Introduction

Frey’s Syndrome is a condition which usually occurs after surgery or injury to one of your salivary glands.¹ It is caused due to abnormal regeneration of the auriculotemporal branch of the mandibular nerve, which connects to sweat glands, resulting in inappropriate sweating when eating. 

It is a condition which is well known to head and neck surgeons, which means it is usually diagnosed quickly.² Treatment is not always needed, but early diagnosis can lead to speedy treatment where appropriate, which can help to improve the symptoms.³

What causes Frey’s Syndrome?

Frey’s Syndrome is a common side effect of having parotidectomy surgery, or if the area around a parotid gland has been damaged.¹

Parotidectomy

The parotid glands lie just in front of the ears and are the glands in the body which produce saliva.⁴ If there is a problem with one gland, a parotidectomy may be performed, ie the affected gland is removed.⁴

In a parotidectomy, the patient is placed under general anaesthesia for the surgery.⁴ The surgeon performs a cut from the front of the ear and either goes down to the neck or curves around the back of the ear.⁴ This allows the removal of the gland, after which the cut is stitched back.⁴

After surgery, some nerve cells can grow back in the wrong place, causing a link between the parotid gland and the sweat glands. This is what brings on the symptoms of Frey’s Syndrome.¹

Other procedures that can cause Frey’s Syndrome

Other procedures can also lead to Frey’s Syndrome. These include:^1,5,6

• Neck dissection ( the lymph nodes are removed from the neck, usually due to cancer risk)
• Facelifts (an operation where the skin of the face is pulled up and backwards with the aim to make the face look smoother and tighter)
• Injury to the area around the parotid gland, causing damage to the nerves 

Signs and symptoms

Frey’s Syndrome (sometimes called gustatory sweating or auriculotemporal syndrome³ causes several symptoms. These are listed below.

The symptoms do not usually cause problems as they are typically mild.¹ However, some cases of Frey’s Syndrome can induce severe symptoms, especially due to sweating triggered by eating. This can result in feelings of discomfort, stress, social anxiety, and pain.¹

Sweating

The most common symptom of Frey’s Syndrome is sweating. This happens when the patient eats or when they think of food.¹ The sweating only occurs around the face, usually behind the ear, on the cheek or at the temple.¹

Burning sensation

People with Frey’s Syndrome can also experience a feeling of burning around the area that has been affected (usually around the ear, including the respective temple and cheek).¹

Pain

Patients who have Frey’s Syndrome sometimes report pain around the temple, ear or same side of the face.¹

Itching

Frey’s Syndrome can also cause itching of the affected area of the temple, cheek and ear.¹

Flushing 

Flushing, or redness/blushing, can be another symptom of Frey’s Syndrome.² This also occurs around the parotid gland and affects the temple, cheek or ear.

Who is at risk of Frey Syndrome?

Certain things can increase the possibilities of developing Frey’s Syndrome. These are discussed in this section.

Type of lump removed

Parotidectomies are usually performed on people with a lump at their parotid gland.⁷ If the lump on the gland is benign (not harmful), it is more likely that the patient will develop Frey’s Syndrome than if the lump is considered malignant.⁷

More than one surgery

If the patient needs to have more than one operation on the affected parotid gland (eg, in cases where the lump was not properly removed during the first surgery), the chance of developing Frey’s Syndrome is higher.⁷

Diagnosis 

Frey’s Syndrome can be diagnosed clinically and confirmed by a specific test called the minor starch-iodine test. 

Medical history

The healthcare professional will ask questions about the symptoms, surgeries or injuries the patient had in the past.¹

Minor starch-iodine test

This is a test that is used to confirm Frey’s Syndrome diagnosis.¹

First, your doctor will spread iodine on the skin of the affected area and wait for it to dry.⁸ Once the iodine has dried, starch powder will be added to the area.⁸ The patient is then given something to eat, which will make them salivate, like for example, a slice of lemon.⁸

The doctor will take several photos to see if a reaction occurs. In Frey’s Syndrome, the patient’s sweat will cause the starch powder to turn blue.⁸ This proves the diagnosis and demonstrates which areas of the neck, head or face are affected.⁸

Treatment

Some people with Frey’s Syndrome do not need any treatment.¹ However, if necessary, some medications can provide comfort to the patient.

Botulinum toxin injections

Frey’s Syndrome has been successfully treated in some patients with botulinum toxin injections.³

Botulinum toxin is made from certain kinds of bacteria and it is used to prevent the nerve from affecting the glands.⁹ It can also paralyse the sweat glands so that they do not produce sweat.¹⁰

Most patients notice improvement with this treatment, and it usually provides relief for a long period.³ If the symptoms return, the injections can be repeated.³

Anticholinergics

People with Frey’s Syndrome sometimes use anticholinergic drugs on the skin to improve their symptoms.¹¹

Anticholinergics prevent the production of a chemical called acetylcholine, which prompts the sweat glands to secrete sweat.¹² Therefore, by using anticholinergics, the sweating in Frey’s Syndrome can be reduced.

Antiperspirants 

Antiperspirants assist in preventing sweating. However, half of the patients who use antiperspirants report no symptom improvement. The patients who found antiperspirants helpful noticed improvement, which lasted less than 24 hours.¹⁰

Summary

Frey’s Syndrome is a condition caused by surgery (usually after parotidectomy or others) or injury to the salivary glands, especially the parotid gland, due to abnormal nerve regeneration to the sweat glands. It results in excessive sweating in response to eating. The symptoms include sweating, burning, pain, itching and flushing of the face on the affected ear, cheek and temple. Diagnosis is made clinically and confirmed with the minor starch-iodine test. Treatment is often unnecessary but can involve botulinum toxin injections, anticholinergic or antiperspirant medication. Most cases are mild but severe cases are not uncommon and can affect the patient’s quality of life.