KOHALA COAST, HAWAII — Underarm injections of botulinum toxin type A reduced underarm sweating by at least 75% in 80%–84% of patients for a median of 7 months in a yearlong study of 322 patients with primary hyperhidrosis, said Dee Anna Glaser, M.D.
Gravimetric measurements of sweat production showed that sweating was reduced by at least 75% in only 21% of patients treated with placebo in the multicenter, double-blind, randomized, controlled trial, she said at a conference on clinical dermatology sponsored by the Center for Bio-Medical Communications Inc. Dr. Glaser previously reported the results at the 2004 meeting of the American Academy of Neurology.
The study included patients with scores of 3 or 4 on the 4-point Hyperhidrosis Disease Severity Scale (HDSS), meaning they reported intolerable or barely tolerable axillary sweating that always or frequently interfered with activities. They were randomized to treatment with injections of 50 or 75 units of botulinum toxin type A (Botox) or placebo in each armpit, and could be reinjected 8 or more weeks after the injections. The patients were followed at 4-week intervals.
In the 50-unit and 75-unit Botox groups, a first treatment improved HDSS scores by at least 2 points (to tolerable or unnoticeable) in 75% of patients, compared with a 2-point improvement in 25% of the placebo group, said Dr. Glaser of St. Louis University. The HDSS score improvements in the Botox groups lasted a median of 7 months after the first treatment.
After a second treatment, 85% in the 50-unit Botox group, 74% in the 75-unit Botox group, and 26% in the placebo group improved HDSS scores by at least 2 points. The improvements lasted a median of about 5 months in the 50-unit Botox group and 6 months in the 75-unit Botox group.
Dr. Glaser is a consultant for and has received research funding from Allergan Inc. which markets Botox, and her family owns stock in the company.
More than half of patients at baseline in each group reported feeling dissatisfied with their ability to perform work activities because of hyperhidrosis. These percentages fell significantly in the Botox groups, to 10% or less, but declined only slightly in the placebo group.
Despite receiving multiple injections in their armpits, 84%–85% of patients in the Botox groups and 20% in the placebo group said that they felt much more satisfied with the results of this therapy, compared with any previous treatments.
The main side effects were some pain or bleeding at the injection site in 3%–12% of patients. Between 4% and 10% of patients thought their hands or feet were sweating a little more after the armpit injections, “but in truth I think that maybe they just started noticing it,” Dr. Glaser said.
Treating Axilla With Botox
To treat the axilla with Botox, Dr. Glaser first delineates the treatment area by Minors starch/iodine test. She dries the armpit, swabs it with Betadine a couple of centimeters beyond what appears to be the axillary border, and applies a light dusting of starch powder.
She uses a makeup brush to apply the powder, but other gentle techniques work as well, such as using a powdered sugar sifter, she said.
The combination of Betadine and powder turns blue-black in the presence of sweat glands, and in 20%–25% of cases identifies little ectopic foci of the axillae that might be missed if the target area is estimated without the powder dusting.
Dr. Glaser marks the perimeter of the axillae and draws points for injection targets every 1.5–2 cm, which is 10–15 injection sites for an average-sized underarm. She reconstitutes 50 units of Botox in 4 cc of saline per underarm and divides the amount by the number of injection sites. Using a 30-gauge needle and a 1-cc syringe, she administers the calculated amount per site in deep dermal or intradermal injections, which should start to produce a wheal.