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DYSPHAGIA AND ASPIRATION
Table 58.1 Causes of dysphagia and aspiration
Congenital
Cleft lip and palate
Cerebral palsy
Vascular rings
Oesophageal atresia
Laryngeal cleft
Tracheo-oesophageal stula
Infection
Pharyngitis
Deep neck space infection
Inammatory
Laryngopharyngeal reux
Gastro-oesophageal reux
Eosinophilic oesophagitis
Patterson-Brown-Kelly syndrome
Scleroderma
Systemic lupus erythematosus
Sjögren’s syndrome
Traumatic
Foreign body
Food bolus
Caustic burns
Head and neck trauma
Spinal trauma
Oesophageal motility disorder
Achalasia
Oesophageal spasm
Presbydysphagia
Neoplastic
Benign tumours
Malignant tumours
Neurological
Cerebrovascular accident
Parkinson’s disease
Multiple sclerosis
Myasthenia gravis
Vocal cord palsy
Miscellaneous
Chemotherapy-radiotherapy
Pharyngeal pouch
Globus pharyngeus
Barium swallow or water-soluble contrast swallow testing provides a useful outline of the
pharyngeal and oesophageal anatomy and is particularly useful for assessment of pharyngeal
pouches and dysmotility.
Where concern about a malignant cause exists, cross-sectional imaging and examination of
the upper aerodigestive tract under general anaesthesia are indicated.
Swallowing Rehabilitation
Successful rehabilitation of patients with dysphagia depends upon accurate diagnosis. In
recent years, dysphagia rehabilitation has broadened from an almost exclusive use of peripheral muscle strengthening to incorporate techniques designed to maximize central control.
Oral Motor Exercises
Originally, oral motor exercises were developed for improving articulatory precision related
to speech. Subsequently, these exercises were logically expanded and transferred to swallowing rehabilitation, with the goal of improving oral-phase movements and facilitating tonguedriving forces involved in the pharyngeal phase of swallowing.
Effortful Swallow
e instructions for the eortful swallow technique are simply to ‘swallow hard.’ Because
increased eort resulted in increased pressure on the bolus, this technique was routinely
applied to reduce pharyngeal residue in patients with pharyngeal motility disorders.
However, a potential complication of the eortful swallow is decreased anterior hyoid movement during swallowing.
Mendelsohn Manoeuvre
Following initiation of swallowing, peak hyolaryngeal excursion is maintained for several seconds before relaxing and completing the swallow. e presumed benet of the
Mendelsohn manoeuvre is prolonged suprahyoid contraction, which results in prolonged
upper oesophageal sphincter (UOS) opening for improved bolus ow into the oesophagus.
298 Head and Neck
DYSPHAGIA AND ASPIRATION
Masako Manoeuvre
In the Masako manoeuvre, the patient is instructed to protrude their tongue and gently hold
it between their incisors. is can be used specically to overcome the signicantly increased
anterior bulge of the posterior pharyngeal wall seen in patients who have undergone base of
tongue resection.
Head-Lift (Shaker) Exercise
e head-li exercise strengthens the oor of the mouth. e individual lies on their back
and raises their head until they can see their feet. Strengthening the muscles of the oor of
the mouth that are involved in both the oral and pharyngeal phases of swallowing increases
laryngeal excursion, increases the width and duration of UOS opening, and consequently
decreases UOS intrabolus pressure in healthy elderly individuals.
Expiratory Muscle Strengthening
Expiratory muscle strength training (EMST) is quickly emerging into more widespread clinical practice and is a promising approach for managing pharyngeal swallowing impairment
and airway protection. EMST is designed to strengthen the contraction of the expiratory
musculature by directing expiratory airow through a one-way, spring-loaded valve that
remains open in the presence of positive airow.
Maximising Central Control
Increased understanding of the neural control of swallowing—particularly the role of the
cerebrum in swallowing neural networks—has brought about a signicant paradigm expansion in the collective approach to swallowing impairment.
Skill Training
Relearning or modifying the complex sequence of swallowing events at the level of central
control is gaining increasing recognition as a type of skill-based training for use aer neurological impairment. To further strengthen this approach, the use of biofeedback from electromyography and manometry is being explored.
