Practice Essentials
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 give origin to 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.
A retrospective study by Amit et al reported that in patients with ITF carcinomas with skull base involvement, patient age, preoperative performance status, and margin status significantly impact disease-specific survival prognosis. Improved tumor control rates and disease-specific survival were associated with the achievement of negative margins, while the probability of local recurrence was greater in association with lower preoperative performance status and positive surgical margins. With negative margins obtained in 23 individuals (58%), patients had median disease-specific survival and local progression-free survival durations of 32 and 12 months, respectively. [5]
Workup in infratemporal fossa tumors
Computed tomography (CT) and magnetic resonance imaging (MRI) scans provide important and complementary information. [6] A CT scan better depicts the remodeling or erosion of the bony skull base, while an MRI scan better depicts the soft-tissue planes (including the interface of the tumor and soft tissues) and the presence of perineural and perivascular tumors.
MR angiography (MRA) and CT angiography (CTA) are noninvasive tests that demonstrate the arterial anatomy of the ITF and brain.
The collateral blood supply to the brain is better evaluated using single-photon emission computed tomography (SPECT) scanning with balloon occlusion, transcranial Doppler, or angiography and balloon occlusion with xenon-enhanced computed tomography (ABOX-CT) scanning.
Whenever possible, obtain a histologic diagnosis before the extirpative surgery.
Management of infratemporal fossa tumors
A tracheotomy (for tracheal toilette) and a gastrostomy tube (for nutrition, hydration, and administration of medications) are often necessary during the perioperative period. Alternatively, patients with a proximal vagal paralysis may benefit from a medialization laryngoplasty and an arytenoid adduction procedure. Laryngeal framework surgery may be performed concurrent with tumor removal or during the early postoperative period. Laryngeal framework surgery improves the glottic closure, thus decreasing aspiration risk and restoring an adequate cough. These improvements often obviate the need for a tracheostomy for the sole purpose of tracheopulmonary toilet.
Approaches to infratemporal tumors include the following:
-
Preauricular (subtemporal) approach
-
Postauricular (transtemporal) approach
-
Anterior transfacial approach (facial translocation)
-
Transorbital approach - Reserve this approach for patients with benign tumors of the orbital apex and cavernous sinus who have lost vision because of tumor growth; a transorbital approach also may be employed for low-grade malignant neoplasms with minimal involvement of the orbital soft apex or optic nerve, to obtain complete tumor removal
-
Endoscopic transpterygoid approach - An endoscopic approach requires a wide corridor created with the removal of the middle turbinate ipsilateral to the lesion, a posterior septectomy, and bilateral wide sphenoidotomies
-
Endoscopic transoral approach - Chan et al described a novel transoral endoscopic approach to the infratemporal fossa and parapharyngeal space that uses the space between the mandibular ramus and maxillary tuberosity as the surgical corridor
Presentation
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.
Indications
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 endoscopic endonasal 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.
Parapharyngeal space tumors
A retrospective study by Poletti et al evaluating surgical treatment of parapharyngeal space tumors indicated that the ITF, transparotid-transcervical, transcervical-transmandibular, or petro-occipital-trans-sigmoid approach is required for large or malignant tumors or for those with skull base involvement and transcranial extension. [7]
Relevant Anatomy
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). [8, 9]
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.
Neurovascular structures within the ITF (eg, ICA) or adjacent to it (eg, CN VII) limit 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.
A study by Lawrence et al indicated that in terms of the ITF’s vascular structures, the dimensions obtained through cadaveric analysis correlate with those determined via CT scanning of the head. Dissection of the infratemporal fossa (two cadaveric specimens, three dissections) revealed the mean distances of the foramen ovale to the internal carotid artery and the middle meningeal artery to be 2.4 cm and 0.8 cm, respectively, while with CT scanning (52 patients, 104 sides) these lengths were determined to be 1.70 cm and 0.73 cm, respectively. [10]
Contraindications
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.
-
Coronal view MRI depicting a V3 neurilemoma.
-
Axial view MRI depicting V3 neurilemoma of the infratemporal fossa.
-
Bicoronal incision with preauricular extension.
-
The superficial layer of the deep temporal fascia has been incised, revealing the temporal fat pad.
-
Exposure of orbitozygomatic complex.
-
Depiction of possible orbitozygomatic osteotomies.
-
Skull base relationships. The lateral pterygoid plate, foramen ovale, and the foramen spinosum are depicted in a straight-line relationship from anterior to posterior. The carotid canal is posterior and medial to these structures.
-
A temporal craniotomy and osteotomy for condylectomy and coronoidectomy.
-
From posterior to anterior (left to right), internal carotid artery (petrous), middle meningeal artery, V3, and V2.
-
Intraoperative photograph after a total parotidectomy, segmental mandibulectomy, and infratemporal fossa resection.
-
Markings depicting the facial incisions for a facial translocation approach.
-
Exposure of the maxillary and orbitozygomatic areas.
-
Osteotomies.
