A case of pure autonomic failure with a long-term-45-year-clinical course since the initial detection of abnormal blood pressure fluctuation.

This report describes the case of an 85-year-old male with a clinical phenotype consistent with pure autonomic failure (PAF) for more than four decades. Despite the presence of neurological manifestations, including bradykinesia, olfactory dysfunction, and visual hallucinations, phenoconversion to another α-synucleinopathy has not been confirmed based on established diagnostic criteria. Orthostatic and postprandial hypotension, low supine plasma norepinephrine levels, and reduced cardiac uptake on 123I-metaiodobenzylguanidine myocardial scintigraphy were observed, consistent with the postganglionic cardiac sympathetic denervation frequently observed in Lewy body disease. Given the extraordinarily prolonged disease course and early central neurological signs, this condition may represent a preclinical stage of Parkinson's disease or dementia with Lewy bodies. This case provides insight into the natural history of PAF and its clinical variability within the Lewy body disease spectrum.