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Types of Autonomic Function Tests: Tilt-Table, Deep Breathing, Valsalva, and Sweat Tests
Many people ask, 'Can I just measure one autonomic nervous system value?' However, because the autonomic nervous system manages diverse functions such as blood pressure, heart rate, and sweating, it is difficult to explain everything with a single test. Depending on the symptoms, we combine postural change tests, deep breathing and Valsalva responses, sweat tests, and blood or cardiac tests to determine the cause and distribution.
Autonomic Function Test Guide
Key points
1Recording symptoms, posture, and medications before the test is as important as the results themselves.
2Orthostatic, cardiovascular, and sweat tests evaluate different functions of the autonomic nervous system.
3A single normal result does not rule out all autonomic nervous system issues.
Selecting tests based on symptom questions
Decide on the questions you want answered before choosing a test name
Tests are selected based on the axis of symptoms rather than receiving all tests at once.
Primary Question
Test Axis
Information to Prepare
Interpretation Cautions
Is there dizziness upon standing?
Orthostatic blood pressure/tilt
Posture, timing, syncope
Do not rely on a single measurement
Is the heart rate reflex appropriate?
Deep breathing/Valsalva
Medications, cardiac history
Do not discontinue prescribed medications arbitrarily
Is sweating abnormal?
Sweat test
Area, body temperature, skin
Evaluate the distribution together
Do symptoms persist despite normal test results?
Medical history, other causes
Daily life records
Normal results do not negate the symptoms
What the clinic checks first
If autonomic nervous system test scores are poor, is the cause of all symptoms revealed?
While tests are tools to objectify functional abnormalities, they cannot independently explain all causes of symptoms. Test results must be interpreted alongside the symptoms and other medical conditions.
More detail
Initial Clinical Evaluation
We do not start with machine tests immediately. The circumstances in which symptoms occur and a basic physical examination determine the direction of the testing.
Medical History and Symptom Mapping
We check the relationship between symptoms and posture, diet, heat, exercise, or bowel movements, as well as the onset time and history of infections or surgeries.
Supine and Standing Blood Pressure and Pulse
We measure values while lying down after stabilization and the changes over time after standing to observe the orthostatic response.
Basic Differential Tests
Depending on the symptoms, we check for other causes such as anemia, electrolytes, blood glucose, thyroid function, and ECG.
Autonomic Function Tests
Since each test evaluates a different neural circuit, the results are interpreted as a comprehensive set.
Tilt-Table Test
By safely adjusting the angle of the body, we observe changes in blood pressure, heart rate, and symptoms to evaluate patterns of syncope or orthostatic intolerance.
Deep Breathing and Valsalva Tests
We examine parasympathetic and sympathetic nerve functions by observing heart rate and blood pressure responses to breathing and straining.
Sweat Test
By measuring the sweat secretion response, we can evaluate the function and abnormal distribution of small autonomic nerve fibers.
Preparation Before Testing
Medications and caffeine can affect the results, but you must not discontinue them arbitrarily.
Reporting Medications
Report all medications and supplements that may affect the autonomic nervous system, including blood pressure medications, diuretics, and antidepressants.
Following Facility Instructions
Follow the specific instructions of the testing facility regarding fasting, restrictions on caffeine, nicotine, and exercise, and whether to discontinue medications.
Days when symptoms differ from usual
Even if you are asymptomatic on the day of the test, providing your usual records along with images or numerical data can assist in the interpretation.
Frequently asked questions
Where can I get an autonomic nervous system test?
Depending on the symptoms and required tests, you may receive a basic evaluation at a neurology or cardiology clinic and then be referred to a facility capable of performing autonomic nervous system tests.
If the tilt table test is normal, does that mean there is no autonomic nervous system issue?
The tilt table test observes specific orthostatic responses. Other autonomic nervous system domains or intermittent symptoms can be evaluated through medical history and additional tests.
Should I stop taking my medication before the test?
This varies by medication, and stopping abruptly can be dangerous. You must follow the guidance of the testing facility and your prescribing physician.
Sources
American Autonomic Society · American Academy of Neurology Consensus Statement — Autonomic TestingComprehensive interpretation of orthostatic, Valsalva, deep breathing, and sudomotor tests
