The Autonomic Nervous System (ANS) is the major part of the nervous system that regulates and manages processes of the internal organs, including the blood vessels, stomach, intestine, liver, kidneys, bladder, genitals, lungs, pupils, heart, and sweat, salivary, and digestive glands. Autonomic testing is an umbrella term that covers testing of the two main divisions of the nervous system, which are the parasympathetic and sympathetic (P&S) nervous system. The P&S nervous systems regulate physiologic processes, such as blood pressure, heart rate, body temperature, digestion, metabolism, fluid and electrolyte balance, sweating, urination, defecation, sexual response, and other processes. This regulation occurs without conscious control, i.e., autonomously and it extends to every organ system in the body. In fact, many organ specific tests are tests of autonomic function.
‘RFa’ is known to be a measure of Parasympathetic activity and ‘LFa’ is known to be a measure of Sympathetic activity, based on reference: Colombo J, Arora RR, DePace NL, Vinik AI, Clinical Autonomic Dysfunction: Measurement, Indications, Therapies, and Outcomes. Springer Science + Business Media, New York, NY; 2014.