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

Definition:

Gustatory (Taste or the technical term, gustation; adj:
gustatory)
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
FS.

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

FS
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.


Incidence:

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


Pathophysiology:

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

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 injury.


Submandibular Gland.  The innervation of the sub-
mandibular gland
is similar to that of the parotid gland; the
difference involves
pre-ganglionic para-sympathetic fibres
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 branches of the greater auricular
nerve
& the lesser occipital nerves served as guiding
structures for the regenerating
parasympathetic nerve
fibres
.  

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

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 between
iodine, dissolved starch and sweat,
confirming
sudoresis (sweating) secondary to gustation.  
The margins of the black spots are drawn with a ball-point
pen.

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).

The
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 Ameliorate FS
Treatment:

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 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 nerves.
  • 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 morbidity.
Useful Websites:

Health on the Net Foundation

Wikipedia

Emedicine.com


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 syndrome.

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 Report.

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

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
Review
Last Updated 11th November 2011