Parapharyngeal Internal Carotid Artery Research Articles

An anatomical road map of the parapharyngeal internal carotid artery in lateral and endoscopic ventral approaches

Objective:To describe the road map of the lateral and endoscopic ventral approaches for the pharyngeal segment of the internal carotid artery, propose a sub-segmentation scheme, systematically and comprehensively understand its anatomical details and relationships with the surrounding structures. Methods:Five fresh cadaveric head specimens（10 sides in total） were dissected through lateral and endoscopic ventral approaches to evaluate the anatomical details of the parapharyngeal internal carotid artery and its relationship with the surrounding structures. Results:From the bifurcation of the common carotid artery to the vertical part of the internal carotid artery, alongside the direction of blood flow, the parapharyngeal internal carotid artery passes through four distinct anatomical tissues. Based on this, the parapharyngeal internal carotid artery can be divided into four sub-segments: nerve, muscle, fascia and osseous sub-segments. The boundaries and important adjacent structures of each segment are described in detail. Conclusion:The anatomical road map of the parapharyngeal internal carotid artery and the sub-segmentation scheme serving as a practical guide to navigate modular endoscopic skull base surgery of the parapharyngeal space while reduce the risk of internal carotid artery injury.

Strategies for patients with recurrent nasopharyngeal carcinoma involved internal carotid artery who are intolerant to embolization.

The surgical treatment of recurrent nasopharyngeal carcinoma (rNPC) involving the internal carotid artery (ICA) is challenging, as the massive bleeding caused by intraoperative rupture of the ICA is life-threatening. We reported that ICA embolization is an effective pretreatment to avoid fatal bleeding, but some patients cannot tolerate the procedure. We used endovascular vascular protection (ICA stents), vascular sacrifice (bypass grafting) and extravascular vascular protection (transcervical external stent placement) of the ICA to provide alternative options for these patients. METHODOLOGYy: This study enrolled patients with rNPC adjacent to or invading the ICA who were unsuitable for ICA embolization from January 2015 to June 2020. ICA pretreatment combined with endoscopic nasopharyngectomy (ENPG) was performed for the 30 patients. We report the survival outcome and incidence of complications after ICA pretreatment. ICA pretreatment was performed for the 30 enrolled patients, among whom 8 underwent endoscopic-assisted transcervical protection of the parapharyngeal ICA combined with ENPG, 6 underwent bypass grafting, and 16 underwent ICA stent implantation followed by ENPG. After pretreatment, at a median follow-up of 43 months (range, 2-80 months), the 3-year locoregional overall survival (OS), progression-free survival (PFS), locoregional recurrence-free survival (LRRFS), and distant metastasis-free survival (DMFS) were 62.9%, 61.3%, 70.2%, and 71.4%, respectively. ICA pretreatment combined with salvage ENPG enables the feasible and effective resection of rNPC lesions involving the ICA in patients who cannot tolerate ICA embolization. Therefore, this treatment may be an effective method for improving outcomes. Multidisciplinary therapy is needed to reduce operation-related complications.

Anatomical Variations of the Ascending Pharyngeal Artery: Implications for Endoscopic Surgery in the Parapharyngeal Space.

Objectives: The ascending pharyngeal artery (APA) travels with the parapharyngeal internal carotid artery (pICA) in the parapharyngeal space (PPS). This study aimed to investigate the anatomical variations of the APA, and to explore their implications for endoscopic surgery in the PPS. Methods: Dissection of the APA in the PPS was performed on 10 cadaveric specimens (20 sides). The relationship between APA and PPS tumors was retrospectively reviewed in 20 patients, attempting to ascertain the APA during the resection of 10 pre-styloid and 10 retro-styloid PPS tumors. Results: During the cadaveric dissections, the APA was identified at the medial, posteromedial, or bilateral aspects of the pICA in 12 (60%) and 4 (20%) sides, respectively. In the remaining 4 sides (20%), the APA branched into several subcategory arteries lying at the medial and lateral aspects of the pICA. Branches of the APA were observed in 13/20 sides (65%). Two branches were found in 9/13 sides and 3 branches in 4/13, respectively. The APA was only identifiable in 1/10 (10%) of pre-styloid tumors, a patient with basal cell adenoma. In contrast, the APA was encountered surrounding the pICA in 8/10 (80%) of patients with retro-styloid tumors, all of which were schwannomas. No inadvertent injury of the APA or the pICA occurred in this cohort. Conclusions: With identification of the ascending pharyngeal artery on preoperative magnetic resonance imaging, it may serve as an additional landmark during the endoscopic extirpation of tumors arising in the PPS.

