gray matter, due primarily to significant (p < 0.001) reductions in frontal and parietal gray matter. Prospective white matter volume changes differed between groups. Controls exhibited a significant (p = 0.0012) increase in total cerebral white matter volume due to significant (p < 0.001) volume increases in the frontal, parietal, and temporal lobes. In contrast, the epilepsy group exhibited nonsignificant white matter volume change in the total cerebrum (p = 0.51) as well as across all lobes (all p's > 0.06). The group by white matter volume change interactions were significant for total cerebrum (p = 0.04) and frontal lobe (p = 0.04).

DISCUSSION

Children with new and recent-onset epilepsy exhibit an altered pattern of brain development characterized by delayed age-appropriate increase in white matter volume. These findings may affect cognitive development through reduced brain connectivity and may also be related to the impairments in executive function commonly reported in this population.