Synaptic alterations and neuronal firing in human epileptic neocortical excitatory networks.

Epilepsy is a prevalent neurological condition, with underlying neuronal mechanisms involving hyperexcitability and hypersynchrony. Imbalance between excitatory and inhibitory circuits, as well as histological reorganization are relatively well-documented in animal models or even in the human hippocampus, but less is known about human neocortical epileptic activity. Our knowledge about changes in the excitatory signaling is especially scarce, compared to that about the inhibitory cell population. This study investigated the firing properties of single neurons in the human neocortex in vitro, during pharmacological blockade of glutamate receptors, and additionally evaluated anatomical changes in the excitatory circuit in tissue samples from epileptic and non-epileptic patients. Both epileptic and non-epileptic tissues exhibited spontaneous population activity (SPA), NMDA receptor antagonization reduced SPA recurrence only in epileptic tissue, whereas further blockade of AMPA/kainate receptors reversibly abolished SPA emergence regardless of epilepsy. Firing rates did not significantly change in excitatory principal cells and inhibitory interneurons during pharmacological experiments. Granular layer (L4) neurons showed an increased firing rate in epileptic compared to non-epileptic tissue. The burstiness of neurons remained unchanged, except for that of inhibitory cells in epileptic recordings, which decreased during blockade of glutamate receptors. Crosscorrelograms computed from single neuron discharge revealed both mono- and polysynaptic connections, particularly involving intrinsically bursting principal cells. Histological investigations found similar densities of SMI-32-immunopositive long-range projecting pyramidal cells in both groups, and shorter excitatory synaptic active zones with a higher proportion of perforated synapses in the epileptic group. These findings provide insights into epileptic modifications from the perspective of the excitatory system and highlight discrete alterations in firing patterns and synaptic structure. Our data suggest that NMDA-dependent glutamatergic signaling, as well as the excitatory synaptic machinery are perturbed in epilepsy, which might contribute to epileptic activity in the human neocortex.

Bilateral subdural hematoma caused by spontaneous intracranial hypotension originating from a discogenic microspur successfully treated with duraplasty: A case report.

Introduction: Discogenic microspurs are calcified outgrowths from the intervertebral disc which can perforate the dura, causing a leak of cerebrospinal fluid (CSF). Spontaneous leaks of the CSF present a recognized cause of spontaneous intracranial hypotension (SIH). Moreover, subdural hematomas (SDH) are a potentially severe complication of SIH. Research question: We present a case of a bilateral subdural hematoma without orthostatic headaches caused by a discogenic microspur protruding from the T1-2 intervertebral disc. The microspur is conjectured to be the culprit of the leak by ventrally perforating the dura and catalyzing the causal chain leading to the formation of the subdural hemorrhage. Material and methods: A 79-year woman noticed a progressive gait disturbance accompanied by a decline of short-term memory over several months without experiencing orthostatic headaches. Magnetic resonance imaging (MRI) showed extensive bilateral subdural fronto-parietal hematoma, signs of CSF hypotension (dilated venous compartments), and computed tomography (CT) myelography revealed a CSF leak originating at the T1-2 level. Results: The leakage site was treated with microsurgical duraplasty leading to a regression of the symptoms and complete resolution of the subdural hematomas within five postoperative months. Discussion and conclusion: Discogenic microspurs can perforate the dura causing a CSF leak, leading to spontaneous intracranial hypotension, finally resulting in a bilateral subdural hematoma. This constellation of symptoms does not necessarily induce orthostatic headaches and can be treated with microsurgical duraplasty.

Bursting of excitatory cells is linked to interictal epileptic discharge generation in humans.

Knowledge about the activity of single neurons is essential in understanding the mechanisms of synchrony generation, and particularly interesting if related to pathological conditions. The generation of interictal spikes-the hypersynchronous events between seizures-is linked to hyperexcitability and to bursting behaviour of neurons in animal models. To explore its cellular mechanisms in humans we investigated the activity of clustered single neurons in a human in vitro model generating both physiological and epileptiform synchronous events. We show that non-epileptic synchronous events resulted from the finely balanced firing of excitatory and inhibitory cells, which was shifted towards an enhanced excitability in epileptic tissue. In contrast, interictal-like spikes were characterised by an asymmetric overall neuronal discharge initiated by excitatory neurons with the presumptive leading role of bursting pyramidal cells, and possibly terminated by inhibitory interneurons. We found that the overall burstiness of human neocortical neurons is not necessarily related to epilepsy, but the bursting behaviour of excitatory cells comprising both intrinsic and synaptically driven bursting is clearly linked to the generation of epileptiform synchrony.

