Endoscopic trans-eustachian tube approach: identifying the precise landmarks, a novel radiological and anatomical evaluation.

PURPOSE: The endoscopic trans-eustachian approach (ETETA) is a less invasive approach to the infratemporal fossa (ITF), providing superior exposure compared to traditional transcranial approaches. The anatomy of the pharyngotympanic (eustachian) tube and adjacent neurovascular structures is complex and requires in-depth knowledge to safely perform this approach. We present a cadaveric and radiological assessment of critical anatomic considerations for ETETA. METHODS: Six adult cadaveric heads were dissected alongside examination of 50 paranasal sinus CT scans. Key anatomic relationships of the pharyngotympanic tube and adjacent structures were qualitatively and quantitatively evaluated. Descriptive statistics were performed for quantitative data. RESULTS: Anatomical and radiological measurements showed lateralization of the pharyngotympanic tube allows access to the ITF. The pharyngotympanic tube has bony and cartilaginous parts with the junction formed by the sphenoid spine and foramen spinosum. The bony part and tendon of the tensor tympani muscle were located at the posterior genu of the internal carotid artery. The anterior and inferior wall of the carotid canal was located between the horizontal segment of the internal carotid artery and petrous segment of the cartilaginous pharyngotympanic tube. CONCLUSION: The combination of preoperative radiographic assessment and anatomical correlation demonstrates a safe and effective approach to ETETA, which allowed satisfactory visualization of ITF. The morphological evaluation showed that the lateralization of the pharyngotympanic tube and related structures allowed a surgical corridor to reach the ITF. Endoscopic surgery through the pharyngotympanic tube is challenging, and in-depth understanding of the key anatomic relationships is critical for performing this approach.

Predictors of postoperative performance status after surgical management of infratemporal fossa malignancies.

Infratemporal fossa (ITF) tumors are difficult to access surgically due to anatomical constraints. Moreover, aggressive ITF carcinomas and sarcomas necessitate aggressive treatment strategies that, along with tumor-related symptoms, contribute to decreases in patient performance status. To assess factors that predict postoperative performance in patients undergoing surgery for ITF tumors. We reviewed medical records for all patients surgically treated for an ITF malignancy between January 1, 1999, and December 31, 2017, at our institution. We collected patient demographics, preoperative performance, tumor stage, tumor characteristics, treatment modalities, pathological data, and postoperative performance data. The 5-year survival rate was 62.2%. Higher preoperative Karnofsky Performance Status (KPS) score (n = 64; p < 0.001), short length of stay (p = 0.002), prior surgery at site (n = 61; p = 0.0164), and diagnosis of sarcoma (n = 62; p = 0.0398) were predictors of higher postoperative KPS scores. Percutaneous endoscopic gastrostomy (PEG) (n = 9; p = 0.0327), and tracheostomy tube placement (n = 20; p = 0.0436) were predictors of lower postoperative KPS scores, whereas age at presentation (p = 0.72), intracranial tumor spread (p = 0.8197), and perineural invasion (n = 40; p = 0.2195) were not. Male patients and patients with carcinomas showed the greatest decreases in KPS scores between pretreatment and posttreatment. Higher preoperative KPS score and short length of stay were the best predictors of higher postoperative KPS scores. This work provides treatment teams and patients with better information on outcomes for shared decision-making.

Dermoid cyst of the infratemporal fossa: a case report of surgical resection by infratemporal fossa type B approach.

OBJECTIVE: This is a case report of a dermoid cyst located in the infratemporal fossa and its surgical removal using infratemporal fossa type B approach. CASE REPORT: A 15-year-old male was referred from a local clinic after an incidental finding of a mass lesion in the skull base area on computed tomography (CT). Pre-operative magnetic resonance imaging showed a large cystic mass lesion, expanding to the foramen ovale with fat component in the right infratemporal fossa region. The lesion was completely excised using an infratemporal fossa type B approach. CONCLUSION: An extremely rare case of dermoid cysts of the infratemporal fossa was managed with infratemporal fossa type B approach without severe complication.

Morphometric analysis of the infratemporal fossa using three-dimensional (3D) digital models.

