The device has a flexible array of electrodes that run from the lower front to the upper back of the neck, allowing researchers to capture electrical activity between different nerves. Other features include an integrated user interface for real-time data visualization and a special algorithm for grouping people according to their nervous systems’ response to stress.
In the past, more reliable methods for measuring nerve activity in the neck called for surgically implanted microelectrodes.
Lerman and Todd Coleman of UC San Diego’s Jacobs School and Stanford University began creating less risky and invasive means of monitoring this part of the nervous system by adapting existing technology that Coleman developed with co-author Jonas Kurniawan. Stanford. The new, flexible array can be worn for up to a day and moves easily with the patient’s head and neck movements for longer, pain-free monitoring.
To study human autonomic biotypes, or groups of patients whose involuntary nervous systems respond similarly to stress, researchers conducted a series of tests in which study participants were asked to place and hold their hands in ice water, followed by timed breathing exercises. The electrode array recorded the cervical nerve signal, called cervical electroneurography by the team, and the subjects’ heart rate both before and after the ice water challenge and during breathing exercises.
The researchers found that the study participants consistently fell into two distinct biotype groups: those whose nervousness and heart rate increased during both tests, and those who showed the opposite trend. The device’s unique algorithm also offers a chance to identify differences in the response of certain nerve groups to stressors such as pain and physical symptoms caused by the ice water challenge, including increased heart rate associated with sweating and breathing problems.
“The results are exciting. Our newly developed sensor array is capable of recording the activity of the autonomic nervous system,” Coleman said. “We were pleasantly surprised to observe a consistent autonomic response between stress test challenges, namely the cold pressor test and the deep breathing challenge. More work is needed to demonstrate our sensor capabilities in larger populations.”
Towards the future of personalized medicine
Although the electrode array can’t pinpoint the nerves that fire in response to the stress and pain of the cold water challenge, the researchers hope it will someday help diagnose and treat conditions including PTSD and sepsis.
Already, Lerman is one of a number of researchers using electrical vagus nerve stimulation to test whether stimulation of these neural structures can reduce inflammation and pain in people with PTSD.
In a related application, the array could also be used to improve the safety of pilots flying military aircraft by detecting flares in neural activity that cause dizziness or nausea.
In a hospital setting, the device can help identify life-threatening patients, such as sepsis, by identifying people who react strongly to physical stress. Sepsis occurs when the body’s immune system overreacts to an infection, damaging its own tissues in the process. The risk of death increases by seven percent every hour. Technology that helps identify and record at-risk hospitalized patients will provide doctors with an early warning to administer antibiotics, increasing the patient’s chance of avoiding or surviving sepsis.
As a next step, the researchers plan to connect the array to additional hardware for a wireless, wearable sensor that can be placed outside the lab. Researchers are now moving forward with a clinical trial that detects sepsis in the hospital.