Highly-parallelized simulation of a pixelated LArTPC on a GPU

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

Brief rhythmic discharges in electroencephalography on an interictal to ictal continuum - Reply

SCOPUS: le.jinfo:eu-repo/semantics/publishe

Delta rhythm in wakefulness: Evidence from intracranial recordings in human beings

A widely accepted view is that wakefulness is a state in which the entire cortical mantle is persistently activated, and therefore desynchronized. Consequently, the EEG is dominated by low-amplitude, high-frequency fluctuations. This view is currently under revision because the 1-4 Hz delta rhythm is often evident during "quiet" wakefulness in rodents and nonhuman primates. Here we used intracranial EEG recordings to assess the occurrence of delta rhythm in 18 awake human beings. Our recordings reveal rhythmic delta during wakefulness at 10% of all recording sites. Delta rhythm could be observed in a single cortical lobe or in multiple lobes. Sites with high delta could flip between high and low delta power or could be in a persistently high delta state. Finally, these sites were rarely identified as the sites of seizure onset. Thus rhythmic delta can dominate the background operation and activity of some neocortical circuits in awake human beings.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Quantification of EEG reactivity in comatose patients

Objective: EEG reactivity is an important predictor of outcome in comatose patients. However, visual analysis of reactivity is prone to subjectivity and may benefit from quantitative approaches. Methods: In EEG segments recorded during reactivity testing in 59 comatose patients, 13 quantitative EEG parameters were used to compare the spectral characteristics of 1-minute segments before and after the onset of stimulation (spectral temporal symmetry). Reactivity was quantified with probability values estimated using combinations of these parameters. The accuracy of probability values as a reactivity classifier was evaluated against the consensus assessment of three expert clinical electroencephalographers using visual analysis. Results: The binary classifier assessing spectral temporal symmetry in four frequency bands (delta, theta, alpha and beta) showed best accuracy (Median AUC: 0.95) and was accompanied by substantial agreement with the individual opinion of experts (Gwet's AC1: 65-70%), at least as good as inter-expert agreement (AC1: 55%). Probability values also reflected the degree of reactivity, as measured by the inter-experts' agreement regarding reactivity for each individual case. Conclusion: Automated quantitative EEG approaches based on probabilistic description of spectral temporal symmetry reliably quantify EEG reactivity. Significance: Quantitative EEG may be useful for evaluating reactivity in comatose patients, offering increased objectivity.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Time-dependent risk of seizures in critically ill patients on continuous electroencephalogram

Objective: Find the optimal continuous electroencephalographic (CEEG) monitoring duration for seizure detection in critically ill patients. Methods: We analyzed prospective data from 665 consecutive CEEGs, including clinical factors and time-to-event emergence of electroencephalographic (EEG) findings over 72 hours. Clinical factors were selected using logistic regression. EEG risk factors were selected a priori. Clinical factors were used for baseline (pre-EEG) risk. EEG findings were used for the creation of a multistate survival model with 3 states (entry, EEG risk, and seizure). EEG risk state is defined by emergence of epileptiform patterns. Results: The clinical variables of greatest predictive value were coma (31% had seizures; odds ratio [OR] = 1.8, p < 0.01) and history of seizures, either remotely or related to acute illness (34% had seizures; OR = 3.0, p < 0.001). If there were no epileptiform findings on EEG, the risk of seizures within 72 hours was between 9% (no clinical risk factors) and 36% (coma and history of seizures). If epileptiform findings developed, the seizure incidence was between 18% (no clinical risk factors) and 64% (coma and history of seizures). In the absence of epileptiform EEG abnormalities, the duration of monitoring needed for seizure risk of <5% was between 0.4 hours (for patients who are not comatose and had no prior seizure) and 16.4 hours (comatose and prior seizure). Interpretation: The initial risk of seizures on CEEG is dependent on history of prior seizures and presence of coma. The risk of developing seizures on CEEG decays to <5% by 24 hours if no epileptiform EEG abnormalities emerge, independent of initial clinical risk factors. Ann Neurol 2017;82:177–185.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Cyclic seizures in critically ill patients: Clinical correlates, DC recordings and outcomes

