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Clinical Neuroscience

SEPTEMBER 30, 2020

Neuroscience highlights: Main cell types underlying memory and spatial navigation

KRABOTH Zoltán, KÁLMÁN Bernadette

Interest in the hippocampal formation and its role in navigation and memory arose in the second part of the 20th century, at least in part due to the curious case of Henry G. Molaison, who underwent brain surgery for intractable epilepsy. The temporal association observed between the removal of his entorhinal cortex along with a significant part of hippocampus and the developing severe memory deficit inspired scientists to focus on these regions. The subsequent discovery of the so-called place cells in the hippocampus launched the description of many other functional cell types and neuronal networks throughout the Papez-circuit that has a key role in memory processes and spatial information coding (speed, head direction, border, grid, object-vector etc). Each of these cell types has its own unique characteristics, and together they form the so-called “Brain GPS”. The aim of this short survey is to highlight for practicing neurologists the types of cells and neuronal networks that represent the anatomical substrates and physiological correlates of pathological entities affecting the limbic system, especially in the temporal lobe. For that purpose, we survey early discoveries along with the most relevant neuroscience observations from the recent literature. By this brief survey, we highlight main cell types in the hippocampal formation, and describe their roles in spatial navigation and memory processes. In recent decades, an array of new and functionally unique neuron types has been recognized in the hippocampal formation, but likely more remain to be discovered. For a better understanding of the heterogeneous presentations of neurological disorders affecting this anatomical region, insights into the constantly evolving neuroscience behind may be helpful. The public health consequences of diseases that affect memory and spatial navigation are high, and grow as the population ages, prompting scientist to focus on further exploring this brain region.

Clinical Neuroscience

JULY 30, 2020

[Decisional collisions between evidence and experience based medicine in care of people with epilepsy]


[Background – Based on the literature and his long-term clinical practice the author stresses the main collisions of evidence and experience based medicine in the care of people with epilepsy. Purpose – To see, what are the professional decisions of high responsibility in the epilepsy-care, in whose the relevant clinical research is still lacking or does not give a satisfactory basis. Methods – Following the structure of the Hungarian Guideline the author points the critical situations and decisions. He explains also the causes of the dilemmas: the lack or uncertainty of evidences or the difficulty of scientific investigation of the situation. Results – There are some priorities of experience based medicine in the following areas: definition of epilepsy, classification of seizures, etiology – including genetic background –, role of precipitating and provoking factors. These are able to influence the complex diagnosis. In the pharmacotherapy the choice of the first drug and the optimal algorithm as well as the tasks during the care are also depends on personal experiences sometimes contradictory to the official recommendations. Same can occur in the choice of the non-pharmacological treatments and rehabilitation. Discussion and conclusion – Personal professional experiences (and interests of patients) must be obligatory accessories of evidence based attitude, but for achieving the optimal results, in some situations they replace the official recommendations. Therefore it is very important that the problematic patients do meet experts having necessary experiences and also professional responsibility to help in these decisions. ]

Clinical Neuroscience

MARCH 30, 2016

[Individual evaluation of loreta abnormalities in idiopathic generalized epilepsy]

CLEMENS Béla, PUSKÁS Szilvia, BESENYEI Mónika, KONKÁDOR István, HOLLÓDY Katalin, FOGARASI András, BENSE Katalin, EMRI Miklós, OPPOSITS Gábor, KOVÁCS Noémi Zsuzsanna, FEKETE István