Stimulation
e development of brain imaging and stimulation techniques has signicantly expanded
our understanding of the neurophysiological mechanisms of swallowing. Approaches like
transcranial magnetic stimulation and direct current stimulation, designed to improve swallowing function through extrinsic modulation of central neuronal circuits involved in swallowing motor control, are being explored.
Chronic Aspiration
Prevention of aspiration occurs primarily through reex laryngeal closure, laryngeal elevation, and cessation of breathing during swallowing, and any aspirated contents are expelled
through coughing. A certain amount of aspiration is normal in humans, especially during
sleep, and it is tolerated without complications in healthy subjects with normal tracheobronchial ciliary function and normal immunology.
e response to even small quantities of aspiration will depend on the pH of the aspirate, the
microorganisms present, and the person’s pulmonary and immunological status. Aspiration
may lead to cough or, in some cases, life-threatening pulmonary complications. In cases
where the cough reex is reduced or absent, silent aspiration may occur. Acute, severe aspiration of a large bolus may cause airway obstruction and may prove fatal, whereas chronic,
small-volume aspiration may risk pneumonia or respiratory failure through chronic pulmonary emphysematous disease or bronchiectasis.
Head and Neck 299
DYSPHAGIA AND ASPIRATION
Principles of Management
e management aims are to protect the airway, to avoid life-threatening respiratory complications, and to achieve adequate nutrition, while also considering the psychological and
social aspects of food and feeding.
Surgery for Aspiration
Cricopharyngeal Myotomy
If pooling of secretions in the hypopharynx due to a hypertonic or uncoordinated cricopharyngeal sphincter, myotomy may help. Trial of medical myotomy using botulinum toxin can
be utilized before considering either transoral laser myotomy or an external approach.
Laryngeal Incompetence
Vocal fold medialisation can help to reduce chronic aspiration if vocal fold immobility and
positioning are contributory. Injection thyroplasty can be used as a trial before considering
a permanent thyroplasty technique.
Glottic closure techniques for aspiration have been described but are not commonly used.
ey are prone to breakdown and render patients dependent upon tracheostomies. Many
surgeons would advise narrow eld laryngectomy over these techniques.
Pharyngeal Pouch
A pharyngeal pouch (Zenker’s diverticulum) is a posterior pulsion diverticulum occurring in
a natural weakness (Killian’s dehiscence) between the bres of the thyropharyngeus and cricopharyngeus. It is associated with an oesophageal motility disorder in the majority of cases.
e symptomatic patient complains of dysphagia, regurgitation of food, coughing, aspiration or repeated chest infections. Treatment is indicated when symptoms aect quality of life
or pose a risk to the patient’s health.
Endoscopic techniques transect the diverticulo-oesophageal wall so that material does not
collect in the pouch. is transection also divides the cricopharyngeus and some upper
oesophageal muscle bres, and it quite neatly performs a synchronous myotomy. Division
of this dividing wall has evolved from using electrocoagulation, the CO2 laser, and, more
recently, endoscopic stapling devices. Unfortunately, the endoscopic approach is not always
feasible if there is poor access, and it is not always suitable for very small or very large
pouches; furthermore, there is still a small incidence of post-operative leaks with the risk of
mediastinitis. In some cases, it is necessary to perform an external approach diverticulectomy combined with a cricopharyngeal myotomy. is does, however, mean a longer hospital
stay and increased morbidity.
Laryngeal Suspension
In severe cases of aspiration where there is reduced laryngeal elevation, excessive pooling
of hypopharyngeal secretions, and reduced laryngeal sensation, or severely discoordinated
swallowing, the aspiration poses a signicant risk to life. If there is also limited likelihood of
recovery of swallow function, yet life expectancy is still reasonable, then the safest option is
to consider a narrow-eld laryngectomy.
ere are, however, some intermediate measures to consider before taking such a drastic
step. Laryngeal suspension techniques aim to elevate the larynx away from hypopharyngeal
secretions and also to pull open the upper oesophageal inlet.
