A research team, supported by the National Institutes of Health (NIH), has made a significant discovery related to breathing failure following seizures in individuals with severe epilepsy. This condition, known as sudden unexpected death in epilepsy (SUDEP), is the leading cause of death among people with severe, uncontrolled epilepsy.
The new findings, published in the journal JCI Insight and conducted by researchers at the University of Iowa in Iowa City, may provide critical insights into SUDEP, a condition for which the causes are not well understood. SUDEP is believed to occur mainly due to a loss of breathing that happens after a seizure, a phenomenon known as postictal apnea.
The study has revealed that individuals experiencing postictal apnea lose the innate sensation of “air hunger,” which is the primal urge to breathe or the alarm signaling the need to breathe. This suggests that during apnea, the brain may struggle to detect and respond to rising levels of carbon dioxide (CO2) in the blood.Â
To investigate this further, the researchers recruited 12 adults and eight children with severe epilepsy that could not be controlled with medications. These individuals were undergoing intracranial electroencephalography (iEEG) as part of their treatment to monitor and attempt to control their seizures. iEEG involves the placement of electrodes inside the skull to record electrical activity in the brain and identify the origin of seizures.
Under medical supervision, the research team induced seizures in the participants using direct electrical stimulation. This allowed them to examine the role of the forebrain in controlling breathing and the occurrence of postictal apnea. The researchers discovered that seizures originating in a specific brain region called the amygdala could trigger postictal apnea.
The amygdala is primarily involved in processing emotions and fear. The study also identified the specific subregion of the amygdala responsible for prolonged periods of breathing loss following a seizure. Interestingly, only five out of the 20 participants developed postictal apnea, suggesting that susceptibility to the condition may vary among individuals with uncontrolled seizures.Â
To gain deeper insights into the connections between the amygdala and the brainstem region responsible for sensing changes in blood CO2 levels and regulating breathing, the scientists used a combination of electrical stimulation and functional MRI (fMRI). This technique allowed them to uncover novel connections between the amygdala and the brainstem. These connections are critical for detecting changes in CO2 levels and controlling breathing.
Together, these findings suggest that seizures originating in a specific amygdala subregion can suppress the urge to breathe and inhibit the sensation of air hunger for extended periods following a seizure. These effects are likely mediated through connections between the amygdala and various brain regions involved in processing bodily signals.Â
While this study offers valuable insights into the role of the amygdala in breathing suppression following seizures, further research is needed to confirm its connection to SUDEP. The findings represent a significant step forward in understanding the mechanisms underlying SUDEP and may contribute to the development of preventative treatments and the identification of individuals most at risk for this devastating condition.Â
The research was supported in part by the National Institute of Neurological Disorders and Stroke (NINDS), a component of the NIH. This groundbreaking discovery has the potential to reshape our understanding of SUDEP and ultimately improve the lives of individuals living with epilepsy, offering hope for reducing the incidence of this tragic outcome.Â
News Reference Â
National Institute of Health, “Small study identifies brain region associated with breathing failure following seizures” Small study identifies brain region associated with breathing failure following seizures | National Institutes of Health (NIH). Â