[Background – Contemporary neuroimaging methods disclosed structural and functional cerebral abnormalities in idiopathic generalized epilepsies (IGEs). However, individual electrical (EEG) abnormalities have not been evaluated yet in IGE patients. IGE patients were investigated in the drug-free condition and after 3-6 month of antiepileptic treatment. To estimate the reproducibility of qEEG variables a retrospective recruited cohort of IGE patients was investigated. 19- channel resting state EEG activity was recorded. For each patient a total of 2 minutes EEG activity was analyzed by LORETA (Low Resolution Electromagnetic Tomography). Raw LORETA values were Z-transformed and projected to a MRI template. Z-values outside within the [+] 1. In drug-free condition, 41-50% of IGE patients showed abnormal LORETA values. 2. Abnormal LORETA findings showed great inter-individual variability. 3. Most abnormal LORETA-findings were symmetrical. 4. Most maximum Z-values were localized to frontal or temporal cortex. 5. Succesfull treatment was mostly coupled with disappearence of LORETA-abnormality, persistent seizures were accompanied by persistent LORETA abnormality. 1. LORETA abnormalities detected in the untreated condition reflect seizure-generating property of the cortex in IGE patients. 2. Maximum LORETA-Z abnormalities were topographically congruent with structural abnormalities reported by other research groups. 3. LORETA might help to investigate drug effects at the whole-brain level.]

Clinical Neuroscience

NOVEMBER 20, 2015

[Mentalizing deficit in neurological disorders: a review article]

HEROLD Róbert, VARGA Eszter, MIKE Andrea, TÉNYI Tamás, SIMON Mária, HAJNAL András, FEKETE Sándor, ILLÉS Zsolt

[Introduction – Mentalization is the ability to attribute mental states (intentions, desires, thoughts, emotions) to others, and hence to predict their behaviour. This ability fundamentally determines our participation in social relationships and adaptation to society. A significant proportion of the disorders of the central nervous system (CNS) affects those brain structures and neurotransmitter systems that play a role in the mentalizing processes. Accordingly, a number of CNS disorders may be associated with mentalizing deficits, which may affect the outcome of these diseases. Here, we review recent research on mentalizing abilities in neurological diseases. Methods – An internet database search was performed to identify publications on the subject. Results – Sixty-two publications in English corresponded to the search criteria. These publications reported impaired mentalization in several neurological disorders (e.g. epilepsy, Parkinson’s disease, multiple sclerosis, dementias, traumatic brain injury). Discussion – The results indicate that a number of neurological disorders associate with mentalizing deficit. This deficit is often present in the early stages of the diseases and has a prognostic value, which in turn emphasizes the importance of the early detection and adequate rehabilitation.]

Clinical Neuroscience

NOVEMBER 20, 2015

[Sleep disordered breathing and epilepsy: relationships and therapeutic considerations]

FALUDI Béla, BÓNÉ Beáta, KOMOLY Sámuel, JANSZKY József

[The importance of the sleep related breathing disorders (obstructive sleep apnea syndrome, central sleep apnea, and Cheyne-Stokes breathing) in the pathophysiology crebro- and cardiovascular disorders is well known. The relationship of sleep related breathing abnormalities and epilepsy is also important but underestimated in the daily practice. The relation is bidirectional. The breathing abnormalities in sleep may play important role in generating epileptic seizure, but the adverse effect of seizure and antiepileptic therapy (generation of apneas and hypopneas) may worsen the seizure control. The effect of new therapies (vagal nerve and deep brain stimulation) on the sleep architecture and sleep disordered breathing must be examined and discussed. Here we present a brief case of epileptic patient with deep brain stimulation therapy on sleep as well. The examination of the sleep related breathing abnormalities in epilepsy patient may help improve the effectiveness of antiepileptic therapy.]

Clinical Neuroscience

JANUARY 30, 2016

Long term follow-up of lesional and non-lesional patients with electrical status epilepticus in slow wave sleep


