Apoptosis and Glial Marker Profiles in Hippocampus and Amygdala of Medically Intractable Temporal Lobe Epilepsy

Surgery: All Ages

Adolescent intermittent ethanol (AIE) exposure leads to persisting increases in glial markers and significantly decreases the neurogenic niche in the dentate gyrus of the hippocampus. Our previous study indicated that donepezil (DZ), a cholinesterase inhibitor, can reverse the AIE effect of decreased doublecortin (DCX), a neurogenic marker, and increased cleaved caspase 3, a marker of apoptosis, in the dentate gyrus of male rats. However, to date, no studies have assessed the effects of DZ on AIE effects in females. The purpose of this study was to determine whether DZ can reverse neuroimmune, neurogenic, and neuronal death effects in adulthood after AIE in female rats. Adolescent female rats were given 14 doses of ethanol (5 g/kg) over 24 days by intragastric gavage. Seventeen days later, DZ (2.5 mg/kg, 1.88 mL/kg, i.g., in water) was then administered daily for 4 days prior to sacrifice. Immunohistochemical techniques were utilized to determine the effects of DZ on AIE-induced changes in neurogenesis, cell death, glial, and neuroimmune markers. As expected, AIE decreased the neurogenic markers DCX, SOX2, and Ki-67 in the dentate gyrus and also caused an increase in the glial markers GFAP and Iba-1 in the hippocampus. The effects of AIE on neurogenic and glial markers were reversed by DZ treatment, but the reversal of AIE effects on glial markers was regionally specific within the hippocampus. Overall, these findings indicate that systemic DZ in adult female rats ameliorates the effects of AIE on neurogenesis, neuronal cell death, neuroimmune markers, and glial activation markers. Future studies will determine if DZ alters hippocampally driven behaviors, as well as the mechanisms underlying donepezil's effects.

Intractable focal epilepsy is commonly associated with cortical glucose hypometabolism on interictal 2-deoxy-2[18F]-fluoro-D-glucose (FDG) positron emission tomography (PET). However, subcortical brain structures also may show hypometabolism on PET and volume changes on magnetic resonance imaging (MRI) studies, and these are less well understood in terms of their pathophysiology and clinical significance. In the present study, we analyzed alterations of glucose metabolism in subcortical nuclei and hippocampus by using FDG-PET in young patients with intractable epilepsy. Thirty-seven patients (mean age, 7.5 years; age range, 1-27 years) with intractable frontal (n = 23) and temporal (n = 14) lobe epilepsy underwent FDG-PET scanning as part of their presurgical evaluation. Normalized glucose metabolism was measured in the thalamus and caudate and lentiform nuclei, as well as in hippocampus, both ipsi- and contralateral to the epileptic focus, and correlated with duration and age at onset of epilepsy, presence or absence of secondary generalization, location of the epileptic focus, and extent of cortical glucose hypometabolism. Long duration of epilepsy was associated with lower glucose metabolism in the ipsilateral thalamus and hippocampus. Duration of epilepsy was a significant predictor of ipsilateral thalamic glucose metabolism in both temporal and frontal lobe epilepsy. Presence of secondarily generalized seizures also was associated with lower normalized metabolism in the ipsilateral thalamus and hippocampus. Extent of cortical hypometabolism did not correlate with subcortical metabolism, and glucose metabolism in the caudate and lentiform nuclei did not show any correlation with the clinical variables. The findings suggest that metabolic dysfunction of the thalamus ipsilateral to the seizure focus may become more severe with long-standing temporal and frontal lobe epilepsy, and also with secondary generalization of seizures.

