ScienceDaily (Oct. 13, 2000) — Finding hints at broader issues in understanding of sleep and brain function

ANN ARBOR, Mich. - As much as a third of people with epilepsy may also have undiagnosed sleep apnea, a potentially serious but treatable condition marked by interruptions in breathing during sleep, according to a new University of Michigan study.

The finding, published today in the journal Neurology, may help doctors better understand how brain function in epilepsy influences sleep, and lead to treatments that may help ease the disorder's seizures and other symptoms. The finding may also aid to understanding of the interplay between sleep and brain function in people without epilepsy.

"Any disorder that fragments, or disrupts, sleep can change the overall excitability, and irritability, of the brain," says Beth Malow, M.D., M.S., an assistant professor of neurology at the U-M Health System. "In a person with epilepsy, the sleep disruption may facilitate a seizure, while in someone without the disorder, the effect may be more like irritability or a short temper during the day, or result in headaches, difficulty concentrating, or daytime sleepiness."

The finding builds on work at the U-M by Malow and the late sleep research pioneer Michael Aldrich, M.D. Their studies were some of the first to document a possible link between epilepsy and sleep apnea. The new study is the first time the connection has been shown prospectively.

Malow and the rest of the U-M team are now starting a clinical trial to study whether receiving treatment for sleep apnea lessens the frequency and severity of epileptic seizures.

To achieve the new finding, Malow and her colleagues surveyed and studied the sleep patterns of 39 patients with epilepsy that did not respond to anti-seizure medication. All the patients were candidates for brain surgery to lessen their symptoms. All were evaluated at the U-M's Michael S. Aldrich Sleep Disorders Laboratory with an overnight polysomnography sleep monitoring test.

They found that a full one-third of the patients had obstructive sleep apnea, a form of the disorder in which breathing is interrupted or diminished at least five times per hour. Thirteen percent had moderate to severe apnea, with breathing problems more than 20 times per hour.

The patients who were found to have obstructive sleep apnea of any severity were more likely to be older, male, and have higher scores on a sleep disorders questionnaire given before their sleep test - all of which are typical indicators for people without epilepsy. But they were also more likely to have seizures at night than epilepsy patients without apnea.

There were no differences between the two groups in their seizure frequency per month, number or type of antiepileptic medications used, or the location of their seizures' starting point in the brain.

"Even more so than the general population, the epilepsy patient population seems to have a high incidence of undiagnosed apnea, and the effect on their daytime functioning may be even greater than in those without epilepsy," says Malow. "Now, we must find out whether addressing that apnea through lifestyle and medical intervention can help."

Patients with four or more epileptic seizures a month and symptoms of obstructive sleep apnea, including loud snoring or witnessed apnea, may be eligible for a new study looking at whether treating sleep apnea improves seizure control, daytime sleepiness, and quality of life. The study involves completion of questionnaires, overnight sleep studies, and other testing at the University of Michigan.

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