Autonomic testing lab focuses on functions patients can't control
By Aline McKenzie
More and more, medical care today gets patients involved, giving them control over what happens to them.
But Dr. Steven Vernino, associate professor of neurology, is also interested in things that patients can’t control — heart rate, blood pressure, pain sensation, pupil reflexes to light, production of tears, salivation, sweating and so on.
|One testing device in the autonomic testing lab records the pupil responses of Vannoy Shaw (foreground) while Dr. Steven Vernino monitors the results.|
Dr. Vernino’s focus is the autonomic nervous system, which unconsciously controls the basic functions of the body.
Several diseases, including diabetes, can affect the autonomic nervous system, so clinically, his team’s assessments can help rate the degree of damage that a disease has caused.
“You can imagine if your heart rate can’t climb, you can’t do very much,” Dr. Vernino said. “Or, if you do very little and your heart rate shoots to 160 beats per minute, you won’t feel very good.”
In the autonomic testing laboratory, Dr. Vernino looks for correlations between patterns of autonomic dysfunction and certain diseases. For instance, the autonomic tests can help distinguish Parkinson’s disease from ailments with similar symptoms but different prognoses. Autonomic tests can also help determine the cause of fainting episodes and diagnose damage to the peripheral nerves earlier in diseases such as diabetes.
“Our primary interest is to provide a clinical service to evaluate disorders of the autonomic nerves,” Dr. Vernino said. “But I also have a research interest in autonomic diseases, so I’m interested in improving the ways that we measure autonomic functions.”
The standard tests measure sweating in the arms and legs and record heart rate and blood pressure during a variety of simple maneuvers.
“Measuring the pupils is not new, but recording the pupil responses in both eyes simultaneously using high-speed cameras and computer analysis is relatively new,” Dr. Vernino said. “This is in the research stage. We see some people who have severe autonomic problems, but their pupils are OK, and other conditions in people whose pupils are abnormal. We hope that pupil studies will soon be a useful part of clinical autonomic testing.”
Vannoy Shaw, 67, a retired sales representative for a medical supplies company, began having problems last fall. She began “graying out,” feeling faint and dizzy.
“It’s like living in a fog,” she said. “I don’t know if I’m going to fall or not.”
One time, she actually did fall.
“They don’t know why,” Mrs. Shaw said. “I think it’s called old age. Everything that can go wrong does go wrong when you get past 60.”
Mrs. Shaw has undergone a battery of tests, literally from head to foot, to monitor the function of her autonomic system. Straps on her foot and other body locations measured her ability to produce sweat — the only really unpleasant part of the testing, she said.
With a strap and electrodes around her chest, she breathed in various patterns — deep or prolonged — to determine how breathing affected her heart rate.
Some tests were repeated as the table she was lying on was tilted nearly upright. When these tests were concluded, she looked into a machine that recorded her pupil responses to a series of flashes.
“There may be 20 labs that do this sort of detailed autonomic testing in the United States,” Dr. Vernino said. “It’s a small field.
“Each lab tends to have a different research interest, such as sweating in athletes, exercise physiology in high-altitude climbers, or children with genetic disorders. One of my interests has been to describe an autonomic disorder that occurs suddenly in adults caused by an abnormal antibody in the blood.”