Laryngectomy
A narrow-eld laryngectomy removes the laryngeal skeleton but spares the hyoid, the
strap muscles, and the hypopharyngeal mucosa, allowing for a multilayer closure with
reduced incidence of a stula. Preservation of pharyngeal mucosa also means that pharyngeal closure can be achieved using a linear stapling device and feeding can commence
within 5–7 days.
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SALIVARY GLAND TUMOURS
Discussion
e ideal surgical procedure for chronic aspiration would be simple, associated with few
complications, allow speech and swallowing, and be easily reversible without long-term
sequelae.
e majority of patients with a reversible neurological decit tend to show recovery within a
few months, and it is the practice in most units to manage these patients with tracheostomies
and feeding tubes, although this may be far from ideal. ere are therefore very few indications for reversible procedures. Dysphagia with mild aspiration due to dysfunction of the
cricopharyngeus muscle, weakness of the hemilarynx, or reduced pharyngeal constrictor
activity can usually be managed with a cricopharyngeal myotomy or vocal cord medialisation with or without excision of the redundant pharyngeal mucosa. Laryngeal or laryngohyoid suspension may be considered in more severe cases.
e dicult decision is with patients who are not going to recover a safe swallow or who
are experiencing either a neurological condition that is progressive or severe scarring and
contracture related to radiotherapy treatment. Supportive procedures described above may
be helpful for a while, but there will come a time when a laryngectomy may become the procedure of choice. It provides a denitive separation of the respiratory and digestive tracts.
Feeding tubes and tracheostomies are avoided and depending on residual dexterity and neurological function surgical voice restoration may be possible.
Further Reading
1. Ludlow CL. Central nervous system control of the laryngeal muscles in humans. Respir
Physiol Neurobiol 2005; 147(2–3): 205–222.
2. O’Keee ST. Use of modied diets to prevent aspiration in oropharyngeal dysphagia:
is current practice justied? BMC Geriatr 2018; 18: 167.
3. Katoh M, Ueha R, Sato T, Sugasawa S, Goto T, Yamauchi A, Yamasoba T. Choice of
aspiration prevention surgery for patients with neuromuscular disorders: report of three
cases. Front Surg 2019; 6: 66.
59. SALIVARY GLAND TUMOURS
Incidence
e incidence of salivary gland cancer (SGC) is 7–12 per 1,000,000. Benign salivary
•
neoplasms are more common, occurring in up to 6 per 100,000.
Most tumours (80%) arise in the parotid glands, of which 30% are malignant, and
•
10% arise in the submandibular glands, 40% being malignant. Less than 1% occur in
the sublingual and minor salivary glands (MiSG), where the majority (70–90%) are
malignant.
Benign tumours aect all age groups, with a peak incidence in the sixth decade.
•
Malignancy is relatively more likely in younger patients.
•
Risk Factors
Salivary malignancy increases with exposure to environmental factors, low-dose ion-
•
izing radiation, and aatoxins.
Smoking is related to development of Warthin’s tumours.
•
Head and Neck 301
SALIVARY GLAND TUMOURS
Clinical Presentation
Most parotid and submandibular gland tumours are slow-growing and asymptomatic. e
patient eventually becomes aware of a rm mass. A small number of tumours cause discomfort by obstructing salivary ow. Deep lobe parotid tumours may be impalpable clinically,
but they may displace the tonsil and palate medially, causing stertor, sleep disordered breathing, altered voice, and Eustachian tube dysfunction.
MiSG are found throughout the entire upper aerodigestive tract and the signs and symptoms
of MiSG tumours depend upon the anatomical site involved. e most common sites are the
oral cavity/oropharynx, and the tumours oen present as rm submucosal swellings.
e following symptoms and signs suggest the tumour may be malignant:
Pain
•
Paraesthesia
•
Rapid growth
•
Facial/other nerve palsy
•
Skin involvement
•
Fixity
•
Irregularity
•
Ulceration
•
Associated lymphadenopathy
•
Investigation
Imaging
Image guidance facilitates ne-needle aspiration cytology (FNAC) or core biopsy, and
•
it increases the ‘hit rate’.
Imaging provides complimentary diagnostic information.
•
Imaging assists with diagnosis and in evaluating the urgency of resection.
•
Imaging aids staging of tumour.
