18 November 2008
“Significant drops in blood oxygen levels are more common than we thought in patients with partial seizures,” said Masud Seyal, professor of neurology at University of California, Davis (UC–D) and co-author of a paper on the subject.
Researchers studied ‘sudden unexpected death in epilepsy’, what doctors call SUDEP, not explained by repeated convulsive seizures, accidents or other mishaps.
“What we’ve known for a long time is that SUDEP appears to be the most important cause of increased mortality in epilepsy patients. What we haven’t known is what causes it,” Seyal said.
The findings suggest that some cases of SUDEP may result from the brain not signaling the patient to continue breathing during seizures, though more conclusive evidence is needed, he said.
“It may have to do with an abnormal heart rhythm or it just may be that the brain stops sending the proper signals to maintain normal breathing,” Seyal said.
Seyal and colleagues examined records of 300 seizures in 57 epilepsy patients with chronic, recurrent, unprovoked seizures. They compared patients with severe convulsive seizures to those with milder symptoms like transient confusion, lip smacking and head turning.
One–third of all seizures were associated with drops in blood–oxygen levels below 90 percent. Seyal said he was surprised to find that 12 percent of these patients’ blood oxygen levels actually dropped below 70 percent during their seizures, said a UC-D release.
The findings support the idea that some cases of SUDEP may be caused by a lack of brain signaling that makes the patient keep breathing, though scientists need to do more research before they know for sure, Seyal said.