Parapharyngeal mass and its management
Dr. T. Balasubramanian M.S.
Synonyms: Parapharyngeal tumors, Parapharyngeal
Anatomy: The parapharyngeal space is a
potential deep neck space, is also known as pterygomaxillary
space, pharyngomaxillary space,or lateral pharyngeal space. It
is more or less shaped like an inverted pyramid with the base
pointing towards the skull base and the apex towards the hyoid
bone. Its boundaries are as follows:
Medial: It is
bounded by the naso and oropharynx
Anterolateral: Bounded by the
Posterolateral: Bounded by the deep lobe of
Posteromedial: Bounded by the retropharyngeal
This space is filled with loose connective tissue,
associated lymphatics, and nodes. The contents of the carotid
sheath may also be considered to be part of the parapharyngeal
For descriptive purposes this space can be
divided into a pre styloid and post styloid compartments. The
styloid process and styloid fascia is used to divide this
Prestyloid compartment: contains
2. inferior alveolar nerve
4. auriculotemporal nerve
This compartment is
related to the lateral wall of nasopharynx superiorly, and tonsillar
Poststyloid compartment contains:
Contents of carotid sheath - internal carotid artery, internal
jugular vein, and cranial nerves 9, 10 and 12.
3. Numerous lymph nodes
Figure showing parapharyngeal
Tumors involving parapharyngeal space produce
symptoms by exerting pressure on the near by structures. These
tumors are commonly benign, and symptoms caused may be subtle in
nature. Expansion of the mass occur along the plane of least
resistance - i.e. medially towards the tonsil and lateral pharyngeal
wall, and laterally between the tail of the parotid and the
submandibular glands, and posteriorly into the retromandibular
The diagnosis should be suspected when a mass is
encountered displacing the tonsil and lateral pharyngeal wall
towards the midline, or when a mass is encountered in the neck close
to the angle of the mandible. Bimanual palpation will help the
physician to recognise the involvement of parapharyngeal space by
Tumors of the parapharyngeal space that are palpable
in the neck would have passed through the stylomandibular tunnel
which is formed by the posterior aspect of the ascending ramus of
mandible and the ligament that extends from the tip of the styloid
process to the mandible (stylomandibular ligament). The
superior aspect of the tunnel is formed by the base of skull.
These tumors will be palpable as a retromandibular mass externally,
whereas internally they displace the medial wall of the pharynx and
tonsil to the midline intraorally.
showing stylomandibular tunnel
If the parapharyngeal mass
is dumb bell shaped it is invariably pleomorphic adenoma developed
from the deep lobe of the parotid gland.
symptoms: of parapharyngeal mass depends on the tissue of origin and
effect of the mass on surrounding structures.
Conductive hearing loss - may occur due to middle ear effusion if
eustachean tube is blocked
2. Involvement of vagus nerve will
cause paralysis of ipsilateral vocal cord
3. Involvement of
hypoglossal nerve may cause paralysis of ipsilateral portion of the
tongue, with deviation of the tongue towards the side of the
4. Involvement of cervical sympathetic chain can cause
5. If the oropharyngeal mass is big it can
cause rhinolalia clausa
6. Trismus is a common feature. It
is caused due to irritation of pterygoid muscles, or due to the
mechanical obstruction to the movement of mandible.
of the cranial nerves in the jugular foramen as they enter the
parapharyngeal space results in jugular foramen syndrome of
otherwise known as Vernet's
Parapharyngeal mass seen intraorally
involving parapharyngeal space: Include salivary gland
neoplasms, neurogenic tumors, and metastatic deposits from primay
elsewhere in the body. The neurogenic tumors include
neurofibroma or paragangliomas. Salivary gland tumors may
arise from the deep lobe of the parotid gland (commonly pleomorphic
adenoma). Occasionally lipomas, rhabdomyomas and meningiomas
may also arise from this area. The malignant counter part of
these benign conditions can also occur in this area.
Metastatic involvement of parapharyngeal lymphatics may occur
from nasopharyneal carcinoma.
Paragangliomas: arise from the paraganglionic bodies
of the autonomic nervous system. These cells are
neuroectodermal in origin. Microscopically, it contains
granular cells containing catecholamines. These tumors are
well encapsulated, brownish colored with firm consistency.
Microscopically the cells demonstrate Zellballen appearance.
It has a highly vascular stroma.
showing Zellballen arrangement of cells
paragangliomas rarely secrete catecholamines. Familial
paragangliomas are notorious in that they secrete catecholamines,
and the patients manifest with fluctuating hypertension. These
patients also have multiple unrecognised lesions.
paragangliomas are named according to their site of origin.
