Automatic pterygopalatine fossa segmentation and localisation based on DenseASPP.

BACKGROUND: Allergic rhinitis constitutes a widespread health concern, with traditional treatments often proving to be painful and ineffective. Acupuncture targeting the pterygopalatine fossa proves effective but is complicated due to the intricate nearby anatomy. METHODS: To enhance the safety and precision in targeting the pterygopalatine fossa, we introduce a deep learning-based model to refine the segmentation of the pterygopalatine fossa. Our model expands the U-Net framework with DenseASPP and integrates an attention mechanism for enhanced precision in the localisation and segmentation of the pterygopalatine fossa. RESULTS: The model achieves Dice Similarity Coefficient of 93.89% and 95% Hausdorff Distance of 2.53 mm with significant precision. Remarkably, it only uses 1.98 M parameters. CONCLUSIONS: Our deep learning approach yields significant advancements in localising and segmenting the pterygopalatine fossa, providing a reliable basis for guiding pterygopalatine fossa-assisted punctures.

Clinically relevant morphometric analysis of pterygopalatine fossa and its volumetric relationship with adjacent paranasal sinuses: a CT-based study.

OBJECTIVES: This study aimed to perform morphometric measurements of the pterygopalatine fossa (PPF), the transition zone to critical neurovascular structures. The second aim was to investigate the relationship between the volumes of the PPF and the paranasal sinuses and the effect of nasal septum deviation (NSD) types on all these measurements. METHODS: We performed PPF's morphometry and all volume measurements on the CT images of 260 patients (130 male and 130 female, age range 18-79). RESULTS: All volumetric measurements and the angle between foramen rotundum (FR) and pterygomaxillary fissure (PMF) were significantly higher in males than females. In contrast, the distance between sphenopalatine foramen (SPF) and PMF was considerably higher in females than in males. The PPF volume, the distance between the pterygoid canal (PC) and maxillary sinus, and the angle between FR and PMF were significantly higher on the right side than on the left. In contrast, the angle between PC and SPF and between greater palatine canal and PPF were considerably higher on the left side than on the right. The angle between PC and SPF decreased markedly with age. Only sphenoidal sinus volume was significantly smaller on the same side as the septal deviation. There was no correlation between PPF volume with maxillary and sphenoid sinus volumes from adjacent paranasal sinuses. CONCLUSIONS: Volumetric and morphometric data obtained from PPF and paranasal sinuses can aid clinicians in diagnosing and treating patients by guiding them in selecting the right surgical approach or tools, especially in endoscopic procedures.

An Intraosseous Pterygopalatine Fossa Dural Arteriovenous Fistula.

Intraosseous dural arteriovenous fistulas (DAVFs) are distinct in that the fistula is located within the bone rather than the dura through which the dural vessels pass. It has been stated that only fistulas within marrow should be considered as intraosseous DAVFs rather than DAVFs with traditional angioarchitecture that erode into bone or are located within a bony foramen. The ambiguity in the definition may have contributed to the oversight and scarcity of relevant cases reported in the literature. Three- or four-dimensional digital subtraction angiography is useful for determining the location of the fistula and developing treatment plans. We present an intraosseous DAVF around the pterygopalatine fossa using a transvenous approach.

Drainage of a Pterygopalatine Fossa Abscess With Chronic Sinusitis via an Endoscopic Nasal Approach.

The pterygopalatine fossa is a clinically inaccessible space deep in the face, and reports of pterygopalatine fossa abscesses are rare. The authors present the case of a 63-year-old woman presenting with a severe headache owing to an abscess involving the pterygopalatine fossa. On a computed tomography scan, inflammation of the right pterygopalatine fossa associated with right maxillary sinusitis and periapical inflammation and a cystic lesion around the tooth were observed. After administering appropriate antibiotics, the headache improved considerably, and endoscopic nasal surgery resulted in adequate abscess drainage. To the authors' knowledge, this case study is one of the few reporting the successful treatment of an abscess in the pterygopalatine fossa through an endoscopic transnasal approach.

Endoscopic-assisted en-bloc pterygomaxillectomy: Identifying an efficient and safe location for the pterygoid osteotomy.

BACKGROUND: For aggressive maxillary sinus and pterygopalatine fossa (PPF) tumors, an en-bloc pterygomaxillectomy may be indicated. METHODS: Five head specimens were used to study the feasibility of an en-bloc pterygomaxillectomy. Eighty-five non-pathological CT scans were used to compare the superior edge of the inferior turbinate (IT) and the middle turbinate tail (MT) as landmarks for the pterygoid osteotomy. RESULTS: Through a combined sublabial-subperiosteal incision and transoral route, a mid-sagittal osteotomy through the hard palate and an axial osteotomy below the infraorbital foramen were performed. For the endoscopic pterygoid osteotomy, an infra-vidian transpterygoid approach was performed, subsequently removing the pterygomaxillectomy en-bloc. As landmarks, the osteotomies at the level of the MT tail and IT resected the pterygoid plates completely, but the IT osteotomy was further away from the vidian canal (7.5 vs. 6 mm). CONCLUSIONS: The endoscopic-assisted en-bloc pterygomaxillectomy is feasible. The IT landmark is safe and ensures complete resection of the pterygoid plates.