•
Ultrasound is usually adequate for most lesions.
•
Consider cross-sectional imaging for large tumours (>3 cm), deep lobe/parapharyn-
•
geal space involvement, or suspicion of malignancy.
MRI is generally preferred due to better denition of tumour–normal salivary gland
•
interface, and it is not aected by dental artefact.
Imaging features that suggest malignancy include an irregular capsule, extracapsular
•
invasion, hypervascularity, and features consistent with necrosis.
FNAC and Core Biopsy
Malignant tumours must be detected and accurately characterized pre-operatively
•
wherever possible, as the staging, workup, and surgery may dier.
FNAC has an accuracy for the diagnosis of benign lesions of around 95%, and an
•
accuracy of 80% for malignancy.
Core biopsy can improve diagnostic accuracy further or may be used as a second-line
•
method if FNAC suggests possible malignancy. eoretical risk of tumour seeding has
been suggested.
Even if FNAC suggests benign disease, removal of the tumour for further histopathol-
•
ogy analysis remains mandatory.
Common Benign Tumours
Pleomorphic Adenomas (PAs)
PAs are derived from intercalated duct/myoepithelial cells. Most parotid PAs are within the
supercial lobe, but a small proportion arise in or involve the deep lobe. Most patients with
a PA should be advised to have surgery on the basis of denitive histology, the tumour’s
302 Head and Neck
SALIVARY GLAND TUMOURS
continued growth if le untreated, and the small chance of malignant transformation (1–5%
per decade). e mucoid nature and exceptionally thin/absent capsule make PAs extremely
fragile, and they can rupture during surgery, inevitably seeding the operative eld and
increasing the risk of recurrence.
Choice of Operation
Controversy exists about the extent of parotidectomy—total supercial parotidec-
•
tomy, partial supercial parotidectomy (the tumour and a cu of normal tissue), or
extracapsular dissection.
Despite a total or partial supercial parotidectomy, there is oen one margin adjacent
•
to the facial nerve (FN) that would be exposed anyway. On this basis, a careful extracapsular dissection may be justied.
Deep lobe tumours generally require total conservative parotidectomy.
•
Parapha ryngeal spa ce PA s can be excised v ia a cervicopa rotid or transma ndibulotomy/
•
transpharyngeal approach. Transoral robotic surgery oers an alternative.
PAs of the submandibular gland are treated with extracapsular excision of the gland
•
(higher rate of marginal mandibular injury).
PAs of the MiSG are treated with wide local excision.
•
Recurrence of PAs
Most recurrences are multicentric (overall recurrence rate up to 2%).
•
Recurrences typically occur a decade aer the original surgery.
•
It is important to repeat imaging and FNAC, because there is a higher rate of malig-
•
nant change within recurrent tumours (3%).
In general, all remaining parotid tissue should be resected. If there is signicant risk
•
to FN, limited surgery may be considered.
Recurrent PA of submandibular gland should be treated with selective neck dissection
•
(Levels I–III), which will remove the tissue that harbours recurrent disease.
Radiotherapy is eective in reducing further recurrence of PA, and it should be con-
•
sidered following revision surgery.
Warthin’s Tumour (Adenolymphoma)
Warthin’s tumours are thought to arise from salivary duct inclusions within intraparotid
lymph nodes. ey account for 20% of benign parotid tumours and are frequently bilateral. Malignant change is exceedingly rare. FNAC and imaging can provide a diagnosis. e
tumour can be managed either conservatively with observation, or with surgery.
Surgery: Parotid Gland
Management of Complications
Facial weakness: Facial nerve injury is a signicant morbidity. Risk of facial nerve
•
damage is related to the extent of the disease, type of resection, and surgical experience. Neuropraxia usually recovers within 4–6 weeks, and more severe injuries, in
6–12 months. Risk of permanent facial palsy is 1–2%.
Sensory loss: Sensory loss in the distribution of the greater auricular nerve (GAN) is
•
unavoidable. Some improvement is seen 12 months post-operatively.
Cosmetic defects: e incision rarely causes huge concern. Loss of bulk behind the
•
mandibular ramus may be visible and can be mitigated with fat transfer if necessary.
