Infratemporal Fossa Approach 

In 1961, Fairbanks-Barbosa was the first to report an infratemporal fossa (ITF) approach, indicated for advanced tumors of the maxillary sinus.^[1] Transtemporal approaches described by Fisch, preauricular approaches described by Schramm and Sekhar, and transmaxillary approaches described by Terz, Janecka, and Cocke validated the efficacy of and indications for this technique, and provided the framework for other modifications.^{[2, 3, 4]} Recently, transnasal endoscopic and endoscopic-assisted approaches have been added to the armamentarium of skull base surgeons. See the image below.

Any of the structures contained within or surrounding the ITF may be the origin of a tumor. Although rare, the ITF may also be affected by metastasis. Evaluation of patients with ITF tumors requires the identification of their nature, origin, and extent. These factors, as well as the biologic behavior of the tumor, the patient's needs and demands, comorbidities, and the training and experience of the surgeon influence the selection of the surgical approach. A multidisciplinary team is critical to ensure an adequate diagnosis, staging, tumor extirpation, and reconstruction of consequent cosmetic and functional deficits.

Patients with ITF tumors can present with various symptoms depending on the structures affected. Mass effects, eustachian tube dysfunction, trismus, and cranial neuropathies are common. Physical examination is inadequate to evaluate the ITF; therefore, imaging is the keystone of the clinical evaluation.

An infratemporal fossa approach is a complex procedure that involves significant time, effort, and cost; therefore, under most circumstances, one must consider the procedure only as part of a curative therapeutic plan. Endoscopic approaches are more appropriate than conventional approaches if the goal is palliation. However, in select patients, a transnasal endoscopic approach may be used as the sole approach, yielding a complete resection that is equivalent to that of a conventional approach. Note that the indications for an endoscopic approach are in a state of rapid flux. Technology, new instrumentation, and experience drive the design and advancement of these and other minimally invasive techniques. Thus, some of these factors determine the selection of a conventional versus an endoscopic approach.

An ITF approach may provide the access required for the resection of a tumor, or it may be adjunctive to other approaches, such as transcranial-subtemporal, Le Fort I, transmaxillary, or anterior subfrontal approaches. Infrequently (ie, when fine-needle aspiration biopsy [FNAB], true-cut biopsies, and other means have failed to obtain an adequate sample), an ITF approach is used to obtain an adequate biopsy. In these cases, the endonasal endoscopic approach is preferable to conventional approaches.

Indications for a preauricular approach include tumors that originate in the ITF and intracranial tumors that originate at the anterior aspect of the temporal bone or greater wing of the sphenoid bone and that extend into the ITF. A preauricular approach may also be combined with other approaches to expose tumors that extend posteriorly or anteriorly. However, the preauricular approach provides inadequate exposure for the resection of tumors that invade the tympanic bone and does not provide adequate access to the intratemporal facial nerve or jugular bulb.

The postauricular approach is designed to expose and resect lesions that involve the temporal bone and that extend into the ITF.

The transfacial approach is best used to resect sinonasal tumors that require maxillectomy and that invade the ITF, the masticator space, or the pterygomaxillary fossa and for tumors of the nasopharynx extending into the ITF. However, the authors reserve its use for cancers of the antrum that extend into the ITF.

The techniques for endoscopic approaches to the ITF are in rapid evolution, spearheaded by the emergence of technology geared to this type of surgery. Indications for these approaches are likewise in a state of flux, parallel to these advancements. At present, the transnasal endoscopic approaches are mostly used for benign tumors of the sinuses, nose, and throat (ie, juvenile angiofibroma), tumors that arise at the infratemporal fossa (eg, trigeminal neurilemoma) or skull base (ie, meningiomas). This approach is also indicated for select malignancies, such nasopharyngeal carcinomas that persist or recur after chemoradiation and do not involve the internal carotid artery (ICA), or as palliative debulking of cancers of the sinuses, nose, and throat, such as adenoid cystic carcinoma.

The infratemporal fossa (ITF) is a potential space bounded superiorly by the temporal bone and the greater wing of the sphenoid bone; medially by the superior constrictor muscle, the pharyngobasilar fascia, and the pterygoid plates; laterally by the zygoma, mandible, parotid gland, and masseter muscle; anteriorly, by the pterygoid muscles; and posteriorly by the articular tubercle of the temporal bone, glenoid fossa, and styloid process. By this definition, the ITF comprises the contents of both the parapharyngeal space (ie, internal carotid artery [ICA], internal jugular vein [IJV], cranial nerves [CN] IV to XII) and the masticator space (ie, V3, internal maxillary artery [IMA], pterygoid venous plexus, pterygoid muscles).

The ITF communicates with the middle cranial fossa via the neurovascular foramina (ie, carotid canal, jugular foramen, foramen spinosum, foramen ovale, foramen lacerum). Medially, the ITF communicates with the pterygopalatine fossa via the pterygomaxillary fissure, which is contiguous with the inferior orbital fissure and, thus, the orbit.

Benign tumors usually respect these boundaries and expand the ITF in the direction of its soft-tissue planes, or they follow preexisting pathways (eg, foramen ovale, pterygomaxillary fissure). Conversely, malignant tumors can infiltrate and destroy all structures within the ITF and adjacent spaces.

The presence of neurovascular structures within the ITF (eg, ICA) or adjacent to it (eg, CN VII) limits the exposure of any particular surgical approach to the ITF. Thus, surgical approaches are designed not only to remove the tumor but also to preserve and identify these neurovascular entities.

Patients in whom an ITF approach or dissection are contraindicated include those with lymphoreticular tumors, which are best treated with radiation and/or chemotherapy; patients who are poor surgical candidates due to pulmonary, cardiac, renal, or other significant co-morbidities; and patients with disseminated disease. The main limiting factor in choosing an ITF approach is extension of the tumor and its relationship to neurovascular structures.