Treatment of gustatory sweating with low-dose botulinum toxin A: a case report

Frey's syndrome, gustatory sweating in the preauricular area, is an unpleasant phenomenon occurring during meals after surgery on the parotid gland. Recently, botulinum toxin A (BTX) has been shown to reduce the symptoms, but the variation in the reported doses is large.

To quantify the effect of treatment with low-dose BTX in a case of Frey's syndrome over a period of 6 months.

A 56-year-old woman was treated with 10 U Botox given as 20 single, intracutaneous injections of 0.5 U, one for each cm(2), 3 years after resection of the parotid gland. Before treatment and repeatedly during the 6-month period, the sweating was rated subjectively on a 100-mm visual analog scale (VAS) and by a severity index, and objectively by assessment of the extent of the involved skin area using Minor's iodine-starch test, staining the area of sweating dark.

The treatment decreased the involved area from 20 to 5 cm(2) and the VAS ratings from 98 to 8 mm. The index showed that treatment affected the sweating intensity, not the frequency. After the 6-month period the patient was still satisfied, but the involved skin area had increased; however, not entirely to pretreatment values.

The effect of BTX injections for gustatory sweating obtained in this case was comparable to results reported using higher doses. Low doses of BTX can therefore be used in the treatment of Frey's syndrome, but studies to clarify the dose-response relationship, in terms of both time-course and obtained effect, are needed.