Surgical anatomy of the parapharyngeal space: Multiperspective, quantification-based study

Management of Parapharyngeal Metastatic Medullary Thyroid Carcinoma Via a Combined Trans-Cervical and Trans-Oral Robotic Approach

INTRODUCTION

Medullary thyroid carcinoma constitutes 5% to 10% of all thyroid cancers. Metastatic adenopathies may pose challenges in intricate anatomical locations, such as the parapharyngeal space. A rare case of metastatic medullary thyroid carcinoma in the parapharyngeal space has been treated in our unit using combined trans-cervical trans-oral robotic surgery. Our objective was to provide a detailed description of the surgery performed on this patient.

METHOD

We reported a singular case report worth of interest.

RESULT

A 42-year-old woman was addressed in our unit for the management of a medullary thyroid carcinoma adenopathy located in the right parapharyngeal space. A parapharyngeal 40.0 mm × 25.0 mm × 12.0 mm adenopathy was removed using a combined trans-cervical and trans-oral robotic approach without sacrifice or injury of vascular or nervous structure. Neither the tracheostomy nor the feeding tube was implemented. Feeding was resumed on postoperative day 1 and hospitalization spanned 7 days.

CONCLUSION

An innovative combined trans-cervical and trans-oral robotic surgery approach was conducted to address a metastatic medullary thyroid carcinoma in the parapharyngeal space. This surgical technique allowed us to circumvent the need for a trans-mandibular approach, tracheostomy, and feeding tube and enabling successful tumor removal without fragmentation. Postoperative care was significantly eased. The sole complication observed was dysphonia, likely resulting from intra-operative stretching of the vagus nerve during the dissection of the carotid artery.

A comparative study of transcervical, endoscope-assisted transcervical, and endoscope-assisted transoral resection of retrostyloid space schwannomas

BACKGROUND

The aim of this retrospective study was to compare the efficacy of transcervical (TC), endoscope-assisted transoral (TO), and endoscope-assisted TC for resection of retrostyloid space schwannomas.

METHODS

The study included patients who underwent complete resection of schwannomas by only one surgical approach. The data we collected included tumor size, estimated blood loss, postoperative complications, and so on. Statistical analysis was performed using one-way analysis of variance and Fisher's exact test.

RESULTS

The study collected 85 patients with tumors mostly located at the oropharyngeal level who were followed up 6 months at least. The results showed that endoscope-assisted TO had certain advantages over others. Additionally, the endoscope-assisted TO set the lowest incidence of neurological complications.

CONCLUSION

Our findings demonstrate that for team with rich experience in the skull base surgery, endoscope-assisted TO is a superior option compared to the other two groups for resection of retrostyloid space schwannomas, with the better preservation of neurological function.

Meningocele in the Parapharyngeal Space: A Case Report and Review of the Literature

The parapharyngeal space has been described as an inverted pyramid shape with the base of the skull and the great cornu of the hyoid bone at the top. Tumors of the parapharyngeal space account for 0.5% of head and neck tumors and a wide range of tumor types can occur in this area, 80% of which are benign, the most common being pleomorphic adenomas of the salivary glands and neurogenic tumors. We present a 39-year-old woman who was hospitalized due to left-sided neck pain with a feeling of blockage in the left ear and hearing loss for 10 months. Imaging showed that the mass was not connected to the cranium and the patient underwent surgical resection via a transoral approach, where the contents of the mass were found to be cerebrospinal fluid, and meningocele in the parapharyngeal space is a rare occurrence. The patient presented mainly with painful symptoms, which were eventually relieved by nerve block therapy.