Fenestrated endovascular repair of a thoracoabdominal aortic aneurysm in chronic dissection / Krónikus aortadissectio talaján kialakult thoracoabdominalis aneurysma endovascularis kezelése fenesztrált sztentgrafttal.

Összefoglaló. Az aortadissectio krónikus stádiumában kialakuló thoracoabdominalis tágulatok megoldása multidiszciplináris megközelítést, nagy felkészültséget és fejlett technológiát igényel. A jellemzoen többlépcsos mutétsorozat mortalitása és morbiditása az endovascularis technológia fejlodésével csökkent, de még mindig jelentos. A fenesztrált endovascularis aortamutét a thoracoabdominalis nyitott mutét alternatívája, mely kisebb mortalitással és morbiditással, rövidebb kórházi tartózkodással jár. Aortadissectio esetén történo alkalmazása az aorta lumenében lévo membrán miatt kihívást jelent. Esetbemutatásunkban egy 56 éves nobeteget demonstrálunk, aki tíz évvel korábban A-típusú dissectio miatt aorta ascendens rekonstrukción esett át. A követés során csaknem a teljes aorta tágulata alakult ki, melynek megoldása három lépésben történt. Az elso lépésben a disszekált aortaív nyitott mutétjét végeztük 'frozen elephant trunk' technikával, majd az aorta descendens tágulatának endovascularis kezelése történt sztentgraft-implantációval. A mutétsorozat záró lépése egy fenesztrált endovascularis aortamutét volt, mely egyben ezen technikának az aortadissectio esetében történt elso hazai alkalmazását jelenti. Orv Hetil. 2021; 162(31): 1260-1264. Summary. Thoracoabdominal aortic aneurysms developing in the chronic phase of an aortic dissection require multidisciplinary approach, experienced operators and advanced technology. The mortality and morbidity rate of these multistage operations were reduced with the latest technical achievements in endovascular repair, but they are still significant. Fenestrated endovascular aortic repair, an alternative of thoracoabdominal open repair, is associated with less mortality and morbidity, shorter hospital stay. Using fenestrated devices in aortic dissection is usually technically demanding due to the dissection membrane. We report the case of a 56-year-old woman, who underwent ascending aortic repair due to type A aortic dissection. During the follow-up, a large thoracoabdominal aneurysm developed involving also the arch. We performed a three-stage operation starting with the open repair of the aortic arch using a 'frozen elephant trunk' device followed by a thoracic endovascular aortic repair of the descending aorta. The final stage was a fenestrated endovascular aortic repair, which is the first use of this technique in aortic dissection in Hungary. Orv Hetil. 2021; 162(31): 1260-1264.

Treatment and Predictors of Recurrent Internal Carotid Artery In-Stent Restenosis.

PURPOSE: We aimed to examine the effectiveness of different therapeutic options for and to identify the possible risk factors of recurrent internal carotid artery (ICA) in-stent restenosis (ISR). METHODS: Forty-six ICA ISRs, which were reintervened at least once, were retrospectively analyzed regarding clinical and imaging characteristics, as well as invasive treatment type (percutaneous transluminal angioplasty [PTA] with a plain balloon, PTA with a drug-eluting balloon [DEB], re-stenting) used. RESULTS: The median follow-up was 29.5 months (IQR, 8.5-52.8 months) in patients who underwent reintervention for ICA ISR. Stent occlusion occurred in 3 patients (6.5%). One ISR recurrence was noted in 10 patients (21.7%); reintervention was carried out in 7 cases (7/10 [70%]; PTA, N = 5; PTA with a DEB, N = 1; re-stenting, N = 1), while 3 patients (3/10; 30%) received best medical treatment. Two ISR recurrences were observed in 3 patients (6.5%); all of them underwent reintervention (PTA, N = 1; PTA with a DEB, N = 2). Three ISR recurrences were seen in 1 patient (2.2%), who was treated with PTA. No recurrence was observed in those patients, who had DEB treatment. Multiple logistic regression analysis revealed statin therapy to be a protective factor against recurrent ISR (OR, 0.17; 95% CI, 0.03-0.84; P = .029). CONCLUSION: Our study suggests that PTA with a DEB is the most effective for the treatment of recurrent ISR, and confirms the importance of statin use in patients who have had a carotid reintervention.

