Infratemporal fossa approach: the modified zygomatico-transmandibular approach

Anatomic Study of Endoscopic Minimally Invasive Lateral Approach to the Infratemporal Fossa

OBJECTIVE

To investigate the feasibility and related anatomical structures of the infratemporal fossa (ITF) through minimally invasive endoscopic lateral approach, so as to provide anatomical data and basis for clinical surgery.

METHODS

Six adult cadaveric heads were used to simulate the surgical dissection of the ITF through a minimally invasive endoscopic lateral approach, and the important vessels, nerves, and other structures in the surgical pathway and the surrounding adjacent relationships were observed, and relevant pictures were collected.

RESULTS

The maxillary arteries of 6 cadaver specimens (12 sides) were located on the surface of the lateral pterygoid muscle in 9 cases, and between the upper and lower heads of the lateral pterygoid muscle in 3 cases, constant branches were the deep temporal artery, pterygoid artery, masseter artery, and buccal artery. The superior posterior alveolar nerve branches off V2 in the ITF and descends along with its accompanying artery by the posterior wall of the maxilla. The buccal nerve branches out from the mandibular nerve and passes between the superior and inferior pterygoid muscles, runs anteriorly between the temporalis and lateral pterygoid muscle, and innervates the buccal muscles.

CONCLUSION

The endoscopic minimally invasive lateral approach can expose the important structures, such as vessels and nerves related to the ITF well, and can be used as a minimally invasive surgical approach to treat the lesions of the infra- temporal fossa; it can also assist the endoscopic anterior approach to treat a series of lesions extending from the deep part of the pterygopalatine fossa to the posterior lateral side of the ITF.

HyperArc radiotherapy for recurrent synovial sarcoma of infratemporal fossa: a rare case report and review of the literature

Background

Synovial sarcoma (SS), a malignant and uncommon soft tissue sarcoma, typically manifests in the extremities and trunk. However, its occurrence in the infratemporal fossa (ITF) of the head and neck is exceedingly rare. Patients afflicted with SS in this anatomical region pose considerable challenges, as radical surgery is often difficult to undertake, leading to a high rate of postoperative recurrence. Moreover, it is often difficult to effectively control the tumor when the cancer relapses. Much of our understanding regarding SS of ITF stems from limited case reports, with a lack of established clinical guidelines for its management. There exists a significant clinical need for effective therapeutic approaches.

Case Description

This case report documents a patient with SS of ITF, experiencing repeated recurrences despite undergoing multiple surgeries and chemotherapy treatments. The patient underwent HyperArc (HA) radiotherapy (RT) in conjunction with concurrent chemotherapy utilizing cisplatin, resulting in a remarkable 3-year follow-up period devoid of recurrence.

Conclusions

The primary objective of this case report is to disseminate knowledge regarding this rare manifestation of SS of ITF, detailing the successful treatment strategy employed. In this case, we employed a comprehensive treatment strategy involving concurrent chemoradiotherapy based on HA. Our findings demonstrate that this approach was effective in achieving disease control and improving patient outcomes.

Giant Pleomorphic Adenoma of Infratemporal Fossa: A Rare Case Report

Of all the head and neck tumors, salivary gland tumors account to 3%. Pleomorphic adenomas are one of the most common benign tumors arising from major salivary glands, although it could also develop from minor salivary glands situated at accessory sites like nasal cavity, pharynx, parapharyngeal space, lacrimal glands etc. Tumors of infratemporal fossa are quite unusual, mainly because of its hidden location in retromaxillary region. We report an unusual case of 65 years old male presenting with complaint of progressive left cheek swelling for 4 years. FNAC revealed pleomorphic adenoma of minor salivary gland tumor. Intraoperatively a giant lobulated tumor was seen occupying almost whole space of infratemporal fossa, which was removed in-toto via open approach. Patient was kept on regular follow up with no evidence of recurrence reported till date.

