Autonomic Testing

Abstract

Autonomic testing is an important addition to neurological evaluations. While there are many excellent textbooks on autonomic disorders, only a few texts focus on how to perform and interpret autonomic tests. This manual fills the gap, dealing mainly with the practical aspects of autonomic testing. In accord with the maxim that “a good picture is worth a thousand words,” signal drawings are heavily used throughout the text to explain and illuminate test results. This book has two parts. The first part describes in detail the Brigham protocol of autonomic tests, which includes cardiovascular tests (deep breathing, Valsalva maneuver, tilt tests), sudomotor assessment (quantitative sudomotor axonal reflex test and electrochemical skin conductance), and skin biopsies for assessment of epidermal and sweat gland small fibers. The cardiovascular tests use heart rate, blood pressure, respiratory parameters (respiratory rate and end tidal CO2), and cerebral blood flow velocity. All tests are graded with an updated quantitative scale for cardiovascular reflex tests and transcranial Doppler—the Quantitative Sudomotor Axon Reflex Test (QASAT)—and small fiber (epidermal sensory and sweat gland) densities from skin biopsies. The second part of the book describes 100 cases covering a variety of autonomic disorders. The cases are thematically grouped into orthostatic intolerance syndromes (neurally mediated syncope, orthostatic hypotension, postural tachycardia syndrome, inappropriate sinus tachycardia, orthostatic cerebral hypoperfusion syndrome, hypocapnic cerebral hypoperfusion, and pseudosyncope), dysautonomia in neurodegenerative disorders, small fiber neuropathies (idiopathic, secondary, inflammatory), and autonomic overactivity. The case descriptions are presented in a consistent format featuring pertinent clinical information, autonomic tests results, interpretation of testing, conclusions, and recommendations. This text is intended to be a guide for autonomic fellows, and for residents in neurology, general medicine, and other specialties, and for anyone who is interested in performing and interpreting autonomic tests.