Endoscopic Transnasal Anatomy of the Infratemporal ...

Original Article 261

Endoscopic Transnasal Anatomy of the Infratemporal Fossa and Upper Parapharyngeal Regions: Correlations with Traditional Perspectives and Surgical Implications Authors

I. Dallan1, R. Lenzi1, M. Bignami2, P. Battaglia2, S. Sellari-Franceschini1, L. Muscatello1, V. Seccia1, P. Castelnuovo2,4, M. Tschabitscher3,4

Affiliations

1

Key words ▶ infratemporal fossa ● ▶ endoscopy ●

Abstract ▼

Bibliography DOI http://dx.doi.org/ 10.1055/s-0030-1263105 Minim Invas Neurosurg 2010; 53: 261–269 © Georg Thieme Verlag KG Stuttgart · New York ISSN 0946-7211 Correspondence I. Dallan, MD ENT Unit Azienda OspedalieroUniversitaria Pisana Via Savi 10 56100 Pisa Italy Tel.: + 39/050/993 284 Fax: + 39/050/993 239 [email protected]

Unit of Otorhinolaryngology, Department of Neuroscience, University of Pisa, Pisa, Italy Otorhinolaryngologic Unit, University of Insubria, Varese, Italy 3 Department of Systematic Anatomy, Medical University of Vienna, Vienna, Austria 4 P. Castelnuovo and M. Tschabitscher should both be considered as last author 2

Background: The aim of this study was to illustrate the endoscopic surgical anatomy of the infratemporal fossa (ITF) and upper parapharyngeal space and to provide useful landmarks by comparing transnasal perspectives with external ones. Materials and Methods: 6 fresh double injected heads were dissected. External lateral dissection was performed through a pre-auricular skin incision while external anterior dissection started with a modified Weber-Ferguson incision. External medial to lateral dissection was performed starting from the rhinopharyngeal and pterygoid regions, after cutting the specimen in 2 halves passing through the nose. Endoscopic dissection was performed through an endonasal approach (0 ° and 45 ° scopes). Results: Among all the structures identified during the dissection, the most useful landmark when dissecting the ITF in a lateral to medial

Introduction ▼ The infratemporal fossa (ITF) is one of the most complex areas of the whole body and represents a great challenge for the head and neck surgeon. Important muscular, vascular and neural structures are present in this region. Up until the 1960 s the ITF area was considered surgically inaccessible and tumors extending into the infratemporal fossa were considered inoperable. Due to the pioneering work of Conley [1] and Barbosa [2], this situation has been overthrown. Nevertheless, the anatomic complexity of this region makes surgical approaches challenging even for the skilled surgeon. The aim of our study is to provide an accurate description of the anatomy of the ITF and the upper parapharyngeal space, correlating the endoscopic vision to the

direction is the lateral pterygoid muscle. In anterior approaches (mostly endoscopic) the role of the lateral pterygoid muscle is less important and the Eustachian tube (ET) represents the most important landmark to point out the upper portion of the parapharyngeal internal carotid artery (ICA). The role of the ET, in lateral dissection is, on the contrary, by far less important given the fact that it is very deep in the surgical field and that the ICA is encountered earlier during surgical approaches. Another crucial landmark during anterior endoscopic surgery is the vidian nerve because it points to the anterior genu of the internal carotid artery. Conclusion: The complex 3-dimensionality of the ITF and the upper parapharyngeal space needs a sound knowledge of the surgical anatomy. The role of the same landmarks changed in different approaches. The ability to orientate oneself in this complex area is related to an accurate knowledge of its anatomy through comparison of endoscopic and external perspectives.

traditional perspectives. The fusion of the different viewpoints is thought to improve the ability to visualize this region 3 dimensionally. Basing our considerations on this, we maintain that a better understanding of this anatomy may lead to less invasive approaches to ITF and upper parapharyngeal pathologies.

