What is the auriculotemporal syndrome?
The auriculotemporal syndrome is characterised by sweating, flushing, and warming over the preauricular area (in front of the ear) and temporal areas (the region of the face behind the eyes) in response to the smell, taste or thought of food .
Lucja Frey, a Polish physician and neurologist, first described the auriculotemporal syndrome in 1923, leading to the alternative name, Frey syndrome . It is also known as gustatory hyperhidrosis, Baillarger syndrome, and Dupuy syndrome.
Who gets auriculotemporal syndrome?
The precise incidence of the auriculotemporal syndrome is unknown . It is probably underreported due to subclinical or minor symptoms .
The auriculotemporal syndrome most frequently occurs as a complication of surgical removal of the parotid gland (parotidectomy) with estimated rates of 4–96% [5,6,7]. Males and females are affected equally.
Infrequently, the auriculotemporal syndrome is observed in infants and children following forceps-assisted delivery . A rare familial, bilateral auriculotemporal syndrome without trauma has been reported .
What causes the auriculotemporal syndrome?
The cause of the syndrome involves aberrant regeneration of the auriculotemporal branch of the mandibular nerve following injury, infection, or surgery in the vicinity of the parotid gland (the large salivary glands in front of the ears) .
The auriculotemporal nerve ordinarily provides sympathetic innervation to the sweat glands and parasympathetic innervation to the salivary gland.
With trauma, the parasympathetic fibres may become misdirected and regenerate along the pathway of the sympathetic nerve establishing a connection with the sweat glands and blood vessels of the skin . Thus, instead of saliva production, sweating and flushing occur with a gustatory stimulus .
Damage to the ganglions within the cervical sympathetic chain may also cause auriculotemporal syndrome .
What are the clinical features of the auriculotemporal syndrome?
Symptoms are often apparent within 12 months of parotidectomy. However, delayed recognition is not unusual . Once symptoms commence, there is often a gradual increase in severity for several months, and they then remain relatively constant thereafter.
Symptoms are triggered by chewing (gustatory sweating) or the sight, smell, or thought of food. They include:
- Flushing, warmth, and excessive sweating (localised hyperhidrosis) of ipsilateral facial skin 
- A burning sensation, itching, or pain in the distribution of the auriculotemporal nerve .
Symptoms are variable in severity ranging from barely perceivable to rather troublesome; 15% of patients rate their symptoms as severe and are especially concerned by the excessive sweating.
What are the complications of the auriculotemporal syndrome?
The auriculotemporal syndrome is associated with significant psychosocial morbidity [1, 14]. See Psychosocial factors in dermatology.
How is the auriculotemporal syndrome diagnosed?
The diagnosis of the auriculotemporal syndrome is based on the recognition of the characteristic symptoms .
The Minor starch-iodine test can be used to confirm hyperhidrosis . Iodine solution is applied to the affected area, allowed to dry, and is followed by the application of starch. Subsequently, the patient is given a stimulus to promote salivation, often an acidic food. Marked discolouration in the affected region indicates disproportionate sweating.
What is the differential diagnosis for auriculotemporal syndrome?
Other conditions that may be considered in a patient with symptoms suggesting auriculotemporal syndrome include:
- Primary generalised hyperhidrosis
- Primary focal hyperhidrosis
- Facial herpes zoster
- Diabetic neuropathy (see Diabetic skin disease)
- Iatrogenic sympathectomy 
- Pancoast tumour (a type of lung cancer) 
- Food allergy (in an infant) [9,17].
What is the treatment for the auriculotemporal syndrome?
Treatment of auriculotemporal syndrome is targeted at symptom control . Patients with mild symptoms do not require treatment.
A Cochrane review was unable to establish the efficacy and safety of various treatments for the auriculotemporal syndrome, due to an absence of randomised control trials .
Pharmacological options to treat troublesome auriculotemporal syndrome include:
Surgical management is reserved for severe and refractory auriculotemporal syndrome and may involve:
- Intracranial glossopharyngeal nerve section
- Tympanic neurectomy
- Musculofascial flap interposition [1,26].
What is the outcome for the auriculotemporal syndrome?
The auriculotemporal syndrome tends to be benign in infants with spontaneous resolution occurring in the majority .
Spontaneous resolution occurs in 5% of adults with the auriculotemporal syndrome. The pharmacological treatments described above generally control symptoms short term. Repeated injections of botulinum toxin A are required every 4–6 months, or earlier if symptoms recur [22,28]. Rarely, refractory cases require surgical management .