Botulinum Toxin Type a for Frey's Syndrome: A Preliminary Prospective Study

Abstract

Fourteen patients with severe Frey's syndrome (occurring after conservative parotidectomy) managed with intracutaneous injection of botulinum toxin type A were prospectively evaluated. Results were analyzed for effectiveness, complications, and adverse effects. Complications were not encountered. The only adverse effect noted was a temporary and slight partial paresis of the upper lip of 3 months' duration in 2 patients. Permanent paresis was not encountered. Frey's syndrome was always controlled within 2 days following the intracutaneous injection of botulinum toxin A. Frey's syndrome recurrence was not encountered with a follow-up duration that varied from 3 to 9 months (mean follow-up 7 months). This preliminary report confirmed that in patients who have Frey's syndrome after conservative parotidectomy, the intracutaneous injection of botulinum toxin is a valuable treatment option that should be further investigated.

Frey syndrome treatment with botulinum toxin☆

“…23,35,37,38 There seems to be an agreement on the 10-mm interinjection distance and on an injection dose of 0.1 mL. The 10-mm interinjection distance is supported by the data of Shaari and Sanders 36 for neuromuscular junctions: injections 10 mm away from the motor end plate band of the rat tibialis anterior muscle are ineffective in inducing paralysis.…”

“…The pain associated with the needle injection was evaluated by our patients to be minimal (2 of 10 on an analog visual pain scale), a result found also in other studies. 23,35 Whether the use of local anaesthetic cream (EMLA, Astra, Sweden) will increase patient's acceptance of this mode of treatment 35 remains to be seen.…”

“…23,35 It is difficult to understand how a strictly intradermal injection can result in the paralysis of facial nerve branches. Also, the membrane receptors responsible for the cholinergic specificity of botulinum toxins are located only in the presynaptic terminals and not in nerve fiber trunks.…”

“…This is probably necessary in zones with intense facial gustatory sweating (dark zone in Fig 1, A). However, others 23,35 have obtained good results with a lower dilution (25 U/mL), and this dosage might be advantageous in patients who have a large surface of gustatory sweating.…”

“…Therefore explanation and reassurance is commonly considered as the most adequate treatment for Frey syndrome. 23 Recently, several studies 24,25 have described a new method for the treatment of Frey syndrome-the local infiltration of botulinum toxin in the involved skin. Botulinum toxin can be viewed as an anticholinergic, and this treatment is effective because the (normal sympathetic and regenerated parasympathetic) synapses on cutaneous vessels and sweat glands are cholinergic 26,27 contrary to other sympathetic postganglionic synapses.…”