To determine the incidence of cerebellar atrophy (CA) in patients with intractable temporal lobe epilepsy, whether any clinical factors are significantly associated with CA, whether CA is unilateral or asymmetric and whether this feature has any relationship to the side of epileptogenicity, and whether the presence of CA is related to epilepsy surgery outcome. We developed a magnetic resonance imaging method of measuring the presurgical volumes of the cerebellar hemispheres of 185 patients who underwent temporal lobectomy for intractable epilepsy and of 80 control subjects. In addition, cerebellar volumes were normalized to the total brain volumes. CA was determined as being present when the measured volume was smaller than two standard deviations from the mean value found in control subjects. Both absolute and normalized cerebellar volumes were found to be significantly reduced in the epilepsy patients compared with the control subjects. Without normalization of the cerebellar volumes, CA was present in 25.9% of the epilepsy patients; with normalization, it was present in only 16.2%. The atrophy was symmetric between the cerebellar hemispheres, and there was no significant difference in volume between the hemisphere ipsilateral and the hemisphere contralateral to the side of the temporal lobectomy. The duration of epilepsy was significantly longer and the age at onset of epilepsy was younger in patients with CA than in those without CA. The presence of CA was not associated with the outcome of temporal lobectomy. CA is symmetric and common in patients with intractable temporal lobe epilepsy. However, the results suggest that the atrophy in one third of patients with CA also proportionately affects the cerebral hemispheres. The duration of epilepsy and the age at onset of epilepsy are associated with the occurrence of CA. Seizure control after temporal lobectomy is not influenced by the presence of CA.

Background Epilepsy has a high prevalence of 1%, which makes it the most common serious neurological disorder. The most difficult to treat type of epilepsy is temporal lobe epilepsy (TLE) with its most commonly associated lesion being hippocampal sclerosis (HS). About 30-50% of all patients undergoing resective surgery of epileptogenic tissue continue to have seizures postoperatively. Indication for this type of surgery is only given when lesions are clearly visible on magnetic resonance images (MRI). About 30% of all patients with focal epilepsy do not show an underlying structural lesion upon qualitative neuroradiological MRI assessment (MRI-negative). Objectives The work presented in this thesis uses MRI data to quantitatively investigate structural differences between brains of patients with focal epilepsy and healthy controls using automated imaging preprocessing and analysis methods. Methods All patients studied in this thesis had electrophysiological evidence of focal epilepsy, and underwent routine clinical MRI prior to participation in this study. There were two datasets and both included a cohort of age-matched controls: (i) Patients with TLE and associated HS who later underwent selective amygdalahippocampectomy (cohort 1) and (ii) MRI-negative patients with medically refractory focal epilepsy (cohort 2). The participants received high- resolution routine clinical MRI as well as additional sequences for gray and white matter (GM/WM) structural imaging. A neuroradiologist reviewed all images prior to analysis. Hippocampal subfield volume and automated tractography analysis was performed in patients with TLE and HS and related to post-surgical outcomes, while images of MRI- negative patients were analyzed using voxel-based morphometry (VBM) and manual/automated tractography. All studies were designed to detect quantitative differences between patients and controls, except for the hippocampal subfield analysis as control data was not available and comparisons were limited to patients with persistent postoperative seizures and those without. Results 1. Automated hippocampal subfield analysis (cohort 1): The high-resolution hippocampal subfield segmentation technique cannot establish a link between hippocampal subfield volume loss and post-surgical outcome. Ipsilateral and contralateral hippocampal subfield volumes did not correlate with clinical variables such as duration of epilepsy and age of onset of epilepsy. 2. Automated WM diffusivity analysis (cohort 1): Along-the-tract analysis showed that ipsilateral tracts of patients with right/left TLE and HS were more extensively affected than contralateral tracts and the affected regions within tracts could be specified. The extent of hippocampal atrophy (HA) was not related to (i) the diffusion alterations of temporal lobe tracts or (ii) clinical characteristics of patients, whereas diffusion alterations of ipsilateral temporal lobe tracts were significantly related to age at onset of epilepsy, duration of epilepsy and epilepsy burden.Patients without any postoperative seizure symptoms (excellent outcomes) had more ipsilaterally distributed WM tract diffusion alterations than patients with persistent postoperative seizures (poorer outcomes), who were affected bilaterally. 3. Automated epileptogenic lesion detection (cohort 2): Comparison of individual patients against the controls revealed that focal cortical dysplasia (FCD) can be detected automatically using statistical thresholds. All sites of dysplasia reported at the start of the study were detected using this technique. Two additional sites in two different patients, which had previously escaped neuroradiological assessment, could be identified. When taking these statistical results into account during re-assessment of the dedicated epilepsy research MRI, the expert neuroradiologist was able to confirm these as lesions. 4. Manual and automated WM diffusion tensor imaging (DTI) analysis (cohort 2): The analysis of consistency across approaches revealed a moderate to good agreement between extracted tract shape, morphology and space and a strong correlation between diffusion values extracted with both methods. While whole-tract DTI-metrics determined using Automated Fiber Quantification (AFQ) revealed correlations with clinical variables such as age of onset and duration of epilepsy, these correlations were not found using the manual technique. The manual approach revealed more differences than AFQ in group comparisons of whole-tract DTI-metrics. Along-the-tract analysis provided within AFQ gave a more detailed description of localized diffusivity changes along tracts, which correlated with clinical variables such as age of onset and epilepsy duration. Conclusions While hippocampal subfield volume loss in patients with TLE and HS was not related with any clinical variables or to post-surgical outcomes, WM tract diffusion alterations were more bilaterally distributed in patients with persistent postoperative seizures, compared to patients with excellent outcomes. This may indicate that HS as an initial precipitating injury is not affected by clinical features of the disorder and automated hippocampal subfield mapping based on MRI is not sufficient to stratify patients according to outcome. Presence of persisting seizures may depend on other pathological processes such as seizure propagation through WM tracts and WM integrity. Automated and time-efficient three-dimensional voxel-based analysis may complement conventional visual assessments in patients with MRI-negative focal epilepsy and help to identify FCDs escaping routine neuroradiological assessment. Furthermore, automated along-the-tract analysis may identify widespread abnormal diffusivity and correlations between WM integrity loss and clinical variables in patients with MRI-negative epilepsy. However, automated WM tract analysis may differ from results obtained with manual methods and therefore caution should be exercised when using automated techniques.