A radioanatomical study of 3rd segment terminal branches of the maxillary artery in the pterygopalatine fossa.

This study describes the clinical anatomical topography and relationship of the terminal branches of the maxillary artery to the bony wall of the maxillary sinus in the pterygopalatine fossa (PPF) to estimate the bleeding risk during surgical interventions. Using contrasted computer tomography records, (i) the route of the maxillary artery in the infratemporal fossa, (ii) the number of the arteries in the critical PPF surgery plane, (iii) the diameter of the largest artery in the area and (iv) its relation to the posterior wall of the maxillary sinus were examined. Furthermore, measurements were extended with (v) the minerality of the bony posterior wall of the maxillary sinus on bone-window images. For statistical analyses Student's t- and Fisher-test were applied. 50 patients (n = 50, 100 cases including both sides) were examined in this study. The maxillary artery reached the pterygomaxillary fissure on the lateral side of the lateral pterygoid muscle in 56% of the cases (n = 32), in 37% (n = 23) on its medial side and in 7% (n = 4) on both sides. The number of arteries at the level of the Vidian canal in the PPF varied between 1 and 4 with a median of 2. The diameter of the biggest branch was 1.2-4.7 mm, the median diameter was 1.90 mm. In 41% (n = 30) of the cases the biggest artery directly contacted the posterior wall of the maxillary sinus, and the mineral density of the posterior wall was decreased in 14.3% (n = 12) of all investigated cases. The present description and statistical analysis of the vasculature of the PPF optimizes operative planning-like clip size or the type and direction of the surgical approach-in this hidden and deep head/neck region.

The application of 3-dimensional magnetic resonance imaging in nasopharyngeal carcinoma with pterygopalatine fossa invasion.

OBJECT: The pterygopalatine fossa (PPF) is a covert neurovascular pathway in the skull base and connects with numerous intracranial and extracranial spaces. The aim of this study was to explore the magnetic resonance imaging (MRI) features of PPF invasion in patients with nasopharyngeal carcinoma (NPC). MATERIAL AND METHODS: The medical records of 88 patients with stage T3 or T4 NPC were retrospectively analyzed. The 3-Dimensional (3D) volumetric images of MRI were reconstructed for the tiny connecting conduits of the invaded PPFs in the NPC patients. The infiltration incidence of conduits and connected further structures were calculated. RESULTS: Forty-six PPFs from 37 patients were invaded by NPC. The proportions of stage T4 NPC and intracranial extension were higher in patients with PPF invasion than that without PPF invasion (P < 0.05). Each connecting conduit of the PPF had corresponding optimal reconstructed orientation based on 3D volumetric MRI images. The first three most common infiltrated conduits were palatovaginal canal, vidian canal and sphenopalatine foramen, which were adjacent to the nasopharynx. Among the conduits connecting with further structures, the most common infiltrated conduit was pterygomaxillary fissure, followed by foramen rotundum and inferior orbital fissure. Furthermore, The NPC lesions involved stage T4 structures via the conduits from 19.6% of the invaded PPFs. CONCLUSIONS: The application of high-quality reconstruction images based on 3D sequence of MRI in NPC patients proved to be feasible and beneficial for the manifestation of the invaded PPFs and connecting conduits.

Radiological evaluation of maxillary artery and descending palatine artery in the pterygopalatine fossa by 3D rotational angiography.

PURPOSE: The aim of this study is to evaluate the branching patterns and topographical features of the third part of the maxillary artery (t-MA) and descending palatine artery (DPA) by 3-Dimensional Rotational Angiography (3DRA) images and to define the radiological classification of their variations, based upon the previous cadaveric studies and a review of the literature. METHOD: This study was conducted from May 2020 through June 2021. All consecutive adult patients who were examined with 3D-RA were enrolled in the study. The morphological evaluations and measurements of t-MA, DPA and their branches were made on maximum intensity projection images with 10-20 mm slice thickness. RESULTS: Eighty-five hemifaces, including 58 females and 45 right sides, were evaluated. The diameter of the t-MA was measured as 1.73 ± 0.30 mm. The most common pattern of the t-MA according to its course was loop type (63/85, 74.1%) and according to branching pattern was Type Ib (29/85, 34.1%). The mean diameter of DPA was 1.19 ± 0.20 mm. The DPA presented as a single trunk in 11/85 cases. Type II, which was defined as one lesser palatine artery originating from distal-DPA, was the most common morphological variation (51.8%). CONCLUSIONS: 3DRA imaging provides valuable information for vascular anatomical studies. The most common morphological variation related to t-MA, DPA is the distal branching pattern.

