It has long been recognized that SUDEP most often occurs at night. People who die of SUDEP are usually found dead in bed in the morning. Most of the time, deaths are not witnessed and frequently, but not always, there is evidence of seizure preceding death. This observation has led physicians and scientists studying SUDEP to ask whether seizures that occur at night, known as nocturnal seizures, are a risk factor for SUDEP. If a person with epilepsy has mainly nocturnal seizures, does that increase their risk of SUDEP?
In February 2012, in the medical journal, Epilepsia, researchers from the Netherlands published a study that examines the relationship between SUDEP and nocturnal seizures. Dr. Robert Lamberts and colleagues compared the seizure patterns of 154 people who died of SUDEP to the seizure patterns of 616 people living with epilepsy. The researchers found that the people who died of SUDEP were more than 3 times more likely to have a history of nocturnal seizures. Also, they found that the people who had a SUDEP occur at night were more likely to have nocturnal seizures than those people that had a SUDEP during the day. You might wonder whether having seizures at night is just a marker for people with more frequent seizures of all types, which we already know is a risk factor for SUDEP. The researchers considered this as well and they found that, even when they took in to account the overall frequency of seizures, having seizures as night still proved to be a risk factor for SUDEP.
Why do seizures at night increase the risk of SUDEP? Unfortunately we don’t yet know the answer to this question. It may be that the heart and breathing system of a sleeping person are more vulnerable to the effect of seizures. It is also possible that when the brain is asleep before a seizure starts it has more difficulty recovering from the effects of that seizure and this results in a slowing of the heart rate and breathing, and sometimes death.
What this study does tell us is that people with nocturnal seizures need to work even harder to reduce the frequency of their seizures. This includes regular appointments with their healthcare provider, taking medications as prescribed and identifying and avoiding triggers for seizures. And if medications are not working to control seizures, all people with epilepsy need to ask their neurologist about other treatments, such as surgery.
By studying the risk factors for SUDEP we will learn not only more about the underlying causes of SUDEP, but also about the best way to prevent it.
In this column I usually report on SUDEP research, but this time around I can’t help but comment on something from the popular press.