Botulinum Toxin A Injection for the Treatment of Crocodile Tear Syndrome: A Case Series

Purpose: We report two cases of crocodile tear syndrome following facial nerve palsy, in which both symptoms and objective findings improved after lacrimal gland injection of botulinum toxin A.Case summary: Case 1: A 36-year-old man with a history of left facial palsy reported excessive tearing in the left eye during meals. External ocular examination and lacrimal drainage tests were unremarkable. The baseline Schirmer test measured 9 mm, which increased to 23 mm during mastication, confirming the diagnosis of crocodile tear syndrome. Four weeks after botulinum toxin A injection into the lacrimal gland, the Schirmer test value during chewing decreased to 13 mm, and the Munk score improved from 3 to 1. Case 2: A 40-year-old man with a history of right facial nerve palsy presented with excessive tearing in the right eye during meals. External ocular examination and lacrimal drainage tests were normal. The baseline Schirmer test measured 13 mm, which increased to 29 mm during mastication, consistent with crocodile tear syndrome. Four weeks after botulinum toxin A injection into the lacrimal gland, the Schirmer value during chewing decreased to 14 mm, and the Munk score improved from 4 to 1.Conclusions: Lacrimal gland injection of botulinum toxin A effectively reduces symptoms and improves subjective and objective outcomes in crocodile tear syndrome.