Frey's Syndrome /
Gustatory Sweating
It is also known as Gustatory Hyper-hydrosis,
Auriculo-Temporal Syndrome
or Baillarger


Gustatory (Taste or the technical term, gustation; adj:
sweating was first described by Duphenix in
1757 in association with
parotid gland trauma, then by
Baillarger in 1853 and subsequently by Łucja Frey in 1923;
not only in association with
parotid gland trauma but
confined to the distribution of the
auriculo-temporal nerve.

Frey´s Syndrome (FS) is the phenomenon secondary to
gustatory stimulus, manifested by flushing and sweating of
parotid, frontal and sub-mandibular areas consequent to
trauma to the
parotid or another major salivary glands (ie
sub-mandibular or sub-lingual) often either after a
parotidectomy or excision of the sub-mandibular gland.

In other words,
FS is characterised by excessive sweating
of the forehead, upper lip, peri-oral region or sternum
subsequent to
gustatory stimuli.

Other regions can be affected in

These include the:

  • Occipital region
  • Cervical region
  • Ear region
  • Temporal hair region
Photo showing Gustatory Sweating (arrowed).  The Superficial Parotidectomy
scar can be seen.
The auriculo-temporal syndrome features facial flushing or sweating limited to the
distribution of the
auriculo-temporal nerve and may develop after trauma to the
parotid gland, in association with parotid neoplasms (benign / malignant cancers)
or following their
surgical removal.

FS is more commonly seen after:

  • Penetrating wound of the parotid region
  • Chronic infection of the parotid region
  • Parotitis
  • Parotid surgery
  • Jugulo-carotid lymph node dissection
  • Submandibular gland surgery
  • Carotid endarterectomy
  • Trauma of the auriculo-temporal nerve after forceps delivery
  • Mandibular & zygomatic fractures
  • TMJ surgery
  • Internal maxillary artery pseudoaneurysm
  • Chorda tympani injury
  • Cervico-thoracic sympathectomy
  • Tumour infiltration of the upper node of the sympathetic plexus
  • Diabetes mellitus
  • Herpes zoster
  • Platinum-induced neuropathy
  • CNS diseases (syringomyelia, CVA, encephalitis)
  • Loss of insulation twixt the post-ganglionic sympathetic & parasympathetic
    nerve sheaths within the auriculo-temporal nerve

is an unusual complication after sub-mandibular salivary gland excision and
neck dissections.  When reported in relation to neck dissection, it has been
associated with
‘radical’ neck dissections, particularly for thyroid cancer and has
tended to occur in the
sub-mandibular area on the upper skin flap.


FS has been reported in > 60% of patients but is usually symptomatic in < 10%
who seek treatment.


FS is related to aberrant regeneration of nerve fibres from the.  Hence, sweating
dermal flush occurs during salivary stimulation (ie eating or thinking of eating /

Parotid Gland.  FS is believed to be the result of mis-directed autonomic nerve
regeneration following injury to the
parotid region.  After injury, the sectioned post-
ganglionic secreto-motor para-sympathetic fibres (auriculo-temporal nerves)
which normally innervate the
parotid gland, become connected to sympathetic
receptors which innervate sweat glands.  Hence, stimuli that normally cause
salivation (aromatic foods, thinking about certain foods) simultaneously cause
pathologic sweating and flushing in the
pre-auricular area on the side of the nerve

Submandibular Gland.  The innervation of the sub-mandibular gland is similar to
that of the
parotid gland; the difference involves pre-ganglionic para-sympathetic
that originate in the superior salivatory nucleus and travel along the Facial
Nerve and the Chorda Tympani to the sub-mandibular ganglion.  Post-ganglionic
para-sympathetic fibres
originate in the sub-mandibular ganglion and travel to the
sub-mandibular gland.  Pre-ganglionic sympathetic fibres originate in the first and
second thoracic spinal nerves, synapse in the superior cervical ganglion with post-
ganglionic sympathetic fibres
and travel along the external carotid artery and the
facial artery to the sweat glands.

During surgical excision of the
sub-mandibular gland, aberrant post-ganglionic
para-sympathetic fibres
can subsequently innervate severed post-ganglionic
sympathetic fibres
, supplying the sweat glands in a misdirected pattern.  This
results in a
hyperhidrosis of the affected area ± concomitant erythema
(reddening) caused by
parasympathetic vascular effects at the site.

Other nerves might be involved such as the
facial nerve, the anterior & posterior
of the greater auricular nerve & the lesser occipital nerves served as
guiding structures for the regenerating
parasympathetic nerve fibres.  

FS does not cause significant physiological harm, profuse gustatory
flushing and sweating can cause social and psychological distress in some patients.

FS / Hyperhidrosis is diagnosed by history and examination but can be confirmed
with the
iodine and starch test (apply iodine solution to the affected area, let dry,
dust on corn starch: areas of sweating appear dark).