Paragangliomas arising from carotid body between the internal and
external carotid arteries are known as carotid
paragangliomas. Some 3% of paragangliomas arise from the vagus
nerve. These are known as vagal paraganglia. The most
common presenting symptom of vagal paraganglia is hoarsenss of voice
due to vocal cord palsy, and aspiration of fluids due to sensory and
motor deficts in the throat. The vagal paragangliomas commonly
arise from the superior vagal ganglion (also known as jugular
ganglion). These tumors are dumb bell shaped with intracranial
and extra cranial components. In some patients it may not be
possible to identify the source as vagal ganglion.
Carotid paragangliomas are also known as
chemodectomas. This is nothing but neoplastic degeneration of
the carotid body. The most common presenting feature of
chemodectoma is a mass in the neck located at the bifurcation of
carotid artery. Large lesions may give rise to pressure
symptoms like dysphasia, cough and hoarseness of voice.
Clincally this mass can be differentiated from enlarged lymph node
by virtue of the fact that it is mobile in the lateral direction and
not mobile in the cephalocaudal direction. Carotid pulsations
could be transmitted through this mass. Angiogram or contrast
CT will clinch the diagnosis
Schwannoma: is always solitary
in nature and is almost never associated with Von Recklinghausen's
disease. The individual nerve fibers actually do not pass
through the mass but is draped over its surface. It is hence
possible to dissect out the mass without damaging the nerve.
Pain and neurologic dysfunction are very rare, but paraesthesias are
common. Histology demonstrates degenerative / cystic
Neurofibroma: Also arises from schwann
cells. It is not encapsulated, nerve fibres are incorporated
inside the mass unlike schwannomas. Cystic and degenerative
elements are uncommon. Hence it is almost impossible to
conserve the nerve while excising a neurofibroma. Von
Recklinghausen's disease is associated with this entity.
Malignant transformation is also common.
showing the neck mass
procedures: CT scan should be performed routinely in all these
patients. Contrast enhancement is also useful. These
scans helps in precise localisation of the mass, and also its
extent. With a CT scan it is possible to localise the
lesion to the pre styloid or post styloid compartments.
Displacement of parapharyngeal fat with tumor helps to define the
margins of the tumor.
Carotid angiogram is a must for
tumors arising from the post styloid compartment to differentiate
chemodectomas. Chemodectomas can be identified in a carotid
angiogram by the presence of the classic separation f internal and
external carotid arteries. This is known as Lyre's
MRI scans help in better delineation of soft tissue
masses. Its relationship with the carotids can be clearly seen
Fine needle aspiration cytology: is
helpful in preoperative evaluation of the mass lesion. It can
easily be performed if the tumor is palpable in the retromandibular
or submandibular areas. Transoral aspiration can also be
attempted in patients in whom mass presents intraorally.
Treatment: Surgical excision is the ideal
management for all benign parapharyngeal tumors. The goal of
parapharyngeal surgery is to provide adequate tumor visualization to
achieve complete tumor removal, to preserve the surrounding nerves
and vessels and control of any hemorrhage. Many
surgical approaches have been reported in the
literature. Overall, transcervical and
transparotid approach are the two main approaches.
Mandibulotomy can be performed to improve
Transparotid approach: is commonly used for
deep lobe parotid tumors. It starts with a
superficial parotidectomy with facial nerve
preservation. The facial nerve is then separated
from the deep lobe of the parotid gland and retracted.
The dissection continued posteriorly and inferiorly around
the mandible. Mandibulotomy can be performed if
necessary to improve exposure. Bass recommended
placing the mandibulotomy site posterior to the entrance of the
inferior alveolar nerve in the body of the mandible.
Or the styloid process can be removed with dislocation of the
mandible anteriorly to allow blunt dissection.
Transcervical approach: Transcervical approach starts with a transverse
incision at the level of the hyoid bone. The
submandibular gland is often removed or retracted
anteriorly. An incision through the fascia deep
to the submandibular space allowed for entry into the parapharyngeal
space and blunt dissection of the tumor. Many
modifications have reported. Some surgeons divide
the digastric, stylohyoid, and styloglossus muscles from the hyoid bone to
improve exposure. The styloid process and the
stylomandibular ligament can also be divided to elevate the mandible
anteriorly to improve access. This approach
frequently involves blind finger dissection in the parapharyngeal
space and does not provide enough exposure for larger benign lesions
extending cranially or those with a more aggressive growth
pattern. This can be combine with mandibulotomy for
better exposure. The key to the site of mandibulotomy is to
avoid injury to the inferior alveolar nerve while providing access
to parapharyngeal space.
showing transcervical approach
transpharyngeal approach: is used to excise large and highly
vascular tumors. In this approach mandibulotomy is performed
anteriorly and incision is made along the floor of the mouth up to
the anterior pillar. The advantage of anterior mandibulotomy
is the ease with which mandible can be swung laterally. It is
thus known as mandibular swing approach.
showing mandibular swing approach
Inoperable cases can be
subjected to irradiation. But it gives very poor
Points to remember:
Pleomorphic adenoma is
the most common tumor involving the prestyloid
Neurogenic tumors commonly involve the post
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