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Head and Neck > Parapharyngeal Space Tumors > Flashcards

Parapharyngeal Space Tumors Flashcards

1
Q

How do masses in the pre-styloid space present? 1

A
  • Mass in the lateral oropharynx, displacing the tonsil medially

Vancouver Page 161

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2
Q

How do masses in the post-styloid space present? 4

A
  • Upper lateral neck mass
  • Nasopharynx or oropharynx pushed medially
  • Cranial nerve IX-XII dysfunction
  • Horner’s syndrome
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3
Q

How can you differentiate between a pre-styloid mass vs. post-styloid compartment mass on CT/MRI?

A

PRE-STYLOID:
1. Displacement of the lateral wall of the pharyngeal space medially
2. Displacement of parotid gland laterally (while maintaining an intact fat plane with the deep lobe of the parotid)
3. Displacement of carotid posteriorly

POST-STYLOID:
1. Antero-lateral displacement of the pre-styloid parapharyngeal fat
2. Anterior or medial displacement of the internal carotid
3. Obliteration of fat planes around the great vessels
4. Extension posterior to the styloid

Vancouver Page 161/162

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4
Q

Discuss the T1, T2 MRI findings & what does it do to the carotid - of the following parapharyngeal space tumors:
1. Plemorphic adenoma
2. Schwannoma
3. Paraganglioma

A

PLEOMORPHIC ADENOMA:
1. T1 - hypointense
2. T2 - Hyperintense
3. Displaces carotid posteriorly

SCHWANNOMA:
1. T1 - hypointense
2. T1 with Gadolinium - enhances
3. T2 - hypertense
4. Displaces carotid anteriorly

PARAGANGLIOMA:
1. T1 and T2 - salt and pepper appearance due to flow voids in both
2. Displaces carotid anteriorly

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5
Q

Briefly describe five surgical approaches to the parapharyngeal space. What are their indications, advantages, and disadvantages?

A

Note: All approaches can be combined with mandibular osteotomies to improve exposure

A. TRANSORAL
1. Indications:
- Small superomedial lesions (< 6cm)
- Presenting as an intraoral mass

  1. Advantages:
    - No cervical incision
  2. Disadvantages:
    - Seldomly used, poor access and exposure - poor visualization and control of the great vessels
    - High risk tumor rupture
    - High risk incomplete removal
    - Massive hemorrhage with diffiiculty to control
    - Nerve injury

B. TRANSCERVICAL
- Most common approach
- Can be divided into parotid or submandibular approach below
- Access via transverse incision at the level of the hyoid bone

  1. Advantages:
    - Allows access to post-styloid compartments and inferior portion of PPS
    - Good visualization of nerves and control of vessels
    - Excellent post-surgical cosmesis

C. TRANSCERVICAL SUBMANDIBULAR
- Dissection of the submandibular triangle to gain access to pre-styloid compartment

D. PAROTIDECTOMY APPROACH / SUBMANDIBULAR
- Modified blair incision with extension to submandibular triangle
- Mainly used for deep parotid lobe tumors
- Improves CNVII exposure

E. LIP-SPLITTING WITH/WITHOUT MANDIBULTOMY
- For pharyngeal malignancies that extend into parapharyngeal space as part of a composite resection

  1. Indications:
    - Improved access for the superior parapharyngeal space
    - Large tumors > 8cm
    - Tumors incasing or involving the internal carotid
    - Malignant tumors invading skull base or vertebrae
  2. Disadvantages:
    - Possible tracheostomy for post-op airway protection
    - Longer length of stay
    - Delay in oral nutrition
    - Risk of malunion/non-union, TMJ dysfunction, loss of dentition

F. INFRATEMPORAL FOSSA OR CRANIOFACIAL APPROACHES OR TRANSMASTOID
- For tumors involving the skull base

  1. Indications:
    - May be combined with a transcervical approach
    - Useful for malignant parapharyngeal space lesions involving skull base, jugular foramen, or intracranial extension

Vancouver 162
Nadia GR lecture

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6
Q

What are four ancillary procedures that can assist in exposing the parapharyngeal space?