Strategies for patients with recurrent nasopharyngeal carcinoma involved internal carotid artery who are intolerant to embolization

BACKGROUND: The surgical treatment of recurrent nasopharyngeal carcinoma (rNPC) involving the internal carotid artery (ICA) is challenging, as the massive bleeding caused by intraoperative rupture of the ICA is life-threatening. We reported that ICA embolization is an effective pretreatment to avoid fatal bleeding, but some patients cannot tolerate the procedure. We used endovascular vascular protection (ICA stents), vascular sacrifice (bypass grafting) and extravascular vascular protection (transcervical external stent placement) of the ICA to provide alternative options for these patients. METHODOLOGYy: This study enrolled patients with rNPC adjacent to or invading the ICA who were unsuitable for ICA embolization from January 2015 to June 2020. ICA pretreatment combined with endoscopic nasopharyngectomy (ENPG) was performed for the 30 patients. We report the survival outcome and incidence of complications after ICA pretreatment. RESULTS: ICA pretreatment was performed for the 30 enrolled patients, among whom 8 underwent endoscopic-assisted transcervical protection of the parapharyngeal ICA combined with ENPG, 6 underwent bypass grafting, and 16 underwent ICA stent implantation followed by ENPG. After pretreatment, at a median follow-up of 43 months (range, 2-80 months), the 3-year locoregional overall survival (OS), progression-free survival (PFS), locoregional recurrence-free survival (LRRFS), and distant metastasis-free survival (DMFS) were 62.9%, 61.3%, 70.2%, and 71.4%, respectively. CONCLUSIONS: ICA pretreatment combined with salvage ENPG enables the feasible and effective resection of rNPC lesions involving the ICA in patients who cannot tolerate ICA embolization. Therefore, this treatment may be an effective method for improving outcomes. Multidisciplinary therapy is needed to reduce operation-related complications.

Endoscopic endonasal transpterygoid nasopharyngectomy: Anatomical considerations and technical note.

The study was designed to identify new landmarks in the parapharyngeal segment of the internal carotid artery (ICA) for nasopharyngectomy and describe a surgical procedure of endoscopic endonasal transpterygoid nasopharyngectomy (EETPN). Four cadaveric specimens were injected with colored silicone and subjected to CT scanning before dissection. The nasopharyngeal skull base was exposed using the endoscopic endonasal transpterygoid approach. The clinical data of four patients with nasopharyngeal malignances who underwent EETPN were reviewed. The lateral edge of the longus capitis muscle medially; the foramen lacerum, petrous apex spine and the stump of the levator veli palatini muscle superior laterally; and the upper parapharyngeal ICA laterally constitute the ICA-longus capitis muscle-petrous apex spine triangle which was a novel landmark for the upper parapharyngeal segment of the ICA. The ICA-longus capitis muscle-petrous apex spine triangle are important landmarks of the upper parapharyngeal segment of the ICA.

Combined subtarsal contralateral transmaxillary retroeustachian and endoscopic endonasal approaches to the infrapetrous region.

