Gustatory sweating, the main symptom of Frey's syndrome, usually occurs after parotid gland surgery. Numerous medical and surgical treatments have been proposed to treat this condition, but there are various drawbacks. Botulinum toxin type A intracutaneous injection is a relatively new treatment modality; its use has never been reported in Taiwan. Here, we present our preliminary experience with this technique and review the literature.
Between March 2002 and June 2005, 10 consecutive patients with severe gustatory sweating were managed with intracutaneous injection of botulinum toxin type A for a total of 16 times. The affected skin was visualized by Minor's starch-iodine test and then recorded. The interinjection distance was 1 cm and a mean dose of 46.4 U (at a concentration of 2.5 U/0.1 mL) was used.
In all 10 cases, gustatory sweating improved within 2 days after injection, with no side effects. Patients in whom the first 13 injections were performed experienced recurrence of gustatory sweating. Mean duration of effectiveness was 9.3 months; the shortest duration of effectiveness was 2 months and the longest was 28 months. One patient also had gustatory flushing, but this symptom did not improve even after 3 treatments.
Intracutaneous injection of botulinum toxin type A is a highly reliable, effective, safe, and minimally invasive treatment for gustatory sweating. Some patients had long-lasting therapeutic results. We recommend it as a valuable treatment option for severe cases of gustatory sweating. However, in our experience, it had no effect on facial skin flushing. Therefore, in addition to acetylcholine, there might be other neurotransmitters that are responsible for skin vasodilatation.