Treatment of Frey's syndrome with type a botulinum toxin: Case report

Abstract

Frey’s syndrome is a well-known sequel of operative procedures in the region of the parotid gland. It occurs frequently after conservative parotidectomies and occasionally after partial or radical excision of the parotid gland. The incidence depends on the size of the glandular compartment removed and on the accuracy of the diagnostic procedures used to verify the presence of the syndrome. Frey’s syndrome occurs less frequently after purulent parotitis, tumors, trauma, typhoid fever, and irritation of the auriculotemporal nerve by dislocated temporomandibular fractures. 1-3 Frey’s syndrome becomes symptomatic when undesirable sweating occurs in the cheek and retroauricular and temporal regions after eating. Symptoms also can occur in the distribution of the greater auricular nerve. There can be flushing and warmness, with overheating of the affected areas of the skin, which in some cases is associated with pain. Pain also can occur as a preliminary sign or be the only symptom. Typically, the symptoms occur several weeks or months after surgery. Gustatory sweating can be verified by using the iodine-starch test, 4 which shows the phenomenon on the basis of a color reaction. Follow-up examinations show that approximately 30% to 50% of postparotidectomy patients experience the symptoms described, and approximately 15% rate their symptoms as severe. 5,6 Pathophysiology The precise pathophysiology of Frey’s syndrome is still unclear. Hypothetical explanations are based on the dense parasympathetic innervation in the region of the parotid. 10 Parasympathetic secretory fibers from the glossopharyngeal nerve to the parotid gland pass through the tympanic nerve, superfical petrosal nerve, and otic ganglion (Jacobson’s anastomosis) to the auriculotemporal nerve, which branches off the trunk of the mandibular nerve. Frey’s syndrome can be explained by local terminal inhibition of the physiologic reflex 1,3 or by malinnervation attributable to misdirection of the parasympathetic fibers of the auriculotemporal nerve for the parotid gland in the process of postoperative regeneration. In the latter situation, fibers follow the sympathetic nerve paths and attach to the proximal sweat glands of the skin