The effects of duration of intractable epilepsy on memory function

To establish a quantitative MRI technique using T2 relaxation time mapping to study systematically the amygdala in patients with intractable temporal lobe epilepsy (TLE). Identification of a focal abnormality on MRI in patients with intractable TLE is important, because outcome from surgery depends largely on the removal of the underlying pathology. Hippocampal sclerosis (HS) is the most common cause of intractable TLE, but epileptogenic lesions can be confined to the amygdala. Twenty control subjects and 82 patients with intractable TLE were studied. Patients who had foreign tissue lesions visible on routine MRI were excluded. All subjects had a hippocampal T2 map and volumetry and an amygdala T2 (AT2) map. Forty-four of the 82 patients (54%) had an abnormal AT2, which was bilateral in 18. Forty-four patients (54%) had unilateral HS on MRI, 25 (57%) of whom had an abnormal AT2. Seven patients (8%) had bilateral HS, four of whom had an abnormal AT2. Thirty-one patients (38%) had normal quantitative hippocampal measures, 15 of whom had an abnormal AT2, which was bilateral in seven. Fluid attenuated inversion recovery (FLAIR) imaging, where appropriate, confirmed that the increased AT2 signal was due to parenchymal changes. Neuropathologic correlates of an increased AT2 included microdysgenesis in one and gliosis in three patients. Patients with an isolated AT2 abnormality were significantly older at the onset of habitual epilepsy and rarely had a history of febrile convulsions, in comparison with patients who had HS. An isolated AT2 abnormality correlated well with interictal EEG findings. The combination of AT2 mapping and FLAIR is a sensitive method to detect lesions that are not seen on routine MRI in the amygdalae of patients with intractable TLE. Further correlational studies will be required to define the role of this technique in the presurgical evaluation of patients with intractable TLE.