[Microanatomical Investigation of the Subtemporal Transtentorial Approach]

Objective

To study the microanatomic structure of the subtemporal transtentorial approach to the lateral side of the brainstem, and to provide anatomical information that will assist clinicians to perform surgeries on the lateral, circumferential, and petroclival regions of the brainstem.

Methods

Anatomical investigations were conducted on 8 cadaveric head specimens (16 sides) using the infratemporal transtentorial approach. The heads were tilted to one side, with the zygomatic arch at its highest point. Then, a horseshoe incision was made above the auricle. The incision extended from the midpoint of the zygomatic arch to one third of the mesolateral length of the transverse sinus, with the flap turned towards the temporal part. After removing the bone, the arachnoid and the soft meninges were carefully stripped under the microscope. The exposure range of the surgical approach was observed and the positional relationships of relevant nerves and blood vessels in the approach were clarified. Important structures were photographed and the relevant parameters were measured.

Results

The upper edge of the zygomatic arch root could be used to accurately locate the base of the middle cranial fossa. The average distances of the star point to the apex of mastoid, the star point to the superior ridge of external auditory canal, the anterior angle of parietomastoid suture to the superior ridge of external auditory canal, and the anterior angle of parietomastoid suture to the star point of the 10 adult skull specimens were 47.23 mm, 45.27 mm, 26.16 mm, and 23.08 mm, respectively. The subtemporal approach could fully expose the area from as high as the posterior clinoid process to as low as the petrous ridge and the arcuate protuberance after cutting through the cerebellar tentorium. The approach makes it possible to handle lesions on the ventral or lateral sides of the middle clivus, the cistern ambiens, the midbrain, midbrain, and pons. In addition, the approach can significantly expand the exposure area of the upper part of the tentorium cerebelli through cheekbone excision and expand the exposure range of the lower part of the tentorium cerebelli through rock bone grinding technology. The total length of the trochlear nerve, distance of the trochlear nerve to the tentorial edge of cerebellum, length of its shape in the tentorial mezzanine, and its lower part of entering into the tentorium cerebelli to the petrosal ridge were (16.95±4.74) mm, (1.27±0.73) mm, (5.72±1.37) mm, and (4.51±0.39) mm, respectively. The cerebellar tentorium could be safely opened through the posterior clinoid process or arcuate protrusion for localization. The oculomotor nerve could serve as an anatomical landmark to locate the posterior cerebral artery and superior cerebellar artery.

Conclusion

Through microanatomic investigation, the exposure range and intraoperative difficulties of the infratemporal transtentorial approach can be clarified, which facilitates clinicians to accurately and safely plan surgical methods and reduce surgical complications.

Infratemporal Fossa Schwannoma Surgery via a Combined Prelacrimal Recess, Caldwell-Luc, and Distal Intraoral Approach

BACKGROUND

The deep location of infratemporal fossa (ITF) combined with the abundant vascular plexus in it increased the difficulty of removing the mass in ITF through endoscope surgery approach. However, under appropriate circumstances, the excision of ITF tumors through a combined prelacrimal recess, Caldwell-Luc, and distal intraoral approach can be safely performed with minimal impact on the surrounding tissues.

CASE PRESENTATION

The Department of Neurology received a 69-year-old male patient who had been experiencing headache, dizziness, and numbness from the mastoid region of his left ear to the corner of his mouth for a duration of 22 days. Cranial magnetic resonance imaging revealed the presence of a tumor located in the ITF. Following transfer to our department, surgical intervention was performed using a combined approach involving the prelacrimal recess, the anterior wall of maxillary sinus, and lateral ITF to successfully remove the tumor. Postoperative pathologic examination confirmed schwannoma as its nature. The patient was discharged in excellent condition without any functional impairment.

CONCLUSIONS

On the basis of this case, the authors believe that this combined approach can offer a distinct endoscopic perspective and adequate surgical workspace, which is crucial for tumor removal while preserving the integrity of surrounding normal tissues. Moreover, the utilization of multiple small incisions has minimal impact on postoperative recovery.