Ultrasound-Guided Suprazygomatic Nerve Blocks to the Pterygopalatine Fossa: A Safe Procedure.

OBJECTIVES: Large-scale procedural safety data on pterygopalatine fossa nerve blocks (PPFBs) performed via a suprazygomatic, ultrasound-guided approach are lacking, leading to hesitancy surrounding this technique. The aim of this study was to characterize the safety of PPFB. METHODS: This retrospective chart review examined the records of adults who received an ultrasound-guided PPFB between January 1, 2016, and August 30, 2020, at the University of Florida. Indications included surgical procedures and nonsurgical pain. Clinical data describing PPFB were extracted from medical records. Descriptive statistics were calculated for all variables, and quantitative variables were analyzed with the paired t test to detect differences between before and after the procedure. RESULTS: A total of 833 distinct PPFBs were performed on 411 subjects (59% female, mean age 48.5 years). Minor oozing from the injection site was the only reported side effect, in a single subject. Although systolic blood pressure, heart rate, and oxygen saturation were significantly different before and after the procedure (132.3 vs 136.4 mm Hg, P < 0.0001; 78.2 vs 80.8, P = 0.0003; and 97.8% vs 96.3%, P < 0.0001; respectively), mean arterial pressure and diastolic blood pressure were not significantly different (96.2 vs 97.1 mm Hg, P = 0.1545, and 78.2 vs 77.4 mm Hg, P = 0.1314, respectively). Similar results were found within subgroups, including subgroups by sex, race, and indication for PPFB. DISCUSSION: We have not identified clinically significant adverse effects from PPFB performed with an ultrasound-guided suprazygomatic approach in a large cohort in the hospital setting. PPFBs are a safe and well-tolerated pain management strategy; however, prospective multicenter studies are needed.

Endoscopic Endonasal and Transmaxillary Approach for Resection of Juvenile Nasopharyngeal Angiofibroma With Preoperative Embolization in a Child.

ABSTRACT: A 13-year-old Japanese boy with a 6-month history of bilateral nasal obstruction and a 3-week history of recurrent epistaxis from the right nose was admitted to our department. Nasal endoscopy revealed a reddish, smooth-walled tumor occupying the right nasal cavity. Computed tomography scan revealed a 3.5 × 4.5 × 7.0-cm heterogeneously enhancing mass involving the right nasal cavity and extending posteriorly to the nasopharynx, and laterally to the pterygopalatine fossa and the medial part of the infratemporal fossa. We diagnosed as juvenile nasopharyngeal angiofibroma with Radkowski classification stage IIC. The internal maxillary and ascending pharyngeal arteries were embolized with polyvinyl alcohol followed by Embosphere using a conventional Seldinger technique. En bloc resection was performed with an endoscopic ipsilateral endonasal and sublabial Caldwell-Luc transmaxillary approach under general anesthesia. As of 3 years postoperatively, no recurrence has been found. We report a child case of juvenile nasopharyngeal angiofibroma successfully treated with less invasive surgery with preoperative embolization.

Localization of the Sphenopalatine Ganglion Within the Pterygopalatine Fossa on Computed Tomography Angiography-A Potential Role in the Setting of Sphenopalatine Ganglion Microstimulator Implantation.

OBJECTIVES: A recent approach to treatment of cluster headaches (CH) employs a microstimulator device for on-demand neuromodulation of the sphenopalatine ganglion (SPG) during an acute CH attack. A precise anatomical localization of the SPG within the pterygopalatine fossa (PPF) is optimal in order to position the SPG electrode array. This study aims to investigate a novel approach for SPG localization using computed tomography angiographic studies (CTA). MATERIALS AND METHODS: Two independent observers identified the location of the SPG on 54 computed tomography angiographic studies (CTA) and measured its position relative to the vidian canal (VC). The qualitative confidence of identification, morphology, position within the PPF and its relation to vascular structures were also recorded. RESULTS: The SPG was detectable in 88% of cases with a variable position. The most frequent positions were superior (56%) and lateral (99%) relative to the VC with a mean (±SD) craniocaudal distance of 0.34 mm (±1.38) and a mean mediolateral distance of 3.04 mm (±1.2). However, in a considerable proportion of cases, the SPG was identified inferiorly to the VC (33%). Interobserver and intraobserver agreement for SPG location were moderate and strong respectively. CONCLUSIONS: Since localization of SPG on CTAs is feasible and reproducible, it has future clinical potential to aid placement, optimal positioning and individualized programming of the electrode array.

