Frey Syndrome is a rare neurological disorder which arises from damage to the nerves near the salivary glands in the face. The result of this is excessive sweating on the face, where the salivary glands are when eating or thinking about food. This is because instead of innervating the gland which causes you to salivate, the damaged nerves heal to innervate the sweat glands. The most common type of Frey Syndrome involves damage to the nerves supplying electrical signals to the parotid gland, most commonly caused by parotidectomy, a surgery to remove part or all of this gland. However, Frey syndrome has also been reported by individuals post neck dissection and facelift procedures, but can occur following any surgery in the region of the face and neck where the salivary gland nerves are present.¹  

Overview of Frey Syndrome

Frey Syndrome is a neurological disorder characterised by flushing and excessive sweating of the face in the regions of the salivary glands when eating or thinking about food.² It presents itself when the nerves responsible for stimulating saliva production get damaged and grow to innervate the sweat glands that are in the area. Hence, when you would typically release saliva before or during a meal, you sweat instead. This is most commonly and associated with parotidectomy, which is a surgery to partially or fully remove the parotid glands due to tumour formation, infection, or inflammation. 

Although this disorder is benign, Frey Syndrome can be a social challenge to those experiencing it. Gustatory sweating and facial flushing during meal times can make one's life extremely uncomfortable. Despite being a rare neurological disorder, Frey syndrome is common following parotidectomy, seen in anywhere from 4 - 62% of post-parotidectomy patients, and is therefore an expected side effect of this surgery.³ Furthermore, Frey Syndrome has also been historically tied to the parotid region, with it being first described in detail in a patient who suffered a gunshot wound to the cheek.⁴ 

The understanding of Frey Syndrome in exceptionally uncommon cases, for example following other neck surgeries, may provide the individuals suffering from it some reassurance and provide them with the knowledge of treatment options and symptom management that they may have not received from medical professionals. 

Neck Surgeries that can cause Frey Syndrome

Because Frey Syndrome is caused by damage to the auriculotemporal nerve, it can occur following any surgery which is in an area close to where this nerve is situated. This includes:⁵

• Removal of neck lymph nodes (neck dissection)
• Thyroidectomy 
• Reconstructive surgery following trauma to the face and neck
• Face lift surgeries
• Removal of the submandibular gland (submandibular gland excision)
• Temporomandibular joint surgery

Occurrence of Frey Syndrome After Neck Dissection

Neck dissection is a surgery performed to remove the lymph nodes in the neck, usually due to tumour growth.⁶ It is not a routine surgery, as it carries with it significant long-term side effects and is typically only performed in cases where cancer is suspected to have spread to the neck. 

Although this is a rarely described side-effect of this surgery, Frey Syndrome can occur in some patients. It may present itself differently than Frey Syndrome following parotidectomy, with the most common place for sweating being the submandibular area, the area under the jawline on the top of the neck.⁷ Because Frey Syndrome is not life-threatening and is relatively uncommon, it is not the point of focus for surgeons performing neck dissection, hence, surgical techniques do not solely focus on its prevention. Instead, there is more focus on the treatment of this disorder. 

Occurrence of Frey Syndrome after other neck surgeries

Frey Syndrome may also occur following other neck surgeries. Thyroidectomy, reconstructive surgeries, and even facelifts can damage the nerves of the salivary glands. It is thought that all surgeries that can cause Frey Syndrome, do so via the same mechanism. This mechanism is described below:

• Surgical trauma first damages a nerve linked to a salivary gland
• When these nerves attempt to heal, they mistakenly innervate the sweat glands which are present above the salivary glands
• Signals that are sent from the brain at meal time to stimulate the flow of saliva to aid in breaking down foods go down these same neurons but now activate the sweat glands instead
• This causes the hallmark symptoms of Frey disease: excessive sweating and flushing in the area of the affected salivary gland when eating or thinking about food

Depending on where the operation takes place, the symptoms can present themselves in different areas of the face and neck. For example, if the affected nerve supplies electrical signals to the parotid gland, the cheek, ear and temple will sweat, but if the damaged nerve was connected to the submandibular gland, the lower jaw, and upper neck area would be affected. 

There has also been a documented case of a temporary Frey Syndrome following thyroidectomy, where a patient had sweating and flushing of one cheek shortly after the surgery. The symptoms, however, went away within a few hours. This was a result of disruption to nerves deep in the neck that then healed correctly.⁸ 

Preventive strategies

Because Frey Syndrome is a common occurrence following parotidectomy, there are a number of surgical techniques that can be employed by the operating surgeon to minimise risk of Frey Syndrome Following this surgery. This includes things like changing the thickness of skin flaps or putting a physical barrier between the sweat gland and salivary gland.³ However, it is unclear whether these techniques could be applied to other neck surgeries and whether it would be worthwhile, as Frey Syndrome is less common in these situations. To date, there aren’t any specific techniques used in neck surgeries other than parotidectomy that aim to decrease the risk of developing Frey Syndrome. 

The effects of Frey Syndrome can be alleviated with the typical treatments for excessive sweating, such as Botulinum Toxin A (BOTOX) injections into the affected area, which prevent the release of sweat from the sweat gland into the surface of the skin.³ This option is not permanent but may help to diminish the psychosocial impacts of this disorder and decrease overall suffering.

Summary

Frey Syndrome is a rare neurological disorder, which is a result of the improper healing of nerves following damage. It arises when the nerves that supply the salivary glands with electrical impulses to stimulate the release of saliva heal in a way that they now supply these impulses to the sweat glands. The result of this is excessive sweating and flushing in the region where the affected salivary gland is when eating or thinking about food. The damage to the nerves of the salivary glands is most commonly a consequence of parotidectomy, the operation to partially or fully remove the parotid salivary glands. However, nerve damage can occur following any surgery in the region. This includes surgeries like neck dissection (removal of the lymph nodes of the neck), removal of the thyroid, reconstructive surgery following trauma, facelift surgeries and more. Frey syndrome in these cases is caused in the exact same way as that seen after parotidectomy, however with the damage of different nerve branches, there may be a difference in the location of the presented symptoms. For example, following neck dissection, the most common area to excessively sweat is the areas under the jawline on the upper neck. 

In the case of parotidectomy, as Frey Syndrome is a common side effect, there have been some surgical techniques implemented that attempt to minimise the risk of developing it. However, the same cannot be said for the other surgeries mentioned, as Frey Syndrome is rarely seen following these surgeries. Instead, Frey Syndrome is treated as a disorder of excessive sweating and can be temporarily alleviated with BOTOX injections, to ease any psychosocial repercussions of the symptoms.

FAQs

Can you get Frey Syndrome without surgery?

Although Frey Syndrome is most commonly associated with surgeries such as parotidectomy, it can be caused by infection or trauma in the region. Anything that can cause nerve damage in the salivary glands has the potential to result in Frey Syndrome. 

Why do people get neck dissection?

Neck dissection is most commonly performed when there is a suspicion that cancer has spread to the neck. It serves many purposes, such as testing to see whether or not cancer has spread to the neck or to remove cancerous lymph nodes.

How many people have Frey Syndrome?

The exact number of people suffering with Frey Syndrome is unknown. The percentage of patients that develop Frey Syndrome after parotidectomy varies greatly from study to study from as little as 4% to 62%.³