Researchers at University of Iowa have identified regions of the human brain responsible for controlling breath and for causing impaired breathing which leads to sudden unexpected death in epilepsy, SUDEP.
According to the paper, “Breathing Inhibited When Seizures Spread to the Amygdala and upon Amygdala Stimulation” which was published in the Journal of Neuroscience, breathing may be impaired during and after seizures without the patient’s knowledge and this impaired breathing plays a critical role in causing SUDEP.
For the study, researchers used electrical stimulation to activate the amygdala on a participant with medically intractable epilepsy and this marks the first time that researchers have stimulated the amygdala in humans to report breathing such as impaired breathing or shortness of breath.
The brain of the participant was continuously monitored during seizures using intracranial electrodes and mapped by high-resolution brain imaging and it was found that when seizures spread to the amygdala, the patient stopped breathing – the patient did not know he was breathing even though he was wide awake at the time.
Researchers told this effect can be reproduced by electrically stimulating the amygdala, so they reproduced the same finding in two other participants.
“Amazingly, the patient was completely unaware that he had stopped breathing,” says Brian Dlouhy, M.D., assistant professor of neurosurgery at UI Carver College of Medicine and lead author of the study.
“It was remarkable to all of us that one of the essentials of life – breathing – could be inhibited and the patients themselves were completely unaware of this.”
“The patient just sat there, unconcerned that he was not breathing,” says John Wemmie, M.D., Ph.D., professor of psychiatry, molecular physiology and biophysics, and neurosurgery at the UI Carver College of medicine, and an author of the paper.
“If we asked him to hold his breath for the same duration of time, it was difficult for him and he could barely do it. But when the amygdala was stimulated, he didn’t even notice that his breathing had stopped.”
Dr. George Richerson, M.D., Ph.D., professor and chairman of neurology, and professor of molecular physiology and biophysics, and neurosurgery at the UI Carver College of Medicine, also an author on the paper, says – “These findings provide an explanation for why SUDEP occurs after seizures, because patients would stop breathing but be completely unaware that their blood oxygen levels are progressively dropping to fatally low levels. The lack of awareness would prevent activation of the reflex that is needed to restore oxygen levels back to normal.”
“The team’s findings may be key in helping to decrease instances of SUDEP,” Dlouhy says.
“Identifying brain areas where seizure spread interferes with breathing may help identify patients at risk for SUDEP and lead to preventive strategies,” he says.
[Hat Tip: University of Iowa, Image via Wired.co.uk]