Objectives – A retrospective study has been done at the Bethesda Children’s Hospital Epilepsy Center with those patients whose EEG records fulfilled in one or more records the criteria of electrical status epilepticus in slow wave sleep (ESES) pattern, occupying at least 75% of NREM sleep with bilateral discharges, and had detailed disease history and long term follow-up data, between 2000 and 2012. Patients and methods – Thirty-three patients (mean 11.1±4.2 years of age) were studied by 171 sleep EEG records. Sleep was recorded after sleep deprivation or during spontaneous sleep at least for one hour length of NREM. From the 492 EEGs, 171 sleep records were performed (average five/patient). Average follow-up time was 7.5 years. Eighty-two ESES records have been analyzed in 15 non-lesional and 18 lesional (11 with dysgenetic and seven with perinatal - asphyxic or vascular origin) patients. Variability of seizure types, seizure frequency and frequency of status epilepticus was higher in the lesional group. Impairment of the cognitive functions was moderate and partial in the non-lesional, while severely damaged in the lesional group. Results – EEG records of 29 patients showed unihemispherial spike fields with a perpendicular axis (in anterior, medial and posterior variants) to the Sylvian fissure, regardless their lesional or non-lesional origin. Only three (1one non-lesional and two lesional) patients had bilateral synchronous spike-wave discharges with bilateral symmetric frontocentral spike fields. The individual discharges of the sleep EEG pattern were very similar to the awake interictal records except their extension in time and field, their increased number, amplitude, and continuity of them and furthermore in the increased trans-hemispheral propagation and their synchronity. Conclusions – Assumed circuits involved in the pathomechanism of discharges during NREM sleep in ESES are discussed based on our findings.

Clinical Neuroscience

MARCH 30, 2020

[Intracranial EEG monitoring methods]

TÓTH Márton, JANSZKY József

[Resective surgery is considered to be the best option towards achieving seizure-free state in drug-resistant epilepsy. Intracranial EEG (iEEG) is necessary if the seizure-onset zone is localized near to an eloquent cortical area, or if the results of presurgical examinations are discordant, or if an extratemporal epilepsy patient is MRI-negative. Nowadays, 3 kinds of electrodes are used: (1) foramen ovale (FO) electrodes; (2) subdural strip or grid electrodes (SDG); (3) deep electrodes (stereo-electroencephalographia, SEEG). The usage of FO electrode is limited to bitemporal cases. SDG and SEEG have a distinct philosophical approach, different advantages and disadvantages. SDG is appropriate for localizing seizure-onset zones on hemispherial or interhemispherial surfaces; it is preferable if the seizure-onset zone is near to an eloquent cortical area. SEEG is excellent in exploration of deeper cortical structures (depths of cortical sulci, amygdala, hippocampus), although a very precise planning is required because of the low spatial sampling. The chance for seizure-freedom is relatively high performing both methods (SDG: 55%, SEEG: 64%), beside a tolerable rate of complications.]

Clinical Neuroscience

MARCH 30, 2020

Effects of valproate, carbamazepine and levetiracetam on Tp-e interval, Tp-e/QT and Tp-e/QTc ratio


Aim - To evaluate P-wave dispersion before and after antiepileptic drug (AED) treatment as well as to investigate the risk of ventricular repolarization using the Tpeak-Tend (Tp-e) interval and Tp-e/QT ratio in patients with epileptic disorder. Methods - A total of 63 patients receiving AED therapy and 35 healthy adults were included. ECG recordings were obtained before and 3 months after anti-epileptic treatment among patients with epilepsy. For both groups, Tp-e and Tp-e/QT ratio were measured using a 12-lead ECG device. Results - Tp-e interval, Tpe/QT and Tp-e/QTc ratios were found to be higher in the patient group than in the control group (p<0.05, for all), while QTmax ratio was significantly lower in the patient group. After 3 months of AED therapy, significant increases in QT max, QTc max, QTcd, Tp-e, Tp-e/QT, and Tp-e/QTc were found among the patients (p<0.05). When the arrhythmic effects of the drugs before and after treatment were compared, especially in the valproic acid group, there were significant increases in Tp-e interval, Tp-e/QT and Tp-e/QTc values after three months of treatment (p<0.05). Carbamazepine and levetiracetam groups were not statistically significant in terms of pre- and post-treatment values. Conclusions - It was concluded that an arrhythmogenic environment may be associated with the disease, and patients who received AED monotherapy may need to be followed up more closely for arrhythmia.

