Autonomic testing

Autonomic testing refers to a set of medical procedures used to evaluate the function of your autonomic nervous system (ANS). The autonomic nervous system is responsible for regulating involuntary bodily functions such as your heart rate, blood pressure, digestion, and temperature control. Disorders such as autonomic neuropathy, autonomic dysfunction, dysautonomia, and other related conditions can be diagnosed using autonomic testing.

Autonomic testing—also known as an autonomic reflex screen or autonomic response testing—is 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. 

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, your Penn care team may ask you to do the following: 

• DO wear comfortable, loose clothing.
• DO shave your legs, including all patients being tested for QSART (sweat test). If you can’t shave the entire leg, a tech may need to shave some areas needed before the test.
• DO hydrate yourself (drinking only water).
• DO NOT eat 4 hours before the test.
• DO NOT use any oils or lotions on your skin (arms and legs) on the day of the test.
• DO NOT have drinks that contain caffeine (coffee, soda, energy drinks, tea etc.) at least 8 hours before the test.
• DO NOT drink alcohol at least 12 hours before the test.
• DO NOT have nicotine (cigarettes) for at least 8 hours before the test.
• DO NOT take any medical or recreational marijuana for at least 3 days before the test.
• DO NOT take any medications that may affect the test results (mostly medications for depression and high blood pressure). Your provider will help you determine which medications should be stopped prior to testing and when you should stop and restart them.
• The Tilt Test cannot be done on patients who weigh more than 300 pounds. 

Penn Medicine is the leading neurology provider in the greater Philadelphia and South Jersey region. We’re the only healthcare system in the area that offers autonomic testing to improve the accuracy of a diagnosis.

• 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: a breathing technique that 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.

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.