Introduction
Certain ethnogeographic groups have been found to have an increased risk of developing nasopharyngeal carcinoma (NPC). Studies have shown that among the Chinese, there is a very high incidence of NPC affecting 10 to 20 per 100,000 for men and 5 to 10 per 100,000 for women, causing NPC to sometimes be called the “Cantonese cancer.” Most of these NPCs originate in the epithelial lining of the fossa of Rosenmüller, an area located posteromedially to the medial crura of the opening of the Eustachian tube.
Screening, diagnosing, and monitoring NPC can now be done using several serological markers after studies demonstrated that a close relationship existed between NPC and the Epstein-Barr virus (EBV), a double-stranded DNA virus. Most NPCs carry the clonal EBV genomes and express EBV proteins. To screen the general population, serological markers such as EBC VCA IgA and DNase are used. RT-PCR methods that measure EBV DNA copy numbers in plasma are used to monitor the response to treatment and for early detection of local recurrence.
Currently, radiation therapy (RT), chemotherapy, or combinations of both are the primary available modalities for treating NPC. More than 80% local control can be achieved through RT because of the high radiosensitivity of NPC, giving patients with early NPC a good possibility for cure. However, for patients with advanced-stage locoregional NPC, the standard treatment is Cisplatin-based chemoradiotherapy with or without neoadjuvant chemotherapy. In spite of its high radiosensitivity, patients with advanced NPC still have a 10% to 30% risk of local failure after the initial RT treatment. If local recurrence is suspected, performing a biopsy under nasopharyngoscopy should be done.
Key Operative Learning Points
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Perform medial maxillectomy and posterior septectomy to improve exposure and increase the working space area.
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Use the two nostrils/four hands technique.
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Resection with LASER on a curved applicator.
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Mark the deep margin of resection as the pharyngobasilar fascia and remove the Eustachian tube cartilage as far laterally as possible.
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Involvement of the bone of the skull base will require a navigation-guided endoscopic resection.
Preoperative Period
NPC patients who are monitored using the EBV serological markers typically do not complain of any symptoms. When there is a local recurrence, the NPC patient may experience the same symptoms experienced at the initial presentation of the cancer. The presence of a mass in the fossa of Rosenmüller or even from the nasopharynx should be investigated further for rNPC. However, there are some patients with whom careful nasopharyngeal examination does not reveal any obvious mucosal lesion. Some may appear as a small submucosal swelling beneath an intact mucosa. Therefore, performing a biopsy under nasopharyngoscopy is mandatory to establish the diagnosis of local recurrence.
The surgeon must evaluate the extent of the cancer by endoscopic examination as well as imaging studies. Magnetic resonance imaging (MRI) is superior in demonstrating soft tissue involvement compared with computed tomography (CT) scan. MRI is able to identify local recurrence, perineural invasion, skull base involvement, suspicious retropharyngeal lymph nodes, and cervical metastasis as well as early cancers that produce mild thickening of the mucosa. These advantages provide important information for good surgical planning and tumor mapping for endoscopic nasopharyngectomy. Salvage surgery is relatively contraindicated for patients who have distant metastasis.
A complete examination of the head and neck must be carried out, particularly in the nasal cavity and nasopharynx, to detect the presence of metastatic lymph nodes, including examination of the cranial nerves. Other important preoperative preparation includes ascertaining any anatomical variation, intraoperative navigation (in selected cases), blood-group matched packed red cells, and preoperative antibiotic. Patients with preexisting significant comorbidities should receive special attention. Anticoagulants or antiplatelet medications should be withheld (if possible) prior to endoscopic nasopharyngectomy.
History
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History of present illness
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Nasal symptoms: nasal obstruction, blood-stained nasal discharge
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Aural symptoms: ear blockage, hearing loss, otorrhea
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Mass in the neck
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Skull base and cranial nerve involvement
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Intractable headache
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Sixth cranial nerve involvement which will be discovered by the presence of abducens nerve palsy
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Unilateral facial numbness from involvement of the fifth cranial nerve
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Trismus
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Symptoms suggesting distant metastasis
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Weight loss, nutritional status
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Smoking
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Past medical history
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Previous radiotherapy with or without chemotherapy
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Previous surgery for NPC
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Pulmonary disease, hypertension, diabetes, or ischemic heart disease
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Immunosuppression; for example, AIDS
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Medications
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Anticoagulants
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Allergies to antibiotics or analgesia
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Physical Examination
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Nasal cavity and nasopharyrnx
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Endoscopic examination of the nasopharynx may reveal a mass in the fossa of Rosenmüller and sometimes a small submucosal swelling
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Determine extent of the tumor
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Lateral extension
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Eustachian tube
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Torus tubarius
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Roof of nasopharynx and posterior choanae
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Inferior extension to oropharynx
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Examination of the neck
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Palpate both necks for the presence of cervical metastases
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Is the mass fixed or mobile?
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Is there bilateral cervical metastasis?
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Examination of the skull base and cranial nerve
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Is there evidence of sixth nerve palsy?
