Also known as auriculotemporal nerve syndrome or gustatory sweating syndrome, is a disease that usually occurs after parotidectomy (resection of parotid gland) or trauma of the gland, or without any evident insult. In some young patients there was delivery with forceps assistance.

The first case of this syndrome is attributed to M. Duhenix in 1757 and to  Baillarger in 1853. But Lucja Frey, a Polish neurologist, in 1923, was who described correctly the symptoms and the role of auriculotemporal nerve.

Frey’s syndrome, tipically unilateral (although some bilateral cases have been reported) is characterized by recurrent episodes of facial flushing and/or sweating in the cutaneous distribution of auriculotemporal nerve ( the area anterior to the ear and on the cheek) within a few seconds of eating, chewing or sight a favorite food that make salivate a great deal (such as salty, sour foods).

Examination shows no swelling, disconfort, tenderness, lymphadenopathy and cutaneous parotid gland region is normal.

It is uncommon in children but it has been reported in the first months of life like an episodic facial flushing without sweating.

In children usually resolve spontaneously.

Parotid gland is a salivary gland, riddled with tiny autonomic nerves (preglanglionic parasympathetic cholinergic  fibers of auriculotemporal nerve).

Autonomic nervous system include nerves that work without any input from the conscious mind, such as sweating, pupils huge or pinpoint, salivating.

When parotid gland is removed, these tiny nerves are disrupted (not as the result of surgeon’s error, but as a possible, inevitable conseguence of surgery). During the healing period, these nerves has an aberrant regeneration resulting in reinervation with sympathetic receptors attached to microscopic sweat glands and subcutaneous vessels of the cheek region.

When people eat foods that make salivate a great deal (such as salty, sour foods), aberrant postganglionic parasympathetic fibers stimulate cutaneous sweat glands and small vessel inducing erythema (flushing) and sweating in the distribution of the auticulotemporal nerve.

Fortunately, as a conseguence of parotidectomy, the sweating and flushing are mild to moderate.
Treatment is usually unnecessary: it is important to recognise the syndrome and give explanation and reassurance. In adults with severe symptoms, topical antiperspirants, surgical treatments, botulin toxin injections have been tried.