Objective To describe EEG and clinical correlates, DC recordings and prognostic significance of cyclic seizures (CS). Methods We reviewed our prospective continuous EEG database to identify patients with CS, controls with non-cyclic status epilepticus (SE) and controls without seizure matched for age and etiology. EEG was reviewed with DC settings. Results 39/260 (15%) patients with electrographic seizures presented with CS. These patients were older (62 vs. 54 years; p = 0.04) and more often had acute or progressive brain injury (77% vs. 52%; p = 0.03) than patients with non-cyclic SE and had a lower level of consciousness, were more severely ill, than matched controls. CS almost always had focal onset, often from posterior regions. Patients with CS trended towards worse prognosis. When available (12 patients), DC recordings showed an infraslow cyclic oscillation of EEG baseline synchronized to the seizures in all cases. Conclusions CS occur mostly in older patients with acute or progressive brain injury, are more likely to be associated with poor outcome than patients with other forms of nonconvulsive SE, and are accompanied by synchronous oscillations of the EEG baseline on DC recordings. Significance CS are a common form of non-convulsive status epilepticus in critically ill patients and provide further insights into the relationship between infraslow activity and seizures; further study on this relationship may shed light on the mechanisms of seizure initiation and termination.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Clinical Correlates and Prognostic Significance of Lateralized Periodic Discharges in Patients Without Acute or Progressive Brain Injury: A Case-Control Study

Purpose: Lateralized periodic discharges (LPDs, also known as periodic lateralized epileptiform discharges) in conjunction with acute brain injuries are known to be associated with worse prognosis but little is known about their importance in absence of such acute injuries. We studied the clinical correlates and outcome of patients with LPDs in the absence of acute or progressive brain injury. Methods: This is a case-control study of 74 patients with no acute brain injury undergoing continuous EEG monitoring, half with LPDs and half without, matched for age and etiology of remote brain injury, if any, or history of epilepsy. Results: Lateralized periodic discharges were found in 145/1785 (8.1%) of subjects; 37/145 (26%) had no radiologic evidence of acute or progressive brain injury. Those with LPDs were more likely to have abnormal consciousness (86% vs. 57%; P 0.005), seizures (70% vs. 24%; P 0.0002), and functional decline (62% vs. 27%; P 0.005), and were less likely to be discharged home (24% vs. 62%; P 0.002). On multivariate analysis, LPDs and status epilepticus were associated with abnormal consciousness (P 0.009; odds ratio 5.2, 95% CI 1.60-20.00 and P 0.017; odds ratio 5.0, 95% CI 1.4-21.4); and LPDs were independently associated with functional decline (P 0.001; odds ratio 4.8, 95% CI 1.6-15.4) and lower likelihood of being discharged home (P 0.009; odds ratio 0.2, 95% CI 0.04-0.6). Conclusions: Despite absence of acute or progressive brain injury, LPDs were independently associated with abnormal consciousness and worse outcome at hospital discharge.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Prognostication of post-cardiac arrest coma: early clinical and electroencephalographic predictors of outcome

Purpose: To determine the temporal evolution, clinical correlates, and prognostic significance of electroencephalographic (EEG) patterns in post-cardiac arrest comatose patients treated with hypothermia. Methods: Prospective cohort study of consecutive post-anoxic patients receiving hypothermia and continuous EEG monitoring between May 2011 and June 2014 (n = 100). In addition to clinical variables, 5-min EEG clips at 6, 12, 24, 48, and 72 h after return of spontaneous circulation (ROSC) were reviewed. EEG background was classified according to the American Clinical Neurophysiological Society critical care EEG terminology. Clinical outcome at discharge was dichotomized as good [Glasgow outcome scale (GOS) 4–5, low to moderate disability] vs. poor (GOS 1–3, severe disability to death). Results: Non-ventricular fibrillation/tachycardia arrest, longer time to ROSC, absence of brainstem reflexes, extensor or no motor response, lower pH, higher lactate, hypotension requiring >2 vasopressors, and absence of reactivity on EEG were all associated with poor outcome (all p values ≤0.01). Suppression-burst at any time indicated a poor prognosis, with a 0 % false positive rate (FPR) [95 % confidence interval (CI) 0–10 %]. All patients (54/54) with suppression-burst or a low voltage (70 % for good outcome. Conclusions: Suppression-burst or a low voltage at 24 h after ROSC was not compatible with good outcome in this series. Normal background voltage without epileptiform discharges predicted a good outcome.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Acute brain failure in severe sepsis: a prospective study in the medical intensive care unit utilizing continuous EEG monitoring

