[Botulinum toxin for treatment of gustatory sweating. A prospective randomized study].

BACKGROUND: Botulinum toxin A has meanwhile become a proven method for treatment of gustatory sweating (focal hyperhidrosis, Frey's syndrome). Clear-cut recommendations regarding dosage of botulinum toxin A in Frey's syndrome are currently not available. The aim of this prospective randomized study therefore was to investigate botulinum toxin A with respect to its efficacy in Frey's syndrome, the ideal dose yielding maximal duration of the effect, and patient contentedness as well as unwanted side effects in patients of the Clinic of OMF Surgery at the Ruhr-University of Bochum.

PATIENTS AND METHOD: Twenty patients suffering from severe Frey's syndrome as a result of operations of the parotid gland were examined with the starch iodine test according to Minor. The gustatory skin areas were re-examined after intracutaneous injection of botulinum toxin A for up to 1 year. The patients ( n=20) were randomly assigned to two different treatment groups (group I: 2 MU/cm(2), n=10; group II: 3 MU/cm(2), n=10).

RESULTS: Mean sweating skin areas in the two treatment groups ranged between 39+/-9 and 32+/-12 cm(2), respectively. A single injection of 3 MU botulinum toxin A resulted in a nearly complete blockade of gustatory sweating for the observation period of 1 year. In the group treated with 2 MU botulinum toxin A, 44% of the total gustatory skin areas were still sweating, thus necessitating a second injection of botulinum toxin A in these patients.

CONCLUSION: Intracutaneous injection of botulinum toxin A represents a highly effective and minimally invasive procedure for the treatment of Frey's syndrome. This study shows for the first time that a dosage of 3 MU/cm(2) of botulinum toxin A achieves a complete and reliable blockade of gustatory sweating lasting for at least 12 months. This dose may therefore be recommended for treatment of this syndrome.