Frey’s Syndrome (also known as Baillarger’s syndrome, Dupuy’s syndrome, auriculotemporal syndrome, or Frey-Baillarger syndrome) is a rare neurological disorder resulting from damage to or near the parotid glands responsible for making saliva, and from damage to the auriculotemporal nerve often from surgery.
The symptoms of Frey’s syndrome are redness and sweating on the cheek area adjacent to the ear (see focal hyperhidrosis). They can appear when the affected person eats, sees, dreams, thinks about or talks about certain kinds of food which produce strong salivation. Observing sweating in the region after eating a lemon wedge may be diagnostic.
Frey’s Syndrome, also known as Gustatory Sweating Syndrome, is a disorder that occurs due to a facial nerve injury, after a surgical procedure is performed (for various reasons), on the parotid gland.
The parotid gland is located in the space between the ear and the cheek, on both sides of the face. They are the largest of the salivary glands.
The proportion of the surgeries that lead to Frey’s Syndrome, vary from anywhere between 2-80%. The disorder induces mild to intense sweating, when any sensation pertaining to food (such as smell, taste, sound, sight, thought, including dreams) is present or comes about.
A treatment of this condition is undertaken based on its intensity, the discomfort it causes, and the tolerance level of an individual.
Frey syndrome is a rare disorder that most often occurs as a result of surgery in the area near the parotid glands. The parotid glands are the largest salivary glands in the body located just below the ears on either side of the face. The main symptoms of Frey Syndrome are undesirable sweating and flushing occurring on the cheek, temple (temporal region), or behind the ears (retroauricular region) after eating certain foods, especially those that produce a strong salivary response. Symptoms are often mild and well-tolerated. In some cases, symptoms may be more severe and therapy may be necessary. The exact underlying mechanisms that cause Frey syndrome are not fully understood. Frey syndrome most often occurs as a complication of surgery to the area of the face near the parotid glands.
The disorder was first reported in the medical literature by Baillarger in 1853. A neurologist from Poland, Dr. Lucja Frey, provided a detailed assessment of the disorder and coined the term “auriculotemporal syndrome” in 1923.
Signs and symptoms include erythema (redness/flushing) and sweating in the cutaneous distribution of the auriculotemporal nerve, usually in response to gustatory stimuli. There is sometimes pain in the same area, often of a burning nature. Between attacks of pain there is sometimes numbness or other alterred sensations (anesthesia or paresthesia). This is sometimes termed “gustatory neuralgia”.
The key signs and symptoms of Frey’s Syndrome are:
- The most common indication of Frey’s Syndrome is a spontaneous sweating in response to a food stimulus, which may be in any form. This is called gustatory sweating. The sweating (that may be mild or profuse) may be around the ears, on the forehead, cheeks, and neck region
- Face appears flushed or reddened
- Feeling of uneasiness, discomfort, embarrassment, at such an occurrence
The symptoms of Frey syndrome typically develop within the first year after surgery in the area near the parotid glands. In some cases, Frey syndrome may not develop until several years after surgery. The characteristic symptom of Frey syndrome is gustatory sweating, which is excessive sweating on the cheek, forehead, and around the ears shortly after eating certain foods, specifically foods that produce a strong salivary response such as sour, spicy or salty foods.
Additional symptoms that may be associated with Frey syndrome include flushing and warmth in the affected areas. This is rarely an important complaint.
While other symptoms have been associated with the syndrome, they are probably unrelated. Pain is sometimes described, but it is probably more related to the surgery than actually to Frey syndrome. The specific area affected, the size of the area, and the degree of sweating and flushing vary greatly among affected individuals. In some patients, symptoms may be mild and affected individuals may not be bothered by the symptoms. In other cases, such as those that experience profuse sweating, affected individuals may require therapy.
Frey’s syndrome often results as a side effect of surgeries 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. The Auriculotemporal branch of the Trigeminal nerve carries parasympathetic fibers to the sweat glands of the scalp and the parotid salivary gland. As a result of severance and inappropriate regeneration, the parasympathetic nerve fibers may switch course, resulting in “gustatory Sweating” or sweating in the anticipation of eating, instead of the normal salivatory response. It is often seen with patients who have undergone endoscopic thoracic sympathectomy, a surgical procedure wherein part of the sympathetic trunk is cut or clamped to treat sweating of the hands or blushing. The subsequent regeneration or nerve sprouting leads to abnormal sweating and salivating. It can also include discharge from the nose when smelling certain food.
Rarely, Frey’s syndrome can result from causes other than surgery, including accidental trauma, local infections, sympathetic dysfunction and pathologic lesions within the parotid gland. An example of such, rare trauma or localized infection; can be seen in situations where a hair follicle has become ingrown and is causing trauma or localized infection near or over one of the branches of the auriculotemporal nerve.