For patients with intractable temporal lobe epilepsy (ITLE), resection of the temporal lobe has been proven to be far superior to continued medical management. The goal of this study was to evaluate on a national level whether race and other sociodemographic factors are predictors of receipt of resective treatment for pediatric ITLE. A retrospective cohort study was performed using the Kids' Inpatient Database covering the period of 1997 through 2003. Only children admitted for resection for ITLE (ICD-9-CM 345.41, 345.51; primary procedure code 01.53) were included. Variables studied included patient race, age, sex, and primary payer. Multivariate analyses revealed no significant difference in the odds of undergoing resection for ITLE for black children compared with nonblack children (odds ratio [OR] 0.66, 95% confidence interval [CI] 0.28-1.53, p = 0.327), or between female and male children (OR 1.11, 95% CI 0.76-1.63, p = 0.586). Older children were more likely to undergo resection for ITLE (OR 1.07, 95% CI 1.03-1.11, p < 0.001 per 1 year increase in age), as were children with private insurance (OR 2.21, 95% CI 1.34-3.63, p = 0.002). In this first nationwide analysis of pediatric ITLE, older age and private insurance status independently predicted which children were more likely to receive surgical treatment for ITLE on a national level, whereas sex did not. Black children with ITLE were no less likely to receive surgical intervention than nonblack children. Future nationwide analyses will be required to determine whether these trends for pediatric ITLE surgery remain stable over time.

Glial fibrillary acidic protein (GFAP) levels, a key marker of astrocyte reactivity, increase in response to Alzheimer's disease (AD) pathology, but its role in AD-related neuroinflammation remains unclear. Dexamethasone, a glucocorticoid, modulates inflammation by binding to glucocorticoid receptors, suppressing pro-inflammatory cytokines and immune cell activation. This study investigates the anti-inflammatory effects of glucocorticoids on astroglial and microglial markers in the TgF344-AD rat model. Male TgF344-AD rats (n=8), in an early amyloid plaque stage (7-8 months), received 0.25 mg/kg of dexamethasone (i.p.) for 14 days. After treatment, blood, cerebrospinal fluid (CSF), and brain tissue were collected. We performed [3H]-glutamate uptake assay on acute cortical tissue slices and analyzed the cortical immunocontent and expression of inflammatory, astroglial, and microglial activation markers. Additionally, plasma and CSF glucose levels were measured with a colorimetric assay. Data were analyzed using Student's t-test (p<0.05). We observed higher plasma glucose levels in dexamethasone-treated animals, confirming the systemic treatment efficacy (p=0.0104) (Figure 1A). Additionally, there was a tendency of reduction in CSF glucose levels (Figure 1B). No significant changes in glutamate uptake and glial activation markers were observed (Figure 1-2). However, the cortical expression of C1qB was reduced in dexamethasone-treated animals (p=0.02) and, contradictory, increased in TNF-α was observed (p=0.04) (Figure 2). Our initial results indicate that, despite no changes in glial marker levels, the treatment reduced C1qB levels while paradoxically increasing TNF-α in the TgF344-AD model. Since both TNF-α and C1qB are predominantly secreted by microglia, further studies are warranted to investigate whether dexamethasone induces a distinct microglial phenotype. Additional experiments are necessary to determine if these changes signify a shift in immune balance and whether they have protective or detrimental effects.

Objective To explore the alterations of hippocampal functional connectivity in patients with intractable temporal lobe epilepsy (ITLE) with resting state functional magnetic resonance imaging (rs-fMRI).Methods Eighteen patients with ITLE,admitted to our hospital from August 2013 to May 2014,and 18 healthy controls were chosen in our study; the fMRI data of the two groups were obtained; analysis of the resting state brain functional connectivity was performed by choosing the left and right hippocampus as the regions of interest (ROIs),and then,the differences of hippocampal functional connectivity were compared between ITLE group and healthy control group.Results When the left hippocampus was selected as ROI,significantly enhanced functional connectivity in the ITLE group was observed in the right cuneus,significantly weakened functional connectivity in the ITLE group was observed in the bilateral caudate nucleus,bilateral septal area and right gyrus rectus,as compared with those in the healthy control group (P＜0.05); when the right hippocampus was selected as ROI,significantly enhanced functional connectivity in the ITLE group was observed in the bilateral cuneus,bilateral lingual gyrus,and left calcarine,significantly weakened functional connectivity in the ITLE group was observed in the bilateral superior temporal gyrus,right middle temporal gyrus,left supramarginal gyrus,left precentral gyrus and left postcentral gyrus,as compared with those in the healthy control group (P＜0.05).Conclusion Hippocampal dysfunction of patients with ITLE could be found based on rs-fMRI,which prompts that the hippocampus plays an important role in the epilepsy network of patients with ITLE. Key words: Temporal lobe epilepsy; Functional magnetic resonance imaging; Functional connectivity; Hippocampus

Neuroprotective activity of the α7-nAChR positive allosteric modulator PNU-120596 on short term outcomes after traumatic brain injury.