Differences in guidelines for patients with carotid artery stenosis in some European countries / A nyaki veroér-szukületes betegek ellátási irányelveinek különbségei Európa különbözo országaiban.

Összefoglaló. A tudomány jelenlegi állása szerint - csoportok összehasonlítására épülo matematikai-statisztikai eszközökkel - a leginkább hatékonynak és hatásosnak vélt kezelési módszerek szisztematikus elemzése mentén, a bizonyítékokon alapuló irányelveken nyugvó gyógyító munkát tekintjük követendonek. A nyaki veroérszukület ellátása esetén az utóbbi években elkészült mind a hazai, mind az európai irányelv, mindemellett a társszakmák irányelveiben is megjelentek kezelési javaslatok. Közleményünkben összehasonlítottuk a témában publikált magyar, angol, német és olasz nyelvu, valamint az európai társaságok által kiadott irányelveket. Az irányelvek alapelveikben hasonlóak, formailag és tartalmilag azonban jelentos (idonként egymásnak ellentmondani látszó) különbségeket találhatunk. Az ellentmondások három leggyakoribb oka: 1) az egyes irányelvek által kituzött célok különbözosége, 2) az aszimptomatikus és szimptomatikus betegcsoport definíciói, valamint 3) az eltéro evidenciaszintek. Az irányelvek összevetése alapján a tünetes, szignifikáns nyaki veroérszukületek sebészi ellátása evidenciának tekintheto. A szimptomatikus nyaki veroérszukület a definíció szerint ellenoldali cerebralis ischaemia okozta, tranziens vagy definitív plegia, paresis, aphasia és az azonos oldali arteria centralis retinae embolisatiója miatti amaurosis fugax. A tünetmentes nyaki veroérszukületek ellátása tekintetében az európai és a nemzeti irányelvek nem azonosak, ezen esetek terápiás döntése egyéni mérlegelést igényel. Tünetmentes, 70%-os stenosis esetén vascularteam-konzílium javasolt. Orv Hetil. 2020; 161(51): 2139-2145. Summary. The correct practice is the one that is proven to be the most effective based on systematic statistical analyses of different treatment methods, and is applied according to evidence-based principles. In recent years, not only has the European Society of Vascular Surgery created a guideline about the management of supra-aortic steno-occlusive disease, but some nations' vascular surgical societies and related disciplines have also developed their own guidance. In this paper, the guidelines by the European societies on the clinical care of patients with carotid artery luminal narrowing is compared to national guidelines published in Hungarian, English, German, and Italian. Although the fundamental points of the guidelines are similar, there are some important differences among them both in presentation and in content; as a result, they sometimes appear to be contradictory. The three main sources of inconsistency are the various goals, the discrepancy in the definition of symptomatic and asymptomatic carotid artery stenosis, and the bias arising from the use of distinct evidence levels. A comparison of guidelines suggests that the treatment of symptomatic significant carotid artery stenosis with surgery can be considered evidence. Symptomatic carotid artery stenosis is defined as transient or definite plegia, paresis, aphasia due to cerebral ischemia, and monocular blindness caused by embolism in the central retinal artery. However, in the case of asymptomatic 70% or greater carotid artery stenosis, the guidelines are quite heterogeneous, and these patients require individual consideration and a vascular team decision is recommended. Orv Hetil. 2020; 161(51): 2139-2145.

Reorganization of Large-Scale Functional Networks During Low-Frequency Electrical Stimulation of the Cortical Surface.

We investigated the functional network reorganization caused by low-frequency electrical stimulation (LFES) of human brain cortical surface. Intracranial EEG data from subdural grid positions were analyzed in 16 pre-surgery epileptic patients. LFES was performed by injecting current pulses (10mA, 0.2ms pulse width, 0.5Hz, 25 trials) into all adjacent electrode contacts. Dynamic functional connectivity analysis was carried out on two frequency bands (low: 1-4Hz; high: 10-40Hz) to investigate the early, high frequency and late, low frequency responses elicited by the stimulation. The centralization increased in early compared to late responses, suggesting a more prominent role of direct neural links between primarily activated areas and distant brain regions. Injecting the current into the seizure onset zone (SOZ) evoked a more integrated functional topology during the early (N1) period of the response, whereas during the late (N2) period - regardless of the stimulation site - the connectedness of the SOZ was elevated compared to the non-SOZ tissue. The abnormal behavior of the epileptic sub-network during both part of the responses supports the idea of the pathogenic role of impaired inhibition and excitation mechanisms in epilepsy.

