Surgical and Radiologic Anatomy (2019) 41:161–168 https://doi.org/10.1007/s00276-018-2136-8 ORIGINAL ARTICLE The pterygopalatine fossa: morphometric CT study with clinical implications Aleksandra Vuksanovic‑Bozaric1 · Batric Vukcevic1 · Marija Abramovic1 · Nemanja Vukcevic1 · Natasa Popovic1 · Miroslav Radunovic1 Received: 29 June 2018 / Accepted: 16 November 2018 / Published online: 23 November 2018 © Springer-Verlag France SAS, part of Springer Nature 2018 Abstract Purpose The pterygopalatine fossa is a deep viscerocranial space containing the maxillary artery and nerve, the pterygopala- tine ganglion, and the nerve of the pterygoid canal (vidian nerve). The endoscopic approach to this area relies on adequate preoperative imaging, such as computed tomography (CT). The aim was to determine the morphometric characteristics of the pterygopalatine fossa and its communications, including several previously unpublished measurements. Methods 100 CT scans (56 male and 44 female patients) were analyzed. The axial, coronal, and sagittal slices, together with the three-dimensional reconstructions, were used in the study. Results The central diameter and the length of the foramen rotundum, the vertical diameter and the length of the pterygoid (vidian) canal, and the diameter of the sphenopalatine foramen were significantly larger in men. The central diameters of the foramen rotundum and the vidian canal were significantly smaller than their anterior and posterior transverse diameters. The vidian canal length of 12.1 mm indicates the presence of the type 3 VC with a sensitivity of 83% and a specificity of 85%. Conclusion Several new descriptions of the pterygopalatine fossa are presented here (such as the angle between the spheno- palatine foramen and the vidian canal, a new aspect in the understanding of the FR, and the distance between the posterior wall of the maxillary sinus to the vidian canal and the foramen rotundum), which might prove useful in the comprehension of the anatomy of the pterygopalatine fossa. Keywords Computed tomography · Morphometry · Pterygopalatine fossa · Pterygoid canal Introduction pterygoid—vidian canal (VC) [27, 32, 33]. Acar et al. sug- gested a new VC classification based on its localization: type The pterygopalatine fossa (PPF) is a deep space of the vis- 1 (the VC is located inside the roof of the PPF), type 2 (the cerocranium, located in front of the pterygoid process of VC partially protrudes into the sphenoid sinus), and type the sphenoid bone, lateral to the perpendicular plate of the 3 (the VC totally protrudes into the sphenoid sinus, with a palatine bone, and posterior to the maxilla. Laterally, the stalk connecting it to the PPF roof) [1]. The palatovaginal PPF communicates with the infratemporal fossa through canal represents a communication between the PPF and the the pterygomaxillary fissure (PMF) [12]. The nasal cavity nasopharynx [26], and the palatine foramina (the greater and the PPF communicate through the sphenopalatine fora- and the lesser) represents a communication between the PPF men (SPF), located between the orbital and the sphenoidal and the oral cavity [10]. The greater palatine foramen leads process of the palatine bone. The inferior orbital fissure into the greater palatine canal (GPC), an inferior extension connects the PPF to the orbit. Posteriorly, the PPF commu- of the PPF [34]. nicates with the middle cranial fossa through the foramen Chen et al. [6] proposed a topographical division of the rotundum (FR), and with the foramen lacerum through the PPF into five parts: the GPC (from the hard palate to the PPF), the infrapterygopalatine segment of the PPF (from * Batric Vukcevic the PMF to the pterygopalatine ganglion), the pterygopala- [email protected] tine—ganglionic segment (in the level of the ganglion), and the suprapterygopalatine segment (from the pterygopalatine 1 Faculty of Medicine, University of Montenegro, ganglion to the superior border of the FR, containing the 20000 Podgorica, Montenegro Vol.:(0123456789)1 3 162 Surgical and Radiologic Anatomy (2019) 41:161–168 SPF, the FR, the VC, and the palatovaginal canal) and the conditions were excluded from the study to evaluate roof of the PPF. normal anatomy. In addition, cases with pneumatized The clinical significance of the PPF lies in its numerous pterygoid processes or pneumatized posterior wall of the communications with the surrounding spaces, as well as the maxillary sinus (MS) were not analyzed. SOMATOM Sen- structures located in it: the maxillary artery and nerve, the sation 64 multi-slice scanner (Siemens Healthcare, Erlan- pterygopalatine ganglion, and the nerve of the pterygoid gen, Germany) was used to scan all the patients, with the canal (vidian nerve) [15, 29, 31]. The normal anatomy of following scanning protocol: exposure 120 kV, mAs 380, the PPF may be changed due to various expansive or inflam- rotation time 1 s, pitch 0.85, slice thickness 1 mm, and matory lesions. The bony structures of the PPF