Interdisciplinary Management of Skull Base Tumors

OBJECTIVE

Endoscopic endonasal skull base surgery has gained acceptance worldwide. Comparative analysis has demonstrated that endoscopic skull base surgery may have advantages for many pathologies of the anterior skull base, e. g., sinonasal malignant tumors; pathologies of the central skull base, e. g., pituitary adenomas, craniopharyngiomas; well-selected cases of planum sphenoidale and tuberculum sellae meningiomas; or for clival lesions, e. g., chordomas, chondrosarcomas, or selected meningiomas. Over the past three decades, interdisciplinary surgical teams, consisting of otolaryngologists and neurosurgeons, have provided detailed anatomical knowledge, suggested new approaches or modifications of established surgical techniques, and offered continued surgical education.

METHOD

A review of pertinent literature was conducted with an emphasis on interdisciplinary endoscopic surgery of skull base lesions.

RESULTS

Based on the authors̓ surgical experience in two different interdisciplinary endoscopic skull base centers, the authors classify approaches for endoscopic endonasal skull base surgery, describe indications, and key anatomic landmarks for common pathologies, and highlight surgical techniques to avoid complications.

CONCLUSION

Interdisciplinary endonasal endoscopic surgery combines surgical expertise, improves resection rates for many pathologies, and minimizes morbidity by reducing the incidence of surgical complications.

Endoscopic endonasal combined transoral medial approach to the nasopharynx, parapharyngeal space, and jugular foramen

OBJECTIVE

This study aimed to validate the feasibility of an endoscopic endonasal combined transoral medial approach for treating lesions in the nasopharynx, parapharyngeal space (PPS), and jugular foramen.

METHODS

Anatomical and imaging information of six patients who underwent surgery via this approach were reviewed and analyzed.

RESULTS

The feasibility and advantages of the endoscopic endonasal combined transoral medial approach, which uses an inside-to-outside medial surgical corridor, were identified. Total resection was achieved in 3 cases with benign tumors. Safe resection margins were obtained in 2 cases with recurrent nasopharyngeal carcinoma (NPC). Pathological biopsy of NPC lesion between the Eustachian tube and arterial sheath was achieved. The internal carotid artery (ICA) was accurately located and protected in all cases and no complications occurred.

CONCLUSION

Lesions in the nasopharynx, PPS, and jugular foramen can be directly assessed via this approach. The ICA can be well identified during the surgery.

The transcervical-transparotid corridor for management of parapharyngeal space neoplasms: strengths and limits in a bi-institutional retrospective series

BACKGROUND AND PURPOSE

Parapharyngeal space (PPS) neoplasms represent 1% of all head and neck tumors and are mostly benign. Surgery is the mainstay of treatment and the transcervical-transparotid (TC-TP) corridor still represents the workhorse for adequate PPS exposure. Our series investigates strengths and limits of this approach on a multi-institutional basis.

METHODS

We reviewed consecutive patients submitted to PPS surgery via TC-TP route between 2010 and 2020. Hospital stay, early and long-term complications, and disease status were assessed.

RESULTS

One hundred and twenty nine patients were enrolled. Most tumors were benign (79.8%) and involved the prestyloid space (83.7%); the median largest diameter was 4.0 cm. The TC-TP corridor was used in 70.5% of patients, while a pure TC route in about a quarter of cases. Early postoperative VII CN palsy was evident in 32.3% of patients, while X CN deficit in 9.4%. The long-term morbidity rate was 34.1%, with persistent CN impairment detectable in 26.4% of patients: carotid space location, lesion diameter and malignant histology were the main independent predictors of morbidity. A recurrence occurred in 12 patients (9.4%).

CONCLUSIONS

The TC-TP corridor represents the benchmark for surgical management of most of PPS neoplasms, though substantial morbidity can still be expected.