The most frequent cause of Frey’s Syndrome is a partial or complete parotidectomy – a surgical procedure performed on the parotid gland, to remove tumors, or resolve an inflammation
There are many facial nerves that run past the parotid gland, which may get affected (or dissected) by this surgical intervention. Frey’s Syndrome is a post-surgical complication of the facial nerve that is affected or realigned, and thereby rendered dysfunctional
The auriculotemporal nerve branch of the facial nerve that originally stimulates the salivary glands, post-operation, excites the sweat glands located in the region, giving rise to gustatory (taste-related) sweating. The effect of the surgical trauma is felt, may be a few months, or a few years after the procedure
Apart from a surgery, sometimes an injury to the face, or a congenital defect, or an injury caused during delivery, may adversely affect the nerve function, triggering the disorder
The degree of severity of the condition depends on the kind of operation, size of the tumor, gland, or tissue removed, incision length and region, and the quality of post-operative reconstruction
The exact underlying cause of Frey syndrome is not completely understood. The most widely held theory is that Frey syndrome results from simultaneous damage to sympathetic and parasympathetic nerves in the region of the face or neck near the parotid glands. Parasympathetic nerves are part of the autonomic nervous system, which is the portion of the nerve system that controls or regulates involuntary body functions (i.e., those functions that occur without instruction from the conscious mind). One function of parasympathetic nerves is to regulate the activity of glands including the parotid glands, but not the sweat glands. Sweat glands and blood vessels throughout the body are controlled by sympathetic fibers.
In Frey syndrome, researchers believe that the parasympathetic and sympathetic nerves near the parotid glands are cut, especially tiny branches originating from the auriculotemporal nerve. The auriculotemporal nerve supplies nerves (innervates) to certain structures in the face including the parotid glands.
Normally, damaged nerve fiber(s) eventually heal themselves (regenerate). In Frey syndrome, it is believed that damaged nerve fibers regenerate abnormally by growing along the sympathetic fiber pathways, ultimately connecting to the miniscule sweat glands found along the skin. Therefore, the parasympathetic nerves that normally tell the parotid glands to produce saliva in response to tasting food now respond by instructing the sweat glands to produce sweat and the blood vessels to widen (dilate). The cumulative result is excessive sweating and flushing when eating certain foods.
Damage to the nerves in the parotid gland region of the face may occur for several different reasons including as a complication of surgery or blunt trauma to the side of the face. In older reports, infections of the parotid glands were suspected, but a detailed examination always points to a surgical drainage of a parotid abscess. The most common reported cause of Frey syndrome is a surgical procedure called a parotidectomy (the surgical removal of a parotid gland). Although the exact percentage is not agreed upon in the medical literature, some sources suggest that more than half of all individuals who undergo a parotidectomy eventually develop Frey syndrome. A recent meta-analysis concluded that the interposition of tissue after parotidectomy might decrease the incidence of Frey syndrome after parotidectomy.
Another rarely described cause (etiology) of Frey syndrome is damage to the main sympathetic nerve chain in the neck.
In extremely rare cases, Frey syndrome has been described in newborns, possibly following trauma due to delivery with forceps. Actual careful examination reveals that the principal symptom is flushing which might be physiologic at a younger age. The key symptom of facial sweating is not emphasized in newborns rising doubts about the correctness of these observations.
- Injection of Botulinum Toxin A
- Surgical transection of the nerve fibers (only a temporary treatment)
- Application of an ointment containing an anticholinergic drug such as scopolamine
- Use of deodorants and anti-perspirants
- Use of anticholinergic ointments, such as scopolamine and glycopyrolate to suppress sweating; the use of antihydrotics (herbs that prevent excess perspiration)
- Use of topical applications, like alpha-adrenergic agonist agents (e.g. clonidine)
- A quick, easy, and safe way to provide relief is the use of botulinum toxin injections, which are effective for about a year
- Reconstructive surgery: A permanent solution can be brought about, apart from setting right any facial scars and deformities that was brought about by the initial parotidectomy surgery. However, performing this surgery requires enormous skill and expertise, otherwise it might further complicate the condition
- If the condition is mild and tolerable, no treatment is usually advised or required
Although Frey syndrome can be mild and well-tolerated, in some individuals, it can cause excessive discomfort. Treatment is symptomatic and directed toward relief of symptoms. Until recently, most treatment measures have generally been unsatisfactory. Treatment options include drug therapy or surgery.
Topical application of drugs that block certain activities of the nervous system (anticholinergics) or drugs that hinder sweating (antihidrotics) have been used. Surgical removal (excision) of the affected skin and the insertion (interposition) of new tissue to the affected area (muscle flaps) has been described, but are considered risky because of the presence of facial nerve fibers right below the skin after parotidectomy.
In the last decade botulinum A toxin has become established as a therapy for individuals with bothersome Frey syndrome. The therapy consists of local injections of botulinum A toxin in the affected skin. Initial results have demonstrated that this therapy results in the suppression of sweating and causes no significant side effects. Another advantage of botulinum A toxin is that it is minimally invasive compared to other therapies. As in other indications, the effect of botulinum toxin is not permanent, lasting on average about 9-12 months.