miraDry®

In February 2011, the U.S. Food and Drug Administration granted clearance for a completely new type of treatment for axillary hyperhidrosis (excessive underarm sweating) called miraDry. miraDry uses a non-invasive handheld device to deliver precisely controlled electromagnetic energy beneath the underarm skin to the specific location of sweat glands, resulting in thermolysis of the sweat glands. It is believed that sweat glands do not grow back after treatment so the effect can be seen almost immediately and results are lasting after two or three physician visits. In a clinical study following 120 patients, 70% of miraDry recipients said their sweating no longer bothered them after 1.5 years. miraDry has been developed by Miramar Labs of Sunnyvale, California.

miraDry is a third generation microwave-based device that selectively heats the interface between the skin and underlying fat where the sweat glands reside. An integrated vacuum system lifts the skin and underlying tissue a few millimeters into the treatment chamber. During the treatment cycle (consisting of energy delivery time and post-cool time) cooling fluid flows through a chamber in contact with the skin, protecting the epidermis and upper dermis from excess heating. Structures deeper than the sweat glands are protected from heat injury due to the limited penetration depth of microwave energy.

In a large, sham-controlled study at 7 sites in the U.S., 120 subjects were randomized (81 in the active treatment group and 39 in the sham treatment group). Treatments were conducted in one to three procedure sessions, typically spaced 2 weeks apart. Subjects in the sham group were followed for 6 months. Subjects in the active group were followed for 12 months. The major findings from the study were:

• A reduction to an HDSS score of 1 or 2 in 89% of subjects (measured 30 days post-treatment) in the active group, and a statistically significant difference between active and sham group was seen (p<0.001)
• HDSS efficacy in the active group was relatively stable from 3 months (74%) to the last study visit at 12 months (69%)
• Gravimetric assessments (weight of sweat) also showed stability in efficacy from 3 to 12 months
• The procedure was well tolerated and a strong safety profile was established

As of November 2011, additional clinical data from two study sites at the University of British Columbia indicates that miraDry reduces underarm sweating by up to 94% after one to three treatments. Patients treated in the University of British Columbia studies rated their satisfaction with the treatment as greater than 90%. Details are as follows.

The miraDry procedure using the commercial device was tested in 2 sites in Canada in a single-group study of 31 subjects. These subjects were treated in one to three procedure sessions, with procedure sessions now being held two to three months apart. The major findings from this study were:

• A reduction to an HDSS score of 1 or 2 in 90% of subjects (measured 30 days post-treatment)
• The procedure and device improvements have stabilized the efficacy seen at later time points compared to prior studies; the last reported efficacy was 94% at 3 months post-treatment
• The average reduction in amount of sweat produced (measured by gravimetric assessment) was 82%.
• Patient satisfaction tracks very closely with efficacy and has been reported at >90%

  Outpatient physician visits for miraDry treatment typically take one hour. With local anesthesia, patients usually experience no discomfort during the procedure.

  To perform the treatment, subjects receive infiltrative local anesthesia in a grid pattern to the entire axilla. The treatment is provided via serial placement of the handpiece, with an active area of approximately 10mm by 30mm. After placement of the handpiece, the treatment cycle is activated. Upon activation, a vacuum is created which gently draws the skin against the thin ceramic treatment plate. Chilled fluid passes behind the plate providing cooling to the superficial levels of the skin. Sensors ensure that the skin is in close apposition to this cooling surface. Microwave energy is then applied non-invasively in a very directed fashion via multiple antennae within the handpiece. The energy is delivered over approximately 30 seconds followed by a 20 second post-cool period. Upon completion, the vacuum is released and the cessation of the audio signal indicates the end of the treatment cycle. The operator then moves the handpiece to the next adjacent treatment area and the process is repeated. Based on clinical testing, two procedure sessions approximately 3 months apart are recommended for optimal efficacy results.

  There is minimal downtime afterwards. Sometimes a mild over-the-counter pain medication and ice packs are recommended for a few days. Most patients are able to return to normal activities or work right after the procedure, and can typically resume exercise within several days.

  The safety data across all three clinical studies has been very good. Almost all subjects noted the expected temporary swelling and discomfort in the treatment area post-treatment with an average duration of approximately one week; altered sensation in the treatment area can last several months.