Epidemiology and Diagnosis
Primary hyperhidrosis is a condition in which patients suffer from excessive, localized sweating. It results from dysregulation of the autonomic nervous system and is characterized by an amount of sweating that is disproportionate to the level of physical, emotional, and environmental stimuli. The thermoregulatory system acts through the sudomotor chain comprising the hypothalamus, cholinergic sympathetic axons and ganglia, and eccrine sweat glands. Although the underlying cause of primary hyperhidrosis remains unknown, several studies have identified associated abnormalities in the anatomy, histology, and physiology along the sympathetic pathway.1 The condition, which affects approximately 0.5% to 5% of the population, has an equal distribution in males and females.1,2 There is also evidence for genetic transmission. Over 30% of patients have a family history of hyperhidrosis, and the condition has been associated with loci identified on chromosomes 2 and 14.1,3,4 Regardless of the underlying cause, the excessive sweating can cause severe functional and social problems that profoundly diminish quality of life.
The diagnosis of primary hyperhidrosis is generally made on the basis of history and physical examination. Patients report excessive sweating localized to one or more specific areas, i.e., the palms (Fig. 147-1), axilla, feet, or face. Sweating tends to be exacerbated in stressful situations and warm climates. Craniofacial symptoms can include blushing. The sweating generally occurs only when patients are awake. In most cases, patients describe developing their symptoms during early childhood or adolescence, often reporting that they have had the problem for most of their lives.4 The excessive sweating can have a profoundly negative impact on the patient’s life, creating problems with social interactions, school and professional work, and sports and other recreational activities. Patients commonly recount having problems with writing because the sweat smears ink and ruins paper; damaging electronics, including computer keyboards, when sweat ruins the circuitry; being embarrassed or afraid in social and professional settings where shaking hands is customary; having problems with performance during sporting activities; and avoiding intimacy. On examination, there is often active sweating involving the affected region, with severity ranging from moisture without droplets to sweat continuously dripping from the area. Patients with palmar sweating will often wipe their hands on their clothing or a handkerchief, and those with axillary sweating may have obvious sweat stains on their shirts.
Severe palmar hyperhidrosis. (Courtesy of Dr. Steven M. Keller.)
Although rarely necessary, several tests have been described to confirm excessive sweating or quantify its severity. In gravimetry, sweat is collected with an absorptive filter paper or cotton balls for a period of time. The paper or cotton is then weighed to calculate the rate of sweat production (mg/min). The starch-iodine test involves application of a 2% iodine solution to the region in question. After the ...