Is cold the new hot in sudden unexpected death in epilepsy? Effect of low temperature on heart rate of rats with epilepsy

Abstract

-Sudden unexpected death in epilepsy (SUDEP) is the commonest cause of seizure-related mortality in people with refractory epilepsy. Several risk factors for SUDEP are described; however, the importance of including low temperatures as risk factor for SUDEP was never explored. Based on this, the aim of this study was to evaluate the heart rate of rats with epilepsy during low temperature exposure. Our results showed that low temperature clearly increased the heart rate of rats with epilepsy. Taken together, we concluded that exposure to low temperatures could be considered important risk factors from cardiovascular abnormalities and hence sudden cardiac death in epilepsy.KEy wOrDS: epilepsy, seizure, SUDEP, low temperatures, heart. É o frio responsável por mortes inesperadas em epilepsia ? Efeito de temperaturas baixas na frequência cardíaca de ratos com epilepsia.Resumo -A morte súbita e inesperada nas epilepsias (SUDEP) é considerada a maior causa de morte em indivíduos com epilepsia refratária. Vários fatores de risco para SUDEP têm sido descritos, no entanto, a inclusão das baixas temperaturas como um possível fator de risco para SUDEP não foi verificada até o momento. Nesse sentido, o objetivo desse estudo foi verificar a freqüência cardíaca de animais com epilepsia expostos as temperaturas baixas. Nossos resultados demonstraram que as baixas temperaturas são capazes de aumentar significativamente a freqüência cardíaca de animais com epilepsia. Dessa forma, concluímos que as baixas temperaturas podem ser consideradas um importante fator de risco de possíveis alterações cardiovasculares e até mesmo morte súbita cardíaca nas epilepsias.PAlAVrAS-chAVE: epilepsia, crises epilépticas, SUDEP, baixas temperaturas, coração. The epilepsies are the most common serious neurological condition. In developed countries, the incidence of epilepsy is around 50 per 100 000 people per year, and is higher in infants and elderly people 1,2 . The most commonly reported etiological factors are tumors, head injuries, stroke, genetic inheritance and infections of the central nervous system 1,3 . In resource-poor countries, endemic infections, such as neurocysticercosis and malaria seem to be major risk factors 1 . Moreover, people with epilepsy are two-to three-fold increase to die prematurely than those without epilepsy and the most common epilepsyrelated category of death is sudden unexpected death in epilepsy (SUDEP).SUDEP is defined as sudden, unexpected, witnessed or unwitnessed, nontraumatic and nondrowning deaths in patients with epilepsy, with or without evidence of a seizure and excluding documented status epilepticus (SE), in which post mortem examination does not reveal a toxicological or anatomical cause of death 4 . Information concerning risk factors for SUDEP is conflicting, but potential risk factors include: age, early onset of epilepsy, duration of epilepsy, uncontrolled seizures, seizure frequency, seizure type and antiepileptic drugs number 5 . The exact pathophysiological causes of SUDEP are unknown, b...

The influence of circadian rhythms on sudden unexpected death in epilepsy

“…Exposure to low temperatures is well-established as one of the risk factors in cardiac mortality 4 , and our group reported that winter temperatures may lead to some cardiovascular abnormalities and hence SUDEP 5 . This hypothesis has been experimentally evaluated and we demonstrated that low temperatures clearly increase the heart rate of rats with epilepsy, suggesting that cold weather could be considered an important risk factor in cardiovascular abnormalities and therefore sudden cardiac death in epi-lepsy 6 . Following this reasoning, colder temperatures have been associated with an increase in vascular resistance, coronary vasospasm, blood pressure, and hemostasis 4 .…”

Sudden unexpected death in epilepsy: From the lab to the clinic setting

“…Many predisposing and triggering factors may coexist in SUDEP [9], including the presence of generalized tonic-clonic seizures, polytherapy with antiepileptic drugs, onset of the disease at an early age, long-term seizure disorder (over 15 years), cold climates [5,10,11], abnormalities of the cardiovascular system, central apnea, and primary brain failure related to seizures (Table 1) [12,13]. The ILAE Commission on Epidemiology identified increased frequency of generalized tonic-clonic seizures, use of polytherapy, longer duration of epilepsy, young age at the onset of the disease, gender, and symptomatic etiology as risk factors for SUDEP [14].…”

Clima e mortalidade: uma abordagem observacional ecológica na cidade de São Paulo

“…Em 2000, o estudo conduzido por Pope [6] resumiu os mecanismos fisiológicos de efeito das partículas finas na saúde humana. A descrição destes mecanismos de efeito aborda diversos desfechos, como doenças cardiovasculares, respiratórias, do aparelho reprodutivo, dentre outras, e surge como foco de investigação de vários autores [7,8,9,10,11] . No entanto, estudos epidemiológicos, com base na morbidade e mortalidade, também são realizados e caracterizam-se como forte instrumento para ampliar esta discussão à saúde pública [1,2] .…”