Clinical Neuroscience

[The concept of epileptic networks. Part 2.]

HALÁSZ Péter

NOVEMBER 30, 2010

Clinical Neuroscience - 2010;63(11-12)

[In this paper we investigate evidences supporting the network concept of epilepsies from different approaches. Firstly the functions of cortical networks in which most of the epileptic networks are embedded, are treated. Then the tentative characteristics of an epileptic network are enumerated and the conversion mechanisms from physiological to epileptic networks are analyzed. Later the role of neuronal oscillations in epileptic networks and aspects of epilepsies provoked by sensory and cognitive tasks is studied. Lastly new fMRI data in mapping BOLD networks underlying spike and seizure discharges are used as arguments in favour of the epileptic network hypothesis. In a second part the well-known epilepsies related, or probably related to physiological networks are shown. Finally consequences of the network approach for creating a new unified epilepsy classification are discussed.]

COMMENTS

0 comments

Further articles in this publication

Clinical Neuroscience

[Account on the scientific meeting of Környey Society in 2010. Part 2.]

Clinical Neuroscience

[Meeting of Hungarian Epilepsy League]

SZUPERA Zoltán

Clinical Neuroscience

[European Association of Young Neurologists and Trainees]

VARGA Edina Tímea, SZTRIHA László, RÓNA-VÖRÖS Krisztina

Clinical Neuroscience

[Special concerns in medical care of severely demented patients suffering from Alzheimer disease]

RAJNA Péter

[While the expected life-time increases dementias will show a pandemic nature. Author analyses the special medical and social concerns of severe states of Alzheimer disease. Having introduced the epidemiologic, diagnostic data and forms of palliatíve therapies he concentrates on the hitherto unsolved problems of patients and caregivers. He belongs to the experts identifying the Alzheimer diseases as a forced aging process. Accepted the theory of L. Hayflick he evaluates the aging process in frame of an evolution model. He states that for aged human beings having already performed the task of reproduction further conditions of living circumstances and even that of death are no more programmed. This hypothesis may have a very negative content at the first sense. But the author rather considers the uncertainty of aging a positive message. He establishes that the occurrence of degenerative processes connecting the aging must be limited by preventive interventions far more efficient than the present possibilities. Concerning these steps we are still on the level of recommendations for preserving our general health and data of relevant science are quite contradictory. Although criteria of “healthy", “qualified” or “assumable” aging are getting defined, we still do not know exactly how we should live optimally and what should we do for this in different epochs of our life. Somatic and psychological parameters are lacking which would be able to signalize the actual level of the aging process in a given person. We, physicians, also do not have exact opinion on the level of severity of dementias at which the patient already lost his her features of personality and individuality on an irreversible way. We have no idea on the phase when the ratio of joy and suffer falls below the value of 1.0 because we still have no tool for its measure. The author pointed the necessity of acceptance of a new preventive attitude and application of new methods in the medical care of the forced or pathological aging, instead of the present approaches based on the “wait and treat” attitude. Because of the intensive increase of the patient population the identification and care of patients can be efficient with a much more involvement of the basic medical network. Financial background can be improved by new theoretical bases of criteria of the palliative treatments. But the direct professional programs can be planned after solution of the existing moral and social dilemmas.]

Clinical Neuroscience

[Importance of hydrocephalus following severe brain injury during postacute rehabilitation]

DÉNES Zoltán, LANTOS Ágnes, SZÉL István, THOMKA Magdolna, VASS Mátyás, BARSI Péter

