Pseudo "fringe sign" in frontal fibrosing alopecia

Abstract

How to cite this article: Gualberto GV, Sampaio FMS, Madureira NAB. Use of botulinum toxin type A in Frey's syndrome. An Bras Dermatol. 2017;92(6):891-2.An Bras Dermatol. 2017;92(6):891-900.The FS or auriculotemporal syndrome or gustatory sweating results from the salivary stimulus during and immediately after eating, seeing, thinking about, or talking about certain foods. 2,3The hypothesis is that, after a parotid gland trauma, a lesion would occur to the auriculotemporal branch of the trigeminal nerve, followed by an anomalous and aberrant regeneration of nerve fibers, with the anastomosis of the parasympathetic fibers with sympathetic fibers of the subcutaneous sweat glands and surface blood vessels. 4 Consequently, not only is the salivary reflex stimulated during chewing, but also the production of sweat and the cutaneous vasodilation of the affected region. 5The symptoms generally arise about six months after the parotid gland trauma, the time necessary for the regeneration of the damaged nerve, but there are reports of medical conditions that began up to 14 years after the traumatic event.4The incidence described for FS after parotidectomy is quite variable and depends on the criteria used to reach this diagnosis. One subjective incidence (based on the perception of the patient's symptoms) was identified between 12.5% and 62%, while an objective incidence (verified by the Minor test) was found between 22% and 98%. In general, the results of botulinum toxin type A for sweating are more prolonged than those obtained in treatments that focus on the reduction of muscular actions. In practice, the successive treatment with the toxin seems to promote a reduction in the severity of the symptoms and the extension of the treated area, as well as space out the period between recurrences. One possible explanation would be the atrophy of the eccrine glands, inhibited for long periods of time. 2,5 Disadvantages that may occur include: dry mouth, weakening of the facial muscles, eyelid ptosis, facial paralysis, as well as short-term local reactions of pain, edema, erythema, and ecchymoses. Allergic reactions and the development of resistance to botulinum toxin type A can occur, and in these cases, the use of botulinum toxin type B would be a plausible alternative.