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.

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.

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.

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.

Unusual Open Surgical Repair of a Type IB Endoleak and a Giant Symptomatic Aortic Aneurysm following Stent Grafting for Type B Aortic Dissection.

Treatment of type IB endoleak after thoracic endovascular aortic repair (TEVAR) for post-dissection aortic aneurysm usually includes attempts of endovascular interventions using coils or plugs to occlude the false lumen or placement of a distal fenestrated endograft. Open conversion usually requires deep hypothermia and circulatory arrest with the associated increased mortality and complications. We present a case of a young patient with a 90 mm descending thoracic aneurysm caused by a chronic type B aortic dissection. A type II endoleak after TEVAR was successfully treated with left subclavian artery transposition. The patient had a rapidly increasing aortic aneurysm with a persistent type IB endoleak in spite of placement of an Amplatzer plug into the false lumen of the dissection. He developed progressive acute compression of the main stem bronchi by the aneurysm sac and his dyspnea worsened by an acute pulmonary embolism treated with anticoagulation. Adequate oxygenation could only be achieved with mechanical ventilation using a double-lumen endobronchial tube. A left thoracotomy was performed and the type IB endoleak was treated with bending of the distal aorta around the stent graft with a Dacron graft sleeve. Aortic clamping and circulatory support devices were avoided. The sac of the aneurysm was opened, a giant hematoma was evacuated, and aneurysmorrhaphy was performed to cover the stent graft. There was no residual endoleak and the bronchi were decompressed. The patient recovered after prolonged hospitalization and he was discharged home in good condition 24 days after admission. He returned to his normal activities and is asymptomatic 5 months later. Computed tomographic angiography showed decreased aneurysm sac, no evidence of endoleak, no residual pulmonary embolus, and no bronchial compression.

[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.

Corticocortical evoked potentials reveal projectors and integrators in human brain networks.

The cerebral cortex is composed of subregions whose functional specialization is largely determined by their incoming and outgoing connections with each other. In the present study, we asked which cortical regions can exert the greatest influence over other regions and the cortical network as a whole. Previous research on this question has relied on coarse anatomy (mapping large fiber pathways) or functional connectivity (mapping inter-regional statistical dependencies in ongoing activity). Here we combined direct electrical stimulation with recordings from the cortical surface to provide a novel insight into directed, inter-regional influence within the cerebral cortex of awake humans. These networks of directed interaction were reproducible across strength thresholds and across subjects. Directed network properties included (1) a decrease in the reciprocity of connections with distance; (2) major projector nodes (sources of influence) were found in peri-Rolandic cortex and posterior, basal and polar regions of the temporal lobe; and (3) major receiver nodes (receivers of influence) were found in anterolateral frontal, superior parietal, and superior temporal regions. Connectivity maps derived from electrical stimulation and from resting electrocorticography (ECoG) correlations showed similar spatial distributions for the same source node. However, higher-level network topology analysis revealed differences between electrical stimulation and ECoG that were partially related to the reciprocity of connections. Together, these findings inform our understanding of large-scale corticocortical influence as well as the interpretation of functional connectivity networks.

[Invasive neuromodulation in the treatment of drug-resistant epilepsies]. / Invazív neuromoduláció a gyógyszerrezisztens epilepsziák kezelésében.

Neuromodulation is one of the most developing new disciplines of medical science, which examines how electrical, chemical and mechanical interventions can modulate or change the functioning of the central and peripheral nervous system. Neuromodulation is a reversible form of therapy which uses electrical or mechanical stimulation or centrally-delivered drugs to modulate the abnormal function of the central nervous system in pain, spasticity, epilepsy, movement and psychiatric disorders, and certain cardiac, incontinency, visual and auditory diseases. Neuromodulation therapy has two major branches. Non-invasive neuromodulation includes transcranial magnetic simulation, direct current stimulation and transcutaneous electric nerve stimulation. Invasive neuromodulation includes deep brain stimulation, cortical stimulation, spinal cord stimulation, peripheral nerve stimulation, sacral nerve simulation, and subcutan stimulation. In this article the authors overview the apparently available neural interface technologies in epilepsy surgery.

