Palmar and Plantar Treatment
The pain associated with BoNT-ONA injections for palmar and plantar hyperhidrosis can deter patients from undergoing the procedure. Due to the rich nerve endings in the palms and soles, pain can be significant with the numerous injections needed to achieve the desired effect. To reduce discomfort from the injection, several anaesthetic methods have been reported, including oral and intravenous sedation, topical lidocaine cream, nerve blocks, and cryoanalgesia (ice block). Radial and ulnar nerve blocks, when administered properly, are very effective in minimising pain and are commonly utilised prior to injection.
For patients who are more sensitive to pain or are wary of the pain associated with the injection, topical 2.5% lidocaine cream is applied 30 to 60 minutes prior to the procedure. Some physicians use vibration in conjunction with ice packs to reduce pain sensation. It is believed that the stimulation of vibration receptors inhibits the interneurons that transmit the pain signal. Vibration can be administered with a handheld massager or other similar device.
Define the injection field as a grid on the palm and sole. Once the field of injection is defined, a total of 100 U per palm of BoNT is injected with a 26- or 30- gauge needle and a TB syringe. The BoNT is diluted in 3 to 4 ml of normal saline and then sub-dermally injected into each 1- cm square area of the palm and three sites in each digit. After the procedure, ice packs are applied for 15 minutes to confirm no immediate reaction to the toxin.
Post-treatment Care
Patients are monitored in the clinic for signs and symptoms of adverse events (AE) and encouraged to report any AE that occur following treatments and between follow-up visits. Patients are routinely advised to attend for a review in 2-4 weeks to check the treatment outcome. Patients are advised to self-refer for repeat treatment once their symptoms begin to return.
Patient Satisfaction
Patients who have undergone BTX-A injections claim a significant decrease in excess sweat production and improvement in quality of life.
Disadvantages
The primary disadvantage to treating hyperhidrosis with botulinum toxin is its temporary improvement. Although there may be an attenuation effect, anhidrosis typically lasts six to nine months, and thus repeated injections are required. It is noted that patients who have had more than four treatments tend to return more frequently for subsequent injections. We speculate that this occurs because patients are less tolerant of symptoms once they become accustomed to the anhidrosis. However, research suggests that some patients may develop antibodies to the toxin, leading to reduced treatment efficacy.