The eustachian tube (ET) limits endoscopic endonasal access to the infrapetrous region. Transecting or mobilizing the ET may result in morbidities. This study presents a novel approach in which a subtarsal contralateral transmaxillary (ST-CTM) corridor is coupled with the standard endonasal approach to facilitate access behind the intact ET. Eight cadaveric head specimens were dissected. Endoscopic endonasal approaches (EEAs) (i.e., transpterygoid and inferior transclival) were performed on one side, followed by ST-CTM and sublabial contralateral transmaxillary (SL-CTM) approaches on the opposite side, along with different ET mobilization techniques on the original side. Seven comparative groups were generated. The length of the cranial nerves, areas of exposure, and volume of surgical freedom (VSF) in the infrapetrous regions were measured and compared. Without ET mobilization, the combined ST-CTM/EEA approach provided greater exposure than EEA alone (mean ± SD 288.9 ± 40.66 mm2 vs 91.7 ± 49.9 mm2; p = 0.001). The VSFs at the ventral jugular foramen (JF), entrance to the petrous internal carotid artery (ICA), and lateral to the parapharyngeal ICA were also greater in ST-CTM/EEA than in EEA alone (p = 0.002, p = 0.002, and p < 0.001, respectively). EEA alone, however, provided greater VSF at the hypoglossal canal (HGC) than did ST-CTM/EEA (p = 0.01). The SL-CTM approach did not increase the EEA exposure (p = 0.48). The ST-CTM/EEA approach provided greater exposure than EEA with extended inferolateral (EIL) or anterolateral (AL) ET mobilization (p = 0.001 and p = 0.02, respectively). The ST-CTM/EEA also increased the VSF lateral to the parapharyngeal ICA in comparison with EEA/EIL ET mobilization (p < 0.001) but not with EEA/AL ET mobilization (p = 0.36). Finally, the VSFs at the HGC and JF were greater in EEA/AL ET mobilization than in ST-CTM/EEA without ET mobilization (p = 0.002 and p = 0.004, respectively). Combining the EEA with the more laterally and superiorly originating ST-CTM approach allows greater exposure of the infrapetrous and ventral JF regions while obviating the need for mobilizing the ET. The surgical freedom afforded by the combined approaches is greater than that obtained by EEA alone.

Maximal exposure of the parapharyngeal internal carotid artery via transnasal and transoral corridors.

The parapharyngeal internal carotid artery (pICA) could be surgically exposed through the transnasal and transoral corridors. However, their potential degree of exposure has not been established sufficiently. This study aims to elucidate the maximal exposure of the pICA via the transnasal and transoral corridors. An endonasal transpterygoid nasopharyngectomy for exposure of the pICA was performed on eight cadaveric specimens (16 sides), while a transoral approach for exposure of the pICA was performed on six additional specimens (12 sides). In addition, the CT angiography of 60 consecutive patients (120 sides) was analyzed to establish the potential maximal exposure of the pICA through each corridor. The hard palate becomes a restricting factor for the inferior exposure of the pICA via the transnasal approach, whereas the entire pICA segment could be adequately displayed through the transoral corridor. The maximal exposed length of the pICA for a transnasal and transoral approach was 3.08 ± 0.30 cm and 6.56 ± 0.57 cm, respectively. This difference was statistically significant (p < 0.001). An endonasal exposure of the pICA seems limited to its superior aspect, whereas the transoral corridor could provide adequate exposure of the entire length of pICA.

Endoscopic trans‐lateral oropharyngeal wall approach to the petrous apex and the petroclival region

A trans-lateral oropharyngeal wall approach (TLOWA) to the petrous apex has not been previously defined. This study aims to assess the feasibility of a TLOWA for surgical access to the petrous apex and the petroclival region. An endoscopic TLOWA for exposure of the petrous apex and petroclival region was performed on five cadaveric specimens (10 sides). Associated anatomical landmarks were defined, and the strategies for maximal exposure of the internal carotid artery (ICA) were explored. Via a TLOWA, the parapharyngeal ICA was widely exposed in all 10 sides. Following transection of the Eustachian tube, the inferior petrous apex and petroclival region could be sufficiently exposed. After drilling the anteroinferior bony canal, the horizontal petrous ICA, foramen lacerum, and the paraclival ICA could be adequately revealed. The TLOWA may provide an alternative corridor for access to the petrous apex and the petroclival region. The parapharyngeal, petrous, lower paraclival ICAs, and the foramen lacerum could be adequately exposed via the TLOWA.

