Vagus nerve stimulation is an adjunctive therapy used to treat patients with refractory epilepsy who are not candidates for resective surgery or had poor results after surgical procedures. Its mechanism of action is not yet fully comprehended but it possibly involves modulation of the locus coeruleus, thalamus and limbic circuit through noradrenergic and serotonergic projections. There is sufficient evidence to support its use in patients with focal epilepsy and other seizure types. However, it should be recognized that improvement is not immediate and increases over time. The majority of adverse events is stimulation-related, temporary and decreases after adjustment of settings. Future perspectives to improve efficacy and reduce side effects, such as different approaches to increase battery life, transcutaneous stimulation and identification of prognostic factors, should be further investigated.Keywords: vagus nerve stimulation; epilepsy.
RESUMOA estimulação vagal é uma terapia paliativa utilizada no tratamento de pacientes com epilepsia refratária que não são candidatos à cirurgia ressectiva ou naqueles com evolução insatisfatória após o procedimento cirúrgico. Seu mecanismo de ação ainda não foi completamente elucidado mas possivelmente envolve a modulação do locus coeruleus, tálamo e circuito límbico através de projeções noradrenérgicas e serotoninérgicas. Atualmente há evidência suficiente para corroborar o uso desta terapia em pacientes com epilepsia focal e outros tipos de crise, com resultados que, apesar de não imediatos, melhoram progressivamente no longo prazo. Os eventos adversos são, em sua maioria, relacionados à estimulação e auto-limitados. Perspectivas futuras para aumentar a eficácia e reduzir os efeitos colaterais como a utilização de baterias com maior durabilidade, estimulação transcutânea e identificação de fatores prognósticos devem ser investigadas.
Palavras-chave: estimulação do nervo vago; epilepsia.Epilepsy is one of the most common chronic neurologic diseases and affects at least 50 million people worldwide 1 . Although much has been understood about its causes, epilepsy is still extremely stigmatizing and many patients are victims of prejudice and social exclusion. The quality of life of those affected by the disease is remarkably compromised due to seizures, antiepileptic drugs (AED), cognitive impairment and physical limitations.Those who do not achieve adequate seizure control, even with multiple AED trials, are considered refractory. Currently, medically resistant epilepsy is regarded as a worldwide health issue as it is endured by approximately one third of epileptic patients. The financial burden is substantial and, among all health costs of uncontrolled patients, nearly 50% are related to epilepsy care costs 2 . For these individuals, whose treatment is generally complex, epilepsy surgery may be indicated and can provide up to 80% seizure control, depending on distinct aspects such as time of follow-up and epileptic focus localization. Figure 1 illustrates the therapy ...
This paper presents an optimization model to reduce the gap between planning and scheduling activities in pipeline networks for supply of petroleum derivatives, so as to effectively operate the plans developed at higher decision levels. Most of the information taken in the petroleum supply chain is unidirectional, from the strategic level passing through the tactical level and finally reaching the operational level. However, unviable schedules are often obtained from an operational standpoint, since operational criteria are not considered when decisions are made at the strategic and tactical levels. In particular, in the supply chain of refined petroleum products, the production campaigns of the refineries are defined for different regions based on the consumer market and no operational conditions related to distribution are accounted at this stage. This fact that may lead to operational infeasibilities. To overcome this type of problem the present paper proposes a Mixed Integer Linear Programming (MILP) approach to validate the refineries' production plans where operational conditions are accounted for, and as a consequence, a decrease in the existent gap between the scheduled and executed operations is obtained. The proposed methodology is applied to a real world case study of a Brazilian Oil company.
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