Surgical approaches to nasopharynx
Nasopharynx is a difficult area to access surgically due to
1. Its central location
2. Its surrounding facial skeleton, skull base
3. Presence of great vessels and lower cranial nerves
Ideal surgical approach to nasopharynx should:
1. Provide adequate exposure to nasopharynx for tumor resection
2. Great vessels must be safely controlled
3. Lower cranial nerves should be spared - a difficult task indeed.
Surgical approach chosen is dependent on
1. Extent of tumor
2. Surgical expertise 3. Facilities available
Classification of surgical approaches:
!. Anterior approach
2. Inferior approach
3. Lateral approach
The following anterior approaches can be used to access nasopharynx.
Transnasal transmaxillary approach
Lefort I osteotomy
Maxillary swing approach
This approach exposes the nasal cavity and choana well. It can be used alone or in combination with other approaches to enhance exposure of nasopharynx. This approach is useful in resection of anteriorly placed tumors.
Transnasal transmaxillary approach:
In this approach lateral rhinotomy is combined with medial / subtotal maxillectomy. This approach exposes the nasopharynx, ipsilateral spheno-ethmoidal complex, pterygopalatine fossa and medial end of infratemporal fossa.
Midfacial degloving approach:
This is a bilateral transnasal, transmaxillary approach. The advantage of this procedure is that it is performed via sublabial incision thereby avoiding facial scar. In this approach infraorbital nerves on both sides are safeguarded, midface is degloved subperiosteally up to the level of root of the nose. Bilateral medial maxillectomy is performed to improve exposure. The pterygopalatine fossa and the medial end of infratemporal fossa is ideally exposed.
Lefort I osteotomy:
In this approach through a sublabial incision a transverse maxillary osteotomy is performed through both maxillary sinuses allowing the whole hard palate and both inferior maxillae to be down fractured. Access to central skull base and nasopharynx is ensured without any visible facial scars.
Maxillary swing approach:
This is one of the common approaches to nasopharynx. It exposes the nasopharynx and surrounding areas from the anterolateral aspect. through Weber Ferguson incision maxilla is separated from its bony attachments and swung laterally intact with the masseter muscle and cheek flap. Access to opposite side can be established by removing the posterior portion of nasal septum. After tumor resection, the maxilla is swung back and fixed to facial skeleton.
Transpalatal approach: Nasopharynx can be accessed by raising palatal mucoperiosteal flap off the hard palate, separating the soft palate from its bony portion. The posterior edge of bony hard palate is removed as much as it is necessary to access the nasopharynx. Greater palatine neurovascular bundle must be mobilized bilaterally to prevent flap necrosis.
Mandibular swing approach:
This is actually a combination of transcervical, transmandibular, transpalatal approach via Frazier incision. Soft tissues including parotid gland are elevated from the mandible. Mid portion of the ascending ramus of the mandible including the coronoid process is cut and removed to facilitate exposure and to prevent post operative trismus. The lateral and medial pterygoid muscles are divided to enter the nasopharynx. Tracheostomy is a must to secure the airway. Dead space after tumor removal needs to be repaired.
This approach is via infratemporal fossa. This approach is limited by facial nerve and carotid sheath. It is used when the tumor extends laterally to involve the parapharyngeal space.