Duration of botulinum toxin effect in the treatment of crocodile tears

Purpose. To provide clinical evidence of the duration of botulinum toxin type A (BTX-A) effect when applied in the palpebral lobe of the lacrimal gland in patients with gustatory epiphora. Methods: Prospective, nonrandomized, nonblinded study. Patients with history of gustatory epiphora were included. A Schirmer test was performed to quantify tearing induced by chewing. Clinical examination included visual acuity, tear-duct syringing, slit lamp examination, corneal staining, and eyelid malpositions. A questionnaire was completed by each patient to asses the severity of hyperlacrimation. A single dose of 2.5 units of BTX-A was injected directly into the lacrimal gland palpebral lobe. Patients were evaluated before and at 1, 4, 12, and 24 weeks after injection. The same person performed the examination and the BTX-A injection. Descriptive statistics, using repeated measures and a paired t test, were used for statistical analysis. Results: Fifteen patients were included. Mean age was 63 years. Before BTX-A injection, mean Schirmer test values were 5.47 mm in the unaffected eyes (NAE) and 12.07 mm in the affected eyes (AE). When comparing Schirmer test values in the AE before and after BTX-A injection, there were statistically significant differences (p < 0.05). Only 2 patients developed mild transitory ptosis. No other complications were noted. Conclusions: The effect of 2.5 units of BTX-A injected into the lacrimal gland lasted 6 months, a duration similar to that reported for other application sites.