Microwave-Based Therapy for Treating Axillary Hyperhidrosis

An Expert Interview With Suzanne L. Kilmer, MD

Steven Fox

April 21, 2011

April 21, 2011 (Grapevine, Texas) — Editor's note: Since neurotoxins were approved in 2004 for treating hyperhidrosis, they have been the primary treatments used to manage this common — but infrequently discussed — medical problem.

Dr. Suzanne L. Kilmer

However, at a presentation here at the American Society for Laser Medicine and Surgery (ASLMS) 31st Annual Meeting, attendees heard about another promising approach: the use of a microwave-assisted device to permanently destroy axillary sweat glands, and thus eliminate underarm hyperhidrosis.

Suzanne L. Kilmer, MD, director of the Laser and Skin Surgery Center, Sacramento, California, as well as associate clinical professor at the University of California–Davis, delivered the presentation. Afterward, she responded via email to questions from Medscape Medical News about this novel use of microwave technology.

Medscape: You have been investigating the use of a microwave-based approach to treat a problem that does not usually get a lot of attention at medical meetings: axillary hyperhidrosis. Would you first of all tell us a bit about how common a problem axillary hyperhidrosis is?

Dr. Kilmer: Axillary hyperhidrosis [excessive underarm sweating] is a condition that can be a substantial burden, affecting people in their workplace [and] in their relationships, and it can even significantly affect their self-esteem.

Some studies have estimated that about 1.4% of the US population meet the criteria for axillary hyperhidrosis, and as many as a third of people surveyed say they perspire too much in their underarms. This is a condition that affects a lot of people, but many don't know that there are options to treat it.

Medscape: Please give us some background on the technique you have been using, and how it works.

Dr. Kilmer: Well, of course as dermatologists we use a lot of energy-based devices, such as lasers, to heat the skin to cause beneficial effects. As you know, microwave devices are widely used in other areas of medicine, so it's natural to apply the technology here.

The sweat glands in your underarms that create the excessive wetness are located just under the skin. What this new microwave device allows us to do is to create very focused heat right at that layer, and eliminate the sweat glands.

Medscape: Please tell us about what you did in your study, and what you found out.

Dr. Kilmer: Our clinic worked with 6 other clinics in the United States to test the microwave technology. We enrolled 120 subjects into 2 groups. One group received the treatment with the device, and the other group received a sham treatment.

Each procedure involved 3 steps: (1) placing a grid on the underarm using a temporary tattoo, (2) injecting local anesthetic in the treatment area, and (3) positioning the handpiece of the device (miraDry, Mirmar Labs) at precise locations on the grid, so that we'd treat one small area at a time. Most subjects (90%) in the study had 2 treatment sessions a couple of weeks apart.

After the treatment sessions, the groups were followed for either 6 months (the sham group) or 12 months (the treatment group). At various follow-up points (30 days, 3 months, 6 months) we compared the amount of sweating reported in each group.

We determined that there was a statistically significant difference in the quality-of-life measure between the treatment and sham groups. For the treatment group that was followed out a full year after their treatments, we found that the efficacy of the treatment was very stable.

Medscape: Is this a permanent fix for hyperhidrosis? If not, how long do the effects usually last?

Dr. Kilmer: [P]atients in the study were followed for 12 months, and the efficacy of the procedure was fairly stable from 3 months out to 12 months, showing sustained results. The developers of the device [have] histology data out to 6 months on several patients that have been treated with miraDry, and this histology data shows that the sweat glands have disappeared. The miraDry procedure thermally destroys the sweat glands in the axilla, and sweat glands do not regenerate.

Medscape: Are there any significant adverse effects associated with using this technique?

Dr. Kilmer: Well, it involves a bit more discomfort than treatment with botulinum toxin injections. Almost all of the patients that were treated experienced some mild swelling and tenderness in their underarms after the procedure, which is to be expected based on how the treatment works. About 71% of the side effects reported in the clinical trial were mild and consisted of issues such as temporary swelling, or some transient altered sensation in the skin. A few patients reported pain that required short-term use of prescription medications.

Medscape: How long do most treatments take? And are there data available on its cost?

Dr. Kilmer: The procedure typically takes about an hour for most patients. This includes all prep time. The procedure is not yet commercially available, so I can't comment on what it will cost.

Medscape: How can clinicians who use the procedure determine if it has been effective in an individual patient? Is there a reliable way to assess that, other than feedback from the patient?

Dr. Kilmer: In our experience it's been very easy for patients to see the effect of the treatment and communicate that to us. If we want independent verification, there are methods that visually show us where a person is still sweating (one is called a starch-iodine test), or we can weigh the amount of sweat that is being produced in a standardized way.

What really matters to the patient, though, is how the procedure reduces embarrassing sweat outbreaks and the constant wetness under their arms. So quality-of-life measures are important.

Medscape: Neurotoxins have been the most common treatment for this problem up until now, correct? How do the results with the microwave-based treatment compare with results using neurotoxins?

Dr. Kilmer: The neurotoxin mechanism of action is very different, in that it more or less just "paralyzes" the nerves that activate sweat.

A key issue with the botulinum toxin injections is that the effect wears off over time, so that approach provides relief for only about 7 months on average. In that limited time, however, the efficacy is quite good. In some randomized studies, the efficacy in treated groups was about 75%, and the efficacy in the placebo group was about 25% — a difference of 50 percentage points.

In our study, if we do the analysis the same way, the efficacy results were 67% for the treatment group [and] 13% for the sham group — a difference of 54 percentage points. So I feel that the results compare very favorably. Considering that our data showed that this microwave-based treatment provides lasting results, I think it's a viable option for patients.

Dr. Kilmer is a consultant to Miramar Labs, and the company has provided grants to support Dr. Kilmer's research.

American Society for Laser Medicine and Surgery (ASLMS) 31st Annual Conference. Presented April 3, 2011.


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