National report - Focal hyperhidrosis (or primary or idiopathic hyperhidrosis) is a common problem that affects about 3 percent of the population and has significant psychosocial implications.
Many people who suffer from this disorder are simply unaware that they have a medical problem, and they often go to considerable lengths to hide their condition. Using the subjective definition of hyperhidrosis, any degree of sweating that produces social discomfort should be viewed as excessive. Traditional therapies have not proven all that effective for most of these patients, which further adds to patient anxiety, says Joel L. Cohen M.D. Dr. Cohen is director of AboutSkin Dermatology in Denver. He also practices in Englewood, Colo. He is an assistant clinical professor of dermatology, University of Colorado.
Symptoms of focal hyperhidrosis usually start in adolescence or the early 20s and affect one or more anatomic regions, the most commonly affected anatomic sites being the axillae (51 percent), palmar (24 percent) and plantar (30 percent). Emotional and thermal stimuli may further accentuate the baseline problem. The excessive moisture subsequently produced can lead to maceration of the skin, which can result in secondary skin infections and contribute to odor.
The first line of therapy in treating focal hyperhidrosis are topical products which have an anhidrotic effect, like aluminium chloride, as well as other metallic salts. Symptomatic improvement can sometimes be seen within three weeks of initiation of therapy. Long-term use can sometimes result in degeneration of the eccrine unit and resolution of the localized hyperhidrosis.
Topical anticholinergics would seem the intuitive option for treating focal hyperhidrosis because eccrine glands are innervated by sympathetic cholinergic fibers, but as Dr. Cohen explains, there are two principal problems with their use in these disorders.
"First, cutaneous absorption is often insufficient. Second, with using more volume of these products to overcome the poor absorption (or simply to treat larger areas), systemic side effects of cholinergic blockade can frequently occur. Also, contact sensitization can be seen with the use of topical anticholinergics," he says.
Iontophoresis is another therapy involving the topical introduction of ionized particles into the skin using direct current. These charged particles are believed to occlude the duct or the electrical change disrupting eccrine gland secretion. Though effective, it is a very time consuming treatment and concomitant local irritation can be significant causing dry, peeling, cracked skin at the treatment site, especially in the axillae. Therefore, it is rather employed for and considered the second line of treatment for palmar and plantar areas.
"Oral anticholinergic agents are the most commonly used systemic therapies for all types of hyperhidrosis," Dr. Cohen says.
"The problem, however, is their lack of specificity, which frequently causes normal physiologic cholinergic processes to be blocked as well. Thus, even when used for focal hyperhidrosis, these agents commonly cause often intolerable side effects including blurred vision, dry mouth, tachycardia, urinary retention and constipation," he explains.
Excisional procedures of the axillary vault have had varying success rates but can be accompanied by complications including infection, bleeding, delayed healing, flap necrosis, significant scarring or scar contracture. Dr. Cohen points out that in an effort to decrease the postoperative morbidity that is associated with excisional techniques, subcutaneous curettage as well as liposuction of the axillary vault, destroying eccrine glandular tissue from beneath the skin surface has been tried, with some success but still risks bleeding, infection and prominent scars.
Botulinum toxin therapy
For years, botulinum toxin (BTX) has been known to block post-ganglionic sympathetic cholinergic fibers to sweat glands.