A
  1. Submandibular gland swing or excision (for transcervical)
  2. Separation of styloid structures provides access to carotid at skull base (stylohyoid, styloglossus, and stylopharyngeus, and stylomandibular ligament)
  3. Separation of sphenomandibular ligament
  4. Disarticulation of the TMJ

Sphenomandibular ligament: https://www.earthslab.com/wp-content/uploads/2018/03/Sphenomandibular-Ligament.jpg

Vancouver Page 163

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7
Q

What are two routes that deep parotid lesions can enter into the parapharyngeal space?

A
  1. Posterior to stylomandibular ligament: round shaped lesion
  2. Anterior to stylomandibular ligament (via tunnel): dumbbell shaped mass
  3. Stylomandibular tunnel: Defined by posterior border of ramus of the mandible, skull base, and stylomandibular ligament
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8
Q

List a differential diagnosis of pre-styloid parapharyngeal space tumors

A
  1. Deep lobe parotid tumors (45%)
  2. Neurogenic tumors (30%) - V3 - schwannoma, paragangliioma, neurofibroma
  3. Lymphoma (25%)
  4. Vascular (3%) - Hemangiopericytoma, hemangioendothelioma, AVM, ICA aneurysm
  5. Minor salivary gland tumors - most frequently malignant, occasionally pleomorphic adenoma
  6. Other: Brachial cleft cyst, lipoma, teratoma, metastases

Note: Pre-styloid almost all salivary - look for fat plane

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9
Q

List a differential diagnosis of post-styloid parapharyngeal space tumors

A
  1. Nerve sheath tumors
  2. Paragangliomas
  3. Metastases (lymph nodes)
  4. Meningioma
  5. Hemangioma
  6. Chondrosarcoma (low grade, usually near Foramen lacerum)
  7. Rhabdomyosarcoma
  8. Perineural metastasis
  9. Lymphoma

Note: Pre-styloid almost all salivary - look for fat plane

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10
Q

What is the breakdown of primary salivary gland pathologies within the parapharyngeal space?

A

Salivary gland tumor = most common PPS tumor (45%), seen in prestyloid space
- Can be parotid or minor salivary gland (look for fat plane between parotid and tumor) - either will displace carotid posteriorly

TYPES:
1. Plemorphic adenoma - most common
2. Mucoepidermoig carcinoma - most common malignant

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11
Q

What are the top 3 most common primary neurogenic pathologies within the parapharyngeal space, in order of most to least common?

A
  1. Schwannoma
  2. Paragangliomas
  3. Neurofibromas
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12
Q

Regarding schwannomas in the parapharyngeal space, discuss:
1. What is the epidemiology?
2. What is the most common schwannoma?
3. How can you tell on imaging?

A

SCHWANNOMAS:
- Most common neurogenic tumor overall
- Most common post-styloid mass

MOST COMMON TYPE:
1. Vagus
2. Sympathetic chain

IMAGING CLUE:
1. Displaces carotid anteriorly within the parapharyngeal space

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13
Q

Regarding paragangliomas in the parapharyngeal space, discuss:
1. What is the epidemiology?
2. What do they most commonly arise from?
3. What are clues for vagal paragangliomas?
4. What are clues for carotid body paragangliomas?

A

PARAGANGLIOMAS:
- 2nd most common neurogenic tumor in the parapharyngeal space
- Seen in the post-styloid space most commonly

EPIDEMIOLOGY:
1. Familial in ~10%
2. Bilateral or multiple in ~10%
3. Malignancy ~5%
4. Secretory 3%

ARISE FROM:
1. Nodose ganglion of the vagus (most common in parapharyngeal space)
2. Carotid body
3. Inferiorly from Jugular bulb
4. Less commonly: glossopharyngeal, superior laryngeal, recurrent laryngeal

VAGAL:
- Displaces carotid anteriorly

CAROTID BODY:
- Lyre sign: splaying of the carotid artery bifurcation

Vancouver Page 164

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14
Q

What is Lyre’s sign?