CBCT study on the positional relationship between marginal points of pterygomaxillary junction and anterior nasal spine.

PURPOSE: This study aimed to locate the inferior end (Pti) and the superior end (Pts) of pterygomaxillary junction (PMJ) relative to anterior nasal spine (ANS) so as to provide references for pterygomaxillary separation. METHODS: The study was based on CBCT images of 109 Chinese patients. We projected Pti and Pts to the frontal plane and measured the distance as well as the positional relationship between the projection points and ANS via three-dimensional reconstruction image. RESULTS: On average, the ANS was 5.18 mm above the Pti and the horizontal distance between the Pti and ANS was 21.86 mm. The horizontal and vertical distances between Pts and ANS was 20.41 mm and 10.91 mm, respectively. The vertical height of PMJ was 16.09 mm. Scatter plots diagrammatic centered on ANS showed that 73% (160/218) Pti and 64% (140/218) Pts appeared in a 45° fan shape ranged from 20 to 25 mm radius in bilateral inferior and superior quadrant, respectively. There was no significant difference in the distance between both sides (P > 0.05). CONCLUSION: During the pterygomaxillary disjunction, it exists a risk of injuring neurovascular bundle of the pterygopalatine fossa 16.09 mm above the lowest border of the pterygomaxillary junction. The region within a 45° fan shape ranged in 20-25 mm radius in inferior quadrant centered on ANS might be suitable for the osteotome position. The positional relationship especially between the ANS and Pti found in this study provides a reference for surgeons during pterygomaxillary disjunction.

Endoscopic Endonasal Resection of Schwannoma of Pterygopalatine Fossa.

Trigeminal schwannomas are benign slow-growing tumors originating from the peripheral nerve sheath. They account for 0.1%-0.4% of all intracranial tumors and 1%-8% of all intracranial schwannomas.1-3 While most of these tumors develop in the trigeminal ganglion within the middle fossa, trigeminal schwannomas can develop anywhere along the course of the trigeminal nerve. As a result, they can be intradural, interdural, and extradural.4,5 Trigeminal schwannomas from the pterygopalatine fossa (PPF) are extremely rare and very difficult to remove because of limited access to this region and the rich neurovascular contents. Numerous traditional microsurgical approaches to the PPF have been described; however, they are more invasive with increased morbidity.6,7 Therefore, endoscopic endonasal surgery is a feasible solution. This technique allows good visualization of the region with decreased morbidity and a shorter recovery period. A previously healthy, 40-year-old woman presented with right facial pain for 3 weeks. On neurologic examination, the patient had hypoesthesia in the territory of the maxillary (V2) branch of the right trigeminal nerve. She had no other symptoms on physical examination. Cranial computed tomography and magnetic resonance imaging were performed and showed a high signal density mass in the right PPF that exhibited heterogeneous contrast enhancement. She was initially treated with low-dose carbamazepine; however, the dose could not be further increased because of drowsiness and dizziness. Given the size and location of the mass, an endoscopic endonasal approach was performed, and the tumor was successfully resected (Video 1). The postoperative course was uneventful, and the patient had significant improvement of her symptoms and was discharged with no new neurologic deficits. However, she continued to have hypoesthesia of the V2 segment of the trigeminal nerve.

Volumetric Analysis of the Pterygopalatine Fossa by Semiautomatic Segmentation of Cone Beam Computed Tomography.

The aim of this study was to provide volumetric data of the pterygopalatine fossa by semiautomatic segmentation based upon cone beam computed tomography.Cone beam computed tomography (CBCT) images of 100 patients were analyzed. By using the open source software "ITK-Snap," the volumetric measurements of 200 pterygopalatine fossae were performed. For statistical investigations paired t test, and independent Student t test were performed. Also, the Pearsons chi-square test was applied. P values P < 0.05 were considered significant.The mean volume was 578.376 mm for the right and 560.979 mm for the left side. The results indicated statistically significant differences according to the right and the left pterygopalatine fossa, regardless of gender (P < 0.05). The analysis of differences between males and females did not show any significant results (P > 0.05), although males present a slightly larger volume than females. According to the median age (59 years), younger patients presented smaller volumes, whereas older patients presented larger volumes. Nevertheless, no statistically significant differences according to age (χ = 3.520; P > 0.05) could be found.Clinical intervention with the application of local anesthetics into the complex and vulnerable anatomy of the pterygopalatine fossa makes a thorough knowledge about the volumetric capacity indispensable. Therefore, the semiautomatic segmentation of CBCT images provides a useful, available and validated tool. Our results show that a final injected anesthetic volume larger than 1 ml exceeds the pterygopalatine fossa capacity considerably and could cause complications. To prevent this, volumetric analysis of this region can provide further information and enables an individualized patients' treatment.