BackgroundAlzheimer’s disease (AD) is the world’s leading form of dementia. The pathogenesis of AD includes increased brain levels of β‐amyloid peptide oligomers (AβOs), neurotoxins associated with AD. The increase in oligomer concentration is neurotoxic and causes, among the damages, synapse loss, mitochondrial dysfunction and impairment of proteostasis mechanisms. Neuroinflammation, notably the activation of microglia and astrocytes to pro‐inflammatory states, has been associated with the pathogenesis of several neurodegenerative diseases. The current work aimed to evaluate the neuroprotective role of microglia in the context of the pathophysiology of AD.MethodThis study aims to investigate potential modulations in morphology and function of glial cells in experimental models of Alzheimer’s disease (AD), evaluating (1) the in vitro activation of microglia and astrocytes promoted by AβOs, and (2) in vivo microglia and/or astrocytic activation in mice receiving intracerebroventricular (icv) administration of AβOs. Expression of cytokines and glial markers were analyzed by RT PCR and Immunocytochemistry.ResultPreliminary results suggest an increase in glial activation markers, such as GFAP and F4/80, and complement immune system markers such as C1q, 7 days after icv infusion of AβOs. No significant differences were observed in the expression of TNF‐α. Immunocytochemical analyzes suggest greater nuclear factor‐KB translocation in microglial cells treated with AβOs compared to vehicle.ConclusionResults are consistent with an important role of glial cells in the pathogenesis of AD, with glial activity altered and activated in both in vitro and in vivo models. In the face of chronic processes, these cells can remain in an activated state, releasing cytokines, complement components and chemokines, which may contribute to the production and accumulation of Aβ and further exacerbate pathology.

Recent Neuroimaging Techniques in Mild Traumatic Brain Injury

To investigate the relationship between the apolipoprotein (ApoE) epsilon4 allele and memory performance (verbal and nonverbal) in patients with medically intractable temporal lobe epilepsy (TLE) who underwent temporal lobectomy. Presurgical and postsurgical memory performance was examined in 87 adult patients with TLE (epsilon4 = 22; non-epsilon4 = 65) to determine whether the expression of ApoE-epsilon4 may be associated with memory performance in this population and to examine how this relationship may be affected by duration of epilepsy. There was a significant interaction between ApoE-epsilon4 status and duration of epilepsy such that epsilon4 carriers with a long duration of epilepsy demonstrated the poorest memory performance on both verbal and nonverbal measures. This relationship was observed both before and after temporal lobectomy, with little change in test performance over time. The ApoE-epsilon4 allele interacts with longstanding seizures to affect memory performance, both verbal and nonverbal, in patients with medically intractable temporal lobe epilepsy.

ApoE- ∊4 Is Associated with Reduced Memory in Long-Standing Intractable Temporal Lobe Epilepsy. Busch RM, Lineweaver TT, Naugle RI, Kim KH, Gong Y, Tilelli CQ, Prayson RA, Bingaman W, Najm IM, Diaz-Arrastia R. Neurology 2007;68(6):409–414. OBJECTIVE: To investigate the relationship between the apolipoprotein (ApoE) 4 allele and memory performance (verbal and nonverbal) in patients with medically intractable temporal lobe epilepsy (TLE) who underwent temporal lobectomy. METHODS: Presurgical and postsurgical memory performance was examined in 87 adult patients with TLE (4 = 22; non-4 = 65) to determine whether the expression of ApoE-4 may be associated with memory performance in this population and to examine how this relationship may be affected by duration of epilepsy. RESULTS: There was a significant interaction between ApoE-4 status and duration of epilepsy such that 4 carriers with a long duration of epilepsy demonstrated the poorest memory performance on both verbal and nonverbal measures. This relationship was observed both before and after temporal lobectomy, with little change in test performance over time. CONCLUSIONS: The ApoE-4 allele interacts with longstanding seizures to affect memory performance, both verbal and nonverbal, in patients with medically intractable temporal lobe epilepsy.