Relevance of the Internal Jugular Vein for Surgery in the Upper Parapharyngeal Space

Objective: Tumors arising from the upper parapharyngeal space (UPPS) may have intimate relationships with the internal carotid artery (ICA) and the internal jugular vein (IJV). The significance of the ICA in UPPS has been sufficiently articulated, whereas the relevance of the IJV has not been addressed. This study aimed to assess the anatomical variations of the IJV within the UPPS, and to explore its implications for surgical procedures. Methods: An endoscopic dissection of the IJV was performed on 10 cadaveric specimens. In addition, 30 patients who underwent transoral or transcervical resection of UPPS tumors were retrospectively reviewed to characterize the IJV and its relation to the tumor. Results: On the cadaveric specimens, the IJV was located at the posteromedial and posterolateral aspects of the styloid process in 13 (65%) and 7 (35%) sides, respectively. In our clinical series, the IJV was not encountered in 18 patients with pre-styloid tumors. In 12 patients harboring retro-styloid tumors, the IJV was partially (n = 5) or completely (n = 7) compressed and was displaced into the posterolateral aspect of the tumor. The IJV was injured intraoperatively in 1 patient, requiring an immediate conversion to an open transcervical corridor that allowed its exposure and ligation without difficulty. Conclusion: This study characterizes the IJV and its relationship with adjacent neurovascular structures in the UPPS, which may provide further safeguards during transoral and transcervical procedures in the UPPS.

Quantitative Anatomical Studies in Neurosurgery: A Systematic and Critical Review of Research Methods

BACKGROUND

The anatomy laboratory can provide the ideal setting for the preclinical phase of neurosurgical research. Our purpose is to comprehensively and critically review the preclinical anatomical quantification methods used in cranial neurosurgery.

METHODS

A systematic review was conducted following the PRISMA guidelines. The PubMed, Ovid MEDLINE, and Ovid EMBASE databases were searched, yielding 1667 papers. A statistical analysis was performed using R.

RESULTS

The included studies were published from 1996 to 2023. The risk of bias assessment indicated high-quality studies. Target exposure was the most studied feature (81.7%), mainly with area quantification (64.9%). The surgical corridor was quantified in 60.9% of studies, more commonly with the quantification of the angle of view (60%). Neuronavigation-based methods benefit from quantifying the surgical pyramid features that define a cranial neurosurgical approach and allowing post-dissection data analyses. Direct measurements might diminish the error that is inherent to navigation methods and are useful to collect a small amount of data.

CONCLUSION

Quantifying neurosurgical approaches in the anatomy laboratory provides an objective assessment of the surgical corridor and target exposure. There is currently limited comparability among quantitative neurosurgical anatomy studies; sharing common research methods will provide comparable data that might also be investigated with artificial intelligence methods.

Skull-Base Surgery—A Narrative Review on Current Approaches and Future Developments in Surgical Navigation

Surgical navigation technology combines patient imaging studies with intraoperative real-time data to improve surgical precision and patient outcomes. The navigation workflow can also include preoperative planning, which can reliably simulate the intended resection and reconstruction. The advantage of this approach in skull-base surgery is that it guides access into a complex three-dimensional area and orients tumors intraoperatively with regard to critical structures, such as the orbit, carotid artery and brain. This enhances a surgeon’s capabilities to preserve normal anatomy while resecting tumors with adequate margins. The aim of this narrative review is to outline the state of the art and the future directions of surgical navigation in the skull base, focusing on the advantages and pitfalls of this technique. We will also present our group experience in this field, within the frame of the current research trends.

Microsurgical transcranial approaches to the posterior surface of petrosal portion of the temporal bone: quantitative analysis of surgical volumes and exposed areas

