A Standardized Head-Up Tilt Test Protocol to Assess Cardiovascular Autonomic Dysfunction in Neurodegenerative Diseases.

Autonomic dysfunction is a common, clinically meaningful feature of neurodegenerative diseases, particularly Parkinson's disease and multiple system atrophy. Its evaluation is important for differential diagnosis, disease phenotyping, monitoring of disease severity, and prognostic prediction. Among the various manifestations of autonomic dysfunction, cardiovascular symptoms are especially important, with orthostatic hypotension being a hallmark feature. The head-up tilt test is widely used as a standard method for evaluating orthostatic hypotension. In this video article, we present a standardized protocol for the head-up tilt test designed to assess autonomic dysfunction in patients with neurodegenerative diseases. Although the head-up tilt test is conceptually simple-evaluating blood pressure changes during postural transition from the supine to the upright position-several methodological considerations are required to ensure reliable and reproducible results. These include the influence of the testing environment on autonomic function and the appropriate assessment of continuously fluctuating blood pressure. This article provides detailed, practical guidance on the implementation of the head-up tilt test, including optimal test timing, control of the testing environment, pre-test dietary conditions, and blood pressure measurement using continuous noninvasive monitoring devices. In addition, we describe key procedural parameters such as tilt table angle, tilt-up speed, and the duration required for blood pressure assessment, as well as essential precautions to ensure patient safety during the examination. Through these demonstrations, we aim to promote the adoption of a standardized, reproducible head-up tilt test protocol that can be applied consistently across different clinical and research settings. A well-standardized, highly reproducible, and clinically applicable method for evaluating cardiovascular autonomic failure will improve the comparability of results between studies and enhance the assessment of autonomic dysfunction in patients with neurodegenerative diseases.