The Multivariate Mixture Dynamics Model: Shifted dynamics and correlation skew

The Multi Variate Mixture Dynamics model is a tractable, dynamical, arbitrage-free multivariate model characterized by transparency on the dependence structure, since closed form formulae for terminal correlations, average correlations and copula function are available. It also allows for complete decorrelation between assets and instantaneous variances. Each single asset is modelled according to a lognormal mixture dynamics model, and this univariate version is widely used in the industry due to its flexibility and accuracy. The same property holds for the multivariate process of all assets, whose density is a mixture of multivariate basic densities. This allows for consistency of single asset and index/portfolio smile. In this paper, we generalize the MVMD model by introducing shifted dynamics and we propose a definition of implied correlation under this model. We investigate whether the model is able to consistently reproduce the implied volatility of FX cross rates once the single components are calibrated to univariate shifted lognormal mixture dynamics models. We consider in particular the case of the Chinese renminbi FX rate, showing that the shifted MVMD model correctly recovers the CNY/EUR smile given the EUR/USD smile and the USD/CNY smile, thus highlighting that the model can also work as an arbitrage free volatility smile extrapolation tool for cross currencies that may not be liquid or fully observable. We compare the performance of the shifted MVMD model in terms of implied correlation with those of the shifted Simply Correlated Mixture Dynamics model where the dynamics of the single assets are connected naively by introducing correlation among their Brownian motions. Finally, we introduce a model with uncertain volatilities and correlation. The Markovian projection of this model is a generalization of the shifted MVMD model

Neurostimulation in the treatment of refractory and super-refractory status epilepticus

Abstract Status epilepticus (SE) is a life-threatening condition with a mortality of up to 60% in the advanced and comatose forms of SE. In one out of five adults, first and second line fails to control epileptic activity, leading to refractory status epilepticus (RSE) and in around 3% to super-refractory status epilepticus (SRSE), where SE continues despite anesthetic treatment for 24 h or more. In this rare but devastating condition, innovative and safe treatments are needed. In a recent review on the use of vagal nerve stimulation in RSE and SRSE, a 74% response rate for abrogation of SE was reported. Here, we review the currently available evidence supporting the use of neurostimulation, including vagal nerve stimulation, direct cortical stimulation, transcranial magnetic stimulation, electroconvulsive therapy, and deep brain stimulation in RSE and SRSE. This article is part of the Special Issue "Proceedings of the 7th London-Innsbruck Colloquium on Status Epilepticus and Acute Seizures"

Transient global amnesia and the forgotten EEG pattern

[no abstract available

Value of tongue biting in the differential diagnosis between epileptic seizures and syncope

AbstractBackgroundTongue biting (TB) may occur both in epileptic seizures and in syncope. A comprehensive search of the literature to determine the accuracy of this physical finding and its prevalence in epileptic seizures and syncope is still lacking.AimsTo undertake a systematic review and a meta-analysis of studies evaluating the prevalence of TB in patients with epileptic seizures and syncope, and to determine sensitivity, specificity and likelihood ratios (LR) of this physical finding.MethodStudies comparing the prevalence of TB in epileptic seizures and syncope were systematically searched. Prevalence of TB was analyzed calculating odds ratio (OR) with 95% confidence intervals (CIs). Sensitivity, specificity, positive and negative likelihood ratio (pLR, nLR) of TB were determined for each study and for the pooled results.ResultsTwo studies (75 epilepsy patients and 98 subjects with syncope) were included. There was a significantly higher prevalence of TB in patients with epileptic seizures (OR 12.26; 95% CI 3.99–37.69). Pooled accuracy measures of TB for the diagnosis of epileptic seizures were: sensitivity 33%, specificity 96%, pLR 8.167 (95% CI 2.969–22.461) and nLR 0.695 (95% CI 0.589–0.82).ConclusionsA pooled analysis of data from the literature shows that TB has great value in the differential diagnosis between epileptic seizures and syncope. Given a certain pre-test probability of seizures, the presence of TB greatly increases the chance that the patient had an epileptic seizure. Systematic reviews with pooled analyses (meta-analyses) of data from the literature allow an increase in statistical power and an improvement in precision, representing a useful tool to determine the accuracy of a certain physical finding in the differential diagnosis between seizures and other paroxysmal events

“Chi l’ha detto?”. Un caso emblematico di errata attribuzione

This article discusses the real authorship of a sentence erroneously attributed to Giovanni Battista Morgagni (1682-1771) but actually by the French physician François Joseph Victor Broussais (1772-1838). This exemplary case shows how a single erroneous attribution risks being reproposed over time, consolidating itself in the scientific literature, so much to replace the original authorship with an erroneous one. It follows the absolute necessity to always and rigorously verify the accuracy of a sentence attributed to a certain author, both in form and in content, as well as in its real authorship.In questo articolo si presenta e discute la reale paternità di una frase erroneamente attribuita a Giovanni Battista Morgagni (1682-1771) e in realtà del medico francese François Joseph Victor Broussais (1772-1838). Questo caso emblematico evidenzia come una singola attribuzione errata rischi di essere riproposta nel tempo consolidandosi nella lettera-tura scientifica, tanto da sostituire la paternità originaria con una erronea. Ne consegue l’assoluta necessità di verificare sempre e in maniera rigorosa l’accuratezza di un’espressione attribuita a un autore, sia nella forma che nel contenuto, oltre che nella sua reale paternità

Differentiating drug-induced parkinsonism from Parkinson's disease: An update on non-motor symptoms and investigations

