Conditions: Frey’s Syndrome
(also known as gustatory sweating)
What is Frey’s syndrome?
Frey's syndrome is a condition that may occur after surgery or trauma to the parotid salivary gland. The symptoms of Frey's syndrome are sweating and/or redness on the cheek directly in front of the the ear when the affected person would normally salivate, such as when he or she eats, sees, dreams, thinks about or talks about certain kinds of food which produce strong salivation.
The reported incidence of Frey syndrome after parotid surgery varies greatly depending on how closely patients are questioned and examined for the condition. The incidence of objectively documented Frey syndrome approaches 95% to 100%, though patient awareness of the problem is between 20% and 65%.
Why is Frey’s Syndrome a problem?
Frey’s syndrome may go unnoticed or may amounts to no more than an annoyance. While Frey’s syndrome may occur to some extent in nearly everyone undergoing parotid surgery, only 15% of affected individuals consider the symptoms bothersome enough to merit treatment.
What causes a Frey’s syndrome?
Frey's syndrome often results as a result of surgery of or near the parotid gland or due to injury to the auriculotemporal nerve, which passes through the parotid gland in the early part of its course. In brief, microscopic nerve branches that normally go to the parotid gland to activate salivation are (necessarily) cut during parotidectomy, and during the healing process, these nerves grow into the sweat glands of the cheek skin. Thus, when the brain signals a need to salivate, the nearby sweat glands become activated to sweat. Nore technically, the auriculotemporal branch of the mandibular branch (V3) of the trigeminal nerve carries parasympathetic fibers to the parotid salivary gland and sympathetic fibers to the sweat glands of the scalp. As a result of severance and subsequent inappropriate regeneration during the post-operative period, the parasympathetic nerve fibers may switch course to a sympathetic response, resulting in "gustatory sweating" or sweating in the anticipation of eating, instead of the normal salivary response. The subsequent regeneration or nerve sprouting leads to abnormal sweating.
HOw is Frey’s syndrome prevented?
Several surgical techniques have been proposed to help prevent development of Frey’s syndrome. Elevating a thick skin flap helps, but does not prevent Frey’s syndrome. Placement of a biological barrier between the deep aspect of the wound and the skin flap may help reduce the incidence of Frey’s syndrome, but is also associated with a higher risk of a fluid collection (seroma) at the wound site. The main predictor for development of Frey’s syndrome is the extent of parotid surgery, which is determined by size of the parotid tumor.
How is Frey’s Syndrome identified?
An affected individual with a history of parotid surgery or trauma may note sweat formation on the cheek during eating or salivation. When the diagnosis is in doubt, observing sweating in the cheek region after eating a lemon wedge may be diagnostic. A slightly more involved, but more definitive test to observe for sweat is the starch-iodine test, also known as the Minor test. The area of skin to be tested is painted with iodine which is allowed to dry, then dry corn starch is applied to this area.. The starch turns blue on exposure to iodine in the presence of sweat.
How is frey’s syndrome treated?
In affected individuals, symptoms typically begin about one year after parotid surgery, and symptoms tend to resolve spontaneously after another year or so.
While symptoms persist, an individual may choose to do nothing or just dab the sweaty with a napkin as needed. For those interested in more proactive treatment, options include:
Applying a clear antiperspirant deodorant to the affected cheek before a meal.
Application of an ointment containing an sweat-reducing medicine, such as scopolamine or 1 to 2% glycopyrrolate, which usually provides several days of relief. This medication is not available commercially as a topical preparation; therefore a lotion or cream must be made specially by a pharmacist. Contraindications to the use of this medication include glaucoma, pyloric obstruction, and prostate hypertrophy.
Injection of botulinum toxin A (e.g., Botox), which decreases or eliminates the sweat production for 3-9 months usually.
Medications to reduce sweating throughout the body (anticholinergics administered orally) tend to have side effects such as dry mouth and blurry vision, and are typically not worth the benefit.