Frey’s syndrome: Gustatory sweating/ushing may be socially embarrassing, but it aects
•
only a minority of patients. Conservative surgery may decrease the risk. Application of an
antiperspirant or subdermal botulinum toxin injection may be necessary.
Salivary stula or collection (sialocele): Sialocele occurs a few days aer surgery and
•
can be tense and painful. Collections are aspirated, and aspiration may need repeating.
Head and Neck 303
SALIVARY GLAND TUMOURS
Antibiotics may be considered to prevent/treat secondary infection. Hyoscine patches
or botulinum toxin injection can reduce saliva production. Both leaks and collections
almost always settle.
Stump neuroma of GAN: When the GAN is cut, the stump can form a painful neu-
•
roma, oen some time aer surgery. It can be managed by simple local excision and
burying of the fresh nerve end in the muscle.
First bite syndrome: Rarely, intense pain occurs in the parotid gland when the patient is
•
just about to eat, but the pain quickly passes. is syndrome is generally self-limiting.
Treatment with botulinum toxin or antineuropathic agents can be eective.
Operative Procedure
e fundamental principle of a parotidectomy is exposure of the FN and then removal of the
gland and diseased tissue from around it. e branching pattern of the FN can vary, and the
nerve may be displaced from its normal position by tumour. e FN monitor can aid identication of the nerve and manipulation of the tissues around it. e FN trunk can be identied
by several anatomical landmarks:
Tragal pointer: inferior portion of cartilaginous external auditory canal. FN lies 1 cm
•
deep and inferior to its tip.
Tympanomastoid suture: FN lies immediately deep and inferior to this at its point of
•
exit from the skull.
Posterior belly of the digastric muscle: FN leaves the skull immediately anterior to the
•
attachment of this muscle.
Styloid process: lies deep to the exit of the FN from the skull, so care must be taken
•
using this landmark.
Retrograde dissection: of terminal FN branches.
•
Surgery: Submandibular Gland
Unlike the parotid, where only a part of the gland is removed, total resection of the submandibular gland is always indicated for tumours of the submandibular gland.
Informed Consent
Marginal mandibular nerve weakness: weakness of the angle of the mouth, most
•
noticeable on smiling/puckering the lips. Permanent weakness 2–3%.
Lingual and hypoglossal nerve damage: is unusual but possible (<1%). Tongue motor
•
dysfunction impairs articulation and mastication, but rapidly compensates.
Malignant Tumours
Introduction
SGC is rare, and it is complex owing to its heterogeneity, both in histological appearance
and in clinical behaviour. e vast majority of salivary gland malignancies are epithelial
tumours (> 80%), the remainder being mesenchymal or haematolymphoid tumours. Patients
are staged using the TNM system (See Staging of Head and Neck Cancer). MiSG cancers are
staged as per the anatomic site they originate in.
Common Malignant Tumours
Acinic cell carcinoma (AcCC): 3% of all SGC, up to 17% in parotid gland. Considered
•
low grade, with good survival. Long natural history, long-term follow-up required.
Mucoepidermoid carcinoma (MEC): high incidence in MiSG. Prognosis mainly inu-
•
enced by clinical stage, histological grade, and surgical margins. Low-grade tumours
have excellent prognosis.
Adenoid cystic carcinoma (AdCC): mainly occurs in MiSG, lesser incidence in major
•
salivary glands. Oen diagnosed at an advanced stage, and complete excision may
not be possible due to complex anatomical location. Propensity for perineural
304 Head and Neck
SALIVARY GLAND TUMOURS
extension and neuronal skip lesions. Tendency for local recurrence and distant metastases (oen pulmonary) despite aggressive treatment.
Polymorphous adenocarcinoma (PAC): 75% arise from MiSG, frequently in palate.
•
Local recurrence may occur even with negative margins and can occur very late in
follow-up.
Carcinoma ex pleomorphic adenoma: 25% of salivary gland cancers. Tend to arise in
•
major glands. Carry a poor prognosis.
Treatment
Parotid, Submandibular, and Sublingual Glands
Surgery is the preferred treatment of parotid and submandibular gland cancers.
