Autonomic History, Examination, and Laboratory Evaluation

Abstract

Autonomic disorders offer a fascinating view of the complexity of the nervous system. Their impact on human health ranges from benign to severe. Deciphering autonomic symptoms and signs draws on the cognitive skills and personal interest in the plight of patients that first attracted many physicians to the field of neurology. This article provides tools to sharpen those skills. Autonomic neuroscience and accumulated clinical knowledge have led to the categorization of autonomic disorders into specific syndromes that can be identified on the basis of clinical phenotypes and physiologic responses to standardized stimuli in the autonomic laboratory. A key development has been the ability to distinguish neurogenic orthostatic hypotension from other causes of hypotension. Quantification of sudomotor responses has proven valuable in the diagnosis of thermoregulatory disorders and small fiber neuropathies such as those related to diabetes mellitus. Increasing attention has focused on autonomic failure as a defining feature of neurodegenerative α-synucleinopathies, especially multiple system atrophy. As awareness of autonomic disorders has increased, the once obscure term dysautonomia has entered into common parlance. With appropriate knowledge and experience, neurologists can diagnose autonomic dysfunction accurately and with confidence. The opportunity to play an important role in caring for patients with autonomic disorders is worth the effort.