α-SYNUCLEIN ACCUMULATION IN SKIN NERVE FIBERS REVEALED BY SKIN BIOPSY IN PURE AUTONOMIC FAILURE

Abstract

Pure autonomic failure (PAF), a rare clinical manifestation of Lewy body (LB) disorders, is characterized by fibrillary aggregates of α-synuclein in the cytoplasm of a select population of neurons and glia. It is a sporadic, idiopathic, neurodegenerative disorder with orthostatic hypotension as the cardinal symptom. Patients may also present with decreased sweating, urinary dysfunction, constipation, and sexual dysfunction. Postmortem studies1-3 have disclosed prominent LB pathology in sympathetic and parasympathetic nervous systems, as well as the substantia nigra and locus ceruleus. Here, we show for the first time α-synuclein accumulation in nerve fibers in the dermis of a patient with PAF. The patient is a 73-year-old man with a 13-year history of severe orthostatic hypotension with recurrent syncope, urinary dysfunction (hesitancy and prolongation), erectile failure, and decreased sweating with heat intolerance. Supine blood pressure was 163/84 mm Hg. After 1 minute of a 60° head-up tilt test, the patient's blood pressure fell to 62/33 mm Hg and he fainted. The patient's pulse was 60 beats/minute before tilting and 65 beats/minute after 1 minute of tilting, and his plasma noradrenaline was 40 and 36 pg/mL before and after tilting, respectively (normal: >100 pg/mL). The coefficient of variation of R-R intervals was 0.81% (normal: >1.5%). Denervation supersensitivity to noradrenaline was detected with infusion testing. A thermoregulatory sweat test revealed a patchy lack of sweating in the legs. The heart-to-mediastinum (H/M) ratio of 131I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy was reduced (early: 1.30, late: 1.25, normal: >1.85). After …