Model Coverage Policy Autonomic Testing Christopher H. Gibbons, MD, FAAN William P. Cheshire Jr., MD, FAAN Terry D. Fife, MD, FAAN BACKGROUND The conceptual framework for autonomic testing began at policy, we will focus on the standard tests of sudomotor the turn of the 19th century with a number of experiments in (sympathetic cholinergic), cardiovagal (parasympathetic) and basic neurophysiology. These original tests were developed sympathetic adrenergic system function. over time into a rigorously defined, standardized series of As is true for other accepted tests of neurophysiologic autonomic tests that are useful in the clinical assessment function and clinical monitoring technologies, randomized and care of patients with suspected autonomic disorders. controlled trials establishing the efficacy of autonomic testing Autonomic testing has been widely used in clinical practice have not been done. However, current data, accumulated for 50 years, with decades of extensive experience and through scientific research and clinical experience and thousands of studies published on its use. Comprehensive published in peer-reviewed journals over the past 50 years, textbooks have been published on the purpose and have defined the role of autonomic testing in the diagnosis methodology of autonomic testing.1–4 and management of autonomic disorders in clinical practice Autonomic testing is an umbrella term that covers testing and established the value of autonomic testing in the of the various branches of the nervous system: the longitudinal study of disease. sympathetic, parasympathetic, and enteric. It should be Autonomic testing is an integral component of the clinical noted that the autonomic nervous system extends to nearly evaluation of patients with autonomic disorders. Autonomic every organ system in the body; so many organ specific tests Disorders is an established subspecialty recognized by are in fact tests of autonomic function (such as urodynamic the United Council on Neurologic Subspecialties (UCNS), studies, gastric motility testing, pupillometry, tests of lacrimal which certifies physicians and laboratories with training and and salivary gland production, etc.). For the purposes of this expertise in this discipline. COMMON AUTONOMIC TESTING TERMS Autonomic Nervous System: The part of the nervous gland. The sweat response is typically recorded from four system that controls involuntary visceral actions. sites (one forearm and three lower extremity sites) and the waveforms generated are assessed for deficits. Cardiovagal: The parasympathetic response measured via cardiac function, which is under control of the vagus nerve, Sudomotor: The sympathetic cholinergic component of the which influences heart rate variability. autonomic nervous system is responsible for sweat gland function and the production of thermoregulatory sweating. Heart Rate Variability: A test of parasympathetic function in which an individual undergoes a standard series of breathing Sympathetic Skin Response: A test to measure a provoked exercises and the variability in the heart rate response is change in the electrical potential of the skin. measured. Diminished heart rate variability (diminished Thermoregulatory Sweat Test (TST): A test of sweat respiratory sinus arrhythmia) is a sign of parasympathetic function and its neurologic regulation in which a generalized dysfunction. thermoregulatory sweating response is elicited by raising Quantitative Sudomotor Axon Reflex Test: A test to the core body temperature and monitoring sweat production evaluate the integrity of postganglionic sudomotor nerves by an indicator dye applied to the skin of the whole body along the axon reflex to define the volume and distribution of (typically the anterior aspect). When the core temperature sweat loss. This is accomplished by releasing acetylcholine rises beyond a hypothalamic thermoregulatory set point, into the skin, which activates distal postganglionic sudomotor sweating occurs. TST investigates the integrity of the central nerves, when then activates receptors on the eccrine sweat and peripheral thermoregulatory sympathetic pathways, from Approved by AAN Board of Directors in October 2014 Autonomic Testing · 1 Autonomic Testing Model Coverage Policy the hypothalamus to the eccrine sweat gland, by use of an Valsalva Maneuver: An autonomic testing maneuver in indicator powder mixture (typically alizarin red or iodinated which the patient exhales against resistance and the blood corn starch). When a core temperature of 38°C is achieved, pressure and heart rate are recorded, typically on a beat- normal sweat production is visualized by a change in color to-beat basis. This test evaluates the complex sympathetic in the indicator powder. Digital photography is used to adrenergic and parasympathetic responses to the transient document the sweat distribution, which can be characteristic reduction in cardiac preload caused by an increase in of neuropathy, ganglionopathy, or generalized autonomic failure. intrathoracic pressure. VARIATIONS IN METHODS OF TESTING, INCLUDING A DISCUSSION ABOUT AUTOMATED DEVICES Autonomic testing using automated devices, in which alone, are sufficient to bill for autonomic testing using 95921– software automatically generates an interpretation, has 95924. Billing code 95943 is the only code appropriate for not been validated. Automated autonomic testing devices autonomic testing using automated devices. perform a simplified battery of autonomic tests—typically Autonomic testing (CPT codes 95921–95922 and 95924) not the heart rate response to deep breathing, the heart rate using automated devices combines a battery of tests that response to a Valsalva maneuver, and the blood pressure typically includes the heart rate response to paced breathing, response to standing. Many devices are severely limited the heart rate response and continuous blood pressure in the validity of the data they generate because they do response to a Valsalva maneuver, the heart rate response not measure or control for expiratory pressure or include and beat-to- beat blood pressure response to a five-minute beat-to-beat blood pressure measurement, both of which stand, and the beat-to-beat blood pressure response to a are requirements, not only for scientifically accurate passive tilt table test of five minutes or longer. The data is assessment, but also for billing of autonomic testing.5, 6 For rigorously reviewed and interpreted by a physician with example, by failing to measure the expiratory pressure and expertise in understanding and interpreting the data in the blood pressure responses to a Valsalva maneuver, these appropriate clinical context. A vast number of medications may devices generate meaningless heart rate data, since it is influence autonomic test results, and physicians who perform not possible to interpret the heart rate without information autonomic testing must be aware of the potential for about its stimulus. Most of these devices generate reports misinterpretation of results in the context of polypharmacy. All automatically and do not allow physician interpretation of the of the extensive data in the literature about autonomic testing raw data, which is a serious design flaw when evaluating is based on these testing methods; extrapolating this literature patients who have, for example, cardiac rhythm abnormalities to automatic devices that omit essential elements of that mislead the testing results. autonomic testing as described would be scientifically In contrast to state-of-the art autonomic testing (as discussed unjustifiable. in detail below), a review of the scientific literature reveals that In regard to the clinical utility of the well-established methods autonomic testing by automated devices has not been validated of autonomic testing discussed above, there has been no by any presentations to our knowledge at scientific sessions debate until recently. With the advent and increasing use of of the American Academy of Neurology or the American automated autonomic testing devices, physicians specializing Autonomic Society, nor does a search of the literature on in autonomic disorders are concerned that erroneous results PubMed discover any published data demonstrating that such obtained from devices of unproven scientific validity could automated testing is clinically meaningful. adversely impact patient care. Additionally, payers have taken Automated testing devices do not satisfy the conditions that notice of increased billing for autonomic testing using these are required for using the billing codes that were developed devices. Cost considerations have generated debate over for autonomic testing. The CPT code 95922 requires a autonomic testing in general. Whereas autonomic testing by five-minute tilt table test and continuous beat-to-beat blood the well-established methods in accordance with autonomic pressure monitoring in order to be billed. It is clear that the CPT codes is performed under carefully controlled conditions, vast majority of bills from code 95922 using automated can take 90–120 minutes to perform correctly, and requires devices do not include beat-to-beat blood pressure testing interpretation by a physician familiar with autonomic nervous and do not include a five-minute tilt table test. Furthermore, system physiology; automated testing devices are designed the new autonomic testing codes also require beat-to-beat to generate data after approximately 10–15 minutes of blood pressure monitoring and a tilt table test. There