Different microsurgical transcranial approaches (MTAs) have been described to expose the posterior surface of the petrous bone (PPB). A quantitative, anatomical comparison of the most used MTAs, for specific areas of the PPB, is not available. Anatomical dissections were performed on five formalin-fixed, latex-injected cadaver heads (10 sides). Six MTAs were analyzed: Kawase approach (KWA), retrosigmoid approach (RSA), retrosigmoid approach with suprameatal extension (RSAS), retrolabyrinthine approach (RLA), translabyrinthine approach (TLA), and transcochlear approach (TCA). Surgical volumes and exposed areas of each approach were quantified with a dedicated neuronavigation system (ApproachViewer, part of GTx-Eyes II, University Health Network, Toronto, Canada) and adjuvant software (ITK-SNAP and Autodesk Meshmixer 3.5). Areas and volumes were compared using linear mixed models. TCA provided the best exposure of Trautmann's triangle and the retromeatal, suprameatal, meatal, and premeatal regions. RSAs provided the best exposure of the inframeatal region, with RSAS gaining significant exposure of the suprameatal region. KWA had the highest surgical volume, and RLA the lowest. Transpetrosal approaches offer the widest exposure of PPB proportionally to their invasiveness. Retrosigmoid approaches, which get to the studied region through a postero-lateral path, are paramount for the exposure of the inframeatal and suprameatal region and, given the adequate exposure of the remaining PPB, represent an effective approach for the cerebellopontine angle (CPA). These anatomical findings must be considered with approach-related morbidity and the pathological features in order to choose the most appropriate approach in clinical practice.

Parapharyngeal Space Tumors: Our Experience

Para-pharyngeal space (PPS) tumors include an heterogeneous group of neoplasms, accounting for approximatively 0.5-1.5% of all head and neck tumors. Management of these neoplasms requires a careful diagnostic workout and an appropriate surgical approach to obtain good outcomes associated with minimal aesthetic drawbacks. In this study we investigated clinical onset, histologic features, surgical treatment outcomes, peri operative complications and follow up of 98 patients treated for PPS tumors in our Centre between 2002 and 2021. Furthermore, we reviewed our preliminary experience of preoperative embolization of hyper vascular PPS tumors trough SQUID12, an ethylene vinyl alcohol copolymers (EVOH) which exhibits many advantages over other embolic agents, due to its better devascularization rate and lower risk of systemic complications. Our data support the hypothesis that transoral surgery scenario should be significantly revised, as it could represent a valid treatment for tumors located in lower and prestyloyd portion of PPS. Moreover, SQUID12, a novel embolization agent, may be a very promising choice for PPS hyper vascularized tumors, ensuring higher devascularization rate, safer procedures and lower risk of systemic dispersion compared to traditional Contour treatment.

Endoscopic transoral approach to the lateral poststyloid space

The lateral poststyloid space (LPSS) located at the posterolateral aspect of the styloid process. This study aims to explore the anatomical relationships in LPSS via a transoral corridor, providing reference for addressing lesions extending to this region. An endoscopic transoral approach for exposure of the LPSS was performed on 6 cadaveric specimens (12 sides). Related landmarks were explored, and transoral extirpation of tumors extended into LPSS was employed in 12 patients. The deep lobe of the parotid gland, extratemporal facial nerve, and the accompanying artery in the LPSS were sufficiently exposed via the transoral corridor in all 12 cadaveric sides. The transoral corridor provided adequate exposure for tumors extending to the LPSS, and en bloc resection was achieved in these 12 patients. No facial nerve or vascular injury occurred, and no recurrence observed in this cohort with an average follow-up of 26 months. An endoscopic transoral approach provides a direct access to the LPSS. Appreciation of the anatomical relationships within the LPSS is valuable for employing a transoral extirpation of tumors extending to this specific region.

The carotid sheath: Anatomy and clinical considerations

Objectives

The distinctive bilateral carotid sheaths (CS) reside in the neck region and form part of the deep cervical fasciae. Aspects of the CS anatomy are controversial, most notably its specific attachment sites and fascial makeup, which are key determinants for the spread of tumours and infections and surgical planning. This review aimed to organise the pertinent aspects relating to CS anatomy and pathology, explore their clinical relevance and highlight areas of disagreement in the literature.

Methods

A narrative review identified key papers relating to CS anatomy, histology, embryology, pathology and clinical and surgical significance using PubMed and Google Scholar. This was supported by a systematic review focused on the fascia forming the CS which was conducted using PubMed, Web of Science and Core Collection which yielded 22 papers.