A

Splaying of the cartoid artery bifurcation classically seen in carotid body paragangliomas

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15
Q

What is Fontaine’s sign?

A
  • Classic carotid body tumor physical exam sign
  • Palpation of tumor shows that it is laterally mobile, but is fixed in the cranial-caudal direction
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16
Q

Regarding neurofibromas in the parapharyngeal space, discuss:
1. What is the origin?
2. Characteristic features on pathology? How does it differ from schwannoma?
3. Epidemiology?

A

NEUROFIBROMAS:
- 3rd most common neurogenic tumor of the parapharyngeal space
- Higher malignancy rate associated with NF Type 1

ORIGIN:
- Schwann cells and perineural fibroblasts

PATHOLOGY:
- Unencapsulated and involves the nerve (as opposed to schwannomas that are encapsulated and do not involve the nerve) –> this means theoretically it is possible to save the nerve with the schwannoma, but impossible with neurofibroma

17
Q

Regarding Syndromic and Hereditary paragangliomas, discuss:
1. What are the risk factors, 5 syndromes, and 2 associations of paragangliomas?
2. What are the genetics and inheritance patterns for familial or hereditary paragangliomas?
3. When do they typically present?
3. Classic features?

A

RISK FACTORS: 60% of PGLs have Solitary etiology (either syndromic or genetic)
1. Syndromes:
- MEN 2A/2B
- Neurofibromatosis Type 1
- Von Hippel-Lindau Disease
- Hereditary PGL syndrome
2. Associations:
- Carney Triad (association b/w PGL, Pulmonary chondroma, Gastric Leiomyosarcoma)
- RET Gene mutations also seen in Non-syndromic PGL
3. Non-Syndromic risks: living at high altitudes (associated with chronic hypoxemia)

HEREDITARY PARAGANGLIOMA SYNDROME:
1. Inheritance: Autosomal Dominant
2. Genetics: Succinate Dehydrogenase inactivation mutation (codes for Succinate Dehydrogenase enzyme complex Subunits D, B, and C) & SDH complex assembly factor 2 (SDHAF2) gene
- PGL1: SDH-D mutation (most common) - most commonly associated with H/N tumors; 75% tumor by age 40, 56% multifocal tumors
- PGL3: SDH-C (lower risk of multicentricity and malignancy)
- PGL4: SDH-B (later onset of disease - 40% by age 40, higher risk of malignancy)

CLINICAL PRESENTATION:
- Generally present in younger patients and multiple sites
- Suspect in anyone with bilateral PGLs

18
Q

Regarding functional paragangliomas, discuss:
1. What % of H/N PGLs are functional?
2. What are symptoms of elevated catecholamines?
3. How are these typically diagnosed?
4. How are the results interpreted?
5. How should these be managed?

A

FUNCTIONAL PGL:
- RARE to present in H/N

SYMPTOMS:
1. Headaches
2. Palpitations
3. Flushing or Diaphoresis

DIAGNOSIS: Routinely performed for multiple or familial PGL, or in presence of catecholamine-related symptoms
1. 24-h urine catecholamine collection
2. Plasma metanephrines

RESULTS:
1. Excess epinephrine = suspicious for PHEO
- H/N PGLs lack enzyme phenylethanolamine-N-methyl transferase (PNMT) –> convert NE to E conversion (only present in adrenal glands)
- Therefore positivity suspicious for PHEO rather than H/N related

  1. Positive results, perform: Metaiodobenzylguanidine (MIBG) scan
    - Should be performed to investigate catecholamine uptake & storage

TREATMENT:
- Functional tumors require alpha and beta-adrenergic blockade prior to surgery

19
Q

What are the most common sites of paraganglia occurence in the head and neck?

A
  1. Carotid body (65%)
  2. Tympanic
  3. Jugular bulb
  4. Intravagal
  5. Glossopharyngeal
  6. Superior laryngeal
  7. Inferior laryngeal
  8. Nasal
  9. Nasopharyngeal
  10. Orbital
  11. Subclavian
  12. Aortico-pulmnonary
  13. Coronary
20
Q

What are the two most common cranial nerves to be affected by a carotid body tumor?