A medialis visceralis rotáció szerepe a suprarenalis aorta sebészetében.

INTRODUCTION: The adequate exposure of the upper abdominal aorta and its side branches are essential for vascular reconstruction of this region. Besides the traditional transperitoneal, retroperitoneal approach or thoracolaparotomy, left medial visceral rotation (MVR) is an option to explore this hardly accessible region. We present our MVR experiences in aortic surgery. METHODS: Using median or subcostal laparotomy we mobilised the left colon, the spleen, the pancreas and performed dissection in the retroperitoneal area leaving the left kidney in place. The indications of surgery were suprarenal aneurysm in one case, extensively calcified aortic atherosclerosis causing significant stenosis in three cases, postoperative anastomotic pseudoaneurysm in one case and type B aortic dissection causing malperfusion in one case. We performed two thrombendarterectomies (TEA), one TEA with aortobifemoral bypass grafting, two aortic interposition with dacron prosthesis and cryopreserved homograft and one aortic refenestration. RESULTS: the median age was 58 years (43-72). The average operation time was 231 ± 80 minutes, average supraceliac crossclamping time was 43 ± 15 minutes. We used cell saver in three cases. Average hospital stay was 16.16 ± 13.53 days. One patient suffered spleen capsule injury requiring splenectomy and 2 patients had reoperation because of bleeding. Two patients developed renal failure, one of them required long-term dialysis. No death, pancreatitis or bowel necrosis occurred. CONCLUSIONS: Based on trauma experience, transabdominal medial visceral rotation provides a good exposure for acute or elective vascular reconstruction of the upper abdominal aortic segment. The intraoperative bleeding control, the approach of the distal part of visceral arteries is more accessible using laparotomy and lateral aortic exploration. The thoracolaparotomy with opening of two body cavities causes higher morbidity, mainly pulmonary complications. Further advantage of MVR is the direct access of abdominal organs and its vessels. During surgery the lesions of parenchymal organs (spleen, pancreas), the intestine and the compression of mesenterium must be avoided.

Fenesztrált stent-graft beültetés Magyarországon.

CASE REPORT: The first case was a 77-year-old man with 5.6 cm juxtarenal abdominal aortic aneurysm who presented with multiple comorbidities. The patient had a single left kidney. A custom-made, single fenestrated stent graft was implanted successfully. The one-month follow-up showed a patent left renal fenestration without evidence of any endoleaks. Four months after the operation the patient was admitted with acute uremia. Imaging studies revealed an occluded left renal stent, which was successfully reopened. The second case was a 71-year-old man with 8.0 cm juxtarenal aneurysm. He presented with severe coronary artery disease among other multiple comorbidities in his medical history. He was successfully treated with a 3-vessel custom-made fenestrated stent graft to the renal and the superior mesenteric arteries. The one-month CT imaging revealed patent fenestrations without endoleaks. DISCUSSION: With the development of fenestrated endograft technology, complex aneurysms with visceral artery involvement can be treated with complete endovascular approaches. The first fenestrated endovascular case in Hungary was treated in the Heart and Vascular Center of Semmelweis University, Budapest. The short and middle-term results are offering improved clinical results when compared with conventional surgery, but the long-term outcomes are difficult to ascertain from the current published series.

Neurophysiological investigation of spontaneous correlated and anticorrelated fluctuations of the BOLD signal.

Analyses of intrinsic fMRI BOLD signal fluctuations reliably reveal correlated and anticorrelated functional networks in the brain. Because the BOLD signal is an indirect measure of neuronal activity and anticorrelations can be introduced by preprocessing steps, such as global signal regression, the neurophysiological significance of correlated and anticorrelated BOLD fluctuations is a source of debate. Here, we address this question by examining the correspondence between the spatial organization of correlated BOLD fluctuations and correlated fluctuations in electrophysiological high γ power signals recorded directly from the cortical surface of 5 patients. We demonstrate that both positive and negative BOLD correlations have neurophysiological correlates reflected in fluctuations of spontaneous neuronal activity. Although applying global signal regression to BOLD signals results in some BOLD anticorrelations that are not apparent in the ECoG data, it enhances the neuronal-hemodynamic correspondence overall. Together, these findings provide support for the neurophysiological fidelity of BOLD correlations and anticorrelations.

