2025 Workshop Handout Bundle-W02A Autonomic testing Using Live Demo Peltier

W02A Autonomic testing Using Live Demo Peltier

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This document presents a comprehensive overview of laboratory evaluation of autonomic function, focusing on standardized, non-invasive, quantitative autonomic tests aligned with Current Procedural Terminology (CPT) codes. The work is primarily based on the Mayo Clinic Autonomic Laboratories' methodology and aims to detect, quantify, and localize autonomic failure.<br /><br />Indications for autonomic testing include suspicion of generalized autonomic failure (e.g., multiple system atrophy, pure autonomic failure, autonomic neuropathies like diabetic or amyloid neuropathy), identification of limited autonomic failure (such as in syncope, distal small fiber neuropathy, or postural orthostatic tachycardia syndrome), differentiation between benign and life-threatening disorders, monitoring disease progression, evaluating therapy response, and research.<br /><br />Core autonomic tests discussed are: <br />1. Quantitative Sudomotor Axon Reflex Test (QSART) – assesses postganglionic sympathetic sudomotor function using iontophoresis of acetylcholine and measures axon-reflex mediated sweat response at multiple limb sites. It helps distinguish preganglionic from postganglionic lesions and maps neuropathy progression.<br />2. Cardiovagal tests – heart rate response to deep breathing (HRDB) and Valsalva ratio (VR), which evaluate parasympathetic cardiovagal function with attention to factors such as age, breathing rate, and medications.<br />3. Beat-to-beat blood pressure (BP) and heart rate monitoring during Valsalva maneuver and head-up tilt – these assess sympathetic adrenergic function, with distinct phases of Valsalva providing insight into peripheral and cardiac adrenergic control. Orthostatic BP responses confirm the presence and severity of autonomic failure.<br /><br />Normative data adjusted for age and gender support test interpretation, and the Composite Autonomic Scoring Scale (CASS) quantitatively grades autonomic dysfunction severity across sudomotor, cardiovagal, and adrenergic domains.<br /><br />The laboratory setup requires a tilt table, continuous heart rate and beat-to-beat BP monitors, and sudomotor testing equipment (e.g., QSART or commercial QSWEAT systems). The tests provide highly reproducible and sensitive measures and are critical for diagnosing autonomic disorders, informing prognosis, guiding treatment, and investigating autonomic pathophysiology.

Keywords

autonomic function testing

Quantitative Sudomotor Axon Reflex Test

QSART

cardiovagal tests

Valsalva maneuver

beat-to-beat blood pressure monitoring

Composite Autonomic Scoring Scale

autonomic failure diagnosis

Mayo Clinic Autonomic Laboratories

orthostatic hypotension