Matching Items (5)
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- All Subjects: Epilepsy
- All Subjects: Disclosure of information
- Creators: Iasemidis, Leonidas
- Resource Type: Text
Description
ABSTRACT Epilepsy is a neurological condition that sometimes pervades all domains of an affected child's life. At school, three specific threats to the wellbeing of children with epilepsy exist: (1) seizure-related injuries, (2) academic problems, and (3) stigmatization. Unfortunately, educators frequently fail to take into account educationally-relevant epilepsy information when making important decisions. One possible explanation for this is that parents are not sharing such information with teachers. This study surveyed 16 parents of children with epilepsy in order to determine the rate at which they disclosed the epilepsy diagnoses to their children's teachers, as well as the difficulty with which they made the decision to disclose or withhold such information. In addition, the relationships between such disclosure and parent-participants' perceptions of the risks of epilepsy-related injuries, academic struggles, and stigmatization at school were examined. Results indicate that all participants disclosed their children's epilepsy diagnoses to their children's teachers, and most (69%) reported that making this decision was "very easy." There were no statistically significant associations between disclosure and any of three parental perception variables (perceptions of the threats of injury, academic problems, and stigmatization at school). Limitations, implications, and directions for future research are discussed.
ContributorsBush, Vanessa (Author) / Wodrich, David L (Committee member) / Blanchard, Jay (Committee member) / Gorin, Joanna (Committee member) / Arizona State University (Publisher)
Created2011
Description
Interictal spikes, together with seizures, have been recognized as the two hallmarks of epilepsy, a brain disorder that 1% of the world's population suffers from. Even though the presence of spikes in brain's electromagnetic activity has diagnostic value, their dynamics are still elusive. It was an objective of this dissertation to formulate a mathematical framework within which the dynamics of interictal spikes could be thoroughly investigated. A new epileptic spike detection algorithm was developed by employing data adaptive morphological filters. The performance of the spike detection algorithm was favorably compared with others in the literature. A novel spike spatial synchronization measure was developed and tested on coupled spiking neuron models. Application of this measure to individual epileptic spikes in EEG from patients with temporal lobe epilepsy revealed long-term trends of increase in synchronization between pairs of brain sites before seizures and desynchronization after seizures, in the same patient as well as across patients, thus supporting the hypothesis that seizures may occur to break (reset) the abnormal spike synchronization in the brain network. Furthermore, based on these results, a separate spatial analysis of spike rates was conducted that shed light onto conflicting results in the literature about variability of spike rate before and after seizure. The ability to automatically classify seizures into clinical and subclinical was a result of the above findings. A novel method for epileptogenic focus localization from interictal periods based on spike occurrences was also devised, combining concepts from graph theory, like eigenvector centrality, and the developed spike synchronization measure, and tested very favorably against the utilized gold rule in clinical practice for focus localization from seizures onset. Finally, in another application of resetting of brain dynamics at seizures, it was shown that it is possible to differentiate with a high accuracy between patients with epileptic seizures (ES) and patients with psychogenic nonepileptic seizures (PNES). The above studies of spike dynamics have elucidated many unknown aspects of ictogenesis and it is expected to significantly contribute to further understanding of the basic mechanisms that lead to seizures, the diagnosis and treatment of epilepsy.
