Development of a Protocol for Treatment of Crocodile Tears Syndrome with Botulinum Toxin.

INTRODUCTION: Crocodile tears syndrome (CTS) is a synkinesis-type sequela seen after facial paralysis. CTS is characterized by hyperlachrymation while feeding. Botulinum toxin A (BTxA) has been used as a treatment for CTS patients. The BTxA mechanism of action in the lacrimal gland is the presynaptic blockade of acetylcholine release at cholinergic nerve endings, thereby reducing the stimulus on the gland activity. This mechanism is similar to that observed in the treatment of hyperhidrosis (sweat glands) and sialorrhea (salivary glands). The purpose of the present study was to determine the incidence of crocodile tears syndrome in patients with long-lasting facial paralysis, and to establish a treatment protocol with BTxA applied into the lacrimal gland.