PURPOSE: The infratemporal fossa contains important neurovascular components and is directly related to other anatomical regions and structures. The morphometric distances between the bones forming its borders have not been thoroughly investigated. The aim of this study was to determine the morphometry of the infratemporal fossa. METHODS: 3D models of the skull of 83 individuals were reconstructed from DICOM datasets, from which length, depth and width measurements were determined and compared between genders and the right and left sides. RESULTS: All measurements obtained were significantly different between males and females. There were also significant differences between the left and right sides for depth and width measurements. CONCLUSION: This is the first study to determine and investigate measurements of the infratemporal fossa; as such it provides a comprehensive view of the morphology of the fossa. It provides valuable information for surgical interventions and differential diagnoses of pathologies in this region, as well as enhancing its understanding in medical education.

Combined endoscopic endonasal transpterygoid and sublabial transmaxillary approaches for a large infratemporal fossa trigeminal schwannoma.

BACKGROUND: Trigeminal schwannomas (TSs) with solitary extracranial location are rare, and surgical excision is challenging. In recent years, the endoscopic endonasal transmaxillary transpterygoid approach (EETPA) has been advocated as an effective strategy for TSs in the infratemporal fossa (ITF). METHOD: We describe the steps of the EETPA combined with the sublabial transmaxillary approach for the surgical excision of a giant mandibular schwannoma of the ITF. Indications, advantages, and approach-specific complications are also discussed. The main surgical steps are shown in an operative video. CONCLUSION: A combined EETPA and sublabial transmaxillary approach represents a safe and effective option for the surgical excision of extracranial TSs.

Transnasal Endoscopy and Combined Approach to Infratemporal Fossa Abscess and Parapharyngeal Abscess.

The infratemporal fossa is a very important anatomical space that is relatively closed with an irregular shape and is adjacent to the parapharyngeal space. Infratemporal fossa abscess is rare clinically. It can occur as a complication of maxillary sinusitis, maxillary sinus fracture, or odontogenic infection. If not handled in time, it may endanger the lives of patients. This paper reports the diagnosis and treatment of infratemporal fossa abscess in 2 diabetic patients. Computed tomography and magnetic resonance imaging are the best methods to diagnose suspected cases of this disease. The key treatment is to combine sensitive antibiotic treatment with endoscopic abscess drainage. Different approaches can be selected according to the range of lesions. If necessary, a combined approach to drain the pus is needed. Early diagnosis, timely initiation of antibiotics, and surgical intervention are essential for curing this disease.

Infratemporal Fossa Chondroblastoma.

INTRODUCTION: Chondroblastoma is a rare, benign mesenchymal tumor that can behave local aggressive. It most often occurs in the area of the epiphyses of long tubular bones, whereas the appearance in the region of the head and neck is rare, only few reports were published in literature. The incidence of chondroblastoma of the craniofacial region is about 6.4%. CLINICAL REPORT: A 46-year-old patient was hospitalized due to growth and pain in the area of the left half of the face, and a tumor of the left infratemporal fossa was diagnosed by computed tomography. The patient was operated with a preauricular surgical approach, parotidectomy, and complete tumor removal was performed. Pathohistological examination revealed chondroblastoma. CONCLUSIONS: Chondroblastoma of the craniofacial region is very rare pathohistological finding, characterized by slow and asymptomatic growth until it reaches the appropriate dimensions, the clinical symptomatology depends on the localization of the tumor. Computed tomography diagnostics provides important information about the location, size of the tumor, invasion of surrounding structures, and significantly contributes to the decision on the appropriate surgical approach. Diagnostic dilemma solving only final pathohistological verification.

Fronto-orbito-zygomatic (FOZ) approach for infratemporal fossa lesions extending to middle cranial fossa: our experience and review of literature.

