Frey's syndrome (gustatory sweating) is a recognized complication of parotidectomy. What is the underlying mechanism?

• A Aberrant regeneration of parasympathetic secretomotor fibers into cutaneous sweat gland sympathetic pathways ✓
• B Injury to the facial nerve causing aberrant regeneration into skin vasculature
• C Damage to the auriculotemporal nerve causing vasomotor instability
• D Scar contracture compressing the great auricular nerve

Explanation

The auriculotemporal nerve carries postganglionic parasympathetic fibers (from the otic ganglion via the lesser petrosal nerve) to the parotid gland. After parotidectomy, these cholinergic fibers regenerate aberrantly and reinnervate the sympathetic pathways of cutaneous sweat glands and blood vessels. Because acetylcholine stimulates both secretomotor parotid fibers and sweat glands, eating (which normally triggers salivation) now paradoxically causes sweating and flushing over the pre-auricular skin — Frey's syndrome.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.