Application of medical thermography to the diagnosis of Frey's syndrome.

BACKGROUND: In Frey's syndrome, the secretory parasympathetic fibers of the parotid gland are thought to communicate with the sympathetic nerve fibers of sweat glands and blood vessels of the skin following parotidectomy. Miscommunication results in subjective gustatory sweating and facial flushing, which appear early with postoperative mastication. In this study, we compared the efficacy of medical thermography to the Minor's starch-iodine test to determine the presence of gustatory sweating in Frey's syndrome.
METHODS: Patients were considered to have Frey's syndrome if signs of gustatory sweating and localized skin flushing of the parotid region were present. In four patients who had undergone unilateral parotidectomy, gustatory sweating and facial flushing were present after gustatory stimulation, and the presence of Frey's syndrome was confirmed with Minor's starch test in all patients. Infrared thermography was then performed, and the same area measured. The contralateral side served as an internal control for each patient.
RESULTS: Before gustatory stimulation, the isothermal pattern of the diseased side and the nonoperative side was similar. Stress thermography using a sialogogue (lemon, 3 mL) showed a cold spot at the operative site in all four patients with Frey's syndrome. The contralateral nonoperative side showed normal skin temperature distribution in all patients. Minor's test was positive in all patients.
CONCLUSIONS: Thermography is a noninvasive, facile test that provides a qualitative visual analysis of the cutaneous capillary response in Frey's syndrome following parotid surgery.