Botulinum toxin for Frey's syndrome: a closer look at different treatment responses

Objective: Botulinum toxin is a widely accepted, effective treatment for Frey's syndrome. While some patients need only one injection, others require repeated treatments. We aimed to describe the clinical features of patients with a more challenging treatment course. Design: Literature review and retrospective analysis of eight consecutive patients treated at a university hospital. Subjects: These patients' treatment responses were categorised (using our own system) and compared with those of 25 published cases. Results: Combined analysis identified no significant correlation between treatment response and age, gender or the extent of primary salivary gland surgery. There was no significant correlation between botulinum toxin dosage and time between treatments. Conclusion: Frey's syndrome should be viewed as a dynamic process in which the stimulus for aberrant reinnervation of parasympathetic nerve fibres can be reduced, in some patients, with higher botulinum toxin dose injections to the treated areas. However, responses are unpredictable, and relapses may occur at different time points and in different areas.