INTRODUCTION
Primary hyperhidrosis (PHH) is the most common disease of the eccrine gland, and is characterized by excessive sweating due to elevated sympathetic stimulation, severely impacting the quality of life.1 PHH is diagnosed clinically in patients with excessive sweat on one or more eccrine-rich body regions that occurs symmetrically at least once weekly for over 6 months, that is absent during sleep, and that causes impairment in daily activities.2
For physiologic sweating, stimuli (ie, warm environment, physical activity, stress) trigger sympathetic signaling, activating the eccrine sweat gland, which in response generates retrograde negative feedback to the hypothalamus.2 In PHH, despite having a normal size, number, and histologic appearance of eccrine glands,3 imbalanced sympathetic signaling results in amplified efferent signaling and overstimulation of cholinergic receptors on sweat glands.2,4
Sensitive skin (SS) is also a condition of neurosensory dysfunction, resulting in cutaneous hyperreactivity to otherwise innocuous stimuli that cannot be attributed to an underlying skin disease. SS is common, with an estimated global prevalence between 40% to 70% of the population, and manifests as sensations of itching, burning, tightness, or stinging.5-9 While SS pathophysiology remains poorly understood, sweat, stress, and hot temperatures are known exacerbants of SS, suggesting that cholinergic stimulation may contribute to symptom flares.10,11 Sweat is also a known skin irritant, causing an inappropriate activation of cutaneous inflammation.12
Given our hypothesis that aberrant cholinergic stimulation contributes to the pathophysiology of both PHH and SS, this study was conducted to assess a potential relationship between these 2 conditions. The purpose of this study was threefold: 1) to provide updated epidemiologic trends for PHH by surveying a large population of HH sufferers, 2) to evaluate the frequency, quality, and location of SS in patients with PHH, and 3) to assess the predictive capacity of machine learning classification models in predicting SS.