[Crocodile tears and retraction syndrome]

Area of Science:

• Neuroscience
• Ophthalmology
• Genetics

Background:

• The association between crocodile tears (gustatory-induced tearing) and Duane's syndrome has been documented in over 50 cases.
• Duane's syndrome is a congenital eye movement disorder characterized by limited outward movement of the eye and retraction of the eyeball with eyelid narrowing upon inward movement.

Observation:

• A 29-year-old male presented with unilateral tearing in the right eye when consuming sour foods.
• The patient exhibited no tearing during psychic weeping (emotional crying) of the right eye.
• The patient was diagnosed with right-sided Duane's retraction syndrome.

Findings:

• In this case of congenital crocodile tears and ipsilateral Duane's syndrome, normal facial muscle function was observed.
• The findings suggest the aberrant neural pathway connecting taste stimuli to the lacrimal gland is not in the facial nerve proximal to the geniculate ganglion.
• The abnormal coupling is hypothesized to be located within the brainstem.

Implications:

• The co-occurrence of crocodile tears and Duane's syndrome suggests a broader issue of abnormal innervational coupling.
• This case implies that aberrant neural connections can affect both cranial nerves controlling facial muscles and those governing eye movements.
• Further research into brainstem pathways may elucidate the mechanisms underlying these associated neurological conditions.