BACKGROUND: Traumatic brain injury (TBI) is an important cause of focal epilepsy. Animal experiments indicate that disruption of the blood-brain barrier (BBB) plays a critical role in the pathogenesis of post-traumatic epilepsy (PTE). OBJECTIVE: To investigate the frequency, extent and functional correlates of increased BBB permeability in patient with PTE. METHODS: 32 head trauma patients were included in the study, with 17 suffering from PTE. Patients underwent brain MRI (bMRI) and were evaluated for BBB disruption, using a novel semi-quantitative technique. Cortical dysfunction was measured using electroencephalography (EEG), and localised using standardised low-resolution brain electromagnetic tomography (sLORETA). RESULTS: Spectral EEG analyses revealed significant slowing in patients with TBI, with no significant differences between patients with epilepsy and those without. Although bMRI revealed that patients with PTE were more likely to present with intracortical lesions (p = 0.02), no differences in the size of the lesion were found between the groups (p = 0.19). Increased BBB permeability was found in 76.9% of patients with PTE compared with 33.3% of patients without epilepsy (p = 0.047), and could be observed years following the trauma. Cerebral cortex volume with BBB disruption was larger in patients with PTE (p = 0.001). In 70% of patients, slow (delta band) activity was co-localised, by sLORETA, with regions showing BBB disruption. CONCLUSIONS: Lasting BBB pathology is common in patients with mild TBI, with increased frequency and extent being observed in patients with PTE. A correlation between disrupted BBB and abnormal neuronal activity is suggested. The Corresponding Author has the right to grant on behalf of all authors and does grant on behalf of all authors, an exclusive licence (or non exclusive for government employees) on a worldwide basis to the BMJ Publishing Group Ltd and its Licensees to permit this article (if accepted) to be published in JNNP and any other BMJPGL products to exploit all subsidiary rights, as set out in our licence (http://jnnp.bmj.com/ifora/licence.pdf). Animal experiments indicate that disruption of the blood-brain barrier (BBB) plays a critical role in the pathogenesis of post-traumatic epilepsy (PTE). Objective: To investigate the frequency, extent and functional correlates of increased BBB permeability in PTE patients. Methods: 32 head trauma patients were included in the study, with 17 suffering from PTE. Patients underwent brain magnetic resonance imaging (bMRI) and were evaluated for BBB disruption, using a novel semi-quantitative technique. Cortical dysfunction was measured using electroencephalography (EEG), and localized using standardized low resolution brain electromagnetic tomography (sLORETA). Results: Spectral EEG analyses revealed significant slowing in TBI patients with no significant differences between epileptic and non-epileptic patients. While bMRI revealed that PTE patients were more likely to present with intracortical lesions (p=0.02)...
Recent animal experiments indicate a critical role for opening of the blood-brain barrier (BBB) in the pathogenesis of post-traumatic epilepsy (PTE). This study aimed to investigate the frequency, extent, and functional correlates of BBB disruption in epileptic patients following mild traumatic brain injury (TBI). Thirty-seven TBI patients were included in this study, 19 of whom suffered from PTE. All underwent electroencephalographic (EEG) recordings and brain magnetic resonance imaging (bMRI). bMRIs were evaluated for BBB disruption using novel quantitative techniques. Cortical dysfunction was localized using standardized low-resolution brain electromagnetic tomography (sLORETA). TBI patients displayed significant EEG slowing compared to controls with no significant differences between PTE and nonepileptic patients. BBB disruption was found in 82.4% of PTE compared to 25% of non-epileptic patients (P = .001) and could be observed even years following the trauma. The volume of cerebral cortex with BBB disruption was significantly larger in PTE patients (P = .001). Slow wave EEG activity was localized to the same region of BBB disruption in 70% of patients and correlated to the volume of BBB disrupted cortex. We finally present a patient suffering from early cortical dysfunction and BBB breakdown with a gradual and parallel resolution of both pathologies. Our findings demonstrate that BBB pathology is frequently found following mild TBI. Lasting BBB breakdown is found with increased frequency and extent in PTE patients. Based on recent animal studies and the colocalization found between the region of disrupted BBB and abnormal EEG activity, we suggest a role for a vascular lesion in the pathogenesis of PTE.
Based on their review, the authors conclude that the extended subcranial approach to the anterior skull base is a safe, versatile, and effective procedure for the surgical treatment of various pathological conditions involving the anterior skull base.
We propose a novel adaptive and causal random linear network coding (AC-RLNC) algorithm with forward error correction (FEC) for a point-to-point communication channel with delayed feedback. AC-RLNC is adaptive to the channel condition, that the algorithm estimates, and is causal, as coding depends on the particular erasure realizations, as reflected in the feedback acknowledgments. Specifically, the proposed model can learn the erasure pattern of the channel via feedback acknowledgments, and adaptively adjust its retransmission rates using a priori and posteriori algorithms. By those adjustments, AC-RLNC achieves the desired delay and throughput, and enables transmission with zero error probability. We upper bound the throughput and the mean and maximum in order delivery delay of AC-RLNC, and prove that for the point to point communication channel in the non-asymptotic regime the proposed code may achieve more than 90% of the channel capacity. To upper bound the throughput we utilize the minimum Bhattacharyya distance for the AC-RLNC code. We validate those results via simulations. We contrast the performance of AC-RLNC with the one of selective repeat (SR)-ARQ, which is causal but not adaptive, and is a posteriori. Via a study on experimentally obtained commercial traces, we demonstrate that a protocol based on AC-RLNC can, vis-à-vis SR-ARQ, double the throughput gains, and triple the gain in terms of mean in order delivery delay when the channel is bursty. Furthermore, the difference between the maximum and mean in order delivery delay is much smaller than that of SR-ARQ. Closing the delay gap along with boosting the throughput is very promising for enabling ultra-reliable low-latency communications (URLLC) applications.Index Terms-Random linear network coding (RLNC), forward error correction (FEC), feedback, causal, coding, adaptive, in order delivery delay, throughput.
Predicting gully initiation at catchment scale was done previously by integrating a geographical information system (GIS) with physically based models, statistical procedures or with knowledge‐based expert systems. However, the reliability and validity of applying these procedures are still questionable. In this work, a data mining (DM) procedure based on decision trees was applied to identify areas of gully initiation risk. Performance was compared with the analytic hierarchy process (AHP) expert system and with the commonly used topographic threshold (TT) technique. A spatial database was used to test the models, composed of a target variable (presence or absence of initial points) and ten independent environmental, climatic and human‐induced variables. The following findings emerged: using the same input layers, DM provided better predictive ability of gully initiation points than the application of both AHP and TT. The main difference between DM and TT was the very high overestimation inherent in TT. In addition, the minimum slope observed for soil detachment was 2°, whereas in other studies it is 3°. This could be explained by soil resistance, which is substantially lower in agricultural fields, while most studies test unploughed soil. Finally, rainfall intensity events >62.2 mm h‐1 (for a period of 30 min) were found to have a significant effect on gully initiation. Copyright © 2012 John Wiley & Sons, Ltd.
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