[Objectives - We report our experiences with hydrocephalus in early rehabilitation over a seven-year period. Method - Retrospective study in Brain Injury Rehabilitation Unit of the National Institute for Medical Rehabilitation, between 1 January 2002 and 31 December 2008. Results - At our institute in the last seven years, we treated 83 patients with secondary and six patients with primary hydrocephalus. The majority of hydrocephalus was of post traumatic origin (52) and remaining 23 following stroke (SAH, AVM, ICH) or brain operation (tumour - seven, and one cranioplasty), and all these patients had undergone ventricular shunt implantation. Mean age of patients was 36 (14-80) years. Hydrocephalus was diagnosed in our rehabilitation unit in 20 of 83 cases and the other patients were shunted before transfer to our unit. The median time point of shunting was 70 (range: 20-270) days after trauma, brain surgery or stroke. Post-operative complications were seen in 12 of 89 patients: six infections and six shunt failure and revision was necessary in 14%. In PTH cases, the post-operative improvement was seen in 40 of 52 patients being shunted and corresponded to FIM scores. At the other 31 cases, with non-traumatic origin, only two patients remain unchanged. Conclusions - Hydrocephalus is considered to be a frequent and important complication after severe brain damage. The incidence of hydrocephalus treated with shunt implantation in our neuro-rehabilitation unit was 4.4%. The postoperative improvement was 77%. Posttraumatic hydrocephalus concerns 5.2% of patients with severe TBI during last seven years in our institution. Diagnosis of posttraumatic hydrocephalus was established in 24%, and complication after shunt implantation (14%) was also recognized in the post-acute rehabilitation unit. It is strongly recommended for the team working at such type of units to obtain clinical practice. Teamwork, good cooperation between acute and postacutecare is necessary for successful rehabilitation of these patients.]

All articles in the issue

Related contents

Clinical Neuroscience

[The role of sleep in the relational memory processes ]

CSÁBI Eszter, ZÁMBÓ Ágnes, PROKECZ Lídia

[A growing body of evidence suggests that sleep plays an essential role in the consolidation of different memory systems, but less is known about the beneficial effect of sleep on relational memory processes and the recognition of emotional facial expressions, however, it is a fundamental cognitive skill in human everyday life. Thus, the study aims to investigate the effect of timing of learning and the role of sleep in relational memory processes. 84 young adults (average age: 22.36 (SD: 3.22), 21 male/63 female) participated in our study, divided into two groups: evening group and morning group indicating the time of learning. We used the face-name task to measure relational memory and facial expression recognition. There were two sessions for both groups: the immediate testing phase and the delayed retesting phase, separated by 24 hours. 84 young adults (average age: 22.36 (SD: 3.22), 21 male/63 female) participated in our study, divided into two groups: evening group and morning group indicating the time of learning. We used the face-name task to measure relational memory and facial expression recognition. There were two sessions for both groups: the immediate testing phase and the delayed retesting phase, separated by 24 hours. Our results suggest that the timing of learning and sleep plays an important role in the stabilizing process of memory representation to resist against forgetting.]

Clinical Neuroscience

[Effect of two month positive airway pressure therapy on the structure of sleep, cognitive function and anxiety]

CSÁBI Eszter, VÁRSZEGI Mária, SEFCSIK Tamás, NÉMETH Dezsõ

[Obstructive sleep apnea is a common disorder, characterized by repeated episodes of upper airway obstruction during sleep, resulting intermittent hypoxia and disruption of the normal sleep pattern, which caused cognitive dysfunction in these patients. Nasal continuous positive airway pressure is the treatment of choice for this disorder. The aim of the study is to evaluate the effect of short-term positive airway pressure on sleep pattern (polisomnographic measures), cognitive function and anxiety. Twenty four newly diagnosed and previously untreated patients with obstructive sleep apnea were evaluated a battery of neuropsychological tests before and after 2 and a half months of the treatment. We focused on working memory, short and long-term episodic memory, executive functions, anxiety and subjective sleepiness. Our results showed that the two and half month of treatment improved the respiration during sleep, sleep pattern and the subjective sleepiness. We found improvement in short- and long-term verbal memory, and complex working memory. Despite of treatment we did not find improvement in visuospatial learning. These results reveal that 2 and a half months of positive airway pressure treatment restored not only the normal respiration during sleep and normal sleep pattern, but also the cognitive functions. Our study suggests that cognitive dysfunction is at least partial reversible in obstructive sleep apnea patients after positive airway pressure treatment.]