Results

and Discussion: The CS surrounds the internal carotid artery, internal jugular vein, cranial nerves IX - XII, lymph nodes and nervous plexuses as they course from the jugular foramen superiorly down along into the mediastinum inferiorly. There are contradicting descriptions regarding the CS attachments at the extracranial skull base and within the mediastinum. Author descriptions of the CS fasciae are complex, varied and incongruent. Pathologies affecting the CS include malignancies of the nerves, vascular lesions and utilisation of the CS space as a corridor for the spread of deep neck infections.

Conclusion

This paper collates and presents pertinent anatomical and clinical aspects regarding the CS. A proper knowledge of the CS anatomy and structural relationships will optimise surgical approaches and orientation when operating within the region.

Quantitative Anatomic Comparison of Endoscopic Transnasal and Microsurgical Transcranial Approaches to the Anterior Cranial Fossa

BACKGROUND

Several microsurgical transcranial approaches (MTAs) and endoscopic transnasal approaches (EEAs) to the anterior cranial fossa (ACF) have been described.

OBJECTIVE

To provide a preclinical, quantitative, anatomic, comparative analysis of surgical approaches to the ACF.

METHODS

Five alcohol-fixed specimens underwent high-resolution computed tomography. The following approaches were performed on each specimen: EEAs (transcribriform, transtuberculum, and transplanum), anterior MTAs (transfrontal sinus interhemispheric, frontobasal interhemispheric, and subfrontal with unilateral and bilateral frontal craniotomy), and anterolateral MTAs (supraorbital, minipterional, pterional, and frontotemporal orbitozygomatic approach). An optic neuronavigation system and dedicated software (ApproachViewer, part of GTx-Eyes II-UHN) were used to quantify the working volume of each approach and extrapolate the exposure of different ACF regions. Mixed linear models with random intercepts were used for statistical analyses.

RESULTS

EEAs offer a large and direct route to the midline region of ACF, whose most anterior structures (ie, crista galli, cribriform plate, and ethmoidal roof) are also well exposed by anterior MTAs, whereas deeper ones (ie, planum sphenoidale and tuberculum sellae) are also well exposed by anterolateral MTAs. The orbital roof region is exposed by both anterolateral and lateral MTAs. The posterolateral region (ie, sphenoid wing and optic canal) is well exposed by anterolateral MTAs.

CONCLUSION

Anterior and anterolateral MTAs play a pivotal role in the exposure of most anterior and posterolateral ACF regions, respectively, whereas midline regions are well exposed by EEAs. Furthermore, certain anterolateral approaches may be most useful when involvement of the optic canal and nerves involvement are suspected.

Transoral Endoscopic Localization of the Parapharyngeal Internal Carotid Artery

Objectives  To define transoral endoscopic surgical landmarks for the parapharyngeal segment of the internal carotid artery (ppICA) using cadaveric dissection. Methods  Ten fresh cadaveric heads were dissected to demonstrate the parapharyngeal space anatomy and course of the ppICA as seen in a transoral approach. Anatomical measurements of the distance between the ppICA and bony landmarks were recorded and analyzed. Results  The stylohyoid ligament, styloglossus, and stylopharyngeus could be considered to be the safe anterior boundary of the ppICA in the transoral approach; among them, the styloid ligament was the most rigid tissue. Dissection between the stylopharyngeus muscle and superior pharyngeal constrictor muscle provides direct access to the ppICA. At the level of the skull base, the distance from the root of the styloid process to the lateral margin of the external aperture of the carotid canal on the left side and on the right side was 8.57 ± 1.97 and 8.80 ± 1.21 mm, respectively. At the level of the maxillary tuberosity, the distance from the ppICA to the maxillary tuberosity on the left side and on the right side was 31.48 ± 2.24 and 31.01 ± 2.88 mm, respectively. Conclusion  The endoscopic-assisted transoral approach can facilitate exposure of the ppICA. The root of the styloid process, styloid ligament, and maxillary tuberosity are critical landmarks in the identification of the ppICA in the transoral approach.