A
  1. Vagus (X)
  2. Hypoglossal (XII)
21
Q

Describe the workup for paragangliomas

A
  1. CT or MRI
  2. 24 hour urine collection of VANILLYMANDELIC ACID and METANEPHRINES
    - If positive, test for both:
    - Serum catecholamines
    - Indium-111 pentetreotide (somatostatin/octreotide analog) or Iodide-131 metaiodobenzyl guanidine (MIBG) scan to look for mulitple lesions (Head/neck not commonly secreting, so look for another source)
  3. CT or U/S abdomen to r/o pheochromocystoma
  4. CT Angiography (and pre-op embolization or balloon occlusion test)
22
Q

What are 5 reasons to perform angiography in the workup of carotid body tumors?

A
  1. Delineate the primary blood supply to the tumor
  2. Identify any collateral feeding vessels
  3. Evaluate the feasibility of pre-operative embolization (e.g. Balloon Occlusion Test)
  4. Evaluate for the presence of carotid involvement
  5. Evaluate for the presence of multifocal disease
23
Q

What are the indications for pre-operative embolization of carotid body paragangliomas? 3

A
  1. Decrease vascularity of large carotid paragangliomas
  2. Jugular foramen and high vagal PGLs (difficult to obtain vascular control intra-op)
  3. Balloon occlusion test (tolerance to ICA occlusion, especially if ICA resection or reconstruction is required) - failing occlusion test may not be suitable surgical candidates
24
Q

What is the classification of carotid body tumors?

A

Shamblin Classification

  1. Type I: Not encasing the carotid
  2. Type II: Partially encasing the carotid
  3. Type III: Completely encasing the carotid

Vancouver Pg 164

25
Q

At what rate per year do paragangliomas tend to grow?

A

1-4mm/ year

(Mean doubling time 7 years; Jansen et al, 2000)

26
Q

What are the 3 general management options for paragangliomas, and what are their general indications and contraindications to do so?

A
  1. Observation: Serial MRI (~6-12 months), reassess earlier if concerning for significant growth, malignancy, pain, neuropathies, or worsening symptoms

Indications:
- Small
- Stable
- Asymptomatic or minimally symptomatic
- Elderly (minimal impact on QOL/life expectancy)
- Significant comorbidities/unfit for OR

Contraindications:
- Secreting/functional tumors
- Rapid growth
- Concern for malignancy

  1. Radiotherapy/Gamma knife (only slows progression, does not eradicate) - long term control rates of stable disease or partial regression ~95-95%

Indications:
- Poor surgical candidates (significant comorbidities)
- Locally advanced tumors, post-op morbidity precludes surgical consideration (e.g. Shamblin III)
- Adjuvant RT for locoregional control of malignant carotiid body tumors

Contraindications:
- Not preferred in young patients due to side effects/risk of malignancy

  1. Surgical: Resection in subadventitial plane ± vascular replacement (saphenous, synthetic, or Superficial Temporal Artery to MCA bypass) ± embolization ± regional neck dissection if malignant

Indications:
- Carotiid body PGLs, especially if: Young and healthy patients, Tumor < 5cm, Shamblin I/II (Type III Radiation considered safer)
- Symptomatic
- Rapidly growing
- Secreting tumors
- Concern for malignancy

Contraindications:
- Controversial: Multi-centric tumors (need one functional vagus nerve to survive; may also get baroreflex failure syndrome secondary to bilateral carotid body denervation, causing unopposed sympathetic flow - marked BP and tachycardia starting 24-72 hours post op)

27
Q

What are the potential surgical complications in resection of carotid body tumors?

What are risk factors to having complications? What is a good pre-op prognostic sign of post-op function?