Atmospheric fronts as minor cardiovascular risk factors, a new approach to preventive cardiology.

BACKGROUND: Cardiovascular diseases are the number one cause of death globally and represent 31% of all global deaths. The aim of our study was to determine the influence of front effects on acute cardiovascular diseases (ACVDs). METHODS: We obtained all ACVD admissions in a Central-European region, Hungary, Budapest. A time-series analysis was applied to 6499 morbidity cases during a five-year period (2009-2013). Poisson-regression model was used and adjusted for air temperature, pressure, humidity, wind velocity, their interactions and seasonality to assess the association of fronts and ACVDs. RESULTS: There is a positive significant association between ACVDs and a cold front effect lagged by one day (p=0.018) with a relative risk (RR) of 1.095 [95% CI (1.021,1.181)]. Our findings show that among patient subgroups with major cardiovascular risk factors (hypertension, diabetes, hyperlipidemia, history of CVDs) the patterns are similar, but occluded fronts also have a significant effect. CONCLUSION: Atmospheric fronts could play an important role in the pathogenesis of ACVDs. Our findings might help to provide a better understanding about fronts as minor cardiovascular risk factors and to organize medical prevention more effectively. Our research project may become a basis of a new field of preventive cardiovascular medicine in the future.

Presence of synchrony-generating hubs in the human epileptic neocortex.

KEY POINTS: •Initiation of pathological synchronous events such as epileptic spikes and seizures is linked to the hyperexcitability of the neuronal network in both humans and animals. •In the present study, we show that epileptiform interictal-like spikes and seizures emerged in human neocortical slices by blocking GABAA receptors, following the disappearance of the spontaneously occurring synchronous population activity. •Large variability of temporally and spatially simple and complex spikes was generated by tissue from epileptic patients, whereas only simple events appeared in samples from non-epileptic patients. •Physiological population activity was associated with a moderate level of principal cell and interneuron firing, with a slight dominance of excitatory neuronal activity, whereas epileptiform events were mainly initiated by the synchronous and intense discharge of inhibitory cells. •These results help us to understand the role of excitatory and inhibitory neurons in synchrony-generating mechanisms, in both epileptic and non-epileptic conditions. ABSTRACT: Understanding the role of different neuron types in synchrony generation is crucial for developing new therapies aiming to prevent hypersynchronous events such as epileptic seizures. Paroxysmal activity was linked to hyperexcitability and to bursting behaviour of pyramidal cells in animals. Human data suggested a leading role of either principal cells or interneurons, depending on the seizure morphology. In the present study, we aimed to uncover the role of excitatory and inhibitory processes in synchrony generation by analysing the activity of clustered single neurons during physiological and epileptiform synchronies in human neocortical slices. Spontaneous population activity was detected with a 24-channel laminar microelectrode in tissue derived from patients with or without preoperative clinical manifestations of epilepsy. This population activity disappeared by blocking GABAA receptors, and several variations of spatially and temporally simple or complex interictal-like spikes emerged in epileptic tissue, whereas peritumoural slices generated only simple spikes. Around one-half of the clustered neurons participated with an elevated firing rate in physiological synchronies with a slight dominance of excitatory cells. By contrast, more than 90% of the neurons contributed to interictal-like spikes and seizures, and an intense and synchronous discharge of inhibitory neurons was associated with the start of these events. Intrinsically bursting principal cells fired later than other neurons. Our data suggest that a balanced excitation and inhibition characterized physiological synchronies, whereas disinhibition-induced epileptiform events were initiated mainly by non-synaptically synchronized inhibitory neurons. Our results further highlight the differences between humans and animal models, and between in vivo and (pharmacologically manipulated) in vitro conditions.

Personalized microstructural evaluation using a Mahalanobis-distance based outlier detection strategy on epilepsy patients' DTI data - Theory, simulations and example cases.