Abstract Drug-induced parkinsonism is the second most common cause of parkinsonism after Parkinson's disease and their distinction has crucial implications in terms of management and prognosis. However, differentiating between these conditions can be challenging on a clinical ground, especially in the early stages. We therefore performed a review to ascertain whether assessment of non-motor symptoms, or use of ancillary investigations, namely dopamine transporter imaging, transcranial sonography of the substantia nigra, and scintigraphy for myocardial sympathetic innervation, can be recommended to distinguish between these conditions. Among non-motor symptoms, there is evidence that hyposmia can differentiate between patients with "pure" drug-induced parkinsonism and those with degenerative parkinsonism unmasked by an anti-dopaminergic drug. However, several issues, including smoking history and cognitive functions, can influence smell function assessment. Higher diagnostic accuracy has been demonstrated for dopamine transporter imaging. Finally, preliminary evidence exists for sympathetic cardiac scintigraphy to predict dopaminergic pathway abnormalities and to differentiate between drug-induced parkinsonism and Parkinson's disease. Imaging of the dopaminergic pathway seems to be the only, reasonably available, technique to aid the differential diagnosis between drug-induced parkinsonism and Parkinson's disease

Italian Wikipedia and epilepsy: an infodemiological study of online information-seeking behavior

Wikipedia is the most commonly accessed source of health information by both healthcare professionals and the lay public worldwide. We aimed to evaluate information-seeking behavior of Internet users searching the Italian Wikipedia for articles related to epilepsy and its treatment. Using Pageviews Analysis, we assessed the total and mean monthly views of articles from the Italian Wikipedia devoted to epilepsy, epileptic syndromes, seizure type, and antiepileptic drugs (AEDs) from January 1, 2015 to October 31, 2017. We compared the views of the article on epilepsy with those of articles focusing on Alzheimer's disease, migraine, multiple sclerosis, syncope, and stroke and adjusted all results for crude disease prevalence. With the only exception of the article on multiple sclerosis, the adjusted views for the Italian Wikipedia article on epilepsy were higher than those for the other neurological disorders. The most viewed articles on seizure type were devoted to tonic-clonic seizure, typical absence seizure, tonic convulsive seizures, and clonic convulsive seizures. The most frequently accessed articles on epilepsy syndromes were about temporal lobe epilepsy and Lennox-Gastaut syndrome. The most frequently viewed articles on AEDs were devoted to valproic acid, carbamazepine, and levetiracetam. Wikipedia searches seem to mirror patients' fears and worries about epilepsy more than its actual epidemiology. The ultimate reasons for searching online remain unknown. Epileptologists and epilepsy scientific societies should make greater efforts to work jointly with Wikipedia to convey more accurate and up-to-date information about epilepsy

Terminology for psychogenic nonepileptic seizures:Making the case for "functional seizures"

PURPOSE: The purpose of the study was to review the literature on the terminologies for psychogenic nonepileptic seizures (PNES) and make a proposal on the terminology of this condition. This proposal reflects the authors' own opinions.METHODS: We systematically searched MEDLINE (accessed from PubMed) and EMBASE from inception to October 10, 2019 for articles written in English with a main focus on PNES (with or without discussion of other functional neurological disorders) and which either proposed or discussed the accuracy or appropriateness of PNES terminologies.RESULTS: The search strategy reported above yielded 757 articles; 30 articles were eventually included, which were generally of low quality. "Functional seizures" (FS) appeared to be an acceptable terminology to name this condition from the perspective of patients. In addition, FS is a term that is relatively popular with clinicians.CONCLUSION: From the available evidence, FS meets more of the criteria proposed for an acceptable label than other popular terms in the field. While the term FS is neutral with regard to etiology and pathology (particularly regarding whether psychological or not), other terms such as "dissociative", "conversion", or "psychogenic" seizures are not. In addition, FS can potentially facilitate multidisciplinary (physical and psychological) management more than other terms. Adopting a universally accepted terminology to describe this disorder could standardize our approach to the illness and facilitate communication between healthcare professionals, patients, their families, carers, and the wider public.</p

Vagus nerve stimulation in refractory and super-refractory status epilepticus - A systematic review.

Abstract Rationale Refractory status epilepticus (RSE) is the persistence of status epilepticus despite second-line treatment. Super-refractory SE (SRSE) is characterized by ongoing status despite 48 h of anaesthetic treatment. Due to the high case fatality in RSE of 16–39%, off label treatments without strong evidence of efficacy in RSE are often administered. In single case-reports and small case series totalling 28 patients, acute implantation of VNS in RSE was associated with 76% and 26% success rate in generalized and focal RSE respectively. We performed an updated systematic review of the literature on efficacy of VNS in RSE/SRSE by including all reported patients. Methods We systematically searched EMBASE, CENTRAL, Opengre.eu, and ClinicalTrials.gov , and PubMed databases to identify studies reporting the use of VNS for RSE and/or SRSE. We also searched conference abstracts from AES and ILAE meetings. Results 45 patients were identified in total of which 38 were acute implantations of VNS in RSE/SRSE. Five cases had VNS implantation for epilepsia partialis continua, one for refractory electrical status epilepticus in sleep and one for acute encephalitis with refractory repetitive focal seizures. Acute VNS implantation was associated with cessation of RSE/SRSE in 74% (28/38) of acute cases. Cessation did not occur in 18% (7/38) of cases and four deaths were reported (11%); all of them due to the underlying disease and unlikely related to VNS implantation. Median duration of the RSE/SRSE episode pre and post VNS implantation was 18 days (range: 3–1680 days) and 8 days (range: 3–84 days) respectively. Positive outcomes occurred in 82% (31/38) of cases. Conclusion VNS can interrupt RSE and SRSE in 74% of patients; data originate from reported studies classified as level IV and the risk for reporting bias is high. Further prospective studies are warranted to investigate acute VNS in RSE and SRSE