Exploration of anatomical landmarks for performing an endoscopic transoral nasopharyngectomy.

Performing a nasopharyngectomy via a transoral approach has been reported; however, defining landmarks to facilitate this approach has not been addressed. This study aims to explore anatomical landmarks to aid in performing a nasopharyngectomy via the transoral corridor. An endoscopic transoral nasopharyngectomy was performed on six cadaveric specimens (12 sides). Related anatomical landmarks were defined, and the strategy to preserve the parapharyngeal internal carotid artery (pICA) was explored. An endoscopic transoral nasopharyngectomy was successfully achieved in all 12 sides. Utilizing the pterygoid hamulus as a landmark, the cartilaginous ET and attachments could be adequately exposed. Identification of the pICA is a prerequisite prior to Eustachian tube (ET) transection. The sphenoidal spine and the petrotympanic fissure could be sufficiently revealed in all 12 sides, which aided in transection of the cartilaginous ET without pICA injury. The ET and the prevertebral contents could be adequately removed via the transoral corridor. The pterygoid hamulus, sphenoidal spine and petrotympanic fissure serve as reliable landmarks for performing a transoral nasopharyngectomy. Identification of the pICA is a prerequisite prior to transection of the ET to avoid pICA injury.

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

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. 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. 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. 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.

Microsurgical anatomy of the internal carotid artery at the skull base.

The aetiology and significance of internal carotid artery variations at the skull base remain controversial after decades, with limited available literature. Approximately 10-40 per cent of the general population has parapharyngeal internal carotid artery variations. A prospective observational study was conducted on internal carotid artery variations in 36 cadavers, in a tertiary care hospital, between March 2019 to March 2020. The most common internal carotid artery variation observed in the specimens was tortuosity, in 30 per cent, followed by kinking in 18 per cent and coiling in 10 per cent. Thirty per cent of specimens had variations present bilaterally. A loop pattern of the internal carotid artery was identified. Coiling of the internal carotid artery may present as a node; hence, meticulous dissection is advocated near the skull base to avoid complications. These variations hold utmost importance for otorhinolaryngologists performing pharyngeal and nasopharyngeal surgical procedures. A detailed knowledge of anatomy, along with its variations, and surgical expertise, will help reduce the incidence of surgical complications.

Individualized imaging analysis of anatomic landmarks of parapharyngeal internal carotid artery via maxillary sinus approach

Objective:To investigate the morphology of bone markers around the parapharyngeal internal carotid artery and its adjacent relationship. Methods:The imaging date of 30 cases which had normal structure of the skull by CTA were randomly selected. Through maxillary sinus approach, the morphology of peripheral bony landmarks （sphenoid spine, vaginal process of the tympanic bone, tympanic crest） from the parapharyngeal internal carotid artery to the entrance of the internal carotid artery and the adjacent relationship with the parapharyngeal internal carotid artery were observed for imaging anatomy. Results:With the external opening of the internal carotid artery as the reference point, the parapharyngeal internal carotid artery was divided into 10 sides （16.7%） in the direction of atlas and 6 sides（10%） in the direction of temporomandibular joint, 44 sides （73.3%） were close to midline. On 53 sides （88.3%）, the morphology of sphenoid spine became triangular shape with upper width and lower width, 6 sides （10%） became irregular type with terminal bifurcation, and 1 side （1.7%） had sphenoid spine missing. The shape of the vaginal process of the tympanic bone （VPTB） was a flat, irregular polygon with a smooth surface and no loss on 60 sides （100%）. The tympanic crest （TC） was a continuation of the VPTB to the sphenoid spine. It was located between the sphenoid spine and the VPTB. 51 sides （85%） of the TC and 9 sides （15%） of the TC were missing. The three constituted a special anatomical structure located in front of the internal carotid artery of the parapharyngeal segment, which can be divided into 43 inverted J-types （71.7%） and 17 irregular types （28.3%）. Conclusion:The special anatomical area composed of sphenoid spine, vaginal process of the tympanic bone, tympanic crest is closely related to the parapharyngeal internal carotid artery observed by maxillary sinus approach, which is the anatomical basis for endoscopic surgery to find the parapharyngeal internal carotid artery. CTA can provide individualized surgical basis.

