Summary
Endoscopic approach for the resection of juvenile angiofibroma (JA) has become the mainstay of treatment of this lesion, and more advanced lesions are being managed by a pure endoscopic approach. In this chapter, we present the endoscopic endonasal approach for JA in a step by step manner.
27 Endoscopic Treatment of Juvenile Angiofibroma: Surgical Technique
27.1 Introduction
JA is a rare vascular lesion of the nasopharynx and nasal cavity. It affects young male adolescents mainly between 9 and 19 years old. 1 JA is a highly vascular tumor composed of a proliferating and irregular vascular component within a fibrous stroma. JA originates from the upper portion of the sphenopalatine foramen where the sphenoid process of the palatine bone meets the sphenoid bone and vomer (▶ Fig. 27.1).
Although benign, JA has a local invasive and destructive behavior, and has the tendency to spread not only through minor resistance areas, but also through fissures and sutures and even by direct invasion of cancellous bone.
JA follows a characteristic pattern of spread, which distinguishes it from other vascular lesions of the pediatric skull base. From its origin in the sphenopalatine foramen, JA spreads to the nasal cavity and nasopharynx in a submucosal and subperiosteal plane. Laterally it usually spreads anterior to the pterygoid plates and involves the pterygopalatine fossa (PPF) in more than 70% of cases. 2 Filling the PPF, the lesion anteriorly displaces the posterior maxillary wall, and in extreme cases the maxillary sinus is obliterated. Posteriorly, the tumor remodels and erode the pterygoid plates and may reach the pterygoid fossa. Laterally, the tumor spreads through the pterygomaxillary fissure to the infratemporal fossa (ITF). Superiorly JA spreads through the inferior orbital fissure (IOF) to involve the orbit and through the superior orbital fissure (SOF) and foramen rotundum it reaches the cavernous sinus. The sphenoid sinus can be involved by a submucosal spread of the tumor from the nasopharynx as well as through erosion and expansion of the vidian canal. A posterolateral route of extension is less common, and consists of tumor spread from the nasopharynx to the pharyngeal recess, and laterally to the pterygoid fossa posterior to the medial pterygoid plate or through erosion of the medial pterygoid plate. From the pterygoid fossa JA may progress to the parapharyngeal space laterally, while superior extension will involve the foramen lacerum and carotid canal. Bony involvement by JA can have one of three patterns: erosion, remodeling, and direct cancellous bone invasion. JA spreads through fissures and foramens by means of expansion, thinning, and remodeling of the involved bones, and has a tendency to erode and involve cancellous bone, most typical in the clivus and pterygoid base. Large tumors with extensive infratemporal spread may also destruct the greater sphenoid wing. Intracranial extension occurs in 10% to 20% of cases, while intradural extension is very rare 3 (Box 27.1).
Box 27.1 Juvenile angiofibroma pattern of spread
JA originate from the sphenopalatine foramen
In more the 70% involve the PPF
Vidian canal and cancellous bone invasion are typical findings
10–20% IC extension, extradurally
Surgical treatment of JA is challenging due to the young age of the patients, the complexity of skull base anatomy, and the rich vascularity of the lesion. Many external approaches have been used for surgical excision of JA, including transpalatal, Le Fort I osteotomies, lateral rhinotomy, midfacial degloving, facial translocation, anterior craniofacial and lateral infratemporal/subtemporal approaches. Each approach has its own advantage over the other according to tumor extent. Midfacial degloving has been widely adopted due to avoidance of facial scars. However, external approaches usually involve extensive osteotomies which are associated with increased blood loss, and may interfere with the normal facial growth of the adolescent patient. Since Kamel 4 first introduced the endoscopic endonasal approach for resection of JA, this approach gained increasing popularity and was recently adopted in large centers for advanced tumors. 5 – 11 The endoscopic approach has many advantages over external transfacial approaches, which include the avoidance of facial incisions, osteotomies, and bone plating, which do not expose young patients to the risk of craniofacial alterations. In addition, the magnified field of view and angled view “behind the corner” may be associated with more complete inspection of the resection cavity and shorter hospitalization time. In this chapter, we present the endoscopic endonasal approach for JA in a step by step manner.
27.2 Diagnosis and Preoperative Management
JA is often suspected when a young male boy presents with nasal obstruction and epistaxis. Nasal endoscopy commonly shows a hypervascularized lobulated mass with a smooth surface typically bulging behind the tail of the middle turbinate, obstructing the choana or completely filling the nasal fossa (▶ Fig. 27.2).
Diagnosis is made by the typical clinical and imaging findings, while tissue biopsy is unnecessary and may lead to brisk hemorrhage. At imaging, JA appears as a highly vascularized and expansile lesion centered on the PPF in both contrast-enhanced computerized tomography (CT) and gadolinium-enhanced magnetic resonance imaging (MRI). CT and MRI are complementary in the diagnosis of JA, as CT emphasizes skull base bony involvement while MRI is superior in the demonstration of intracranial, orbital, and cavernous sinus invasion. On both T1- and T2-weighted, unenhanced MRI, the lesion shows flow-void spotty signals, due to enlarged blood vessels. The typical pattern of spread of JA and the typical bony changes associated with this lesion as well as its rich vascularity distinguish this lesion from other lesions that may involve the skull base, and obviate the risk of tissue sampling (▶ Fig. 27.3).
Staging is most commonly according to Andrews 12 or Radkowski’s 13 staging systems. Recently, Snyderman et al 15 proposed the UPMC staging system, emphasizing the role of residual tumor vascularization by the ICA following embolization and the route of intracranial extension (medial or lateral to ICA and cavernous sinus) as the most important factors for determining the feasibility of endoscopic resection and the risk of residual or recurrent tumor. ▶ Table 27.1 shows the staging systems most commonly highlighted in the literature.
Preoperative embolization is usually considered for all cases of JA except for very small lesions. Embolization is done through a transarterial approach (TAE). This technique uses small particle material (PVA—polyvinyl alcohol, microspheres, …) that is introduced by a superselective catheterization of the feeding vessels. In advanced JA lesions, a blood supply from the ICA branches should be sought, as embolization in these feeders is discouraged, as it may result in neurologic complications due to particle dislodgement to the central nervous system. Embolization should be done close to the scheduled operation, usually within 24 to 72 hours before the surgery, as collateral blood supply may develop and reduce the efficacy of embolization (Box 27.2).
Box 27.2 Preoperative embolization
Transarterial embolization should be done 24–72 hours before surgical intervention
Embolization is discouraged in cases with significant ICA blood supply
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