Sudden unexpected death in epilepsy (SUDEP) is becoming increasingly recognized as a very real and devastating problem in which impaired breathing is thought to play a critical role. Researchers believe breathing may be impaired during and after seizures, without the patient’s knowledge. Now, by using electrical stimulation to activate the amygdala, a group of University of Iowa researchers have identified areas of the human brain in which breathing is controlled and in some cases, impaired, providing an important insight into SUDEP. The team state that to their knowledge the new study marks the first time researchers have stimulated the amygdala in humans and reported loss of breathing.
The current study investigated a research participant with medically intractable epilepsy, which is epilepsy which can’t be well-controlled with two or more medications. The patient’s brain was already being monitored to map the focus of seizures. The data findings showed that when seizures spread to the amygdala, the patient stopped breathing. The results also showed that the effect could be reproduced by electrically stimulating the amygdala. The team note that strikingly, the patient wasn’t aware he wasn’t breathing even though he was wide awake at the time. This finding was reproduced in two other human subjects.
The researchers state that the patient was completely unaware that he had stopped breathing. They go on to add that it was remarkable to all of them that one of the essentials of life, breathing, could be inhibited and the patients themselves were completely unaware of this. The team state that when the patient was asked to hold his breath for the same duration of time, it was difficult for him and he could barely do it. However, they go on to add that, when the amygdala was stimulated the patient didn’t even notice that his breathing had stopped.
The team state that these findings provide an explanation for why SUDEP occurs after seizures, because patients would stop breathing and would be completely unaware that their blood oxygen levels are progressively dropping to fatally low levels. They conclude that the lack of awareness would prevent activation of the reflex that is needed to restore oxygen levels back to normal.
The researchers surmise that the findings may be key in helping to decrease instances of SUDEP. They go on to add that identifying brain areas where seizure spread interferes with breathing may help identify patients at risk for SUDEP and lead to preventive strategies.
Source: UI Carver College of Medicine