The author reports on the entity known as pure autonomic failure. The author details the clinical features, pathogenesis and pathophysiology, and the oftentimes difficult differential diagnosis. In addition, the author sheds light on developments, including predictive factors for phenotype conversion of patients with an earlier diagnosis of pure autonomic failure and more sinister diagnoses like multiple system atrophy or dementia with Lewy bodies.
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• Pure autonomic failure remains a diagnosis of exclusion.
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• Careful history taking, physical exam, and meticulous workup are needed to exclude other similar differential diagnoses.
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• More sinister synucleinopathies, notably multiple system atrophy, often start with a similar clinical picture to pure autonomic failure.
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• Specific attention should be directed toward some of the clinical features that were found to predict future development of multiple system atrophy or dementia with Lewy bodies in cases that are diagnosed initially with pure autonomic failure.
Historical note and terminology
In 1898, Langley coined the term “autonomic nervous system.” He identified the enteric, sympathetic, and parasympathetic components. Cannon later added the adrenal-hormonal component in the early 20th century.
In 1925, Samuel Bradbury and Cary Eggleston first described the entity now known as pure autonomic failure, which encompasses the failure of both the sympathetic and the parasympathetic nervous systems. Initially, these 2 clinicians described 3 patients with idiopathic orthostatic hypotension, which is the key characteristic of this uncommon disease (03). The nomenclature evolved from idiopathic orthostatic hypotension (Bradbury-Eggleston syndrome) into pure progressive autonomic failure and finally to the generally accepted term, pure autonomic failure. Some cardiologists still employ the term “idiopathic orthostatic hypotension.” The name pure autonomic failure was introduced by Oppenheimer as one of the primary chronic autonomic failure syndromes in addition to Parkinson disease with autonomic failure and multiple system atrophy.
Pure autonomic failure was defined by the 1996 Consensus Committee of the American Autonomic Society and the American Academy of Neurology to be “an idiopathic sporadic disorder characterized by orthostatic hypotension usually with evidence of more widespread autonomic failure and no other neurological features” (07).