Testing is necessary only to confirm foci of sweating (as in
FS or to locate the
area needing surgical or
botulinum toxin treatment) or in a semi-quantitative way
when following the course of treatment.

Minor Starch-Iodine Test

This test entails ‘painting’ the affected side of the face with iodine and waiting for it
to dry.  The area is subsequently powdered with cornstarch which renders visible
the sweating reaction.  To elicit salivation / sweating, the patient is then asked to
chew a lemon slice for 5 minutes.  The appearance of black spots over the
starched field constitutes a positive result, generated by a chemical reaction
iodine, dissolved starch and sweat, confirming sudoresis (sweating)
secondary to
gustation.  The margins of the black spots are drawn with a ball-point

As alluded to earlier, the black spots can be used to pinpoint where to use the
Botox and gives a semi-quantitative recording of how the gustatory sweating is
improving (or not).

Minor Starch-Iodine Test  has drawbacks:
  • difficult to use in hair-bearing areas of the skin
  • does not allow evaluation of the severity of the gustatory sweating

Other methods have been tried but have not gained widespread usage.

•        Weighing filter paper
•        Thin facial tissue papers
Iodine paper histogram
•        1 step methods using dyes
•        impression materials using
silicone or polyvinyl
•        bio-sensoring methods with enzymatic electrodes
infra-red medical thermography
•        evaluation of evaporation
Photos showing the Minor Starch-Iodine Test & the Use (& Efficacy) of Botox to

In most cases,
FS patients do not complain of their symptoms and are often
treated effectively with topical anti-perspirant gels applied to the affected area.

However, when symptoms become bothersome, various prophylactic and
therapeutic surgical strategies have been proposed to minimise the incidence or
severity of
FS following parotidectomy.

These include:

  • Botox (patients who are unresponsive to topical therapy may want to consider
    a trial of botox before considering surgical options)
  • Topical anti-perspirant (20% aluminium chloride solution)
  • Application of an ointment containing an anti-cholinergic drug such as 3%
    scopolamine, 2% glycopyrolate or diphemanil methylsulphate
  • Topical application of α adrenoceptor agonist (clonidine)
  • Blockage of parasympathetic outflow by way of alcohol injection or 2%
    lignocaine injections at various sites such as the otic ganglion & the auriculo-
    temporal nerve

None of these approaches allows a definitive cure and relief is only temporary.

Botox appears to be the easiest and safest method that provides the longest
period of relief with the lowest morbidity & adverse incidents rates.

  • Radiation to the affected skin region causes skin atrophy and is a highly
    efficient methods in patients with FS.  However, this option is not used
    anymore because of the high risk of radiation-induced skin carcinoma.
  • Temporal Fascia grafting
  • Application of synthetic materials to the surgical field at the time of surgery
  • Ligature (transaction/resection) of the auriculo-temporal and chorda tympani
  • Tympanic neurectomy
  • Intra-cranial division of the 9th cranial nerve

However, none of these surgical procedures results in definitive cures because
anastomotic connections between the greater & lesser superficial petrosal nerves
allow aberrant regeneration pathways and none is without significant risk of major
Useful Websites:

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Useful Articles:

Arch Otolaryngol Head Neck Surg 1999.  Clinical Note.  Frey Syndrome -
Treatment With Temporoparietal Fascia Flap Interposition.

Current Opinion in Otolaryngology & Head and Neck Surgery 2000.  Management
options for gustatory sweating (Frey syndrome)

Clin Auton Res 2002.  Historical Note.  Understanding Gustatory Sweating.  What
have we learnt from Lucja Frey and her predecessors.

Clin Auton Res 2002.  Editorial.  Mechanism of gustatory flushing in Frey’s

Arch Facial Plast Surg 2003.  Use of AlloDerm Implant to Prevent Frey Syndrome
After Parotidectomy.

Arq Neuropsiquiatr 2003.  Botulinum Toxin for Treatment of Frey’s Syndrome.  
Report of 2 cases.

Med Oral Patol Oral Cir Bucal 2008.  Clinical results in the management of Frey’s
Syndrome with injections of Botulinum Toxin.

JADC 2009.  Management of Frey Syndrome Using Botulinum Neurotoxin - A Case

The Open Dermatology Journal 2009.  Hyperhidrosis - A Review of a Medical

BJOMS 2009.  Short communication.  An unusual cause of Frey syndrome.

J Oral Maxillofac Surg 2011.  Frey Syndrome — An Underreported Complication
to Closed Treatment of Mandibular Condyle Fracture. Case Report & Literature

Cochrane Collaboration 2012.  Interventions for the Treatment of Frey's Syndrome

JOMS 2012.  Gustatory Sweating in the Submandibular Region following Neck
Dissection. A Case with Thermographic Evaluation & Review of the Literature
Last Updated 16th January 2014