Evoked effective connectivity of the human neocortex.

The role of cortical connectivity in brain function and pathology is increasingly being recognized. While in vivo magnetic resonance imaging studies have provided important insights into anatomical and functional connectivity, these methodologies are limited in their ability to detect electrophysiological activity and the causal relationships that underlie effective connectivity. Here, we describe results of cortico-cortical evoked potential (CCEP) mapping using single pulse electrical stimulation in 25 patients undergoing seizure monitoring with subdural electrode arrays. Mapping was performed by stimulating adjacent electrode pairs and recording CCEPs from the remainder of the electrode array. CCEPs reliably revealed functional networks and showed an inverse relationship to distance between sites. Coregistration to Brodmann areas (BA) permitted group analysis. Connections were frequently directional with 43% of early responses and 50% of late responses of connections reflecting relative dominance of incoming or outgoing connections. The most consistent connections were seen as outgoing from motor cortex, BA6-BA9, somatosensory (SS) cortex, anterior cingulate cortex, and Broca's area. Network topology revealed motor, SS, and premotor cortices along with BA9 and BA10 and language areas to serve as hubs for cortical connections. BA20 and BA39 demonstrated the most consistent dominance of outdegree connections, while BA5, BA7, auditory cortex, and anterior cingulum demonstrated relatively greater indegree. This multicenter, large-scale, directional study of local and long-range cortical connectivity using direct recordings from awake, humans will aid the interpretation of noninvasive functional connectome studies.

Intrinsic functional architecture predicts electrically evoked responses in the human brain.

Adaptive brain function is characterized by dynamic interactions within and between neuronal circuits, often occurring at the time scale of milliseconds. These complex interactions between adjacent and noncontiguous brain areas depend on a functional architecture that is maintained even in the absence of input. Functional MRI studies carried out during rest (R-fMRI) suggest that this architecture is represented in low-frequency (<0.1 Hz) spontaneous fluctuations in the blood oxygen level-dependent signal that are correlated within spatially distributed networks of brain areas. These networks, collectively referred to as the brain's intrinsic functional architecture, exhibit a remarkable correspondence with patterns of task-evoked coactivation as well as maps of anatomical connectivity. Despite this striking correspondence, there is no direct evidence that this intrinsic architecture forms the scaffold that gives rise to faster processes relevant to information processing and seizure spread. Here, we demonstrate that the spatial distribution and magnitude of temporally correlated low-frequency fluctuations observed with R-fMRI during rest predict the pattern and magnitude of corticocortical evoked potentials elicited within 500 ms after single-pulse electrical stimulation of the cerebral cortex with intracranial electrodes. Across individuals, this relationship was found to be independent of the specific regions and functional systems probed. Our findings bridge the immense divide between the temporal resolutions of these distinct measures of brain function and provide strong support for the idea that the low-frequency signal fluctuations observed with R-fMRI maintain and update the intrinsic architecture underlying the brain's repertoire of functional responses.

[Occurrence of acute cardiovascular diseases under different atmospheric parameters]. / Akut cardiovascularis kórképek vizsgálata különbözo légköri paraméterek tükrében.

INTRODUCTION: Research on the effects of meteorological parameters on cardiovascular diseases may allow the development of novel prevention strategies. AIM: The aim of the authors was to examine the correlation between meteorological parameters and the occurrence of acute cardiovascular diseases. METHOD: A retrospective analysis was performed in 343 patients diagnosed with acute cardiovascular disease and treated at the Department of Vascular Surgery, Semmelweis University in 2010. RESULTS: Acute cardiovascular diseases showed a seasonal variation with the highest occurrence in winter months (p = 0.0001). The daily increase of the events (n ≥ 3) were associated with front movements days (in 62.5% of cases). A significant correlation was found between the intraday temperature difference (p<0.0001), the intraday atmospheric pressure difference (p = 0.0034), the lowest maximum daily temperature (p<0.0001) and the occurrence of acute cardiovascular diseases. During the days with front movements 64% of the patients were older than 66 years of age. Among risk factors, hypertension showed front sensitivity. CONCLUSIONS: Meteorological parameters are minor risk factors in the occurrence of acute cardiovascular diseases.