Endoscopic Nasopharyngectomy Combined With Internal Carotid Artery Pretreatment for Recurrent Nasopharyngeal Carcinoma

Salvage endoscopic nasopharyngectomy (ENPG) is a reasonable choice for resectable recurrent nasopharyngeal carcinoma (rNPC). However, in past decades, complete removal of the tumor was not feasible when the recurrent lesion was adjacent to the internal carotid artery (ICA). The present article introduces innovative strategies to ensure sufficient surgical margins while avoiding accidental injury to the ICA. Retrospective study. Tertiary care center. We retrospectively reviewed rT2-3 rNPC patients with tumor lesions adjacent to the ICA (<5 mm) who underwent ENPG at the Sun Yat-sen University Cancer Center between January 2015 and June 2020. Thirty-seven patients were selected for this study. Seventeen patients underwent ENPG using direct dissection, 10 patients underwent endoscopic-assisted transcervical protection of the parapharyngeal ICA combined with ENPG, and 10 patients underwent ICA embolization followed by ENPG. With a median follow-up duration of 31 months (range, 5 to 53 months), the 2-year overall survival, progression-free survival, locoregional recurrence-free survival, and distant metastasis-free survival rates of salvage ENPG for rNPC adjacent to the ICA were 88.7%, 72.0%, 72.0%, and 97.3%, respectively. The incidences of grade 1-2 and grade 3-5 postoperative complications were 16.2% and 13.5%, respectively. Two patients experienced ICA rupture during direct dissection but were out of danger after vascular embolization therapy. One patient had a positive margin. Two patients had severe nasopharyngeal wound infections with mucosal flap necrosis. ENPG combined with ICA pretreatment allows the feasible and effective resection of rNPC lesions adjacent to the ICA.

Surgical Landmarks for Parapharyngeal Internal Carotid Artery During Extended Endoscopic Surgery of Nasopharynx: A Cadaveric and Radiological Study.

Nasopharynx is a complex region situated at the center of skull surrounded by various vital neurovascular structures. Surgical access to the nasopharyngeal space poses significant challenges due to the position of the internal carotid artery (ICA). Open approaches to nasopharynx utilize the lateral to medial anatomy but the endoscopic endo-nasal approach warrants knowledge about the medial to lateral anatomy. In this study we attempted to find the consistent surgical landmarks for parapharyngeal portion of internal carotid artery at the level of nasopharynx by means of cadaveric and radiological study. Eight fresh frozen cadavers (16 sides) and 30 CT angiography (60 sides) were included in the anatomical and radiological study respectively. Superior aspect of the torus tubarius was taken as the reference point in cadaveric study and C1-C2 interspace was used as the reference point for the radiological study. The distance between the ICA to the landmarks such as fossa of Rosenmullaer, torus tubarius, medial and lateral pterygoid plates were recorded. The mean distance of ICA to the fossa of Rosenmuller was 8.5 ± 1.4mm and 9.1 ± 1.1mm in the cadaveric and radiological study respectively. The mean distance between ICA to torus tubarius was 19.8 ± 1.3mm in cadaveric and 20.6 ± 1.0mm in radiological study. The mean distance of ICA to medial and lateral pterygoid plates were 25.3 ± 1.4mm and 18.2 ± 1.4mm in the cadaveric study and 25.9 ± 1.2mm and 18.8 ± 1.3mm in the radiological study respectively. On correlating the measurements between cadaveric and radiological study, the p values were not statistically significant (p > 0.05). The closest landmark to the ICA was the fossa of Rosenmuller. ICA was located at the same sagittal plane as that of the lateral pterygoid plate. The nasopharynx is a complex anatomical region closely related to ICA. Inadvertent injury to ICA is one of the dreaded complications of nasopharyngeal surgery. Fossa of Rosenmuller is only few millimeters away from the ICA and must be treated very cautiously. During the endoscopic approach, the ICA is at the sagittal plane as of the lateral pterygoid plate. This must be kept in mind when advancing toward the ICA by keeping intact the lateral pterygoid plate when possible and one should stay in the plane of medial pterygoid plate as the ICA lies posterolateral to it. Cadaveric dissections supported by radiological data would definitely aid surgeons to successfully perform surgeries in nasopharynx.