AIM OF THE STUDY: Tumours of the infratemporal fossa (ITF) are rare and include primary tumours, contiguity lesions and metastases. Surgical resection is the gold standard. The fronto-orbito-zygomatic (FOZ) approach is commonly used in order to obtain safe access to the lateral skull base and ITF to resect intra- and extra-cranial tumours. We here describe our series of ITF lesions extending to the middle cranial fossa and/or orbit, treated by single- or two piece FOZ. MATERIAL AND METHODS: All cases of single- or two-piece FOZ approach for an infratemporal fossa lesion extending to the middle cranial fossa operated at our Institution from January 2014 to January 2018 were retrospectively reviewed. The follow-up was for a minimum of four months and a maximum of 60 months. The inclusion criteria were lesions involving the ITF with an extension to the middle cranial fossa and/or orbit. Baseline characteristics of patients, tumour localisation, tumour extension, diffusion route, histology, extent of tumour resection, postoperative treatment, and post-operative complications were evaluated. RESULTS: Nine patients underwent a surgical procedure with a FOZ approach, two of them with a single-piece approach and the remainder with a two-piece one. All patients had an ITF localisation. Gross total removal (GTR) was achieved in 7/9 patients. Only one patient, with non-total removal (NTR), underwent radiotherapy. CONCLUSIONS: For the treatment of ITF fossa tumours extending to the orbit and or middle cranial fossa, we believe that both FOZ techniques are effective and allow a good medial extension toward the cavernous sinus and parasellar region. But a two-piece craniotomy may ensure a more medial extension and a wider angle of work compared to a one-piece craniotomy.

[Metastatic Tumor of the Uterine Cervical Cancer Occurred in the Infratemporal Fossa].

A 46-year-old woman presented with discomfort in her right lateral gaze, right-sided headache, and facial numbness 17 days after concurrent chemoradiotherapy(CCRT)for a Stage ⅢB cervical cancer. The initial imaging investigations, maxillofacial and otolaryngology reviews did not reveal a diagnosis. After 54 days of CCRT, her symptoms deteriorated. Magnetic resonance imaging(MRI)showed a tumor in the right infratemporal fossa and its biopsy confirmed a metastatic cervical cancer. In view of the rapid deterioration and the potential visual loss, palliative intensity-modulated radiotherapy(IMRT) was given. Although the symptoms improved temporarily, multiple metastases were subsequently found. Despite chemotherapy, the patient died 11 months after developing the symptoms of infratemporal fossa metastasis.

Combined biportal unilateral endoscopic endonasal and endoscopic anterior transmaxillary approach for resection of lesions involving the infratemporal fossa.

BACKGROUND: Approaching tumors involving the infratemporal fossa (ITF) is technically challenging due to the complex relationships between several neurovascular structures and the deep-seated location of these lesions. METHODS: The authors describe in detail a minimally invasive approach to the ITF, consisting on a single-nostril endoscopic endonasal transmaxillary approach aided by an anterior transmaxillary port (EEA-ATMa). Anatomical landmarks and surgical tenets of this approach are highlighted and reviewed with the goal to guarantee successful tumor resection and avoid operative complications. CONCLUSION: The EEA-ATMa is technically feasible and offers excellent surgical exposure to the anterior and lateral aspect of ITF, without the need of transecting the Vidian nerve or performing a wide septectomy.

[Application of iodine staining technique for tumor identification in Micro-CT of mouse model with skull base-infratemporal fossa tumor].

OBJECTIVE: To establish an animal model with malignant tumor in the skull base-infratemporal region, and to explore the role of iodine staining technique in identifying tumor tissues with Micro-CT data. METHODS: Sedation anesthesia was carried out on 12 BABL/c nude mice using inhaled isoflurane, and then WSU-HN6 cells that cultured and immortalized from human tongue squamous cell carcinoma were injected into the right infratemporal fossa via the submandibular area. The procedure was carried out under ultrasonographic guidance. The nude mice were sacrificed after 3 weeks observation. The head specimens were fixed and scanned by Micro-CT, and repeated scans were performed after staining with 3.75% compound iodine solution. Following decalcification in 20% EDTA for 2-4 weeks, the head specimens were embedded and sectioned. Hematoxylin and eosin staining and Pan-Keratin immunohistochemical staining were carried out. Bright-field microscopy and stereomicroscopy were used to visualize. The Micro-CT data were analyzed using iPlan software (Brainlab). RESULTS: Non-traumatic ultrasonography was used to guide HN-6 cells injection and confirm skull-base tumor formation in all the animals. Ultrasonographic guidance reduced the risk of cervical vessel injury when transferring tumor cells into the skull base space. An obvious asymmetrical appearance was detected via ultrasonography 3 weeks after tumor cell injection. The Micro-CT analysis showed that the bone was obviously damaged on the right side of the skull base, but the soft tissue image was unrecognizable. After four days staining with compound iodine solution, the morphology of the tumor and surrounding soft tissue could be clearly identified. Hematoxylin and eosin staining showed the tumor formation of the right infratemporal fossa region accompanied by bone destruction. Human keratin immunohistochemical staining showed that the tumor tissue originated from human squamous cell carcinoma, and the polynuclear osteoclasts could be seen at the margin of the skull base bone resorption. CONCLUSION: The animal model with malignant tumor in the skull base-infratemporal region could be successfully established via submandibular injection under ultrasound-guidance. Bone changes of the skull were easily observed on Micro-CT, but the tumor counter was not able to be distinguished from surrounding soft tissue. The 3.75% compound iodine staining of the head specimen could help discern the tumor and surrounding soft tissue in more details.

