Triological Society Best Practice
How can Frey's syndrome be prevented or treated following parotid surgery?
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After parotid surgery, traumatized auriculotemporal, postganglionic, parasympathetic nerve fibers reinnervate the sweat glands and subcutaneous vessels resulting in gustatory sweating and facial flushing. Because Frey's syndrome (FS) does not spontaneously resolve, multiple prevention and treatment strategies have been proposed. The literature supports evidence-based best practices for procedures in selected patients directed at the prevention and treatment of FS who are likely to have improved long-term quality of life after parotidectomy.
FS is reported in a questionnaire survey as the most disturbing sequela in patients at more than 5 years after parotid surgery for benign disease. The discomfort of FS becomes more frequently disturbing to patients with time, with 25.7% at 1 to 2 years and 50.9% at 5 years (P = 0.01). Scores in this study for other sequelae were not progressive.
FS is impacted by the amount of parotid parenchyma resected. Subjective perception of FS was significantly greater in total parotidectomy than SP (P < .001) and in SP than partial SP (P < .001). Subjective FS has been reported in 171/368 (47%) of total parotidectomy patients, 158/930 (17%) of superficial parotidectomy (SP), 64/615 (10%) of partial SP, and 30/1050 (3%) of extracapsular dissections (ECD). A meta-analysis concludes that FS is 10 times more common with SP compared to ECD.
Interposition of a sternocleidomastoid muscle (SCM) flap, superficial aponeurotic system flap (SMAS), temporoparietal fascial flap, dermal graft, fat graft, alloplast (polytetrafluoroethylene), and homograft (AlloDerm [LifeCell Corp., Branchburg, NJ], lyophilized dura) have been suggested to prevent FS. Meta-analysis suggests that the use of interposition techniques decreases the likelihood of symptoms of FS. The meta-analysis for all techniques gave an odds ratio (OR) of 3.88 (95% confidence interval [CI], 2.81–5.34) for prevention of subjective FS, and an OR of 3.66 (95% CI, 2.32–5.77) for prevention of objective FS. Although success has been reported with each of the reported methods, the analysis also suggests that total prevention is unlikely to be achieved with any technique because FS is found, to some degree, in all treated sample groups. A complete barrier, not always accomplished with the SCM flap, is required to prevent FS. When assessed as an independent factor, the OR for the SCM flap favors benefit but suggests that benefit may not be statistically significant. Donor site morbidity, including injury to the spinal accessory nerve, must be considered in the SCM flap. SMAS layer interposition can also result in failure if the barrier is incomplete, made more likely if part of the SMAS is resected during extirpation.
The temporoparietal flap provides a broad well-vascularized flap separate from the parotid bed, but risks injury to the frontal branch of the facial nerve, alopecia, atrophy of the temporalis, and some fullness over the zygomatic arch. Alloplastic implants, although effective, are expensive, should not be used in cases of malignancy, and can result in foreign body reactions and contour deformities. Homografts may also prove costly and are associated with variable degrees of resorption and infection. An adequately informed consent should be obtained when using alloplastic implants and homografts. Fat grafting alone suffers from the risk of resorption. Fat grafting coupled with SMAS has been reported to significantly reduce FS for the 2-year follow-up period.
Treatments for FS of historical interest include external beam radiation therapy (XRT), tympanic neurectomy, and topical anticholinergics. XRT, if indicated for malignancy, will reduce the incidence and severity of FS. Tympanic neurectomy frequently results in recurrent symptoms. Topical anticholinergics (scopolamine cream, glycopyrrolate, aluminum chloride) are often abandoned, because their use entails skin drying with a hair dryer and the avoidance of shaving.
Botulinum toxin inhibits the release of acetylcholine by cleaving cytosol proteins, preventing fusion of acetylcholine vesicles with the cell membrane. A total of 100 IU of botulinum toxin type A (BOTOX; Allergan, Irvine CA) is diluted in 5 mL normal saline. The Minor's test demarcates the treatment area, and 0.1 mL of BOTOX is injected intradermally at 1-cm intervals. Functional quality of life is significantly improved (P = 0.0004). All patients said that the effects were beneficial, that they would undergo new injections if necessary, and that they would recommend this treatment to other patients. The benefit lasted 1.5 years for 60% of patients. The duration of the effect was longer than the reported physiological effect of botulinum toxin on acetylcholine receptors.
Many patients with FS do not request therapy. This is important to consider because potentially preventative interposition methods add to the cost and risk of the procedure. All barrier techniques have a reported rate of failure, whereas botulinum toxin injection is associated with very high rate of beneficial effect. Botulinum toxin injection may need to be repeated beyond 1.5 years. Interposition grafts theoretically offer a permanent prevention in some, but not all patients. Their durability for a mean of 2 years has been reported4; however, the literature does not have durability reports beyond 3 years addressing the possible return of FS.
FS is reduced by parotid parenchyma-sparing procedures and interpositional grafts in selected patients. The treatment of choice for FS is intradermal botulinum toxin type A injections.
LEVEL OF EVIDENCE
The levels of evidence for the literature reviewed are 2a, 2b, 3b and 4.