Frey syndrome is the term used to describe abnormal sweating that is triggered in the face and neck area during the consumption of food or by various stimuli such as chewing or tasting.
What is Frey syndrome?
Frey syndrome (Gustatory sweating, Auriculotemporal syndrome) is a very pronounced sweating in the neck and head area that occurs due to gustatory stimuli. It was named after the neurologist Lucja Frey-Gottesmann, who described the syndrome in more detail in 1923. Lucja Frey studied a man who developed sweating during eating after a cut, which occurred mainly in the area of the parotid gland. However, there are earlier descriptions of Baillarger, so the condition is often called Frey-Baillarger syndrome. Frey syndrome has been described or studied several times over the years. Larger studies originate for example from Laage-Hellmann, in which they also dealt with the time period between the occurrence and the suffered trauma. Overall, two forms of gustatory sweating can be distinguished:
- Profuse sweating due to congenital or physiological causes. An indication of this is usually a symmetrical sweating that occurs on both cheeks mainly after spicy food.
- Abnormal sweating due to disease-related causes. A typical feature of this is the uneven course over the entire facial area.
Causes
One possible cause of Frey’s symptom is surgical removal of the parotid gland (parotis), although the syndrome usually does not appear until months later. The surgery can affect nerve fibers, causing improper cross-linking and preventing stimuli from being directed to the correct location. After surgery, sweating areas are found mainly in those regions supplied by the auricularis magnus nerve and the auriculotemporal nerve, respectively. Frey’s symptoms can also develop after inflammation of the parotid or submandibular glands or after injuries. Another cause can be a local trauma of glands, which can occur due to a fracture of the temporomandibular joint. The removal of cervical lymph nodes can also trigger gustatory sweating under certain circumstances. However, central nervous disorders such as encephalitis or cerebral atrophy are also considered possible triggers of Frey syndrome.
Symptoms, complaints, and signs
Affected individuals suffer from profuse facial sweating that occurs within minutes of a gustatory stimulus. Other symptoms include redness and swelling of the skin and a burning or tingling sensation in the affected areas.
Diagnosis
To determine the extent to which sweating occurs, the physician performs Minor’s iodine-starch test. The iodine–strength test uses an alcoholic solution containing 10 percent castor oil and 1.5 percent iodine. The skin is smeared with this solution over the region of the parotid gland and dusted with starch powder. A gustatory stimulus is then elicited to determine which area is particularly affected by sweating using a blue coloration.
Treatment and therapy
Frey syndrome is treated with both medication and surgery. One option for treatment is to cut the secretory nerve fibers to prevent them from sprouting into the sweat glands. Another approach is to separate the nerve fibers from the sweat glands by inserting alloplastic material or muscle. In addition, solutions for application to the skin are also prescribed, including, for example, scopolamine. However, these are only effective for a short time and must be repeatedly reapplied to the affected areas. It is also advisable to use deodorants that contain aluminum chloride. Aluminum chloride is an antiperspirant substance that is contained in many commercially available deodorants. However, the concentration of the salt is much higher in medical deodorants, which also makes them more effective than regular deodorants. Aluminum salts penetrate into the sweat ducts, where they combine with keratin and block the glandular outlets. An effective therapy is also an injection of botulinum toxin. Botulinum toxin is a protein substance whose production is carried out by bacteria.The bacteria secrete the toxin, which shuts down the transmission of excitation from the nerve cells to the muscles. The toxin is bound to the peripheral nerve endings, which use acetylcholine as a neurotransmitter (transmitter). Acetylcholine also activates the sweat glands. When botulinum toxin is injected, a blockage of the signal transmission occurs and the secretion of the sweat glands is reduced. Botulinum toxin consists of two chains, which are of different lengths and are connected by disulfide bridges. The long chain is responsible for absorbing the toxin into the nerve endings, and the short chain is the actual toxin. For the injection, the skin region is marked according to the iodine-strength test and divided into areas of 2×2 cm each. The area of skin to be treated is anesthetized or iced in advance with an ointment so that the patient does not feel any pain. Then 2.5 IU of botulinum toxin in 0.1 ml solution is injected into each area. A total dose of 100 IU should not be exceeded. Within a few days the injection starts to work and lasts for about a year. As a result, the symptoms appear in a greatly attenuated form.
Prevention
Frey syndrome represents a reduction in quality of life for anyone affected. Various techniques have now been developed in surgery to prevent the syndrome. For example, skin fat grafts are formed during surgery, and implants are also used to be able to prevent Frey syndrome from occurring.