Endoscopic transoral nasopharyngectomy.

A minimal access technique for the management of nasopharyngeal tumors extending below the palatal plane and laterally beyond the pterygoid musculature is yet to be developed. In this study we demonstrate the feasibility of endoscopic transoral nasopharyngectomy (ETON) for resection of large nasopharyngeal lesions as a natural orifice alternative to traditional approaches. ETON was completed in three latex-injected specimens. Surgical freedom (SF) and angles of attack (AoA) were calculated along the internal carotid artery (ICA). An endoscopic transoral approach was successfully used to identify the parapharyngeal ICA and subsequently perform a complete nasopharyngeal resection. SF and AoA (sagittal) were found to be the greatest at the anterior genu of the ICA. ETON is feasible. It provides wide exposure of the skull base and proximal control of the ICA. It may be indicated for the management of nasopharyngeal tumors with inferolateral extension, involving the ICA.

Practical Guide for Identification of Internal Carotid Artery During Endoscopic Nasopharyngectomy.

View Supplementary Video 1 Laryngoscope, 2020

An endoscopic anatomical study of the levator veli palatini and its relationship to the parapharyngeal internal carotid artery.

The objectives of this study are to describe the levator veli palatini (LVP) as a landmark for the parapharyngeal internal carotid artery (pICA) and the endoscopic course of the pICA. Cadaver dissection and illustrative case study. Seven cadaveric heads (12 sides) were dissected. In all 12 sides, the LVP was consistently located between the Eustachian tube and the pICA near the skull base, making the LVP just anterior to and the closest structure to the pICA. The distance between the pICA and the nares ranged from 9.0 to 12.7 cm. The distance between the pICA and the midpoint of the nasopharynx ranged from 1.9 to 3.7 cm. The case study illustrated the applicability of these findings. The LVP is a reliable and precise landmark for the pICA. A safe working distance to the pICA is 1.9 cm from the midpoint of the nasopharynx and 9.0 cm from the nares.

Characterization of Anatomical Landmarks for Exposing the Internal Carotid Artery in the Infratemporal Fossa Through an Endoscopic Transmasticator Approach: A Morphometric Cadaveric Study

The Eustachian tube and sphenoid spine have been previously described as landmarks for endonasal surgical identification of the most distal segment of the parapharyngeal internal carotid artery (PhICA). However, the intervening space between the sphenoid spine and PhICA allows for error during exposure of the artery. In the present study, we have characterized endoscopic endonasal transmasticator exposure of the PhICA using the sphenoid spine, vaginal process of the tympanic bone, and the "tympanic crest" as useful anatomical landmarks. Endonasal dissection was performed in 13 embalmed latex-injected cadaveric specimens. Two open lateral dissections and osteologic analysis of 10 dry skulls were also performed. A novel and palpable bony landmark, the inferomedial edge of the tympanic bone, referred to as the tympanic crest, was identified, leading from the sphenoid spine to the lateral carotid canal. Additionally, the vaginal process of the tympanic bone, viewed endoscopically, was a guide to the PhICA. The sphenoid spine was bifurcate in 20% of the skulls, with an average length of 5.98 mm (range, 3.9-8.2 mm), width of 5.81 mm (range, 3.0-10.6 mm), and distance to the carotid canal of 4.48 mm (range, 2.5-6.1mm). The sphenoid spine and pericarotid space has variable anatomy. Using an endoscopic transmasticator approach to the infratemporal fossa, we found that the closest landmarks leading to the PhICA were the tympanic crest, sphenoid spine, and vaginal process of the tympanic bone.

