What Is Autonomic Nervous System (ANS) Testing?

During a typical exam, healthcare professionals rely on several separate diagnostic measurements to assess a patient’s health, including blood pressure, body temperature, and heart rate. Some progressive practitioners are beginning to consider another type of measurement to help them make sense of perplexing symptoms: autonomic nervous system (ANS) testing.

The ANS controls involuntary biological functions, such as the beating of the heart; widening and constricting of blood vessels; respiration; and digestion. ANS tests measure how well two divisions of the system — the sympathetic and parasympathetic — are working together. They provide a more comprehensive view of patient health than individual biomarkers do, explains functional-medicine practitioner Gregory Plotnikoff, MD, MTS, FACP.

Dysregulation of the ANS can reflect underlying disease and cause symptoms of its own, says Plotnikoff. “Lack of coordination between parasympathetic and sympathetic branches, as well as imbalance or excess of either, can drive numerous perplexing symptoms and can represent significant health risks themselves.”

The ability to assess the state of the ANS isn’t new, but until now medical modalities that produce an accurate, comprehensive picture of its coordination and function have been cumbersome, expensive, and often invasive. (Wearable consumer devices that test ANS coordination via measurements like heart-rate variability, or HRV, provide insight but are not diagnostic.)

Plotnikoff — whose practice serves patients with complex illnesses that have eluded successful diagnoses or treatments — uses ANS testing early in the diagnostic process with every new patient.

“ANS testing makes the invisible visible,” he says, and that enables him to focus attention on what might ­underlie disabling symptoms. It can help identify optimal therapies for people with a host of conditions, ­including type 2 diabetes, hypertension, previous heart attacks or heart surgeries, anxiety and depression, ­migraines and seizures, gastrointestinal disturbances, and even long COVID.

During the 15-minute assessment, specialized monitoring technology with a blood-pressure cuff, electrodes, pulse oximeter, and temperature sensor measures average heart rate, blood pressure, blood oxygen saturation, and body temperature with the patient at rest and in various states of physiological stress: while breathing deeply; performing a heart-straining breath technique called the Valsalva maneuver; and standing for five minutes. The system then uses an algorithm to calculate sympathetic and parasympathetic activity, which the practitioner interprets.

ANS testing technologies like the system Plotnikoff uses are not yet in widespread use. It’s similar to the early days of MRI, he explains, when physicians weren’t trained in the technology or its application, and it was prohibitively expensive for most practices.

“It’s far on the horizon, but I predict this will someday be part of the annual exam — it’s the stethoscope of the future.”

This article originally appeared as “The Stethoscope of the Future” in the March 2023 issue of Experience Life.