Materials and Methods ▼ This study was carried out at the Department of Systematic Anatomy of the Medical University of Vienna. The study was approved by the local institutional research committee. 6 fresh heads were prepared for dissection after the injection of coloured liquid silicone into the arterial and venous beds (red and blue, respec-

Dallan I et al. Endoscopic Transnasal Anatomy of the Infratemporal Fossa … Minim Invas Neurosurg 2010; 53: 261–269

262 Original Article

tively). The heads were considered good specimens for dissection if the small vessels of the tongue had been well injected. External dissection was performed using microscope and loupes (6 × ) while endoscopic dissection was performed using 0 ° and 45 ° endoscopes. Powered instrumentation was seldom used because it is considered not optimal for obtaining adequate images. External lateral dissection started with a pre-auricular skin incision extending from the neck to the superior temporal line with an anterior displacement of the superficial flap. Anatomic structures of the infratemporal fossa were identified and dissected stepwise until the skull base and lateral pharyngeal wall were exposed. External anterior to posterior dissection started with a modified Weber-Ferguson incision with a lateral displacement of the superficial flap. The creation of a maxillary window opens up into the infratemporal and pterygopalatine fossae, that were subsequently dissected carefully. External medial to lateral dissection was performed starting from the rhinopharyngeal and pterygoid regions, after cutting the specimen in 2 halves passing through the nose. Documentation of the dissection was obtained both with a digital camera and recording system and correlated with illustrative 3 dimensional reconstructions.

Anatomic Results ▼ Anatomically the infratemporal fossa is located below and medial to the zygomatic arch, behind the maxilla and inferior to the temporal bone. From a lateral perspective, access through

Fig. 1 a Anatomic reconstruction showing the relationship between vascular, neural and muscular structures of the right infratemporal fossa. b–f Cadaver dissection. Right infratemporal seen from anterior view (b), lateral view (c). In d it is showed an endoscopic vision of the paramandibular region of the left infratemporal fossa. e Endoscopic vision of the right infratemporal fossa; f endoscopic vision of the left infratemporal

and below the parotid gland leads to a narrow space where the retromandibular vein, external carotid artery (ECA) and, superficially, the facial nerve dividing into its major branches can be identified. On opening up this space the posterior belly of the digastric muscle and the stylohyoid muscle become visible on a deeper plane. The ECA, originating from the common carotid artery, lies deeper to the posterior belly of the digastric muscle close to the stylohyoid muscle. Medially to these muscles the occipital artery arises from the ECA, passes between them and reaches the mastoid process of the temporal bone running over the posterior belly of the digastric muscle. The maxillary artery (MA), one of the 2 terminal branches of the ECA, usually runs anteriorly over the sphenomandibular ligament first and the lateral pterygoid muscle after [3]; the relationship of the artery with this muscle is not constant and the artery can be located on the medial or lateral surface of the muscle itself. The MA travels along the ITF and it is possible to identify 3 segments: mandibular, pterygoid and pterygomaxillary. The artery reaches the pterygomaxillary fissure, a space that divides the ITF from the pterygopalatine fossa. At this level the MA divides into its terminal branches (sphenopalatine a., descending palatine a., infraorbital a., palatovaginal a.). As a whole all these vessels create a complex vascular network. In anterior approaches this network is the first anatomic plane after the realization of the maxillary window and the resection of the periostium. Endoscopically this vascular arborization is clearly visible. Coming from the anterior, below the vascular plane it is possible to identify the lateral pterygoid muscle, horizontally oriented, that connects the neck of the mandibular con▶ Fig. 1). dyle to the lateral aspect of the pterygoid plate (● Caudally positioned to the lateral pterygoid muscle the medial

fossa. ATn, auricolotemporal nerve; ET, Eustachian tube; IAN, inferior alveolar nerve; LN, lingual nerve; LPM, lateral pterygoid muscle; MA, maxillary artery; MMA, middle meningeal artery; MPM, medial pterygoid muscle; ICAp, parapharyngeal portion of the internal carotid artery; TM, temporalis muscle; TVPM, tensor veli palatini muscle; V3, mandibular nerve.