Quantitative MRI methods have recently gained extensive interest and are seeing substantial developments; however, their application in single patient vs control group comparisons is often limited by inherent statistical difficulties. One such application is detecting malformations of cortical development (MCDs) behind drug resistant epilepsies, a task that, especially when based solely on conventional MR images, may represent a serious challenge. We aimed to develop a novel straightforward voxel-wise evaluation method based on the Mahalanobis-distance, combining quantitative MRI data into a multidimensional parameter space and detecting lesion voxels as outliers. Simulations with standard multivariate Gaussian distribution and resampled DTI-eigenvalue data of 45 healthy control subjects determined the optimal critical value, cluster size threshold, and the expectable lesion detection performance through ROC-analyses. To reduce the effect of false positives emanating from registration artefacts and gyrification differences, an automatic classification method was applied, fine-tuned using a leave-one-out strategy based on diffusion and T1-weighted data of the controls. DWI processing, including thorough corrections and robust tensor fitting was performed with ExploreDTI, spatial coregistration was achieved with the DARTEL tools of SPM12. Additional to simulations, clusters of outlying diffusion profile, concordant with neuroradiological evaluation and independent calculations with the MAP07 toolbox were identified in 12 cases of a 13 patient example population with various types of MCDs. The multidimensional approach proved sufficiently sensitive in pinpointing regions of abnormal tissue microstructure using DTI data both in simulations and in the heterogeneous example population. Inherent limitations posed by registration artefacts, age-related differences, and the different or mixed pathologies limit the generalization of specificity estimation. Nevertheless, the proposed statistical method may aid the everyday examination of individual subjects, ever so more upon extending the framework with quantitative information from other modalities, e.g. susceptibility mapping, relaxometry, or perfusion.

Intracortical Dynamics Underlying Repetitive Stimulation Predicts Changes in Network Connectivity.

Targeted stimulation can be used to modulate the activity of brain networks. Previously we demonstrated that direct electrical stimulation produces predictable poststimulation changes in brain excitability. However, understanding the neural dynamics during stimulation and its relationship to poststimulation effects is limited but critical for treatment optimization. Here, we applied 10 Hz direct electrical stimulation across several cortical regions in 14 human subjects (6 males) implanted with intracranial electrodes for seizure monitoring. The stimulation train was characterized by a consistent increase in high gamma (70-170 Hz) power. Immediately post-train, low-frequency (1-8 Hz) power increased, resulting in an evoked response that was highly correlated with the neural response during stimulation. Using two measures of network connectivity, corticocortical evoked potentials (indexing effective connectivity), and theta coherence (indexing functional connectivity), we found a stronger response to stimulation in regions that were highly connected to the stimulation site. In these regions, repeated cycles of stimulation trains and rest progressively altered the stimulation response. Finally, after just 2 min (∼10%) of repetitive stimulation, we were able to predict poststimulation connectivity changes with high discriminability. Together, this work reveals a relationship between stimulation dynamics and poststimulation connectivity changes in humans. Thus, measuring neural activity during stimulation can inform future plasticity-inducing protocols.SIGNIFICANCE STATEMENT Brain stimulation tools have the potential to revolutionize the treatment of neuropsychiatric disorders. Despite the widespread use of brain stimulation techniques such as transcranial magnetic stimulation, the therapeutic efficacy of these technologies remains suboptimal. This is in part because of a lack of understanding of the dynamic neural changes that occur during stimulation. In this study, we provide the first detailed characterization of neural activity during plasticity induction through intracranial electrode stimulation and recording in 14 medication-resistant epilepsy patients. These results fill a missing gap in our understanding of stimulation-induced plasticity in humans. In the longer-term, these data will also guide our translational efforts toward non-invasive, personalized, closed-loop neuromodulation therapy for neurological and psychiatric disorders in humans.

Complex effects of atmospheric parameters on acute cardiovascular diseases and major cardiovascular risk factors: data from the CardiometeorologySM study.

Several studies have examined the cardiovascular effects of atmospheric parameters as separate factors; however, few have investigated atmospheric parameters' joint effects. We aim to explore the joint effects of atmospheric parameters on acute cardiovascular diseases (ACVDs) and on major cardiovascular risk factors (CRFs). We correlated all ACVD admissions with major CRFs and local atmospheric conditions during a 5-year study period. A seasonal variation was detected in a higher incidence rate during cold atmospheric conditions. There were significant incidence relative ratios, including: 1.140 (95% CI [1.020, 1.283]) for daily temperature change (≥5 °C); 0.991 (95% CI [0.988, 0.994]) for average daily temperature; and 1.290 (95% CI [1.090, 1.599]) for the interaction of daily temperature change (≥5 °C) with humidity change (≥40%). We observed a significant association between the atmospheric parameters' joint effects and hyperlipidaemia, diabetes, and previous ACVDs. Patients with diabetes had the highest significant incidence relative ratio at 2.429 (95% CI [1.088, 5.424]) for humidity-temperature interactions. Thus, the atmospheric parameters' joint effects play an important role as minor CRFs. These unfavourable atmospheric situations are predicted to increase the number of ACVDs mainly. Our study may help to organize prevention strategies more effectively and to reduce cardiovascular risks.

