Use of botulinum toxin type A in Frey's syndrome*

Dear Editor, Frey’s syndrome (FS) is characterized by sweating and erythema in the parotid gland region, related to salivary stimulus, and emerges after parotid gland traumas, such as parotidectomy, the drainage of abscesses, gunshot wounds, and shingles.1 We present a case of a 60-year-old, white, female patient, who underwent a partial left parotidectomy 10 years ago due to a benign tumor, and who, some months after the procedure, began to suffer from sweating and erythema in the mandibular angle, pre-auricular and retro-auricular ipsilateral regions. In spite of the discomfort during meals, she never sought out treatment. As the hypothesis of FS was put forth, the Minor test was performed by applying a 2% iodine tincture in the region indicated by the patient, followed by the placing of corn starch on the location (Figure 1). The patient ate a lime popsicle, provoking the immediate appearance of brownish spots and adjacent erythema, confirming the clinical picture of gustatory sweating (Figure 2). The affected region was marked by a white pencil to map the treatment with a botulinum toxin type A. Antisepsis with 2% chlorhexidine and a unit of toxin (Onabotulinum toxin type A with a dilution of 100U/ml) applied per injection point along the demarcated region, with a distance of approximately 1cm between the points, totaling 35 applied units. No anesthesia or ice was used before the application, and the patient considered the procedure to be quite tolerable. After two weeks, the patient returned with an excellent clinical response. When compared to the Minor test, there was still a positive reaction in the region near the left earlobe, where five units of botulinum toxin type A were applied, totaling 40 units used in the treatment (Figure 3).