•
e extent of surgery depends on the size of the lesion, its relationship to FN, and
•
extraparotid tissue invasion.
e majority of parotid cancers (80%) are located in the supercial parotid lobe, with
•
a normal functioning FN. A standard supercial partial parotidectomy would be
adequate for the majority of small cancers.
Total parotidectomy may be advocated in locally advanced, high-grade tumours,
•
because intraparotid lymph nodes that may harbour metastatic disease may be
overlooked.
FN-preserving parotidectomy, allowing for microscopic remnant disease if unavoid-
•
able, followed by radiotherapy in a patient with a pre-operatively functioning FN, is
considered the standard of care.
Gross tumour involvement of the FN requires nerve resection followed by immediate
•
cable graing. GAN is usually adequate for this purpose.
For submandibular gland malignancy, the minimally required surgery is a gland
•
resection within a Level I–III neck dissection.
e N+ neck requires surgery (Levels I–V). N0 neck should be treated electively surgi-
•
cally or by radiotherapy, depending on the risk factors (tumour >4 cm, histological
high-grade).
Post-operative radiotherapy in advanced disease or in the presence of poor prognostic
•
features improves locoregional control and survival.
Radiotherapy can be used in unresectable disease or in patients who are not surgical
•
candidates. Chemotherapy remains of palliative use in salivary gland cancer.
MiSG Cancer
Treatment of MiSG cancer is wide local resection with clear margins. Radiotherapy
•
to the primary site is generally recommended for most patients, unless tumour is a
low-grade variant.
Treatment of the neck is considered in patients with N+ or high-grade cancers, but risk
•
of occult metastasis is otherwise low.
Histiotyping, Grading, and Prognosis
Histological diagnosis can be dicult in SGC. A reclassication rate of up to 29% has been
observed. Dierent histological subtypes are divided into low, intermediate, and high
grades as a surrogate marker for biological behaviour (Box 10.1). However, a clear relationship between histological subtype, grading, and biological aggressiveness is oen lacking.
Furthermore, grading oen has little therapeutic relevance, as most salivary gland cancers
are treated similarly with surgery and post-operative radiotherapy. Treatment results for
both major and minor salivary gland cancers are comparable, with 60–70% 5-year survival
and 50–60% 10-year survival. Prognosis varies widely depending on patient, tumour, and
treatment related factors.
Head and Neck 305
PARAPHARYNGEAL SPACE
BOX 10.1 GRADING OF SALIVARY GLAND MALIGNANCIES BASED
ON CLINICAL BEHAVIOUR
Low Acinic cell carcinoma (AcCC)
Polymorphous adenocarcinoma (PAC)
Low-grade mucoepidermoid carcinoma (MEC)
Intermediate Adenoid cystic carcinoma (AdCC)
High High-grade MEC
Salivary duct carcinoma (SDC)
Carcinoma ex pleomorphic adenoma
Adenocarcinoma not otherwise specied (NOS)
Undifferentiated carcinoma
Further Reading
World Health Organization Classication of Head and Neck Tumours (4th edition) 2017:
Salivary gland tumours.
60. PARAPHARYNGEAL SPACE
Parapharyngeal Tumours
Lesions of the parapharyngeal space are rare, accounting for only 0.5% of head and neck
masses. However, they may involve a wide spectrum of primary pathologies.
Anatomy
e parapharyngeal space is an inverted, pyramidal-shaped neck space lled with fat and
areolar tissue (Figure 60.1). Its superior base comprises the sphenoid and temporal bones and
includes the jugular and hypoglossal canal and the foramen lacerum. Its inferior apex is at
the greater cornu of the hyoid bone. It has three sides, medial, lateral, and posterior, and an
anterior leading edge that is the pterygomandibular raphe.
e medial surface is distensible and comprises the superior pharyngeal constrictor muscle,
the buccopharyngeal membrane, and the pharynx. e lateral surface, which is relatively
immobile, comprises the medial pterygoid muscle, the ramus of the mandible, the deep lobe
of the parotid gland, and the posterior belly of the digastric muscle. e posterior surface is
part of the prevertebral fascia, bordered by the carotid sheath posterolaterally and the retropharyngeal space posteromedially.