and the interval 1 mm. The images were analyzed as native scans, infratemporal fossa are used as landmarks in the diagnosis as well as multiplanar and volume rendering technique and treatment of different pathological processes affecting reconstructions in sharp algorithm, using syngo fastView the soft tissues of the face [30]. Therefore, the preoperative software on a dedicated workstation. Two observers (M.A. approach in the surgical management of viscerocranial dis- and B.V.) measured all the structures independently. Every ease includes modern imaging techniques such as computed measurement was taken three times, with the mean value tomography (CT), to provide adequate comprehension of the used for the further analysis. The intraclass correlation patient’s facial skeleton. ranged from 0.8 to 0.9 for all the measurements. The aim of the study was to determine the morphometric The axial slices (Fig. 1) were used to analyze the suprap- characteristics of the PPF and its communications, with sev- terygopalatine segment of the PPF according to Chen et al. eral measurements that were not published previously. The [6]. The slices displaying the maximum diameter and the results of the study may influence the surgery of the PPF, total length of the FR, the VC, and the SPF were used to take especially the endoscopic approach. the following measurements: 1. the transverse diameter of the FR and the VC at three Materials and methods levels: their anterior opening, central segment, and the posterior opening (Fig. 1a: 1, 2, and 3; Fig. 1b: 6, 7, and A retrospective study on 100 patients’ (56 male and 44 8, for the FR and the VC, respectively) female; age range 33–62) CT scans was performed. Cases 2. the length of the FR (Fig. 1a: 4) and the VC (Fig. 1b: 9) of facial fractures or skeletal disruptions, previous max- 3. the transverse diameter of the SPF and the PMF (at the illofacial surgery, sinonasal tumors, or inflammatory level of the VC) (Fig. 1b: 10 and 11, respectively) Fig. 1 Axial slices of the right pterygopalatine fossa used in measur- anterior, central, and posterior segment, respectively. 9 The length of ing the vidian canal, the foramen rotundum, and the sphenopalatine the vidian canal. 10, 11 The transverse diameter of the sphenopala- foramen (the left pterygopalatine fossa). A anterior, P posterior, M tine foramen and the pterygomaxillary fissure, respectively. 12 The medial, L lateral, MS maxillary sinus, ITF infratemporal fossa, SS distance between the medial border of the anterior opening of the vid- sphenoid sinus, NC nasal cavity. a Level of the foramen rotundum; ian canal to the posterior boundary of the sphenopalatine foramen. 13 with 1, 2, and 3 representing its anterior, central, and posterior diam- The distance from the posterior wall of the maxillary sinus to the vid- eter, respectively. 4 The length of the foramen rotundum. 5 The dis- ian canal. 14 The angle between the axis of the sphenopalatine fora- tance from the posterior wall of the maxillary sinus to the foramen men to the vidian canal rotundum. b The level of the vidian canal. 6, 7, 8 The diameter of its 1 3 Surgical and Radiologic Anatomy (2019) 41:161–168 163 4. the direct distance between the medial boundary of the anterior opening of the VC to the posterior margin of the SPF (Fig. 1b: 12) 5. the direct distance between the posterior wall of the MS to the anterior opening of the FR (Fig. 1a: 5) and the VC (Fig. 1b: 13) 6. the angle between the SPF axis (a line perpendicular to the SPF) and the VC axis (Fig. 1b: 14). The coronal slice depicting the maximum diameter of the VC and the FR was used to measure the direct distance from the FR and the VC to the midline (located at the level of the sphenoidal rostrum) (Fig. 2a: 1 and 2, respectively), as well as direct distance between the FR and the VC. Furthermore, the coronal slices were used to evaluate the VC type accord- ing to Acar et al. [1] (Fig. 2a). The sagittal slice showing the complete “inverted pyramid” shape of the PPF was used to Fig. 3 The three-dimensional image used in the study (depicting the measure its vertical diameter [the distance from the roof of left pterygoid process), with 1 and 2 representing the vertical diam- the PPF to the superior opening of the GPC (Fig. 2b: 3)]. eter of the anterior openings of the vidian canal (VC) and the fora- The 3D reconstruction of the posterior wall of the PPF was men rotundum (FR), respectively; 3 as the direct distance between the S I M L used to confirm the direct distance between the VC and the aforementioned openings. superior, inferior, medial, lateral, SS sphenoid sinus FR (Fig. 3: 3), as well as to measure the vertical diameters of their anterior openings (Fig. 3: 1 and 2, respectively). There was no significant difference between the values of The standard statistical protocol for descriptive statistics the direct FR-VC distance measurement from the coronal was used, including the Shapiro–Wilk and the Kolmogo- slices and the 3D reconstructions.