The Syndrome of Crocodile Tears

Treatment of gustatory hyperlacrimation (crocodile tears) with injection of botulinum toxin into the lacrimal gland

“…[1][2][3] It was first described in 1913 and since then many cases have been reported in the medical literature. This rare phenomenon usually follows a Bell's palsy or a traumatic facial paralysis.…”

“…4 The most commonly accepted mechanism for the pathogenesis of this abnormal reflex appears to be the misdirection of regenerating gustatory fibers from either the facial or glossopharyngeal nerves. After being injured the nerves may redirect themselves through the greater superficial petrosal nerve to reach the lacrimal gland, and cause ipsilateral tearing when the patient eats [1][2][3] (Figure 1). An alternative hypothesis is that the nerve fibres do not actually regenerate, but rather form an artificial synapse at the site of the injury which allows the crossover of impulses from one fibre to another and interaction between afferent and efferent axons.…”

Frey’s Syndrome following Submandibular Gland Excision: An Unusual Postoperative Complication

“…This is Frey's [3] original theory; (ii) diffusion of acetylcholine, produced by damaged salivary glands, stimulating the sweat glands [17]; (iii) hypersensitivity of the denervated blood vessels and sweat glands to 'previously unapparent cranial sudomotor impulses', i.e. a normally existing reflect deprived of its inhibitory fibres [15]; (iv) transaxonal excitation between regenerated sympathetic and parasympathetic fibres whose insulating sheaths have been damaged [18,19].…”

Isolated acquired primary gusto-lacrimal reflex from a brainstem glioma

“…5 Another hypothesized explanation for this phenomenon is ephaptic transmission and reorganization within the superior salivatory nucleus. 6 Although the gusto-lacrimal reflex occurs most often after an acute facial nerve paresis and may or may not be associated with other evidence of facial nerve dysfunction, 2 slow-growing lesions that affect the facial nerve rarely can cause a primary gusto-lacrimal reflex. 3,4 In such cases, other evidence of facial nerve dysfunction, including aberrant regeneration of the motor nerves, almost always is present.…”