pterygoid muscle is visible, originating medially at the pterygoid plate and connecting this structure with the inner surface of the mandibular ramus and angle. On its lateral surface lie the infe▶ Fig. 1). Usually, by rior alveolar nerve and the lingual nerve (● means of careful dissection, it is possible to identify, on the posterior aspect of the lingual nerve, the anastomosis with the chorda tympani nerve (from the VII c. n.), coming out from the petrous bone. The venous network within the infratemporal fossa is extremely variable in shape and forms the so-called pterygoid plexus. Attempts to describe this network in detail are usually frustrating and certainly, given its extreme variability, of limited surgical interest. Just behind the lateral pterygoid muscle, in the medial portion of the ITF, the tensor and levator veli palatini muscles lie. These muscles are strictly related to the Eustachian tube (ET). The tensor, lateral to the superior constrictor muscle, runs inferiorly and curves horizontally at the level of the hamulus of the medial pterygoid plate while the levator muscle runs medially and inferiorly, medial to the superior constrictor muscle and reach the ▶ Fig. 2). By passing rhinopharyngeal surface of the soft palate (● laterally in relation to the tensor veli palatini muscle and the superior constrictor muscle we reach the parapharyngeal portion of the ICA and immediately lateral to it the internal jugular ▶ Fig. 3). vein (IJV) with the lower cranial nerves (● On the lateral surface of the IJV it is possible to visualize the styloid process and the muscles attached to it (stylopharyngeus, styloglossus and stylohyoid). At this point the posterior surface of the rhinopharyngeal wall with the longus capitis muscle and, a little further down, the longus colli muscle can be exposed. By lateralizing the internal carotid artery and passing through this narrow window the stellate ganglion (sometimes) and the

hypoglossal nerve can be visualized in this latero-vertebral ▶ Fig. 4). By moving upward the hypoglossal canal at the region (● basiocciput can be visualized as well. Covered by the lateral pterygoid muscle the mandibular nerve (V3) emerges from the ▶ Fig. 5) and skull base passing through the foramen ovale (● divides after a short course into 2 main trunks: the anterior and the posterior one. The latter further divides into 3 branches, the auricolotemporal nerve, inferior alveolar nerve and lingual nerve. From the anterior one generally originate 2 or 3 branches for the temporal muscle, the buccal nerve, the masseteric nerve and the nerve for the lateral pterygoid muscle. Before dividing the mandibular nerve gives rise to 3–4 branches: for the middle cranial fossa dura, for the medial pterygoid muscle, for the tensor tympani muscle and the tensor veli palatini muscle. The auricolotemporal nerve runs posteriorly to reach and join the superficial temporal artery in its course. Doing this, it encounters and envelops, dividing temporarily into 2 branches, the middle meningeal artery (MMA). This vessel is a branch of the MA that runs vertically to enter into the skull through the ▶ Fig. 6), a little posterior and lateral to the foramen spinosum (● foramen ovale. In lateral approaches the MMA is visualized earlier than V3. From an endoscopic viewpoint it is not so easy to identify the nerves for the medial pterygoid muscle, the tensor tympani muscle and the tensor veli palatini muscle. Regarding the vascular network it is possible to visualize endoscopically other branches of the MA within the infratemporal fossa (the inferior alveolar a., the sphenopalatine a., the descending pala▶ Fig. 6). The tine a., the palatovaginal a. and the infraorbital a.) (● palatovaginal a. can be better visualized in the roof of the rhinopharynx, once the mucosa has been dissected away from the basisphenoid. Rarely the deep temporal arteries (anterior and Fig. 2 a Anatomic drawing: medial view of the right parapharyngeal region. b Cadaver dissection: medial view of the left rhinopharyngeal region. c Cadaver dissection: endoscopic anterior view of the right infratemporal fossa. d Anatomical drawing: right infratemporal fossa from an anterolateral perspective. ET, Eustachian tube; ICAp, parapharyngeal portion of the internal carotid artery; LVPM, levator veli palatini muscle; MA, maxillary artery; MPP, medial pterygoid plate; SCM, superior constrictor muscle; TVPM, tensor veli palatini muscle; VP, venous plexus; V3, mandibular nerve.



Fig. 3 Relationship between the great vessels of the neck and the surrounding structures seen through a lateral (a) and endoscopic anterior views of the right infratemporal fossa (b, c, d). DM, digastric muscle, ET, Eustachian tube; ICAp, parapharyngeal portion of the internal carotid artery; IJV, internal jugular vein; LN, lingual nerve; LVPM, levator veli palatini muscle; PG-AT, parotid gland-adipous tissue; SMs, styloid muscles; SP, styloid process; TVPM, tensor veli palatini muscle; V3, mandibular nerve.

Fig. 4 a Anatomic drawing of the right infratemporal fossa seen from an anterior perspective. b–d Endoscopic anterior views of the right infratemporal fossa. HN, hypoglossal nerve; ICAp, parapharyngeal portion of the internal carotid artery; IJV, internal jugular vein; LC, longus capitis; MA, maxillary artery; MPM, medial pterygoid muscle; NS, nasal septum; RP, rhinopharynx; SCM, superior constrictor muscle; SP, soft palate; TVPM, tensor veli palatini muscle; V3, mandibular nerve.



