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Neurology

Expanded short circuit

Electric over stimulation of the brain can affect the heart and lead to sudden death from epilepsy

SANTIAGO RAMÓN Y CAJAL INSTITUTE / WIKIMEDIAConnections: neurons drawn by Santiago Ramón y Cajal, 1906 Nobel Prize laureateSANTIAGO RAMÓN Y CAJAL INSTITUTE / WIKIMEDIA

Some epileptics have higher than average heartbeats and therefore are at risk – three times higher than that of healthy people – of sudden death for no apparent reason. Now the two characteristics of this condition seem to have an explanation: tachycardia, which is the excessively rapid or irregular heartbeat – could be one of the mechanisms that trigger sudden death because of epilepsy, according to recent studies conducted in Brazil and in other countries.

“The more constant the epileptic crises and tachycardia, the higher the risk,” says Fulvio Scorza, professor of the Federal University of São Paulo (Unifesp). He says that he presented the conclusions of the study to a group of cardiologists from Unifesp, who are interested in the possibility of applying the referred results. The two groups are preparing a constant cardiac monitoring study of people with epilepsy that do not respond to conventional treatment. The objective of this study is to lower the incidence of sudden death, the main cause of death among epileptics.

On average, one out of every one thousand individuals with this neurological disturbance die suddenly, during or right after a crisis, while they are sleeping or when they are awake. From 2000 to 2009, Vera Terra, a physician at the Epilepsy Surgery Center of the University of São Paulo (USP) in Ribeirão Preto, kept track of 1,054 children (from 0 to 18 years old) with epilepsy; 12 died suddenly. Defined as non-witnessed death or death from no apparent causes, sudden death by epilepsy has been a difficult condition to investigate, because it cannot be predicted – nor can the crises, which entail intense contractions and muscular tremors.

Several risk factors have already been defined: patients from the age of 27 to 39 years, early onset and duration of epileptic crises, frequency of uncontrolled crises, continuous exposure to cold environments, and side effects from medications used to treat epilepsy. The causes of sudden death however remained unexplained. There were indications that the electric over stimulation of regions of the brain that generated epileptic crises caused the fatal acceleration of the heartbeat or a sudden drop in blood pressure.

In 2004, Scorza began investigating possible causes and forms of prevention of this problem. He was motivated to do so by a comment made by neurologist Marly de Albuquerque, who was working at Unifesp at the time and is currently teaching at the University of Mogi das Cruzes. On a Monday evening, she told Scorza that an adolescent patient that had been going to her for treatment had died suddenly. Scorza was moved by Marly’s sadness and, as his son Miguel had just been born, sympathized with the despair of the parents whose son had recently passed away.

Abnormal pace
In one of his first experiments, he and Diego Colugnati, who currently teaches at the Federal University of Goiás, observed that the hearts of rats with induced epilepsy had tachycardia. However, if the hearts were removed and maintained in functioning condition through the appropriate means out of the animal?s body, the tachycardia stopped and the heartbeat went back to normal. “The heart goes into tachycardia in a body with a sick brain,” says Scorza. The group’s latest study – published in November 2010 in Epilepsy & Behavior journal, detailed this phenomenon, which registered brachycardia – the slowing down of the heartbeat – in rats right after the onset of an epileptic crisis. The brachycardia was followed by tachycardia, which continued even after the electrical discharge that had caused the crisis had stopped.

Four months before, Scorza, Ricardo Arida and Esper Cavalheiro, of Unifesp, and Vera Terra, of USP, wrote an editorial in Epilepsy & Behavior proposing some ways to prevent sudden death: control the crises as strictly as possible; reduce the stress that can trigger the crises; expand the participation of epileptics in sports activities; provide night supervision, especially for epileptic children, by means of monitors or alarms; and increase the knowledge of family members about heart resuscitation techniques.

Scorza, like other researchers from São Paulo’s research centers, verified that the daily consumption of polyunsaturated fatty acids of the omega-3 kind, complementing traditional medication, can reduce the frequency and intensity of the crises, which would reduce the risk of sudden death. In 2008, he and his group showed that omega-3 helps regulate the functioning of the neurons subject to electrical non-control and induces the formation of new neurons.

There is still an additional problem that has to be solved: should physicians tell epileptics and their families that, in addition to being forbidden from driving or drinking liquor, they are subject to sudden death? During the end of the doctorate studies at Unifesp, Ively Abdalla noted that most of the 44 physicians interviewed for the study said that they only inform patients who ask about the possibility of sudden death.

Martin Brodie, a professor at the University of Glasgow in Scotland and co-author of an article published in 2008 in Epilepsy, argues that all patients and their family members have the right to be informed of the risks of the treatment. The other author, Gregory Holmes at the University of Dartmouth in the United States, says that it is not necessary to inform all patients, and only patients with higher risk factors, such as the ones who have constant crises that do not respond to conventional treatments, should be informed. The opinions are conflicting, because the risk of sudden death is not the same in all epileptics. Most of the patients diagnosed with epilepsy stop having crises when they start taking medication and the patients that have all the risk factors do not always die a sudden death.

“Informing the patient of the risk of sudden death or not informing him depends on the situation,” says Marly. “I usually don’t inform patients diagnosed with epilepsy because most of them are not at risk; in addition, most of them don´t ask this question. We have to move slowly, because patients have too much information to assimilate.”

Scientific articles
PANSANI, A.P. et al. Tachycardias and sudden unexpected death in epilepsy: a gold rush by an experimental route. Epilepsy & Behavior. v. 19, n. 3, p. 546-7. nov. 2010.
SCORZA, F. et al. What can be done to reduce the risk of SUDEP? Epilepsy & Behavior. v. 18, n. 3, p. 137-8. jul. 2010.

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