Endoscopic endonasal bony landmarks of vertical petrous internal carotid: anatomic study

BackgroundEndoscopic endonasal direct exposure or vascular control of basal internal carotid artery (ICA) is difficult among soft tissue of infratemporal fossa.ObjectiveThe aim of this work was to develop surgical instructional model for direct exposure of vertical petrous (Vp) ICA relatively dependent on bony fixed landmarks.Materials and methodsEndoscopic endonasal drilling of 14 sides of dry skull models was presented. Different bony landmarks and measurements of Vp ICA canal were obtained.ResultsEndoscopic endonasal transpterygoid approach was performed. The medial pterygoid process and base were drilled to expose the vidian canal and foramen rotundum. The lateral pterygoid process was drilled following the slope of skull base to medial and lateral ends of foramen oval (FO). The spine of the sphenoid was drilled to obscure the tensor tympani canal and the bony Eustachian tube (ET). The bony end of ET was identified lateral to FO. The Vp ICA was exposed retrogradely by drilling the tubal process of tympanic bone (bone between FO and bony ET) downward, backward, and medially toward carotid foramen, forming an acute angle with horizontal petrous (Hp) ICA. The carotid foramen lies medial to styloid process. Three processes are identified sequentially from endonasal perspective; spine of sphenoid, tubal process of tympanic bone, and vaginal process of tympanic bone enclosing the styloid process laterally. The mean length of Vp ICA canal was 12.93±2.23 mm, mean width of FO was 5.04± 0.8 mm, and distance between FO and bony ET was 6.68±1.42 mm, representing surgical width of Vp ICA ~10 mm. The surgical corridor was ~10mm wide and 15mm long.ConclusionEndoscopic endonasal systematic orientation of bony fixed landmarks of Vp ICA exposure is described. The proposed endonasal bony pathway relatively bypasses the muscular compartment of infratemporal fossa. This model can help to obtain vascular control of basal ICA and retrograde identification of parapharyngeal ICA.

Potential Surgical Exposure of the Parapharyngeal Internal Carotid Artery by Endonasal, Transoral, and Transcervical Approaches.

Objectives Endoscopic and endoscopic-assisted approaches to the parapharyngeal space have been reported; however, their potential for vascular exposure has not been previously assessed. This study aims to compare the potential exposure and control of the parapharyngeal internal carotid artery (ppICA) via various approaches. Design and Main Outcome Measures Ten cadaveric specimens were dissected bilaterally, exposing the ppICA via endonasal, transoral, and transcervical approaches. Length of the exposed vessel and potential control were assessed (feasibility and time required to place an encircling suture). Results Endoscopic transoral and transcervical-transmandibular approaches expose a significantly longer segment of the ppICA (6.89 and 7.09 cm) than the transoral and endonasal approaches. Vascular control was achieved via endoscopic-endonasal, endoscopic-transoral, and open techniques in 121.6, 64.8, and 5.2 seconds, respectively. Conclusion Histopathology, goals of surgery, and familiarity of the surgeon with each technique may ultimately determine the choice of approach; however, this study suggests that exposure of the ppICA by endoscopic-assisted transoral approach is comparable to that of a transcervical-transmandibular approach. Vascular control was feasible under elective circumstances. However, the difficulty varied widely, potentially reflecting the challenges of controlling an injured ppICA. However, one must note that active bleeding obscures the surgical field in ways that may impair ppICA control. Furthermore, the results may not reflect clinical scenarios where tumor distorts the surgical field. Nonetheless, the study suggests that, in properly selected patients, the endoscopic-assisted transoral approach avoids problems associated with unsightly scars, mandibular osteotomy, and facial nerve manipulation, whereas, the transcervical-transmandibular approach offers the swiftest vascular control.