Treatment

For those patients with symptomatic gustatory sweating, the first line of treatment includes management with antiperspirant deodorants or anticholinergics like scopolamine cream. These treatments only provide temporary relief of symptoms, but may allow patients a functional level of tolerance. For those patients in which conservative treatment is unacceptable, botulinum toxin type A has become the treatment of choice for both long-term control or eradication of the gustatory sweating. Drobik and Laskawi were the first to publish the use of subcutaneous Botox as an effective treatment of gustatory sweating [14]. Botulinum toxin acts by binding presynaptically to high-affinity recognition sites at the cholinergic nerve terminals. Once internalized it binds to SNARE proteins effectively preventing the fusion of synaptic vesicles with the axon membrane. This in turn prevents the release of acetylcholine, causing an overall neuromuscular blocking effect. The Botox is to be delivered at the level of the superficial dermis and usually diffuses within a 5 mm radius. A visible wheal confirms placement in the proper plane of the skin. If the injections are too deep, the muscles of the face may be temporarily weakened, and this risk factor should be openly discussed with the patient prior to treatment. For patients who develop resistance or in which treatment with botulinum toxin type A is ineffective, botulinum toxin type B has been shown to be an effective alternative [15]. The dose of botulinum toxin A needed varies but generally falls between 0.5 and 2.5 units per cm².

Occasionally, there are circumstances when Frey syndrome is inadequately treated medically, and therapeutic surgical intervention is necessary. Various flaps have been used prophylactically at the time of parotid resection or postoperatively, after gustatory sweating has developed. These flaps not only act as a physical barrier to prevent abnormal connection between the parasympathetic and sympathetic fibers of the auriculotemporal nerve but also can provide soft tissue bulk to improve a cosmetic deformity after resection of the parotid gland. The sternocleidomastoid, superficial musculoaponeurotic system (SMAS), and temporoparietal fascia flaps have all been reported in literature to decrease or eradicate gustatory sweating [1618]. In addition to autologous barriers, numerous implants have also been proposed. AlloDerm,™¹ an acellular dermal matrix, is one such implant. It has been shown to reduce the incidence of Frey syndrome effectively and safely and improve overall facial contour [19]. The clinical approach to both physical diagnosis and treatment of gustatory sweating is relatively simple (Fig. 6.3). ^[1]

Fig. 6.3 Treatment algorithm for Frey syndrome from Clayman et al. [5]

• [1] ™LifeCell, Bridgewater, NJ, USA.