Endoscopic transnasal transmaxillary approach to the upper parapharyngeal space and the skull base.

PURPOSE: Treatment of tumors arising in the upper parapharyngeal space (PPS) or the floor of the middle cranial fossa is challenging. This study aims to present anatomical landmarks for a combined endoscopic transnasal and anterior transmaxillary approach to the upper PPS and the floor of the middle cranial fossa and to further evaluate their clinical application. METHODS: Dissection of the upper PPS using a combined endoscopic endonasal transpterygoid and anterior transmaxillary approach was performed in six cadaveric heads. Surgical landmarks associated with the approach were defined. The defined approach was applied in patients with tumors involving the upper PPS. RESULTS: The medial pterygoid muscle, tensor veli palatini muscle and levator veli palatini muscle were key landmarks of the approach into the upper PPS. The lateral pterygoid plate, foramen ovale and mandibular nerve were important anatomical landmarks for exposing the parapharyngeal segment of the internal carotid artery through a combined endoscopic transnasal and anterior transmaxillary approach. The combined approach provided a better view of the upper PPS and middle skull base, allowing for effective bimanual techniques and bleeding control. Application of the anterior transmaxillary approach also provided a better view of the inferior limits of the upper PPS and facilitated control of the internal carotid artery. CONCLUSIONS: Improving the knowledge of the endoscopic anatomy of the upper PPS allowed us to achieve an optimal approach to tumors arising in the upper PPS. The combined endoscopic transnasal and anterior transmaxillary approach is a minimally invasive alternative approach to the upper PPS.

Herniation of orbital fat through the inferior orbital fissure and into the infratemporal fossa: a cadaveric case report and review.

Orbital fat herniation is primarily in a subconjunctival location. However, herniation through the inferior orbital fissure (IOF) has been scantly reported. Here, we report a cadaveric case of herniation of orbital fat through the inferior orbital fissure and into the infratemporal fossa. The cadaver's orbital anatomy and orbital fat herniation were found during routine dissection. The details of this case are reported. We also discuss anatomical variations of the inferior orbital fissure as well as the related vascular and nervous system structures related to orbital fat herniation. This is a rare case of a cadaver with this anatomical abnormality.

[The morphometric parameters of projection triangle of visceral cranium and infratemporal fossa under various degree of integrity of upper dentition].

In order to study the change in the morphometric parameters of projection triangles of the facial skull during tooth loss in adult patient, 185 categorized skulls were studied from the craniological collection of the Museum of the Department of Normal Anatomy of the Military Medical Academy. The skulls belonged to adults aged from 22 to 75 years and were separated into two groups - with complete set of teeth and complete absence of teeth on the upper jaw (100 and 85 skulls respectively). Based on standard points, the following projection triangles were developed: lateral front triangle, anterior maxillary triangle, lateral maxillary triangle, lateral infratemporal triangle. It was established that the morphometric characteristics of the proposed projection triangles of the facial skull and infratemporal fossa reliably change with tooth loss. In this case, only those sides that pass through the points located on the alveolar process of the upper jaw change. It is proved that the sides drawn through the alveolar point and the most lateral and posterior points on the alveolar process are most affected. The selection of the proposed projection triangles and the study of their features depending on the degree of preservation of the upper dentition is important for planning and anatomical justification of surgical access on the structures of the middle zone of the face.

Chondrosarcoma of right big toe with metastases to left orbital and left infra temporal region.

