Autonomic testing

Autonomic testing, also known as autonomic reflex screen or autonomic response testing, is a non-invasive test that measures how the autonomic nervous system (ANS) works to control blood pressure, heart rate, digestion, and sweating. Disorders such as autonomic neuropathy, autonomic dysfunction, dysautonomia, and other related conditions can be diagnosed using autonomic testing.

Autonomic testingis typically conducted by Penn Medicine neurodiagnostic professionals, or specialists in autonomic disorders. The results of these tests can help your Penn care team identify an autonomic nervous system dysfunction, diagnose autonomic disorders, and develop appropriate treatment plans to manage symptoms and improve your quality of life.

Your Penn Medicine care team may recommend ANS testing if you have the following symptoms:

• Abnormal sweating patterns, such as excessive sweating or absence of sweating
• Cardiovascular symptoms, such as rapid heart rate or fluctuations in blood pressure
• Difficulty urinating or experiencing incontinence
• Digestive issues, such as difficulty swallowing, bloating, constipation, or diarrhea
• Dizziness or lightheadedness, especially when standing up
• Erectile dysfunction
• Fainting or episodes of sudden loss of consciousness
• Feeling excessively hot or cold without environmental reasons
• Unexplained fatigue or weakness

In addition, patients with conditions such as diabetes, Parkinson's disease, multiple system atrophy, autoimmune diseases, and certain neurological disorders are also common candidates for autonomic testing because these conditions can affect autonomic nervous system function. 

Penn Medicine is the leading neurology provider in the southeastern Pennsylvania and New Jersey regions. We’re the only healthcare system in the area that offers autonomic testing to improve the accuracy of a diagnosis.

Autonomic testing consists of activities designed to stimulate the autonomic nervous system to produce changes in blood pressure, heart rate, breathing and sweating in a controlled setting. The test can take up to two hours in total and includes:

• Heart rate deep breathing: HRDP testing measures the variation in time intervals between your heartbeats, which reflects the function of the autonomic nervous system in regulating your heart rate. This test lasts less than 10 minutes.
• Valsalva maneuver: This breathing technique can be used to help determine a problem with the autonomic nervous system (ANS). The test involves breathing out hard against a closed airway by breathing through a mouthpiece. This test lasts about 10 minutes.
• Quantitative sudomotor axon reflex test (QSART): QSART measures the sweat response in different parts of your body by stimulating your sweat glands with a small electric current. You won’t feel any pain from the electric current. This test lasts about 30 minutes.
• Tilt table test: This test involves monitoring changes in your heart rate and blood pressure while you’re tilted to a 70 degree angle on a special table. It helps diagnose conditions such as orthostatic hypotension and vasovagal syncope. This test lasts about 10 minutes. Note: The tilt table test cannot be done on patients who weigh more than 300 pounds.

Your referring provider will determine if you need autonomic testing and give you time to ask questions. Your doctor will do a medical history review and physical examination to assess symptoms and identify potential underlying conditions. To ensure the best possible outcome of your autonomic response test, make sure you’re well hydrated.

In addition, you should prepare by doing the following:

• Wear comfortable, loose clothing (loose pants/sweats or shorts and a loose t-shirt)
• No oils or lotions on your skin the day of your test.
• Shave your legs from the knee down on the day before your test. If you don’t want to shave or can’t shave your leg, , a member of the care team may shave some areas on the day of the test.
• No nicotine (cigarettes) for at least 24 hours before your test.
• No caffeine, including coffee, cola, energy drinks, and tea, for at least 24 hours before your test.
• No alcohol for at least 24 hours before your test.
• No medical or recreational marijuana for at least three days before your test.
• Stay hydrated by drinking only water.
• Don’t eat any food for four hours before the test.
• Don’t take any medications that may affect the test results. Antidepressants, blood pressure medications, aspirin, ibuprofen, and acetaminophen should be stopped 24 hours before your test. Over-the-counter medications for sleep or cold and flu relief should not be taken for 72 hours (three days) before your test. Your provider will help you determine which medications should be stopped prior to testing and when you should stop and restart them. You may also need to get approval from the provider who prescribed your medications.

Since most autonomic response tests are non-invasive and don’t involve any incisions or anesthesia, patients can generally resume their normal activities immediately after the testing is complete.

However, if certain tests require fasting or medication adjustments beforehand, you may need some time to return to your regular routine. Some patients may experience temporary discomfort during certain autonomic tests, such as mild dizziness or lightheadedness during tilt table testing. These symptoms usually resolve quickly once the test is over, and patients are monitored closely by their Penn Medicine care team during the procedure to ensure their safety and comfort.