ContributorsKrishnan, Balu (Author) / Iasemidis, Leonidas (Thesis advisor) / Tsakalis, Kostantinos (Committee member) / Spanias, Andreas (Committee member) / Si, Jennie (Committee member) / Arizona State University (Publisher)
Created2012
Description
Development of post-traumatic epilepsy (PTE) after traumatic brain injury (TBI) is a major health concern (5% - 50% of TBI cases). A significant problem in TBI management is the inability to predict which patients will develop PTE. Such prediction, followed by timely treatment, could be highly beneficial to TBI patients. Six male Sprague-Dawley rats were subjected to a controlled cortical impact (CCI). A 6mm piston was pneumatically driven 3mm into the right parietal cortex with velocity of 5.5m/s. The rats were subsequently implanted with 6 intracranial electroencephalographic (EEG) electrodes. Long-term (14-week) continuous EEG recordings were conducted. Using linear (coherence) and non-linear (Lyapunov exponents) measures of EEG dynamics in conjunction with measures of network connectivity, we studied the evolution over time of the functional connectivity between brain sites in order to identify early precursors of development of epilepsy. Four of the six TBI rats developed PTE 6 to 10 weeks after the initial insult to the brain. Analysis of the continuous EEG from these rats showed a gradual increase of the connectivity between critical brain sites in terms of their EEG dynamics, starting at least 2 weeks prior to their first spontaneous seizure. In contrast, for the rats that did not develop epilepsy, connectivity levels did not change, or decreased during the whole course of the experiment across pairs of brain sites. Consistent behavior of functional connectivity changes between brain sites and the "focus" (site of impact) over time was demonstrated for coherence in three out of the four epileptic and in both non-epileptic rats, while for STLmax in all four epileptic and in both non-epileptic rats. This study provided us with the opportunity to quantitatively investigate several aspects of epileptogenesis following traumatic brain injury. Our results strongly support a network pathology that worsens with time. It is conceivable that the observed changes in spatiotemporal dynamics after an initial brain insult, and long before the development of epilepsy, could constitute a basis for predictors of epileptogenesis in TBI patients.
ContributorsTobin, Edward (Author) / Iasemidis, Leonidas (Thesis advisor) / Tsakalis, Konstantinos (Committee member) / Muthuswamy, Jitendran (Committee member) / Arizona State University (Publisher)
Created2012
Description
In this study, the entrainment of brain dynamics in epilepsy was investigated in a thorough, systematic way. In the first part of the study, diagnosis of epilepsy, elements from the theory of chaos were used to measure the brain dynamics over time from EEGs (electroencephalograms) recorded in humans with either epileptic or non-epileptic seizures. In the second part of the study, treatment of epilepsy, data from rats undergoing VNS (vagus nerve stimulation) treatment were analyzed in the same way. The results suggest that a) the differential diagnosis in humans with epileptic and non-epileptic seizures can be significantly improved by analysis of brain dynamics, and b) the Vagus Nerve Stimulation may be working by controlling the entrainment level of brain dynamics.
ContributorsRoth, Austin Edward (Author) / Iasemidis, Leonidas (Thesis director) / Tsakalis, Kostas (Committee member) / Spano, Mark (Committee member) / Barrett, The Honors College (Contributor) / Harrington Bioengineering Program (Contributor)
Created2013-05
Description
Managers’ control over the timing and content of information disclosure represents a significant strategic tool which they can use at their discretion. However, extant theoretical perspectives offer incongruent arguments and incompatible predictions about when and why managers would release inside information about their firms. More specifically, agency theory and theories within competitive dynamics provide competing hypotheses about when and why managers would disclose inside information about their firms. In this study, I highlight how voluntary disclosure theory may help to coalesce these two theoretical perspectives. Voluntary disclosure theory predicts that managers will release inside information when managers perceive that the benefits outweigh the costs of doing so. Accordingly, I posit that competitive dynamics introduce the costs associated with disclosing information (i.e., proprietary costs) and that agency theory highlights the benefits associated with disclosing information. Examining the context of seasoned equity offerings (SEOs), I identify three ways managers can use information in SEO prospectuses. I hypothesize that competitive intensity increases proprietary costs that will reduce disclosure of inside information but will increase discussing the organization positively. I then hypothesize that capital market participants (e.g., security analysts and investors) may prefer managers to provide more, clearer, and positive information about the SEO and their firms. I find support for many of my hypotheses.
ContributorsBusenbark, John R (Author) / Certo, S. Trevis (Thesis advisor) / Semadeni, Matthew (Committee member) / Cannella, Albert (Committee member) / Arizona State University (Publisher)
Created2017