A
  1. Interal Carotid artery Injury
  2. Vascular complications (hemorrhage, thrombosis, hematoma)
  3. CNS complications (e.g. stroke)
  4. Cranial nerve Injury (VII, IX-XII)
  5. Horner’s syndrome
  6. First bite syndrome
  7. Cardiovascular collapse (e.g. secreting carotid body tumor)
  8. Death

Risk factors:
1. Large tumors - 1.5x increased risk with each 1cm closer to skull base

Prognosticator:
- Gradual loss of CN function is usually better tolerated by elderly patients than sudden loss due to surgery (more time to get used to dysfunction)
- Observation or delayed removal is recommended in elderly to have time to have “decrease in function”

28
Q

What are the advantages, disadvantages, and possible complications of radiotherapy for paragangliomas?

A

PROS:
1. Lower/no risk to cranial nerves
2. Lower/no risk of stroke
3. Most tumors will stop growing

CONS:
- Risk of microvascular and carotid artery disease
- RIsk of radiation induced malignancies
- May have to operate in a radiated bed
- Risk of osteoradionecrosis

COMPLICATIONS:
1. Carotid atherosclerosis
2. Radiation-induced malignancy
3. Mucositis
4. Hearing loss
5. Dysequilibrium
6. Osteoradionecrosis

29
Q

What are the steps that need to be done pre-operatively for a secreting Carotid body tumor? 5

A
  1. Type and cross match (consider autologous blood)
  2. ICU bed
  3. Balloon occlusion test
  4. Consult vascular surgery
  5. Pre-operative embolization
  6. Alpha and beta antagonist (blockades)
30
Q

Regarding first bite syndrome, discuss:
1. In what conditions is this typically seen?
2. Natural history?
3. Pathophysiology?
4. Clinical presentation?
5. Treatment?

A

CONDITIONS: Occasionally from tumor itself, but mainly a complication of surgery in the following areas (any surgery that sacrifices the sympathetic chain):
1. Parapharyngeal space
2. Deep lobe of the parotid
3. Infratemporal fossa

NATURAL HISTORY:
- Can start days, months, or years after original surgery
- Usually self-limiting

SYMPTOMS:
- Acute, intense pain (spasm) in the parotid region during the first bite of each meal, that diminishes over the next several bites

PATHOPHYSIOLOGY (Proposed):
- Surgical damage to the sympathetic innervation of the parotid –> parasympathetic hyperactivation (unopposed) stimulates an exaggerated myoepithelial cell contraction –> causes pain

TREATMENT:
1. Observational
2. Medical:
- Botox injections (parotid gland/region)
- Carbemazepine
- TCAs
- Radiation (in severe cases)
- Not effective: typical medications, NSAIDs, anti-inflammatories (but can aid in diagnosis)

31
Q

What is the difference between the carotid body and carotid sinus?

A

Carotid body: Contains chemoreceptors (regulate pH and temperature)
- Located at the bifurcation of the internal and external carotid artery

Carotid sinus: Contains baroreceptors (regulate HR and BP)
- Located in the adventitial layer of the carotid bulb of the internal carotid artery (looks like a dilatation within the artery)

Vancouver Pg 166

32
Q

Discuss the general steps in the surgical resection of carotid body tumors?

A
  1. Oblique neck incision made anterior to SCM, raise subplatysmal flaps to provide wide exposure of the carotid system
  2. Limited selective neck dissection performed: retract IJV; sample LN for mets; identify CNXI/X/XII; divide ansa; CNXII retracted superiorly
  3. Common, external, and internal carotid arteries proximal and distal to the tumor are controlled (vessel loops); if the external carotid is involved within the tumor, it can be sacrificed
  4. Subadventitial dissection in the plane of Gordon-Taylor (subadventitial plane)
  5. Tumor is dissected away from the surface of the internal carotid; excessive bleeding may be avoided by ligation of the small tumor-feeding vessels on the posterior aspect of the carotid birfurcation
  6. Tumor freed from the bifurcation is retracted superiorly to allow dissection of. thesuperior laryngeal nerve away from the deep surface of the tumor
  7. If more exposure is needed superiorly, the digastrics is taken down along with the stylohyoid muscle
  8. If the carotid is involved with the tumor, it is sacrificed and replaced with either a venous or synthetic graft
33
Q

What is the most common feature of malignant paragangliomas?

A

Metastases

Head and Neck (15 decks)

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