Pterygopalatine/Pterygomaxillary Space Approaches, Maxillary Artery Ligation, and Approach to Juvenile Nasopharyngeal Angiofibroma

Pterygopalatine/pterygomaxillary space (PPS) approaches are used to treat lesions in areas posterior to the maxillary sinus, including the pterygopalatine fossa and lateral recess of the sphenoid sinus (LSR). Pathologic processes within the PPS are rare; the most common ones are juvenile nasopharyngeal angiofibroma (JNA), neurogenic tumors such as schwannoma, and perineural extension of sinonasal malignancy. A characteristic lesion found within the LSR is the encephalocele, which is commonly associated with idiopathic intracranial hypertension (IIH).

Endoscopic, endonasal PPS approaches have paved the way for minimally invasive treatment of these lesions, providing excellent visualization and instrument accessibility, as well as reduced morbidity. In contrast, surgeons have traditionally used open transfacial approaches (e.g., midfacial degloving, lateral rhinotomy) with medial maxillectomy and/or subtemporal craniotomy to treat these lesions. Compared with these options, a PPS approach may obviate the need for open incisions, although at times an adjunctive canine fossa incision is a useful complement to the endoscopic approach, especially for posterolateral access.

Exposure of the pterygopalatine fossa through a PPS approach allows maxillary artery ligation both for management of refractory/recurrent epistaxis and for arterial control during resection of tumors, such as JNA.

The PPS is bounded by the posterior wall of the maxillary sinus (anterior), perpendicular plate of the palatine bone (medial), pterygoid process of the sphenoid bone (posterior), and body of the sphenoid bone (superior). Inferiorly, it is in continuity with the greater palatine canal. Laterally, it connects with the infratemporal fossa ( Fig. 24.1 ).

Several foramina provide passageways for neurovascular structures residing in the PPS and thus form the path of least resistance to the orbit, palate, skull base, infratemporal fossa, and nasal cavity for pathologic processes.

The vascular and neural structures are located anteroinferiorly and posterosuperiorly, respectively, within the PPS. The sphenopalatine artery, a terminal branch of the maxillary artery, is found between the sphenoid and palatine bones and enters the nasal cavity at the sphenopalatine foramen. If access posterior to the artery is necessary (e.g., LSR), then once the artery is identified it can sometimes be retracted down. However, it will often need to be divided and ligated, as simple retraction may increase the risk of arterial avulsion and subsequent hemorrhage.

The maxillary artery is a terminal branch of the external carotid system. In traditional anatomic nomenclature, it has been referred to as the internal maxillary artery.

The maxillary division of the trigeminal nerve (V ₂ ) and the vidian nerve emanate from the posterior wall of the space, from the foramen rotundum (superomedial) and the pterygoid canal (inferolateral), respectively. They form the pterygopalatine ganglion and branch into the infraorbital nerve exiting through the inferior orbital fissure and the greater and lesser palatine nerves passing through the correspondingly named foramina. Through these terminal branches, the maxillary nerve provides sensation to the cheek skin, lower eyelid, upper lip, nasal sidewall, and hard and soft palate. The vidian contributors traveling with the maxillary branches produce secretory function of the lacrimal, nasal, and palatal glands. The vidian canal is found within the floor of the sphenoid sinus and can often be identified by elevating the mucosa overlying the anterior face of the sphenoid sinus off the bone in an inferolateral direction.

Posterior to the PPS, pneumatization of the lateral portion of the sphenoid bone can result, forming a lateral sphenoid recess. This is observed in up to 25% to 48% of patients; the bone is extensively pneumatized in 8% of cases. The roof of this space can lie directly beneath the temporal lobe in the middle cranial fossa and is a common location for middle cranial fossa encephaloceles.

The need for transfusion should be anticipated given the proximity to the maxillary arterial system and pterygoid venous plexus, especially for vascular lesions such as a JNA. Preoperative angiography and embolization may be necessary with certain pathologic processes such as JNA.

Neurosurgical consultation should be strongly considered, particularly in the setting of an encephalocele or cerebrospinal fluid (CSF) leak, or if there is intracranial extension of pathology.

Magnetic resonance imaging (MRI) and computed tomography (CT) should both be performed; image-guided surgical navigation is useful intraoperatively. When an LSR encephalocele is being addressed, intrathecal administration of diluted fluorescein may be necessary to identify or confirm the site of the leak intraoperatively ( Fig. 24.2 ).

Whether a nasoseptal flap will be necessary for skull base reconstruction should be determined. The flap may be raised at the beginning of surgery and tucked posterolaterally (i.e., in the nasopharynx) for the remainder of the procedure to avoid trauma to the flap while the approach is performed.

The patient should be counseled on the possible sequelae of PPS approaches, including ipsilateral palatal or cheek numbness or dry eye.

0-degree and 30-degree endoscopes

Standard endoscopic sinus surgical tray

4-mm diamond choanal atresia bur or 15-degree angled diamond bur

Extended-length Kerrison rongeurs

Through-cutting instruments

Endoscopic clip applier

Suction monopolar cautery or endoscopic bipolar cautery, to have available for small branches of the maxillary artery

Endoscopic microscissors

Blunt dissecting instrument, such as curette or ball-tip probe

Image-guided surgical navigation system

A wide maxillary antrostomy allows appropriate exposure of the PPS and provides fixed anatomic landmarks for dissection. For large lesions, consideration should be given to a medial maxillectomy for exposure.

Use of image guidance is important.

Specific surgical landmarks of the palatine bone (orbital, pterygoid roots) should be identified.

A drill should be used when necessary to remove the dense bone of the pterygoid process.

One should be prepared to extend the approach with a Caldwell-Luc procedure or endoscopic Denker approach (see Chapter 22 ) for expanded access lateral to the infraorbital nerve.

Any branches of the maxillary artery encountered must be identified and cauterized. They may go into spasm and can cause profuse bleeding postoperatively.

Undertake the usual preparations for endoscopic sinus surgery:

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  Topically vasoconstrict and anesthetize the nasal cavities with pledgets soaked in 4% cocaine, oxymetazoline, or 1:1000 epinephrine.

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  Inject 1% lidocaine with 1:100,000 epinephrine into the axilla of the middle turbinate and the region of the sphenopalatine foramen. Intraoral injection of the greater palatine foramen can be performed as well.

Maxillary artery ligation is often performed as part of pterygopalatine fossa surgery for both access and preemptive vascular control.