Incomplete circle of Willis is associated with a higher incidence of neurologic events during carotid eversion endarterectomy without shunting.

OBJECTIVE: A complete circle of Willis (CoW) is considered an important collateral network to maintain blood flow during cross-clamping in carotid endarterectomy (CEA). The aim of this study was to evaluate the impact of an incomplete CoW with isolated middle cerebral artery (iMCA) on immediate neurologic events (INEs) after CEA. METHODS: We prospectively collected the clinical data and outcomes of 902 patients who underwent CEA under general anesthesia between 2013 and 2015. All patients had preoperative computed tomography angiography of the extracranial and intracranial cerebral circulation. Indications were asymptomatic (52%) and symptomatic (48%) carotid artery disease. Patients who had CEA with shunt (n = 35) and those with inadequate intracranial imaging to assess CoW were excluded (n = 322) only. Computed tomography angiography images were reviewed retrospectively and independently by two vascular radiologists who were blinded for treatment outcomes. Imaging assessment included the vertebral and carotid circulation and each segment of the CoW, which was classified as normal, hypoplastic (diameter < 0.8 mm) or absent. The ipsilateral MCA was considered isolated if there was an absence of the anterior and posterior communicating branches from the contralateral carotid or posterior circulations. INE was defined as any transient ischemic attack (TIA) and stroke diagnosed immediately after the procedure. RESULTS: Of the 545 included patients (331 males; mean age, 69 ± 8 years), 12 (2.2%) had a stroke in the postoperative period. There were 20 INEs (8 strokes and 12 TIAs). A complete CoW was rare; it was only detected in 19 patients (3.5%) and an iMCA was found in 34 patients (6.3%). When at least one collateral circulation was complete (in 330 patients), we observed only four INEs (1.2%). Of the 34 patients with an iMCA, 8 (24%) had INE (6 TIAs and 2 strokes). Overall, iMCA was an independent predictor of INEs (odds ratio, 11.12; 95% confidence interval, 3.57-35.87; P < .001). With logistic regression, the model included hypertension, smoking, diabetes, hyperlipidemia, carotid clamping time (minutes), contralateral significant internal carotid artery stenosis of greater than 90%, ipsilateral significant internal carotid artery stenosis of greater than 90%, preoperative symptoms in 6 months, and iMCA; above iMCA only symptomatic patients had significant risk (odds ratio, 3.34; 95% confidence interval, 1.19-9.73; P = .02), whereas all other parameters were not significant. CONCLUSIONS: An iMCA carries more than a 10-fold higher the risk of INEs after CEA with cross-clamping without shunt protection. In these patients, routine shunting is recommended to prevent INEs.

Hyperexcitability of the network contributes to synchronization processes in the human epileptic neocortex.