Fig. 5 a Anatomic drawing of the right infratemporal fossa seen from an anterior perspective. b Endoscopic transnasal view of the right infratemporal fossa. c External anterior view of the right infratemporal fossa. d Medial view of the left infratemporal fossa. CT, chorda tympani; DPA, descending palatine artery; ET, Eustachian tube; ICAp, parapharyngeal portion of the internal carotid artery; LC, longus capitis; LN, lingual nerve; LPM, lateral pterygoid muscle; LPP, lateral pterygoid plate; MA, maxillary artery; MMA, middle meningeal artery; MPM, medial pterygoid muscle; NS, nasal septum; RP, rhinopharynx; SCM, superior constrictor muscle; SP, soft palate; VN, vidian nerve; V3, mandibular nerve.

Fig. 6 Maxillary artery and its branches seen from external lateral view (a, d), from an anterior non-endoscopic approach (b) and from an endoscopic approach (c). aDTA, anterior deep temporal artery; ATn, auricolotemporal nerve; CT, chorda tympani; DPA, descending palatine artery; ET, Eustachian tube; IOA, infraorbital artery; LN, lingual nerve; LPM, lateral pterygoid muscle; LLP, lateral pterygoid plate; MA, maxillary artery; MMA, middle meningeal artery; pDTA, posterior deep temporal artery; PPG, pterygopalatine ganglion; SAA, superior alveolar artery; SPA, sphenopalatine artery; TM, temporalis muscle; V2, maxillary nerve; V3, mandibular nerve.



Fig. 7 a Relationship between the internal carotid artery and Eustachian tube seen from lateral view (left infratemporal fossa). b Anatomic preparation of the same region (axial section). c Anatomic drawing, from anterolateral view (right infratemporal fossa). d endoscopic transnasal view of the left infratemporal fossa. BA, basilar artery; ET, Eustachian tube; FN, facial nerve; ICAh, horizontal portion of the internal carotid artery; IAN, inferior alveolar nerve; ICAp, parapharyngeal portion of the internal carotid artery; IJV, internal jugular vein; LN, lingual nerve; MA, maxillary artery; MMA, middle meningeal artery; MPM, medial pterygoid muscle; TM, temporalis muscle; tM, tympanic muscle; TVPM, tensor veli palatini muscle; VN, vidian nerve; V3, mandibular nerve.

posterior), the buccal artery and other minor vessels that feed the surrounding soft tissues can be recognized clearly. Certainly their position is quite variable within the infratemporal fossa and for this reason dissection has to be as careful as possible. The mandibular nerve, becoming extracranial at the foramen ovale, lies on the lateral surface of the Eustachian tube which from the middle ear descends inferiorly, anteriorly and medially to open into the rhinopharynx. The intimate relationship between the ICA, the ET and V3 must be strongly underlined ▶ Fig. 7). We strongly uphold the critical role of the ET in (● detecting the superior portion of the parapharyngeal ICA and consequently the jugular foramen area. From a clinical point of view the extreme variability of the position of the parapharyngeal portion of the ICA represents a great challenge for the surgeon. This structure is in close relation with the pharyngeal wall; sometimes it can be located behind the posterior wall or more commonly in close relation to the lateral wall of the pharynx. In lateral dissection this aspect is less important because the vessel is under visual control once the carotid canal and the jugular foramen area are exposed. From an endoscopic perspective the infraorbital nerve is identified in the roof of the maxillary sinus and by tracing this nerve posteriorly, it is possible to visualize the maxillary nerve and, step by step, the foramen rotondum. From here the door to the gasserian ganglion and cavernous sinus can be opened after the bone of the great sphenoidal wing is drilled out around the skull base foramina. A little medial and inferior to the maxillary nerve it is possible to identify the vidian canal. The easiest way to identify the vidian canal endoscopically is to drill at the base of the medial pterygoid plate. It is possible to create a surgical operative corridor to the Meckel’s cave passing between the vidian canal and V2 [4].

As stressed by many authors the vidian nerve is a crucial landmark to identify the ICA during endonasal skull base surgery ▶ Fig. 8). Once the anterior genu of the carotid is under [5, 6] (● control and the carotid artery is exposed as far as the intracranial portion, it is possible to extend the dissection laterally to fully expose the cavernous sinus.

