28.1 Introduction

Juvenile angiofibromas (JA) are challenging tumors to treat surgically because of their vascularity and anatomical location. They likely originate from remnants of the first branchial arch artery and some authors consider them to be vascular malformations. ^{1 , 2} Traditionally, JAs are classified as benign tumors with locally aggressive features. They arise from the lateral basisphenoid and extend through foramina and fissures: (1) the sphenopalatine foramen into the nasopharynx and paranasal sinuses, (2) the pterygomaxillary fissure into the infratemporal fossa, and (3) the infraorbital fissure into the orbit. JAs have the potential for skull base erosion and intracranial extension, as seen in 10 to 20% of cases. ³ True dural invasion is rare and the tumor will usually have a well-circumscribed pushing border. Tumors that extend medial to the orbital apex can erode the bone of the planum sphenoidale to gain access to the anterior cranial fossa. JA can also extend to the middle cranial fossa through the inferior orbital fissure, orbital apex, and superior orbital fissure.

Recent advances in endoscopic endonasal surgery (EES) now allow surgeons to resect advanced JAs. A growing body of evidence supports purely endoscopic and endoscopic-assisted approaches. Case series and systematic reviews demonstrate favorable rates of residual and recurrent disease with reduced morbidity (▶ Table 28.1). ^{4 – 6}

28.2 Preoperative Evaluation and Anesthesia

Evaluation of tumor extension and staging is mandatory for optimal surgical planning. Computed tomography (CT) and magnetic resonance imaging (MRI) are both essential to assess tumor extension and can be used for intraoperative image guidance. Imaging should be obtained prior to angiographic embolization as embolized tumor segments are more challenging to delineate. CT is superior for identification of bony landmarks and remodeling and destruction of bone. Characteristic findings include anterior bowing of the posterior wall of the maxillary sinus (Holman–Miller sign) and tumor infiltration of the pterygoid base. ^{7 , 8} CT angiogram is useful for intraoperative navigation of the internal carotid artery (ICA). MRI is better for assessing soft tissues and intracranial extension. On MRI, JAs appear isointense to hyperintense on T1- and T2-weighted sequences. Flow voids related to small high-flow vessels supplying the tumor can be seen. There is intense enhancement following administration of gadolinium contrast.

Angiography is used to identify vascular contributions to the tumor. Combined with embolization, it reduces blood loss that improves visualization and tumor resection. It is commonly performed 24 to 48 h before the surgery. ⁸ In advanced JAs, both external carotid artery (ECA) and ICA can supply feeding vessels to the tumor. Bilateral vascular supply is also common in advanced tumors. ⁹ Residual vascularization from the ICA following embolization of ECA branches is predictive of increased operative blood loss. ¹⁰ Although feeders from the ICA can be embolized, the risk of complications (stroke, visual loss, facial paralysis, carotid dissection) is significant and its routine use is not recommended. ^{11 – 14} Preoperative balloon occlusion testing of the ICA may be considered with extensive tumors that encase the ICA, especially in surgical or radiation failures where risk of vessel injury is higher. This will assess the adequacy of the collateral circulation and the feasibility of carotid sacrifice, if necessary.

UPMC staging system (▶ Table 28.2 and ▶ Fig. 28.1) accounts for tumor vascularity derived from intracranial circulation and the route of intracranial extension. ^{10 , 15} Compared to previous staging systems, the UPMC staging system demonstrates stronger correlation with intraoperative blood loss, need for multiple surgeries (staged), and residual or recurrent tumor.

Advanced JAs demand special anesthetic consideration. Prior adjuvant radiation therapy, angiographic embolization, or surgical dissection of the masticatory space can result in difficult intubation due to trismus. ¹⁶ Large tumors may displace the soft palate inferiorly or extend to the oropharynx. With intracranial extension, increased intracranial pressure (ICP) may be present. ¹⁷ Measures to be considered in this setting are: smooth induction of anesthesia, invasive monitoring of blood pressure, and promotion of moderate hyperventilation. Invasive hemodynamic monitoring will provide safe hypotensive anesthesia and guide intravascular replacement strategies, if needed. In EES for advanced JAs, the average blood loss is more than 1000 mL. ⁴ In a patient population with low intravascular volume, excessive blood loss with consumption, dilution, and dysfunction of clotting factors and platelets can result in intraoperative coagulopathy. ¹⁸ Monitoring with thromboelastometry and early replacement of clotting factors are part of the management. ¹⁹ Restrictive transfusion strategies have been proposed to reduce the potential for transfusion-related complications (at Hb of 7–8 g/dL). ²⁰ However, a strict transfusion threshold is difficult to recommend as this decision depends on many factors such as patient comorbidities and ongoing surgical variables. ¹⁸ Staging of surgery should be considered for large UPMC stage IV/V tumors if blood loss is excessive (50–100% of total blood volume), especially if significant tumor remains.

In patients where there is risk of ICA injury, neurophysiologic monitoring of cortical function (somatosensory-evoked potentials) is performed to detect global brain ischemia. Cranial nerves with motor function (III, IV, VI, and V₃) can be monitored with electromyography (EMG). EMG aids in detection and protection of nerves with dissection and provides prognostic information for recovery. ²¹