[Early and late mortality and morbidity after elective repair of infrarenal aortic aneurysm]. / Electiv infrarenalis aortaaneurysma sebészi kezelésének korai és késoi mortalitása és morbiditása.

INTRODUCTION: The open repair (OR) of infrarenal aortic aneurysm (AAA) has low mortality in tertiary care centres, however, endovascular repair (ER) could be more beneficial for some cases. The aim of our study was to compare the mortality and morbidity of the different AAA repair techniques. MATERIAL AND METHODS: In a single centre retrospective study we evaluated the postoperative complications, the early and late mortality of patients underwent open or endovascular AAA repair. RESULTS: Total of 431 patients underwent OR and 59 had ER. Early mortality was below 2% in both groups (statistically non-significant [NS] difference). Postoperative complications were found in 14.4% in the OR group and 11.9% in the ER group (NS). The intraoperative blood loss and use of blood products were higher, the operation time was significantly longer in the OR group (p < 0.001). The average follow-up time was 37 ± 22 months. Long term mortality and the prevalence of stroke and acute myocardial infarction were similar in both groups. 16% of the patients in the OR group developed incisional hernia. Patients after ER needed further vascular intervention more frequently than patients in the OR group (16.2% vs. 6.2%; p = 0.0327). CONCLUSION: The early and late mortality was similar after open and endovascular AAA repair. Postoperative complications did not show significant difference between the two groups. We found significant difference in the use of blood products, the prevalence of incisional hernias and the number of reinterventions. According to our results, stent graft implantation is mainly recommended in high risk patients and open aortic repair still has a role in the low-moderate operative risk group.

[Limb saving surgery in cases of bone sarcomas]. / Végtagmegtartó mûtétek csontsarcomáknál.

At the Orthopedic Department of Semmelweis University we operate an internationally recognized bone and soft tissue tumor center. Our specialty is the treatment of benign and malignant bone tumors, tumor-like lesions and surgery of soft tissue tumors. Our main aim, taking into account the appropriate oncologic radicality, is to create the conditions for the development of limb saving surgery. Limb saving surgery is an interdisciplinary activity both in diagnosis and in treatment. We have proper pathology, radiology and interventional radiology background for the fast and advanced pathomorphological and radiomorphological diagnosis of different tumors. Using modern chemotherapy, radiotherapy and other advanced cancer treatment protocols rapid access to oncology background is provided for children and adults as well, both primary and secondary bone tumors and soft tissue sarcoma cases of the extremities. The limb saving surgery after removal of the tumor is essentially a reconstructive surgery. Reconstructive surgery in childhood and younger ages mean mainly the biological solutions (vascularized autologus bone grafts and/or homologous bone graft), otherwise in elderly ages implantation of tumor endoprostheses has a greater significance. Furthermore, the final tumor surgery requires experienced abdominal surgeon, vascular surgeon and plastic surgeon to ensure the background as well. The professional background of our clinical practice is based on participating in international conferences and spending several months abroad in different big tumor centers. Over the past 15 years, several international cancer congresses were organized in Hungary by our Department.

Intracortical mechanisms of single pulse electrical stimulation (SPES) evoked excitations and inhibitions in humans.