Purpose: Investigate the prevalence, risk factors and impact of continuous EEG (cEEG) abnormalities on mortality through the 1-year follow-up period in patients with severe sepsis. Methods: Prospective, single-center, observational study of consecutive patients admitted with severe sepsis to the Medical ICU at an academic medical center. Results: A total of 98 patients with 100 episodes of severe sepsis were included; 49 patients (50%) were female, median age was 60 (IQR 52–74), the median non-neuro APACHE II score was 23.5 (IQR 18–28) and median non-neuro SOFA score was 8 (IQR 6–11). Twenty-five episodes had periodic discharges (PD), of which 11 had nonconvulsive seizures (NCS). No patient had NCS without PD. Prior neurological history was associated with a higher risk of PD or NCS (45 vs. 17%; CI 1.53–10.43), while the non-neuro APACHE II, non-neuro SOFA, severity of cardiovascular shock and presence of sedation during cEEG were associated with a lower risk of PD or NCS. Clinical seizures before cEEG were associated with a higher risk of nonconvulsive status epilepticus (24 vs. 6%; CI 1.42–19.94) while the non-neuro APACHE II and non-neuro SOFA scores were associated with a lower risk. Lack of EEG reactivity was present in 28% of episodes. In the survival analysis, a lack of EEG reactivity was associated with higher 1-year mortality [mean survival time 3.3 (95% CI 1.8–4.9) vs. 7.5 (6.4–8.7) months; p = 0.002] but the presence of PD or NCS was not [mean survival time 3.3 (95% CI 1.8–4.9) vs. 7.5 (6.4–8.7) months; p = 0.592]. Lack of reactivity was more frequent in patients on continuous sedation during cEEG. In patients with available 1-year data (34% of the episodes), 82% had good functional outcome (mRS ≤ 3, n = 27). There were no significant predictors of functional outcome, late cognition, and no patient with complete follow-up data developed late seizure or new epilepsy. Conclusions: NCS and PD are common in patients with severe sepsis and altered mental status. They were less frequent among the most severely sick patients and were not associated with outcome in this study. Lack of EEG reactivity was more frequent in patients on continuous sedation and was associated with mortality up to 1 year after discharge. Larger studies are needed to confirm these findings in a broader population and to further evaluate long-term cognitive outcome, risk of late seizure and epilepsy.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

New-onset refractory status epilepticus (NORSE) and febrile infection–related epilepsy syndrome (FIRES): State of the art and perspectives

We report the proceedings of the First International new-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES) Symposium. To promote awareness of this condition and foster research efforts, we conveyed the First International new-onset refractory status epilepticus (NORSE) and febrile infection-related epilepsy syndrome (FIRES) Symposium. The conference was supported by The NORSE Institute (http://www.norseinstitute.org). This article summarizes the discussions that were held during the Symposium and presents our strategy to unravel the cause of these disorders and to improve patient care. The standardized definitions for these disorders that have been developed, are required to improve communication and facilitate the development of multicenter registries and biobanks. A distinction between childhood- and adult-onset forms of the syndrome is not supported by strong scientific evidence and it is argued that both should be studied together. Although the pathophysiology remains elusive, nascent evidence suggests a role for a postinfectious cytokine-mediated mechanism, which should be further investigated. It also appears important to develop tools for their early recognition and prompt treatment. Recent evidence suggests that specific electroencephalography (EEG) features might be helpful. The optimal treatment options remain to be determined; immune therapies are usually disappointing, but the ketogenic diet has proved effective in uncontrolled trials. NORSE and FIRES represent a very delicate clinical situation with specific communication issues between physicians and with patients and families. Standardized consensus definitions and a multidisciplinary multicenter strategy will help research efforts and improve clinical care for patients with NORSE and FIRES.SCOPUS: re.jinfo:eu-repo/semantics/publishe