Discussion ▼ The infratemporal fossa is one of the most complex and fascinating areas of the human body. The anatomic knowledge of its structure is crucial for the skull base surgeon, although most surgeons are not familiar with this anatomy. This is particularly true when talking of endoscopic anatomy of the ITF. Furthermore, the close relation to the ET and the parapharyngeal area, where critical neurovascular structures lie, makes the ITF very important for approaching these regions. Preliminary anatomic reports, with endoscopic perspectives [7, 8], have been proposed but a careful description with correlation between endoscopic and traditional perspectives is still lacking. Pathologies arising primarily in the infratemporal fossa are usually benign neoplastic lesions, therefore surgical approaches should be as least traumatic as possible. Usually in these cases the tumor displaces anatomic landmarks making orientation even more complex. In this respect trigeminal schwannomas and juvenile angiofibromas should be considered good candidates for these approaches. Preliminary clinical reports [9, 10] and also our experience confirm this possibility. When dealing with malignant neoplasms involving the ITF or the upper parapharyngeal region a wide resection is mandatory, and the choice to treat these kind of patients surgically must be well evaluated.



Fig. 8 a–c Anatomical drawings showing the crucial role of the vidian nerve in pointing the anterior genu of the internal carotid artery. d–f Cadaver dissection: endoscopic approach to the left internal carotid artery (d), lateral view of the right cavernous sinus (e) and medial view of the left infratemporal fossa (f). ET, Eustachian tube; LPM, lateral pterygoid muscle; MMA, middle meningeal artery; MPM, medial pterygoid muscle; VC, vidian canal; VN, vidian nerve; V1, ophthalmic nerve; V2, maxillary nerve; V3, mandibular nerve.

Notwithstanding, in selected cases, endoscopic approaches to rhinopharyngeal and infratemporal regions can be proposed with success [11]. In this sense, anatomic knowledge, surgical expertise, humanity and common sense are mandatory when dealing with such patients. From a surgical viewpoint many routes to the infratemporal fossa have been proposed [3, 12–15], largely divided into 2 main groups: anterior and lateral. Many such approaches are based on the monumental works of Fisch et al. [16], Sekhar et al. [17] and Janecka et al. [18]. The transzygomatic approach by Terasaka et al. [19] represents another possible alternative for managing infratemporal and parapharyngeal lesions. Furthermore, the ITF should not be considered exclusively as a target of surgery, since theoretically it can act as a corridor to deeper areas. The management of pathologies invading parapharyngeal spaces and the jugular foramen area can be achieved by passing through ITF, both anteriorly and laterally. From the endoscopic perspective the muscular plane of the pterygoid muscles becomes visible once the fat pad is removed. On the fat pad the superficial arborization of the MA, that forms a complex vascular network, is visible. After managing this network and removing the medial portion of the lateral pterygoid muscle, it is possible to identify the tensor and levator veli palatini muscles. Passing on the lateral surface of these muscles and posteriorly on the lateral surface of the superior constrictor muscle, the parapharyngeal portion of the ICA is addressed. This medial corridor is limited laterally by the muscle coming from the styloid process. The critical role of the lateral pterygoid muscle must be underlined also from an endoscopic viewpoint. Generally the MA lies on this muscle, but this vessel should not be considered a safe landmark during ITF surgery because its relationship with the lateral pterygoid muscle is not constant. We have personally found the artery medial to this muscle, lying between the medial

pterygoid muscle and branches of V3, and this anatomic variation can disorientate an inexperienced surgeon. As previously stated, when performing anterior approaches, the first structure coming into view is the fat pad filling the lateral aspect of the ITF that continues with the Bichat fat pad. Once the fat has been removed, in the lateral portion of the ITF, the triangular corridor between the lateral and the medial pterygoid muscle becomes visible. This space leads to the mandibular condyle. We maintain, in agreement with others, that the most useful landmark when dissecting the ITF in an external lateral approach is the lateral pterygoid muscle [3, 20]. When changing perspective, in anterior approaches or mostly in endoscopic ones, the Eustachian tube represents a very useful landmark to point out the upper portion of the cervical ICA. On the tube itself lies the third branch of V3, coming out from the foramen ovale; this close relationship must be well understood. The role of ET in lateral dissection is, on the contrary, by far less important given the fact that it is very deep in the surgical field and that the ICA is encountered earlier during surgical approaches. Another crucial landmark in skull base surgery is the vidian nerve; this structure, even if not properly included in the anatomy of ITF, is really important because it points to the anterior genu of the ICA. Obviously this aspect is far more important in anterior (endoscopic) approaches compared to lateral ones. In fact, in lateral approaches management of the ICA is usually obtained by identifying the artery within the temporal bone and the vidian nerve is found really deep in the surgical field. From a technical viewpoint, working laterally within the infratemporal fossa needs the creation of an operational space for instruments in order to pass through different anatomic structures. This critical problem requires, in the authors’ opinion, different answers that depend on what we are treating. In other words, it depends on the pathology to be treated and the site where it is located. In cases of benign pathologies extending



