The Gusto-Lachrymal Reflex: The Syndrome of Crocodile Tears

Abstract

The gusto-lachrymal reflex means lachrymation in connection with meals. It usually appears after a facial paralysis on the affected side. There are 67 cases mentioned in the literature. Assuming that the syndrome is more common, a follow-up investigation has been made on 118 adults treated for facial palsy. Among 82 examined, 16 patients had noticed eye-watering at meals. Schirmer's test was used for measuring lachrymal secretion. This method is not very reliable, but the best of those available. In spite of this the examination probably revealed two cases of the syndrome unnoticed by the patients themselves. There are many different theories regarding the etiology. The probably correct one is that salivary nerve fibers in the injured facial nerve regenerate in a false direction and reach the lachrymal gland. The present investigation, which included a study of the mimic function, revealed synkinesias in all cases with the syndrome. Those without the symptom exhibit a lesser degree of remaining facial paralysis and one-third of the cases lack synkinesias. In our opinion this supports the theory of misdirected regeneration.