Transoral versus transfacial surgical approach to maxillary tumors: evaluation of outcomes and perspectives

Neoplasms of the maxilla have multiple different origins and histology, and often extend towards the infratemporal fossa, orbit, or skull base. Extensive resection may be required, often leading to poor esthetic and functional results. Usually, these lesions are removed via a transfacial approach. The aim of this study was to compare the outcomes of the transoral versus transfacial approach for maxillary tumors. A single-institution retrospective study was conducted on patients with maxillary-midface tumors, treated between January 2009 and December 2019. The patients were divided into two groups according to the surgical approach, transfacial or transoral, and the following outcomes were assessed: extent of the resection based on Brown's classification; postoperative pathology margin assessment; reconstruction technique; esthetic/functional results. A total of 178 patients were included. A satisfactory resection was obtained in both groups, with the transoral cohort achieving a higher rate of clear oncological margins (positive margins: transoral group 3.7% versus transfacial group 6.8%, P = 0.389) and a significantly higher University of Washington Quality of Life score (mean 72.2 versus 67.8, P < 0.001). Even large and invasive tumors can be treated successfully with the transoral approach, avoiding unesthetic facial scars while still providing complete resection of the tumor.

Morphometric and morphologic analysis of the foramen spinosum in the Slovenian population with clinical correlations

Background

The foramen spinosum (FS) is a pivotal passage for neurovascular structures within the skull base. We performed a detailed morphometric and morphological analysis of the FS to emphasize its clinical relevance.

Materials & Methods

The study was performed on dried skull specimens obtained from the anatomical collections of the Institute of Anatomy and Institute of Forensic Medicine of the University of Ljubljana. The morphometric and morphologic features of FS in 126 whole human skulls and 15 skull halves were analyzed, including dimensions, shape, and other anatomical variations, as well as relationships to surrounding structures. Measurements were done with a digital sliding caliper.

Results

The mean length and width of the FS were 2.45 ± 0.65 mm and 2.03 ± 0.53 mm on the right side and 2.49 ± 0.61 mm and 2.08 ± 0.48 mm on the left side. The most frequently observed shape was round (56.7%), followed by oval (28.2%), irregular (8.7%) and drop shaped (6.3%). Several anatomical variations were also noted, including FS duplication, confluences with other foramina, and FS obstruction due to marginal bony outgrowths.

Conclusion

The FS exhibits notable interindividual differences in anatomical characteristics which should be considered during neurosurgical procedures and radiological interventions in the skull base.

Enbloc resection of primary oral cancer involving infratemporal fossa: A systematic "out to in and top to bottom" surgical approach and outcomes

AIM AND INTRODUCTION

The oral cavity Squamous Cell Carcinoma (OCSCC) involving infratemporal fossa (ITF) is considered as cT4b stage per AJCC 8th classification. The treatment of these group of patients is challenging due to the difficulty in achieving negative resection margin status. In this study we have highlighted our surgical technique with oncological outcome of enbloc resection of primary oral cancer involving ITF.

METHODOLOGY

- This was a single center retrospective study which included only patients with OCSCC extending into ITF. Our surgical technique of systematic "out to in and top to bottom" approach was detailed. The perioperative outcomes, histopathological details, survival outcomes were measured.

RESULTS

- Over the period of 1 year a total of 340 patients with OCSCC reported to our outpatient department, out of which 120 patients belonged to cT4 category and 32 patients were cT4b stage with involvement of ITF. Amongst 32 patients, 2 patients had distant metastasis and were excluded from the study. The 5 patients received neoadjuvant chemotherapy followed by surgery and rest all patients were taken up for upfront curative surgery. There were no significant intraoperative and postoperative complications. None of the margins were found to be involved or close in the final histopathology report. The median DFS and OS were 31 months and 27 months respectively at a median follow up of 29 months.

CONCLUSION

- Our systematic approach of enbloc resection of primary oral cancer involving ITF is safe and easily reproducible with high rate of negative resection margin status.