Two fascial condensations in the parapharyngeal space are of surgical importance. e aponeurosis of Zuckerkandl and Testut (Figure 60.2) is fascia that joins the styloid process to the
tensor veli palatini. It divides the parapharyngeal space into the pre-styloid and post-styloid
compartments. e pre-styloid compartment contains adipose tissue, lymphatics, ectopic
salivary gland tissue, small nerves and vessels, a small branch of the trigeminal nerve to the
tensor veli palatini muscle, and branches of the ascending pharyngeal artery and pharyngeal
venous plexus.
e post-styloid compartment is posteromedial and contains the internal carotid artery,
internal jugular vein, cranial nerves IX to XII, the cervical sympathetic chain, lymph nodes,
and glomus bodies.
306 Head and Neck
PARAPHARYNGEAL SPACE
e stylomandibular ligament is formed by a band of the cervical fascia that extends from
near the apex of the styloid process to the angle and posterior border of the mandible (Figure
60.3). It and the posterior border of the mandible form the stylomandibular tunnel. e tunnel
is a deep relation of the deep lobe of the parotid gland. Tumours of the deep lobe can extend
into the parapharyngeal space through this tunnel, giving rise to a dumbbell-shaped tumour.
Primary Pathology
A comprehensive review of the literature identied 70 dierent histological subtypes of lesions,
of which 82% were benign and 18% were malignant. e most common tumours were of salivary
gland origin (45%). ese arose in the pre-styloid compartment. e vast majority (75%) were
benign and most (64%) were pleomorphic adenomas. Adenoid cystic carcinoma and mucoepidermoid carcinoma were the most common primary malignancies. e second most common
tumour s were neurogenic in origi n, accounting for 41%. e majority of t hese lesions were benign,
and of these 52% were paragangliomas, 27% were schwannomas, and 9% were neurobromas.
1
Secondary Pathology
e parapharyngeal space may be directly invaded by malignancy from the nasopharynx,
tonsil, retromolar trigone, palate, and tongue base.
e most common metastases to the parapharyngeal space are from nasopharyngeal cancer.
Parapharyngeal nodes may also be involved in oropharyngeal and maxillary sinus cancers.
Rarely, these nodes may be involved with metastases from distant sites, such as breast, colon,
and prostate cancer.
Clinical Presentation and Evaluation
Parapharyngeal tumours are usually asymptomatic oropharyngeal masses, found on incidental examination. ey may present with nasal obstruction, snoring, or hearing loss due
to Eustachian tube occlusion. Rarely, they may present with cranial nerve dysfunction causing hoarseness, dysphagia, or cough, due to pressure on, or involvement of, the hypoglossal,
vagus, or glossopharyngeal nerve.
Bimanual palpation helps assess tumour mobility and size, and appreciation of the displacement of the tonsil or the posterior pharyngeal wall provides clues to whether the lesion has
its origins from the pre-styloid or post-styloid compartment.
Imaging and Other Investigations
Imaging of the parapharyngeal space is essential to planning surgical resection. Multiplanar
imaging with ne-slice computed tomography (CT) and magnetic resonance imaging (MRI)
provides the detail required. Further information regarding vascularity and relationship to the
neurovascular structures can be gained from angiography. erapeutic interventions, such as
pre-operative embolization, or balloon occlusion studies can be performed at the same time.
Knowledge of the displacement patterns of fat and the internal carotid artery within the
parapharyngeal space will aid in the localization of lesions.
Some lesions will have characteristic appearances on cross-sectional imaging that can provide diagnostic information.
Treatment
Lesions of the parapharyngeal space are predominantly treated by surgery. e aim of surgery is to remove the lesion with minimal morbidity. Adjuvant radiotherapy is reserved for
malignant lesions or recurrent benign lesions with a high risk of recidivism. Chemotherapy is
administered when indicated by specic histology, such as rhabdomyosarcoma, positive margin status, tumour histology, and perineural and lympho-vascular spread. Radiotherapy has
also been used in patients who are considered a high surgical risk or for unresectable lesions.
e choice of surgical technique is dependent on the tumour size, its relationship to the
parotid gland and skull base, and whether the tumour is malignant.
Head and Neck 307
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