Semiology, EEG, and neuroimaging findings in temporal lobe epilepsies

Central expression and peripheral levels of MMP-9 and TIMP-1 in patients with temporal lobe epilepsy

PURPOSE

Thirty percent of epilepsy patients are drug-resistant (DR) and, in adults, temporal lobe epilepsy (TLE) is the most common form of DR- epilepsy. Patients with TLE exhibit a neuroinflammatory response associated with blood-brain barrier dysfunction. In this context, the main aim of our study was to evaluate peripheral levels and central expression of MMP-9 and TIMP-1 in TLE patients and assess their association with drug resistance and inflammatory markers.

METHODS

Three groups of patients were included, 41 DR-TLE patients, 10 non-DR-TLE patients, and 20 healthy controls (HC). MMP-9 and TIMP-1 were assessed by ELISA in sera in all patients, and by immunohistochemistry and immunofluorescence in the cerebral cortex and hippocampus in a subgroup of DR-TLE patients and 3 controls. Peripheral and central cells phenotypes were determined by flow cytometry and immunohistochemistry, respectively, while cytokines were determined in the two compartments by ELISA.

RESULTS

Central expression of MMP-9 and TIMP-1, and peripheral expression of TIMP-1, were higher in DR-TLE patients than in controls, while peripheral levels of MMP-9 and TIMP-1 were higher in DR-TLE patients compared with non-DRE-TLE patients. MMP-9 levels in serum increased with seizure severity and decreased after successful epilepsy surgery. MMP-9 levels in the serum of DR-TLE patients were positively correlated with several markers of peripheral inflammation, which was not the case in the groups of non-DR-TLE patients and healthy controls. MMP-9 and TIMP-1 expression in the hippocampus of DR-TLE patients correlated positively with various markers of central inflammation. Negative correlations between their peripheral levels and central expression were observed.

CONCLUSION

MMP-9 and TIMP-1 are markers that seem to be associated to the central and peripheral inflammatory reaction occurring in DR-TLE patients. The significant negative correlations between central and peripheral markers are interesting to note, and further studies need to be carried out to fully understand the complex regulation of these proteins during DR epilepsy.

Working memory deficit in patients with focal epilepsy is associated with higher interictal theta connectivity

OBJECTIVE

Interictal cognitive disturbances are frequent in patients with focal epilepsies and the links with alteration of resting state brain oscillations are not well known. Changes in theta oscillations, may contribute to cognitive impairment. This study aimed to investigate whether changes in theta activity are related to cognitive disturbances.

METHODS

Retrospective data of 23 patients with temporal/frontal lobe epilepsy were included. Theta connectivity, power and interictal spikes rate from five-minute interictal resting state stereoelectroencephalography datasets were computed. Cognitive performances were assessed by Wechsler Intelligence Scale (WAIS-IV) and Weschler Memory Scale (WMS-III). Linear regression was performed to evaluate effect of interictal activity and seizure related parameters on cognitive scores.

RESULTS

WAIS-IV working memory score in patients with epilepsy showed negative correlation with frontotemporal theta connectivity (F(1,17) = 5,239, p = 0,036, R2 = 0,200, β = -0,497). Moreover, theta connectivity was correlated with mesial temporal spike rate and theta power (F(2,17) = 10,967, p = 0,001, adj.R2 = 0,540).

CONCLUSIONS

Patients with focal epilepsy often encounter compromised cognitive functions, particularly notable in the domain of working memory. This impairment might be attributed to physiological mechanisms involving increased theta connectivity within the frontotemporal regions and interictal spiking.

SIGNIFICANCE

Our study highlights the relation between theta connectivity and working memory impairments in patients with focal epilepsy.

Functional Neurological Disorder: Diagnostic Pitfalls and Differential Diagnostic Considerations

Functional neurologic disorder (FND) is a "rule-in" diagnosis, characterized by positive examination signs or semiological features. Similar to other clinical diagnoses, providers should ideally see robustly present features, including if possible the identification of multiple features consistent with FND for the diagnosis to be made with a high degree of certainty. Diagnostic pitfalls need to be guarded against and vary depending on FND symptom subtype and the specific patient presentation. This perspective article aims to review pitfalls based on an FND symptom subtype, as well as discuss differential diagnostic considerations with respect to both neurologic and psychiatric entities.

Cortical type: a conceptual tool for meaningful biological interpretation of high-throughput gene expression data in the human cerebral cortex

The interpretation of massive high-throughput gene expression data requires computational and biological analyses to identify statistically and biologically significant differences, respectively. There are abundant sources that describe computational tools for statistical analysis of massive gene expression data but few address data analysis for biological significance. In the present article we exemplify the importance of selecting the proper biological context in the human brain for gene expression data analysis and interpretation. For this purpose, we use cortical type as conceptual tool to make predictions about gene expression in areas of the human temporal cortex. We predict that the expression of genes related to glutamatergic transmission would be higher in areas of simpler cortical type, the expression of genes related to GABAergic transmission would be higher in areas of more complex cortical type, and the expression of genes related to epigenetic regulation would be higher in areas of simpler cortical type. Then, we test these predictions with gene expression data from several regions of the human temporal cortex obtained from the Allen Human Brain Atlas. We find that the expression of several genes shows statistically significant differences in agreement with the predicted gradual expression along the laminar complexity gradient of the human cortex, suggesting that simpler cortical types may have greater glutamatergic excitability and epigenetic turnover compared to more complex types; on the other hand, complex cortical types seem to have greater GABAergic inhibitory control compared to simpler types. Our results show that cortical type is a good predictor of synaptic plasticity, epigenetic turnover, and selective vulnerability in human cortical areas. Thus, cortical type can provide a meaningful context for interpreting high-throughput gene expression data in the human cerebral cortex.

Evaluation of the Antioxidant Activity of Levetiracetam in a Temporal Lobe Epilepsy Model

Epilepsy is a neurological disorder in which it has been shown that the presence of oxidative stress (OS) is implicated in epileptogenesis. The literature has shown that some antiseizure drugs (ASD) have neuroprotective properties. Levetiracetam (LEV) is a drug commonly used as an ASD, and in some studies, it has been found to possess antioxidant properties. Because the antioxidant effects of LEV have not been demonstrated in the chronic phase of epilepsy, the objective of this study was to evaluate, for the first time, the effects of LEV on the oxidant–antioxidant status in the hippocampus of rats with temporal lobe epilepsy (TLE). The in vitro scavenging capacity of LEV was evaluated. LEV administration in rats with TLE significantly increased superoxide dismutase (SOD) activity, increased catalase (CAT) activity, but did not change glutathione peroxidase (GPx) activity, and significantly decreased glutathione reductase (GR) activity in comparison with epileptic rats. LEV administration in rats with TLE significantly reduced hydrogen peroxide (H2O2) levels but did not change lipoperoxidation and carbonylated protein levels in comparison with epileptic rats. In addition, LEV showed in vitro scavenging activity against hydroxyl radical (HO•). LEV showed significant antioxidant effects in relation to restoring the redox balance in the hippocampus of rats with TLE. In vitro, LEV demonstrated direct antioxidant activity against HO•.