Access to the infratemporal fossa: A modified transzygomatic approach with preservation of masseter attachment and a long-term follow-up period

This study aimed to introduce and evaluate the feasibility of a modified transzygomatic approach with preservation of masseter attachment for the management of infratemporal fossa tumors. This retrospective study included 20 patients treated at Shanghai Ninth People's Hospital, Shanghai Jiao Tong University, between June 2007 and August 2017. Pre- and postoperative radiological findings (magnetic resonance imaging and computed tomography) were obtained from all patients. During an average 67 months of follow-up, no clinical or radiographic signs were found of recurrence or absorption of zygomatic arch defects. The mean visual analog scale score changed from 5.5 preoperatively to 0.6 postoperatively (P<0.001), while the mean maximum inter-incisal opening improved from 21.5 mm preoperatively to 38.7 mm postoperatively (P<0.001). Thus, managing infratemporal lesions using the modified transzygomatic approach may provide functional and esthetically established outcomes.

Endonasal access to the lateral poststyloid space: Far lateral extension of an endoscopic endonasal corridor

The styloid process constitutes the posterolateral boundary for an endonasal exposure of the infratemporal fossa. This study aims to explore the feasibility of a far-lateral extension to the lateral poststyloid space via an endonasal corridor. An endonasal dissection was performed on six cadaveric specimens (12 sides). Following an endoscopic endonasal access to the parapharyngeal space, the styloid process and the tympanic portion of the temporal bone were removed to reveal the jugular bulb and the extratemporal facial nerve. Distances from the anterior nasal spine to the relevant landmarks were measured using a surgical navigation device. Through an endonasal corridor, only the anteroinferior aspect of the jugular bulb was exposed. Conversely, the extratemporal facial nerve could be sufficiently exposed, and the deep temporal nerve could be transposed to the stylomastoid foramen. The average horizontal distances from the nasal spine to the posterior tract of V₃ , styloid process, and facial nerve were 79.33 ± 3.41, 97.10 ± 4.74, and 104.77 ± 4.42 mm, respectively. Access to the lateral poststyloid space via an endonasal corridor is feasible, potentially providing an alternative approach to address select lesions extending to this region. The deep temporal nerve has a similar diameter to that of the facial nerve; thus, providing potential reinnervation of the facial nerve.

Infra-Temporal and Pterygo-Palatine Fossae Tumors: A Frontier in Endoscopic Endonasal Surgery—Description of the Surgical Anatomy of the Approach and Report of Illustrative Cases

Infratemporal and pterygopalatine fossae (ITF and PPF) represent two complex paramedian skull base areas, which can be defined as jewelry boxes, containing a large number of neurovascular and osteomuscular structures of primary importance. They are in close communication with many craniofacial areas, such as nasal/paranasal sinuses, orbit, middle cranial fossa, and oral cavities. Therefore, they can be involved by tumoral, infective or inflammatory lesions spreading from these spaces. Moreover, they can be the primary site of the development of some primitive tumors. For the deep-seated location of ITF and PPF lesions and their close relationship with the surrounding functional neuro-vascular structures, their surgery represents a challenge. In the last decades, the introduction of the endoscope in skull base surgery has favored the development of an innovative anterior endonasal approach for ITF and PPF tumors: the transmaxillary-pterygoid, which gives a direct and straightforward route for these areas. It has demonstrated that it is effective and safe for the treatment of a large number of benign and malignant neoplasms, located in these fossae, avoiding extensive bone drilling, soft tissue demolition, possibly unaesthetic scars, and reducing the risk of neurological deficits. However, some limits, especially for vascular tumors or lesions with lateral extension, are still present. Based on the experience of our multidisciplinary team, we present our operative technique, surgical indications, and pre- and post-operative management protocol for patients with ITF and PPF tumors.