To report a case of chondrosarcoma of right big toe with left orbital and left infra temporal metastases. Chondrosarcoma is the second most frequent primary malignant tumour of the bone. A 56 year old man had history of trauma on his right big toe, which was amputated and the biopsy in 2011 at Sindh Institute of Urology and Transplantation (SIUT) revealed chondrosarcoma with clear margins. Eventually the patient was presented with swelling of the left eye, pain and gradual loss of vision of that eye. Later a CT scan of his chest, brain and orbit showed pulmonary and pleural based nodule, with mediastinal and hilar lymphadenopathy representing metastatic deposit in left orbit, extending to left infra temporal region. A treatment of palliative chemotherapy was started with doxorubicin and ifosfamide, after which he was referred for radiotherapy. At that time he had loss of vision, pain and exopthalamus, and palliative radiotherapy was delivered to the left orbit with the prescribed dose of30 Gy/300cGy×10 fraction. Thereafter his case will be followed up at the oncology OPD after a 03 month interval.

Metastatic Pleomorphic Adenoma in the infratemporal fossa and neck following total parotidectomy after 30 years.

Metastasising pleomorphic adenoma is rare and may occur years after surgical excision of a pleomorphic adenoma (PA). We present a 61-year-old woman with a right infratemporal PA with metastases to the cervical lymph nodes after 30 years following a total parotidectomy. She was treated successfully with a resection of the tumour with combined neck and mandibulotomy approach along with postoperative radiotherapy given subsequently.

Anatomic Step-by-Step Dissection of Complex Skull Base Approaches for Trainees: Surgical Anatomy of the Infratemporal Fossa Approach to the Jugular Foramen.

BACKGROUND AND OBJECTIVES: The infratemporal fossa (ITF) is a complex region bounded by the temporal bone, maxilla, sphenoid, pterygoid plates, and mandibular ramus. Containing a high density of neurovascular and musculoskeletal structures, the ITF can house a number of pathologies, and access is challenging. The ITF approach and its variations can be challenging due to complex anatomy and unfamiliarity by many surgeons. The objective of this study was to present a step-by-step 3-dimensional anatomic dissection for the classic Fisch Type A and modified ITF approach from the surgeon's perspective. METHODS: Six sides of 3 formalin-fixed latex-injected specimens were dissected under microscopic magnification (JRD and AMN). Standard Fisch Type A and modified ITF approaches were performed on contralateral sides of each specimen. Representative high-quality 3-dimensional photography was performed for each key step. RESULTS: The ITF approach affords excellent access to the posterior ITF and jugular foramen. Modifications to this approach include preservation of the ear canal and limiting facial nerve transposition, thus limiting morbidity while generally still providing sufficient access to key anatomic structures. CONCLUSION: The ITF approach provides access to the lateral skull base for jugular foramen paraganglioma and other lesions. Modifications of the classic Fisch Type A technique can be used to access pathologies in this region without sacrificing conductive hearing or facial nerve function. Three dimensional operatively oriented neuroanatomy dissections provide surgeons with a valuable resource for learning this complex surgical approach.

[The efficacy and safety analysis of endoscopic resection for infratemporal fossa benign mass].

Objective: To investigate the efficacy and safety of endoscopic resection of infratemporal fossa mass and to determine the indications for surgery. Methods: A retrospective case series study was conducted, including a total of 29 patients who underwent endoscopic surgery to treat infratemporal fossa mass in the Department of Rhinology of Beijing Tongren Hospital, Capital Medical University, from April 2008 to December 2021. Ten males and 19 females were included in the study, with age of (46.5±13.7) years. Pre-and post-operative sinus CT, sinus or nasopharyngeal enhanced MRI were evaluated, respectively. The main outcome measurements were the total resection of mass and the incidence of surgery-related complications. Results: Among the 29 cases of infratemporal fossa mass, 22 were schwannomas, 3 were cysts, 2 were neurofibromas, 1 was pleomorphic adenoma and 1 was basal cell adenoma. Preoperative imaging showed well-defined lesion boundaries, and postoperative pathology confirmed the benign nature of all cases. The endoscopic transnasal approach was used in 28 patients, while the combination of the transnasal approach and the transoral approach was used in 1 patient. Complete tumor removal was achieved in all cases with a 100% resection rate. The average follow-up time was 38 months (7-168 months), and no tumor recurrence was observed. Conclusions: The Endoscopic transnasal approach is a safe and effective surgical approach for the treatment of benign tumors or masses in the infratemporal fossa.