KEY POINTS: Hyperexcitability and hypersynchrony of neuronal networks are thought to be linked to the generation of epileptic activity in both humans and animal models. Here we show that human epileptic postoperative neocortical tissue is able to generate two different types of synchronies in vitro. Epileptiform bursts occurred only in slices derived from epileptic patients and were hypersynchronous events characterized by high levels of excitability. Spontaneous population activity emerged in both epileptic and non-epileptic tissue, with a significantly lower degree of excitability and synchrony, and could not be linked to epilepsy. These results help us to understand better the role of excitatory and inhibitory neuronal circuits in the generation of population events, and to define the subtle border between physiological and pathological synchronies. ABSTRACT: Interictal activity is a hallmark of epilepsy diagnostics and is linked to neuronal hypersynchrony. Little is known about perturbations in human epileptic neocortical microcircuits, and their role in generating pathological synchronies. To explore hyperexcitability of the human epileptic network, and its contribution to convulsive activity, we investigated an in vitro model of synchronous burst activity spontaneously occurring in postoperative tissue slices derived from patients with or without preoperative clinical and electrographic manifestations of epileptic activity. Human neocortical slices generated two types of synchronies. Interictal-like discharges (classified as epileptiform events) emerged only in epileptic samples, and were hypersynchronous bursts characterized by considerably elevated levels of excitation. Synchronous population activity was initiated in both epileptic and non-epileptic tissue, with a significantly lower degree of excitability and synchrony, and could not be linked to epilepsy. However, in pharmacoresistant epileptic tissue, a higher percentage of slices exhibited population activity, with higher local field potential gradient amplitudes. More intracellularly recorded neurons received depolarizing synaptic potentials, discharging more reliably during the events. Light and electron microscopic examinations showed slightly lower neuron densities and higher densities of excitatory synapses in the human epileptic neocortex. Our data suggest that human neocortical microcircuits retain their functionality and plasticity in vitro, and can generate two significantly different synchronies. We propose that population bursts might not be pathological events while interictal-like discharges may reflect the epileptogenicity of the human cortex. Our results show that hyperexcitability characterizes the human epileptic neocortical network, and that it is closely related to the emergence of synchronies.

The Hippocampus and Amygdala Are Integrators of Neocortical Influence: A CorticoCortical Evoked Potential Study.

Brain stimulation is increasingly viewed as an effective approach to treat neuropsychiatric disease. The brain's organization in distributed networks suggests that the activity of a remote brain structure could be modulated by stimulating cortical areas that strongly connect to the target. Most connections between cerebral areas are asymmetric, and a better understanding of the relative direction of information flow along connections could improve the targeting of stimulation to influence deep brain structures. The hippocampus and amygdala, two deep-situated structures that are crucial to memory and emotions, respectively, have been implicated in multiple neurological and psychiatric disorders. We explored the directed connectivity between the hippocampus and amygdala and the cerebral cortex in patients implanted with intracranial electrodes using corticocortical evoked potentials (CCEPs) evoked by single-pulse electrical stimulation. The hippocampus and amygdala were connected with most of the cortical mantle, either directly or indirectly, with the inferior temporal cortex being most directly connected. Because CCEPs assess the directionality of connections, we could determine that incoming connections from cortex to hippocampus were more direct than outgoing connections from hippocampus to cortex. We found a similar, although smaller, tendency for connections between the amygdala and cortex. Our results support the roles of the hippocampus and amygdala to be integrators of widespread cortical influence. These results can inform the targeting of noninvasive neurostimulation to influence hippocampus and amygdala function.

[Surgical treatment of atypical aortic coarctation -- long-term results]. / Atípusos aortacoarctatiók sebészi kezelésének hosszú távú eredményei.

INTRODUCTION: Aortic coarctation is a frequent congenital cardiovascular disorder representing 5-8% of all cases. It is typically localized in the isthmic region. However, in about 1% of cases coarctation may develop in atypical sites of the aorta and it is frequently complicated with severe hypertension. AIM: The aim of the authors was to present diagnostic and surgical methods used in 27 patients with atypical aortic coarctation during the last 35 years with special interest on long-term results. METHOD: There was a great advance in diagnostic and surgical treatment methods during the time period analyzed in this study. Nowadays morphologic diagnosis is most commonly obtained using computed tomography angiography and magnetic resonance angiography. Some cases were treated with endovascular techniques, but the authors used also a wide variety of surgical approaches in these patients with atypical aortic coarctation. RESULTS: No patient died after surgery and hypertension was reduced in all patients, too. Reintervention was necessary in patients operated in childhood due to change of body measures. CONCLUSIONS: Atypical aortic coarctation can be treated surgically with good early and late outcomes. Somatic growth of children may indicate surgical revision.

Proximal scalloped custom-made Relay® stent graft in chronic type B dissection: endovascular repair in a drug abuser patient.

The best solution for enlarging chronic type B aortic dissection is not known. Hybrid surgical and endovascular procedures offer a reliable solution in such circumstances, but technically complex stent-graft designs are sometimes needed when the treatment segment of the aorta presents anatomical challenges. We report a case of a proximally scalloped custom-made stent-graft implantation following left subclavian artery transposition in a formerly cocaine-abuser patient. The one-month follow-up computed tomography angiography showed a proximal endoleak (type Ia) which was successfully solved by coil embolization. Proximally scalloped stent grafts offer a reliable solution in complex aortic dissections involving the supra-aortic branches.