Abstract Details

Title Autonomic Innervation in Neuropathic and Non-Neuropathic Postural Tachycardia Syndrome

Topic Autonomic Disorders

Presentation(s) S37 - (-)

Poster/Presentation
Number 005

Objective

Background The postural tachycardia syndrome (POTS) is defined as an exaggerated heart rate in the upright position with orthostatic intolerance. Some patients with POTS have an underlying small fiber neuropathy.

Design/Methods Twenty-four subjects (17F) with POTS and 10 healthy control subjects (7F) had skin biopsies performed at the distal leg and distal thigh with analysis of intra-epidermal nerve fiber density (IENFD), sweat gland nerve fiber density (SGNFD) and pilomotor nerve fiber density (PMNFD). Skin biopsies were stained with the pan-axonal marker (PGP9.5), the adrenergic marker tyrosine hydroxylase (TH) and the cholinergic marker vasoactive intestinal peptide (VIP). Individuals with neuropathic POTS were defined by abnormal IENFD and quantitative sensory testing or sudomotor testing.

Results Nine individuals had neuropathic POTS, 15 had non-neuropathic POTS. Subjects with neuropathic POTS had lower IENFD at all sites (5.1±0.9 POTS vs. 14.1±5.5 fibers/mm control distal leg P<0.001; 8.2±1.1 POTS vs. 16.3±5.9 fibers/mm control, P<0.001) but no difference in SGNFD or PMNFD compared to controls and non-neuropathic POTS. Patients with neuropathic POTS had an increase in sympathetic adrenergic innervation within sweat glands compared to non-neuropathic POTS and control subjects (28±12% vs. 7±4% at the distal leg, P<0.01; and 25±16% vs. 6±2% at the distal leg, P<0.001).

Conclusions Patients with neuropathic and non-neuropathic POTS have different patterns of cutaneous innervation seen on skin biopsy. Individuals with neuropathic POTS had significantly increased levels of sympathetic adrenergic fibers within sweat glands despite reductions in sensory nerve fiber density. These findings suggest that neuropathic and non-neuropathic POTS have different pathophysiological mechanisms that underlie the postural tachycardia.

Authors/Disclosures
Ningshan Wang, MD, PhD (BIDMC) PRESENTER	Dr. Wang has nothing to disclose.
Christopher H. Gibbons, MD, FAAN (Beth Israel Deaconess Medical Center)	Dr. Gibbons has received personal compensation for serving as an employee of CND Life Sciences. Dr. Gibbons has or had stock in CND Life Sciences.Dr. Gibbons has received publishing royalties from a publication relating to health care.
	No disclosure on file
Alasdair Coles, MD, PhD (University of Cambridge)	Dr. Coles has nothing to disclose.
	No disclosure on file
Roy L. Freeman, MD (Beth Israel Deaconess Hosp)	Dr. Freeman has received personal compensation in the range of $50,000-$99,999 for serving as a Consultant for Cutaneous Diagnostic Life Sciences. Dr. Freeman has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Vertex. Dr. Freeman has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Theravance. Dr. Freeman has received personal compensation in the range of $10,000-$49,999 for serving as an officer or member of the Board of Directors for Inhibikase. Dr. Freeman has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for Elsevier. The institution of Dr. Freeman has received research support from NIH. The institution of Dr. Freeman has received research support from Theravance. The institution of Dr. Freeman has received research support from Biohaven. The institution of Dr. Freeman has received research support from Lundbeck. Dr. Freeman has received research support from Regeneron.

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