The parotid gland is the most common site for salivary
tumours. Most tumours arise in the superficial lobe and
present as slow growing, painless swellings below the ear,
in front of the ear or in the upper aspect of the neck. Less
commonly, tumours may arise from the accessory lobe
and present as persistent swellings within the cheek.
Rarely, tumours may arise from the deep lobe of the gland
and Present parapharyngeal masses.
Symptoms
include difficulty in swallowing and snoring. Clinical
examination reveals a diffuse firm swelling in the soft
palate and tonsil.
Some 80–90 per cent of tumours of the parotid gland are
benign, the most common being pleomorphic adenoma.
Malignant salivary gland tumours are divided into two
distinct subgroups:
1
Low-grade
malignant
tumours,
e.g.
acinic
cell
carcinoma, are indistinguishable on clinical examination
from benign neoplasms.
2
High-grade
malignant
tumours
usually
present
as
rapidly growing, often painless swellings in and around
the parotid gland. The tumour presents as either a discrete
mass with infiltration into the overlying skin or a diffuse
but hard swelling of the gland with no discrete mass.
Presentation with advanced disease is common, and
cervical lymph node metastases may be present.
Investigations
•
CT and MRI scanning are the most useful imaging
techniques.
•
Fine-needle aspiration biopsy may aid in obtaining a
preoperative diagnosis.
•
open
surgical
biopsyis
contraindicated
unless
malignancy
is
suspected,
and
preoperative
histological diagnosis is required as a prelude to
radical parotidectomy.
All tumours of the superficial lobe of the parotid gland
should be managed by superficial parotidectomy. There is
no role for enucleation even if a benign lesion is
suspected. The aim of superficial parotidectomy is to
remove the tumour with a cuff of normal surrounding
tissue. The term ‘suprafacial parotidectomy’ has been
used as not all branches of the facial nerve need be
formally dissected, particularly if a tumour lies in the
lower pole of the parotid gland
Parotidectomy
Superficial parotidectomy
Superficial parotidectomy is the most common procedure
for parotid gland pathology.
Phases of operation.
1-Incision and development of a skin flap
The most commonly used incision is the ‘lazy S’ pre-
auricular– mastoid–cervical
2-Mobilisation of the gland
This phase of the dissection aims to free the posterior
margin of the gland, allowing identification of the facial
nerve.
dissection in the line of the facial nerve trunk. Use of a
facial nerve stimulator is optional.
Landmarks commonly used to aid identification of the
trunk of the facial nerve are: the inferior portion of the
cartilaginous canal. This is termed Conley’s pointer and
indicates the position of the facial nerve, which lies 1 cm
deep and inferior to its tip.
3-. Location of the facial nerve trunk
4-Dissection of the gland off the facial nerve
Once the facial nerve trunk is identified, further exposure
of the branch of the facial nerve can be achieved The
upper division divides into a temporal and a zygomatic
branch, and the lower division into mandibular and
cervical branches.
Closure
The patient is placed into a Trendelenburg position to
identify any residual bleeding vessels. A suction drain is
applied for a period of 24–48 hours, and the wound closed
in layers.
Radical parotidectomy
Radical parotidectomy is performed for patients in whom
there is clear histological evidence of a high-grade
malignant tumour, e.g. squamous cell carcinoma. Low-
grade malignant tumours can usually be managed by
standard superficial parotidectomy.
Radical parotidectomy involves removal of all parotid
gland tissue and elective sectioning of the facial nerve,
usually through the main trunk .
Complications of parotid gland surgery
Complications of parotid gland surgery include:
• haematoma formation;
• infection;
• temporary facial nerve weakness;
• transection of the facial nerve and permanent facial
weakness;
• sialocoele;
• facial numbness;
• permanent numbness of the ear lobe associated with
great auricular nerve transection;
• Frey’s syndrome.
Frey’s syndrome;
Frey’s syndrome (gustatory sweating) is now considered
an
inevitable
consequence
of
parotidectomy,
unless
preventative measures are taken . It results from damage
to the autonomic innervation of the salivary gland with
inappropriate
regeneration
of
parasympathetic
nerve
fibres that stimulate the sweat glands of the overlying
skin.
clinical features include;
sweating and erythema over the region of surgical
excision of the parotid gland as a consequence of
autonomic stimulation of salivation by the smell or taste
of food. The symptoms are entirely variable and are
clinically demonstrated by a starch iodine test. This
involves painting the affected area with iodine, which is
allowed to dry before applying dry starch, which turns
blue on exposure to iodine in the presence of sweat.
Sweating
is
stimulated
by
salivary
stimulation.
The
management of Frey’s syndrome involves the prevention
as well as the management of established symptoms.
Prevention;
There are a number of techniques described to prevent
Frey’s syndrome following parotidectomy. These include:
• sternomastoid muscle flap;
• temporalis fascial flap;
• insertion of artificial membranes between the skin and
the parotid bed.
All these methods place a barrier between the skin and the
parotid bed to minimise inappropriate regeneration of
autonomic nerve fibres.
Management of established Frey’s syndrome
Methods
of
managing
Frey’s
syndrome
include•
antiperspirants, usually containing aluminium chloride;
• denervation by tympanic neurectomy;
• the injection of botulinum toxin into the affected skin.
The last is the most effective and can be performed as an
outpatient.