in the infratemporal fossa, it is the disease itself that creates the space and the tumor-bed can be used as a corridor-working space. Otherwise in cases, although rare, of benign pathology originating directly in the ITF or in the parapharyngeal regions, dissection and eventually sacrifice of structures must be evaluated in consideration of expected post-op QoL. In other words management of paucisympomatic benign lesions should be performed after a careful evaluation of the possible complications related to surgical approach. This is particularly true in cases of malignant disease, when evaluation of the treatment should be well calculated and made after balancing risks and benefits. When surgery is decided upon every effort to create a corridor in negative tissue should be made [11]. In this sense we confirm, based on solid experience, that the sacrifice of the branches of the maxillary artery or even the artery itself also is not associated with serious complications. ENT surgeons are in fact used to managing and even closing this artery in oncological surgery of the ITF, maxillary sinus, tonsillar or retromolar regions (commando operation). The same sacrifice of the V3 branches and pterygoid muscles is not so rare in these oncological procedures, and the QoL of the patients is usually acceptable. From a surgical point of view, we believe that the advantages of the endoscopic approach are mainly related to 3 aspects: the use of a natural corridor (extended as needed) to reach the target so the need of unnecessary osteotomies is really limited, the possibility to use the tumor as a corridor-bed (especially in benign ones), but most of all reduced or even no manipulation of the brain. This latter act represents an important limitation in most of the traditional lateral approaches to the ITF. One limitation of the endoscopic approach can be difficult manipulation and visualization in case of bleeding; notwithstanding this, we maintain that the 4-hands technique allows the skilled team to overcome this kind of difficulty in most cases. We strongly underline the importance of obtaining the best hemostasis possible. In this sense the use of hemostatic agents, clips, bipolar forceps, double suction techniques, optic cleaning systems and high definition cameras are critical tools to obtain this condition and to permit a safe procedure. Another aspect to be addressed carefully in endoscopic approaches is the management of ICA. In high risk planned cases collaboration with interventional neuroradiologists with the insertion of an endovascular stent is advisable. Transnasal control of this vessel is maybe less safe compared to lateral approaches and for this reason the need for neuronavigation is mandatory. Unfortunately, the precision of current navigation systems is probably not sufficient when dealing with lateral non-osseous structures, and this is the reason why we strongly maintain the importance of a serious anatomic knowledge of these areas. In fact, the ultimate aim of our study is only to provide our anatomic experience on this topic and to point out critical landmarks. It is the opinion of the authors that nowadays the concept of one single surgeon, master of a single technique, should be overcome; this kind of pathology must be addressed by a skilled skull base team, with different abilities, able to cope with different situations by proposing a variety of approaches. In this sense surgical techniques must be tailored to the need of the patient and not the patient to the skill of the surgeon. Based on this consideration obviously not all lesions should be addressed endoscopically, especially when dealing with malignant ones. In these cases, when a significant invasion of the infratemporal fossa is present, endoscopic techniques are not adequate and should not

be proposed. Notwithstanding this, we are convinced that clinical experience, critically and honestly evaluated, and possibly not performed by just a few teams, will tell us in the future the real value of these fascinating procedures. In this sense we maintain that the base for facing these challenges is sound and accurate knowledge of the anatomy of these regions, achieved through comparison of endoscopic and external views.

Conclusion ▼ Surgical anatomy of the infratemporal fossa and upper parapharyngeal space is extremely complex given the many important vascular and neural structures contained within it. For this reason traditional surgical approaches to the ITF and upper parapharyngeal space are challenging and associated with not negligible morbidity. Detailed knowledge of the anatomy of these complex regions is crucial to perform surgical procedures that avoid trauma as much as possible.

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