Clinical Neuroscience

SEPTEMBER 30, 2019

[Newer studies on the strong link between sleep and epilepsy: Epilepsy as an epileptic transformation of sleep plastic functions]


[Aims - Overview of the new data about the strong link of sleep and epilepsy and conjoining cognitive impairment. Methods - Search for relevant references and summary of our own research activity on the topic. Results - Strong interrealtionship exists between epilepsy and plastic brain functions (memory processing and synaptic homeostasis) and the working modes of NREM sleep. In the most frequent childhood and adult epilepsy networks responsible for plastic functions can be derailed to an epileptic level of excitability, and suffer a transitory or permanent epileptic transformation. Exampling on the three big epilepsies: absence epilepsy; medial temporal lobe epilepsy; and childhood idiopathic focal age dependent epilepsy spectrum we demonstrate the most important features of this epileptic transformation. The association of cognitive impairment to certain sleep dependent epilepsies gains explanation by the epilepsy caused interference with slow wave decline (ICFE) and memory consolidation (MTLE) during NREM sleep. This paper serves also to introduce the concept of sleep dependent system epilepsies. Conclusions - We provide evidences about shared mechanisms among sleep related epilepsies being the derailment of sleep plastic funcions toward exaggerated excitability determined by the inherent possibilities of the signal transduction properties. ]

Clinical Neuroscience

JULY 30, 2019

Relationship between Status Epilepticus Severity Score and etiology in adult NCSE patients

GENC Fatma, ERDAL Abidin, AKCA Gizem, KARACAY Ertan, GÖKSU Özaydın Eylem, KUTLU Gülnihal, GÖMCELI Bicer Yasemin

Purpose - Nonconvulsive status epilepticus (NCSE) is a heterogeneous, severe neurological disorder of different etiologies. In this study, the outcomes of NCSE episodes was assessed in a large series of adult patients. Our objective was to evaluate relationship between Status Epilepticus Severity Score (STESS) and etiology and the role of etiological factors on predicting the outcomes. Method - In this retrospective study, the medical records of 95 patients over 18 years of age who were diagnosed with NCSE between June 2011 and December 2015 were reviewed. Their treatment and follow-up for NCSE was performed at the Epilepsy Unit in Department of Neurology, Antalya Research and Training Hospital. Etiological factors thought to be responsible for NCSE episodes as well as the prognostic data were retrieved. The etiological factors were classified into three groups as those with a known history of epilepsy (Group 1), primary neurological disorder (Group 2), or systemic/unknown etiology (Group 3). STESS was retrospectively applied to patients. Results - There were 95 participants, 59 of whom were female. Group 1, Group 2, and Group 3 consisted of 11 (7 female), 54 (33 female), and 30 (19 female) patients, respectively. Of the 18 total deaths, 12 occurred in Group 2, and 6 in Group 3. The negative predictive value for a STESS score of ≤ 2 was 93.88% (+LR 2.05 95% CI: 1.44-2.9 and -LR 0.3 95% CI 0.10-0.84 ) in the overall study group. While the corresponding values for Group 1 (patients with epilepsy), Group 2 (patients with primary neurological disorder), and group 3 (patients with systemic or unknown etiology) were 100%, 92.59% (+LR 2.06 95%CI: 1.32-3.21 and -LR 0.28 95% CI 0.08-1.02 ) 83.33% (+LR 1.14 95%CI: 0.59-2.9 and -LR 0.80 95% CI 0.23-2.73). Conclusions - This study included the one of the largest patients series ever reported in whom STESS, a clinical scoring system proposed for use in patients with status epilepticus, has been implemented. Although STESS appeared to be quite useful for predicting a favorable outcome in NCSE patients with epilepsy and primary neurological disorders, its predictive value in patients with systemic or unknown etiology was lower. Further prospective studies including larger NCSE samples are warranted.