Cortico-cortical evoked potentials (CCEPs) elicited by single-pulse electric stimulation (SPES) are widely used to assess effective connectivity between cortical areas and are also implemented in the presurgical evaluation of epileptic patients. Nevertheless, the cortical generators underlying the various components of CCEPs in humans have not yet been elucidated. Our aim was to describe the laminar pattern arising under SPES evoked CCEP components (P1, N1, P2, N2, P3) and to evaluate the similarities between N2 and the downstate of sleep slow waves. We used intra-cortical laminar microelectrodes (LMEs) to record CCEPs evoked by 10 mA bipolar 0.5 Hz electric pulses in seven patients with medically intractable epilepsy implanted with subdural grids. Based on the laminar profile of CCEPs, the latency of components is not layer-dependent, however their rate of appearance varies across cortical depth and stimulation distance, while the seizure onset zone does not seem to affect the emergence of components. Early neural excitation primarily engages middle and deep layers, propagating to the superficial layers, followed by mainly superficial inhibition, concluding in a sleep slow wave-like inhibition and excitation sequence.

Bone mineral density is associated with site-specific atherosclerosis in patients with severe peripheral artery disease.

Recent studies have highlighted a significant association between the severity of atherosclerosis and bone mineral density (BMD) among healthy subjects, although its connection to angiographically determined peripheral artery disease (PAD) has never been investigated. We evaluated the connection between the angiographic severity and site specificity of peripheral atherosclerosis and osteoporosis among patients with chronic lower limb ischemia. In our cross-sectional study we investigated 172 patients with PAD. The anatomic sites of the lesions were analyzed. The severity of atherosclerosis was diagnosed using the Bollinger angiographic score (BS). BMD was measured at the lumbar spine (l-BMD) and at femoral (f-BMD) and radial (r-BMD) sites by dual-energy X-ray absorptiometry. Dyslipidemia, the level of vitamin D(3), and different bone turnover markers were also noted. Among PAD patients, regardless of the lesion site, we did not find any association between BMD and BS. Among patients with iliac disease, BS was associated with l-BMD (p = 0.038, r = -0.467) and with f-BMD (p = 0.002, r = -0.642). The level of r-BMD among patients with iliac disease was not associated with BS (p = 0.233, r = -0.306). We did not find any difference between the group of patients with and that without dyslipidemia and low or normal levels of vitamin D(3). Our results show a connection between the severity of atherosclerosis and osteoporosis among patients with PAD, specific to the site of the lesion. The findings regarding dyslipidemia, bone markers, and site specificity support the hypothesis that reduced blood flow is the key factor responsible for the inverse association of BMD with atherosclerosis.

[Efficacy of deep brain stimulation in our patients with Parkinson's disease]. / A mély agyi stimuláció hatékonysaga Parkinson- kóros betegeink kezelésében.

BACKGROUND AND PURPOSES: In advanced Parkinson's disease, medically refractory motor fluctuation or medically resistant tremor considerably affects quality of life. However, these symptoms can be mostly successfully treated by deep brain stimulation. We analyzed the efficacy of bilateral subthalamic stimulation in our patients with Parkinson's disease. METHODS: We assessed the clinical data of ten patients who have been treated in the Department of Neurology, Semmelweis University and have been operated in the National Institute of Neurosciences between 2008 and 2011. The Hoehn-Yahr scale score, the Unified Parkinson's Disease Rating Scale score and the Parkinson's Disease Questionnaire 39, as well as the dose of antiparkinson medication were documented prior to and one year after surgery. RESULTS: Patient condition improved according to the Hoehn-Yahr scale, approximately by two stages. The dose of antiparkinson medication could be reduced by 63.4% (p = 0.005) post operation. Unified Parkinson's Disease Rating Scale scores decreased by 70.9% (p = 0.005). 12 hours after medication withdrawal, execution of daily activity improved by 57.1% (p < 0.01) and motor functions developed by 79.1% (p < 0.01). Duration of dyskinesias decreased by 62.5% (p = 0.018), duration of akinesia diminished by 87.5% (p = 0.005). Quality of life rose by 41.6% (p < 0.01). Neuropsychological tests detected improvement in verbal memory. CONCLUSION: With deep brain stimulation, the dosage of antiparkinson medication could be significantly reduced, with considerable improvements in motor function and quality of life. Although the number of patients is still low, good results have been established by careful patient selection, precise neurosurgical procedure and by appropriate programming and patient care.