Clinical Neuroscience

[New vistas and views in the concept of generalized epilepsies]

HALÁSZ Péter, KELEMEN Anna

[The aim of this work is to show explicitly why the “idiopathic generalized epilepsy” concept becomes outfashioned and untenable. As the concept of “generalized epilepsies” is from long ago closely related to the thalamo-cortical system, we briefly summarize the functional anatomy, the double working mode of the thalamo-cortical system in different vigilance states and it’s role in development of the spike - wave pattern. The next part shows weaknesses of this concept from the EEG, seizure semiology, and neuroimaging point of view. Further experimental and clinical arguments are accumulated from the reflex epileptic features in IGE, indicating local/regional cortical hyperexcitability. A separate part is devoted to genetic aspects of the question. Lastly implications to epilepsy classification are shown and an outlook toward a unified epilepsy concept is provided. The epileptic disorder of the thalamo-cortical system is responsible for the development of “generalized", synchronous spike-wave paroxysms as the common neurophysiological background in “primary” - idiopathic and in “secondary” generalized epilepsies. This disorder is specifically related to the burstfiring working mode of the thalamo-cortical system during NREM sleep (is an epileptic exageration of it). The “generalized” epilepsy category should be abandoned, being misleading. Epilepsies are proposed to be classified according to their network properties and relations to different physiological systems of the brain. The different phenotypes, named earlier idiopathic (primary) generalized, or symptomatic (secondary) generalized (with encephalopathic features), should be delineated depending on the following factors: 1. speed and extent of syncronization within the thalamo-cortical system, 2. the way how the thalamo-cortical system is involved, 3. which kind of cortical triggers play role, 4. the degree and level of the disorder (restricted to the molecular level or extended to the level of structural alterations - in the cortex or more diffusely, 5. genetic targets and features.]

Clinical Neuroscience

[SLEEP DISORDERS IN PARKINSON SYNDROMES]

SZŰCS Anna, KOVÁCS Gábor Géza, NARULA Lalit, HALÁSZ Péter

[About 90% of neurodegenerative diseases with parkinsonism are associated with sleep disorders including daytime sleepiness, sleep-related breathing disorders and parasomnias. It is hard to define what ratio of insomnia and daytime hypersomnia is caused by the antiparkinsonian tratment, by the somatic and mentalemotional symptoms of the neurodegenerativ disease and by the neurodegenerative brain process itself. Recent research suggests that the latter group is more important than expected. In Parkinson syndromes the structures included in sleep regulation - mainly within the brainstem - are also affected resulting in specific sleep disorders being the primary biological symptoms of these diseases. The recently described parasomnia - REM sleep behavior disorder - has a specific significance in this respect: it may prevent by several years a high ratio of the parkinsonian disorders - especially synucleinopathies - offering the possibility of prevention by identifying the affected individuals. There seems to exist a similar although less clarified association between daytime sleepiness and Parkinson disease. Analysing the behavior of the orexin system in neurodegenerative diseases may help to learn more about this, recently described neurohumoral system and may clear the association of narcolepsy with neurodegeneration. By understanding the associations of parkinsonian disorders and sleep disorders new therapeutical strategies may be invented and may offer new aspects to understand the mechanism of them.]

Lege Artis Medicinae

[How do physicians sleep and dream?]

SUSÁNSZKY Éva, SZÁNTÓ Zsuzsa

[INTRODUCTION - Satisfying sleep is especially important for physicians. Our study analyses physicians’ sleep and dream from the point of view of continuous nightand- day duty. SAMPLE AND METHOD - Questionnaires were completed by 125 physicians among whom the proportion of night shift taking and only day-time working persons was equal. The questionnaire contained the Athens Insomnia Scale and the Dream Quality Questionnaire as well as questions about demographical characteristics and work circumstances. RESULTS - Almost each doctor mentioned sleep problems, principally daytime sleepiness (78%) and sleep deprivation (70%). Long sleep latency is reported more often by women doctors; the frequency of night awakenings increases, while daytime sleepiness decreases by age. The feeling of performance-loss is more prevalent among night shift takers. Dream characteristics differ significantly neither along demographical characteristics nor by work shifts. CONCLUSION - Although sleep problems are more frequent among physicians when comparing to the Hungarian general population, the frequency of clinical level insomnia is not higher. On the other hand, physicians can recall their dreams more often (25% vs 7%) and the emotional load of their dreams influence their daytime mood more commonly.]