Frey's syndrome is a rare, neurological disorder that causes a person to sweat excessively while eating. It most often occurs as a complication of surgery involving the parotid gland (a major salivary gland located below the ear). It may also occur following neck dissection
, facelift procedures, or trauma to the area near the parotid gland. Symptoms usually develop within several months of the procedure or trauma, but may develop several years later. The main symptoms include flushing and excessive sweating (hyperhidrosis
) on the cheek, temple, or behind the ear, when eating or thinking about food (gustatory sweating
). Some people with Frey’s syndrome may experience a burning sensation, itching, or pain around the affected area. The symptoms are usually mild but can be severe, causing significant discomfort or social anxiety.
Frey’s syndrome is thought to be caused by damage to both the nerves that regulate the sweat glands, and the nerves that regulate the parotid glands. It is believed that the damaged nerves regrow abnormally and connect to the wrong glands. Frey’s syndrome is diagnosed based on medical history (e.g. a history of surgery or trauma) and symptoms. The diagnosis can be confirmed with a test called the Minor's starch-iodine test
Treatment, when needed, is focused on controlling the symptoms and often involves injections of botulinum toxin A
(Botox) and/or topical antiperspirants. Repeat Botox injections are often needed as symptoms return, which occurs yearly on average. Of note, although Botox injections have been reported to improve symptoms and quality of life, no randomized controlled trials of its use to treat Frey’s syndrome have been documented.