Anatomy of the sphenoidal spine and its implications in endoscopic endonasal surgery of the infratemporal fossa

BACKGROUND

The sphenoidal spine protrudes from the roof of the infratemporal fossa (ITF). This study aims to assess the anatomic relationships among the sphenoidal spine and other structures within the ITF from the perspective of an endoscopic endonasal access (EEA), and to explore the implications of these relationships.

METHODS

An EEA to the ITF was completed on six cadaveric specimens (12 sides). The anatomical relationships among the sphenoidal spine and adjacent structures were explored and associated distances from each other were measured using a navigation system.

RESULTS

The foramen spinosum is located anterosuperior to the sphenoidal spine, whereas the chorda tympani courses caudal and medial to the sphenoidal spine and the Eustachian tube and parapharyngeal internal carotid artery (pICA) are at its posterior aspect. Two virtual vertical planes, at the anterior and posterior aspects of the sphenoidal spine, respectively, correspond to the posterior trunk of V₃ and middle meningeal artery, and the stylopharyngeal aponeurosis. The average length of sphenoidal spine was 8.5 ± 2.43 mm, and the distance from distal apex of the sphenoidal spine to the foramen ovale, foramen spinosum, and pICA were 10.82 ± 0.83 mm, 6.42 ± 0.52 mm, and 5.02 ± 0.54 mm, respectively.

CONCLUSIONS

The sphenoidal spine is a meaningful landmark for endonasal approaches to the ITF. Measurements and conceptualization of vertical planes prior and posterior to the sphenoidal spine are beneficial to better appreciate the anatomic relationships in the ITF.

[Research advances on endoscopic surgical approach for infratemporal fossa tumors]

The tumors occurring in infratemporal fossa （ITF） and parapharyngeal space account for 0.5%-1.0% of head and neck tumors, 80% of which are benign and 20% are malignant. At present, a variety of ITF surgical approaches have been described in domestic and foreign literatures. However, the selection of surgical approaches in clinical practice is still based on the habits and experience of the operators, there is still a lack of standardized clinical guidance. This article mainly introduces the advantages and disadvantages of the latest anatomical division of ITF and the corresponding endoscopic surgical approach as well as the research progress, so as to provide reference for the selection of the optimal surgical approach for ITF tumors.

Endoscopic Paramaxillary Approach to the Infratemporal Fossa and Pterygomaxillary Space: Computer Modeling Analysis and Clinical Series

Objective Several different open and endoscopic approaches for the pterygomaxillary space and infratemporal fossa have been described. Limitations to these approaches include restricted exposure of the infratemporal fossa and difficult surgical manipulation.

Study Design Consecutive clinical cases utilizing a novel approach to access lesions in the infratemporal fossa and pterygomaxillary space were reviewed. Data was collected on pathology, lesion location, and surgical approach(es) performed. Computer modeling was performed to analyze the full extent of surgical access provided by the paramaxillary approach to the range of target locations.

Results Ten consecutive cases met inclusion criteria. Surgical access to the target lesion was achieved in all cases. Computer modeling of the approach derived the anatomical boundaries of the paramaxillary approach. Wide access to the posterior maxilla, and lateral or medial to the mandibular condyle allows for variability in endoscopic angles and access to more medial pterygomaxillary space lesions. The lateral extent is limited proximally only by the extent of cheek/soft tissue retraction and by the zygomatic arch more superiorly. The superior limit of dissection is at the temporal line.

Conclusion The endoscopic paramaxillary approach is a transoral minimally disruptive approach to the ITF and PS that provides excellent surgical exposure for resection of lesions involving these areas. Compared with previously described endoscopic approaches, there are no external incisions; tumor manipulation is straightforward without angled endoscopy, and all areas of the infratemporal fossa and pterygomaxillary space can be accessed.

Rerouting the Dissection of the Infratemporal and Submandibular Regions

Introduction

Teaching and learning in anatomy are necessarily dependent on cadaveric dissection. Skillful dissection is the tool which helps in proper visualization of structures in a cadaver. Proper understanding about the course of lingual nerve, hypoglossal nerve, nerve to mylohyoid, and relations between structures present in infratemporal and submandibular regions is important for medical students. The aim of this study is to describe a modified technique of dissection and evaluate medical students' and teachers’ response to this approach.