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Trismus
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Anticipate difficult intubation and may require tracheostomy
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Examination of the ears
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Middle ear effusion
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Examine oral cavity, pharynx, and larynx for synchronous primaries
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General health
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Nutrition
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Cardiovascular
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Respiratory
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Abdominal
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Imaging
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MRI
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Superior soft tissue resolution and tumor delineation
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Parapharyngeal space or infratemporal fossa
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Intracranial extension
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Perineural invasion
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Deep invasion to the vertebra body
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Vascular involvement (carotid artery, cavernous sinus)
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Presence of cervical metastasis
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PET CT scans
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Restaging
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To exclude distant metastasis (bone, lung, and liver)
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To exclude cervical metastasis
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CT scan
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Not required in all cases
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MRI is preferred if available
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Chest radiograph
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Metastases
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Pulmonary and cardiac status
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Ultrasound of the liver
Indications
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Mainstay of treatment after radiotherapy failure
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Lesions of the central, roof, or floor of the nasopharynx with minimal lateral extension
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Recurrent NPC with skull base bone involvement with the aid of navigation
Contraindications
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Parapharyngeal space or infratemporal fossa involvement
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Not a good candidate for salvage surgery, as it is difficult to achieve oncologically safe surgical margins in these areas
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Significant dural involvement and intracranial extension
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Internal carotid artery or cavernous sinus involvement
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Medically unfit for surgery
Preoperative Preparation
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Evaluations
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Otorhinolaryngologist—head and neck surgeon
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Oncologist
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Anesthesiologist
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Nutritionist (if necessary)
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Internal Medical Specialist optimizing medical illness (cardiopulmonary disease) if required
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Treat sinusitis if present
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Not rare in rNPC patients
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Bacterial culture of nasal secretion is obtained and culture-directed antibiotics prescribed for at least 7 days
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Perform frequent nasal douching with saline before surgery
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Intraoperative navigation (if required)
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Postoperative high-dependency care (depending on the center)
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Discontinue antiplatelet drugs if possible
Operative Period
Anesthesia
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General anesthesia
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Oral endotracheal tube
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In patients who have trismus, intubation under fiberoptic guidance may be necessary. Temporary tracheostomy should be considered in patients who have severe trismus.
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The endotracheal tube is positioned away from the surgeon so as not to interfere with the operative site.
Positioning
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The patients are placed in the supine position with the neck slightly extended and the head resting on a donut.
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The nasal cavity is decongested for 15 minutes with cotton pledgets saturated with epinephrine 1:100,000.
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Careful inspection of the nasopharynx with a rigid endoscope: Inspection of the cancer and its extent is mandatory in order to formulate a good surgical plan.
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Lidocaine 1% mixed with 1:80,000 epinephrine is used to infiltrate the mucoperichondrium of the nasal septum, middle, and inferior turbinates, and around the cancer.
Perioperative Antibiotic Prophylaxis
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Clean contaminated surgery.
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Prophylactic intravenous antibiotics based on previous available bacterial culture data or antibiotic with good CSF penetration (intravenous clindamycin).
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Additional intraoperative doses of antibiotic can be given every 6 hours in longer surgery.
Monitoring
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Routine anesthesia monitoring
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Hypotensive anesthesia (to reduce intraoperative bleeding that will obscure operative field)
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Intraoperative heating blanket to prevent hypothermia
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Maintain hydration and hemoglobin
Instruments and Equipment to Have Available
Endonasal skull base surgery set including:
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Navigation system
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Sinuscope set using the 0-degree and 30-degree Hopkins’ scopes
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Kerrison rongeurs, suctions, forceps, curettes, tru-cutting instruments, and dissectors
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Cutting and diamond burrs
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Contact LASER set with curved applicator
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Bipolar cauterization set
Key Anatomic Landmarks
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Most cephalad portion of the upper aerodigestive tract
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Measuring nearly 4 cm in transverse diameter and 2 cm in its anterior-posterior dimension
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Boundaries:
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Superior: sphenoid sinus and upper clivus
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Posterior: lower clivus and body of the first cervical vertebra
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Lateral: medial pterygoid plate
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Anterior: communicates with the posterior nasal choanae
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Inferior: communicates with the oropharynx
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Posterior and lateral walls lined by the pharyngobasilar fascia
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Tough fibrotic layer
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Inserts superiorly to the basosphenoid and laterally to the medial pterygoid plate
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Continuing downward it becomes the buccopharyngeal fascia
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Between the roof and the lateral wall of the nasopharynx is a recess that is located superior to the torus tubarius where most NPC tumors are located. This area is called the fossa of Rosenmüller.
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Inferolateral wall is the Sinus of Morgagni, an incomplete cartilaginous ring through which the Eustachian tube and tensor veli palatini muscle travels.
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Tensor veli palatine muscle
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Attached to Eustachian tube on its lateral side and to the scaphoid fossa floor
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Muscle fibers converge into a tendon that curves around the pterygoid hamulus
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Inserts into the palatine aponeurosis of the soft palate
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Contracture of this muscle facilitates opening of the Eustachian tube lumen
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Levator veli palatine muscle
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Originates from the petrous temporal bone’s inferior surface
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Traverses through the Sinus of Morgagni
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Inserts into the palatine aponeurosis
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Prerequisite Skills
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Experience in skull base surgery and familiarity with the complex anatomy.
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Open approach (see Chapter 43 ).
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Cancer involving the carotid artery or unexpected extension, not amenable to endoscopic surgery and the patient may require conversion to an open approach.
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Operative Risks
The major operative risk of endoscopic nasopharyngectomy is similar to any skull base surgery such as:
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Intracranial hemorrhage
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Pneumocranium or tension pneumocephalus
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CSF leak
Surgical Technique
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Intraoperative evaluation after patient has been intubated
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Ensure the nose is properly decongested and anesthetized
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Reassess the extent of the primary cancer ( Fig. 41.1 )
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