Ann Clin Neurophysiol.  2022;24(1):1-6. 10.14253/acn.2022.24.1.1.

Quantitative sudomotor axon reflex test (QSART) as a diagnostic tool of small fiber neuropathy

• Suh BC

• KMID: 2529500
• DOI: http://doi.org/10.14253/acn.2022.24.1.1

Abstract

Small fiber neuropathy is a painful neuropathy that cannot be assessed using nerve conduction studies. A skin biopsy and quantitative sensory testing (QST) are the gold standards for small fiber neuropathy diagnosis. However, a skin biopsy is invasive and commercially unavailable in Korea. QST is a method involving a thermal threshold, but its results can be affected by cognition as well as lesions of the central nervous system. Quantitative sudomotor axon reflex test (QSART) is a quantitative method of assessing sweat glands innervated by small fibers. In this review, we assessed the utility of QSART in evaluating small fiber neuropathy.

Keyword

Small fiber neuropathy; Sweat; Autonomic fibers; Quantitative sudomotor axon reflex test; Quantitative sensory testing

Figure

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  Fig. 1. The sudomotor axon reflex. Ten% acetylcholine applied through iontophoresis (shown with the black arrows) bind to muscarinic receptors causing local sweat production (dashed arrows). The action potential travels antidromically and then it reaches nerve branching sites, anterograde propagation reaches to neighboring eccrine sweat gland and induce indirect sweat response (dotted arrows). Reprinted from Illigens and Gibbons20 with permission.

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