Methods

The comparative observational study was conducted bilaterally on six adult cadavers. We compared the method of dissection given in standard textbooks with the modified method introduced. The validity and reliability of the newer method of dissection for teaching purpose was assessed by first-year undergraduate medical students using a questionnaire-based tool and feedback from postgraduate students and senior residents.

Results

The modified method was described as less time consuming, easy to perform, and allowed extensive exploration of the structures in the infratemporal and submandibular regions.

Conclusions

Proper understanding of the course and relations between structures present in infratemporal and submandibular regions is important for medical students.The modified approach to infratemporal and submandibular regions will facilitate better understanding of the human anatomy.

Infratemporal fossa surgical approaches to primary/recurrent malignancies of salivary origin: paradigm surgical shift, patient selection, and oncologic outcomes

PURPOSE OF REVIEW

To review, the surgical approaches available on diagnosing a patient with salivary gland malignancy in the infratemporal fossa (ITF). To comment on patient evaluation and method of treatment selection. To identify and report on patient outcome data and make recommendations on future needs.

RECENT FINDINGS

There is a need to define the anatomic boundaries contents of the ITF, masticator space, parapharyngeal space (PPS), pterygopalatine fossa, ventral skull base, and paramedian skull base, as evidence from publications. The pathological subtypes identified mainly include adenoid cystic and mucoepidermoid carcinomas. The source of these tumours originates from primary disease in the sinonasal tract and nasopharynx superiorly, and the PPS/deep lobe of parotid inferiorly. Current surgical options available, in suitable selected patient, available in tertiary head and neck cancer hospitals, which have available facilities and staffing is the endoscopic endonasal approach. This approach offers patients a 'complete margin-free surgical excision', minimal complications, shorter hospital stay, and no delay with commencement of any adjuvant treatment compared with the traditional 'open transcutaneous' approach.

SUMMARY

The current evidence specifically to the surgical management of salivary gland malignancy involving the ITF is sparse, with great difficult identifying treated patients and their details among a heterogeneous group of patients with many lesions. There is a need for patient data that have specific pathologic conditions to be amalgamated from such centers and publish on outcome events.

Anterolateral Approach for Retrostyloid Superior Parapharyngeal Space Schwannomas Involving the Jugular Foramen Area: A 20-Year Experience

BACKGROUND

Schwannomas encompassing the superior parapharyngeal space are challenging lesions because of the anatomical complexity of this region and the frequent involvement of the neurovascular structures of the jugular foramen. The purpose of this study is to report the technical aspects and the advantages of the anterolateral approach, here proposed for schwannomas of this complex area.

METHODS

The main steps of the anterolateral approach are described in detail, along with the results of a consecutive series of 38 patients with a retrostyloid superior parapharyngeal schwannoma involving the jugular foramen operated on by means of this route between 1999 and 2019.

RESULTS

The supine position is generally preferred. The medial border of the sternocleidomastoid muscle, mastoid tip, and superior nuchal line are the landmarks for the hockey-stick skin incision. The accessory nerve is retrieved and mobilized cranially. Detachment of the sternocleidomastoid, digastric, and nuchal muscles allows for a 180° exposure of the extracranial side of the jugular foramen. Three working corridors, namely the pre-carotid, pre-jugular, and retro-jugular, allow access to the deeper part of the jugular foramen area and the superior parapharyngeal space. In the present series, a gross total resection was achieved in 89.4% of the patients. Three recurrences occurred after an average follow-up of 80.5 ± 51 months.

CONCLUSIONS

The anterolateral approach is highly effective in the treatment of retrostyloid superior parapharyngeal space schwannomas involving the jugular foramen. Its simplicity of execution, versatility, and very low morbidity are among its main strengths.