A retrospective analysis of surgery in prestyloid parapharyngeal tumors: Lateral approaches vs transoral robotic surgery

OBJECTIVE

Surgery is the standard treatment for most tumors in the prestyloid parapharyngeal space (PPS) but it can be a challenging procedure because of the anatomical complexity of the area. Prestyloid surgery can be performed with various lateral approaches or with a medial approach using transoral robotic surgery (TORS)-either alone or in combination with a transcervical incision. We have retrospectively compared our center's results with lateral and medial approaches.

METHODS

Between 2015 and 2020, 28 patients with prestyloid PPS tumors underwent surgery at our center: 14 with lateral approaches, including transcervical, transcervical-parotid, and transcervical-mandibular, and 14 with medial approaches (12 with TORS and two with TORS plus a transcervical incision). We compared surgical time, postsurgical complications, length of hospital stay, need for feeding tube, and relapse-free survival in the two patient groups.

RESULTS

Pleomorphic adenoma was the most frequent tumor and 60.7% of the tumors were benign. Tumor volume and maximum length were similar in the two groups of patients. Intraoperative image guidance and ultrasound were used in 33% of TORS. TORS was associated with less surgical time, fewer complications, and shorter hospital stays. Recurrence rates were similar in the two groups.

CONCLUSION

The medial approach by TORS offers superior results in prestyloid tumors than the open lateral approach and can be refined by intraoperative guidance. Level of Evidence: 4.

Management of parapharyngeal space tumors with transparotid-transcervical approach: analysis of prognostic factors related with disease-control and functional outcomes

PURPOSE

Different therapeutic strategies have been developed to improve surgical and functional outcome of parapharyngeal space (PPS) neoplasms. The transparotid-transcervical approach (TTa) is a valid surgical option to manage most PPS tumors. Its short- and long-term disease control and cranial nerve (c.n.) function outcomes have not been discussed extensively.

METHODS

All patients who underwent TTa over a 10-year period at a tertiary academic center were retrospectively reviewed. Data about preoperative imaging, clinical presentation, tumor's size, location and histology, and postoperative oncological and functional results were registered and analyzed.

RESULTS

Sixty patients matched the inclusion criteria. Most of the lesions were benign (71.7%), involved the prestyloid PPS (63.3%) and measured more than 30 mm (75%). Fifty-two (86.7%) lesions were resected en-bloc. Clear margins were achieved in 91.7% of the cases, with positive margins solely associated with malignancy (p = 0.008). Post-operative c.n. function was satisfactory, with X c.n. function significantly associated with the retrostyloid location (p = .00) and neurogenic tumors (p = 0.02). Local disease-control was achieved in 96% of the cases after a median follow-up of 46 (± 19.7-82.0 IQR) months.

CONCLUSIONS

The TTa was safe and effective, achieving a satisfactory local control rate. Nevertheless, malignancies maintain a higher rate of positive margin due to their infiltrative nature and the complex anatomy of the PPS. In such cases, multiportal approaches might be more effective. However, post-operative c.n. function remained satisfactory, irrespective of lesions' size and histopathologic behavior. A higher X c.n. deficit rate was observed in retrostyloid and neurogenic lesions.

Quantitative Anatomic Comparison of Microsurgical Transcranial, Endoscopic Endonasal, and Transorbital Approaches to the Spheno-Orbital Region

BACKGROUND

The spheno-orbital region (SOR) is a complex anatomic area that can be accessed with different surgical approaches.

OBJECTIVE

To quantitatively compare, in a preclinical setting, microsurgical transcranial approaches (MTAs), endoscopic endonasal transpterygoid approach (EEA), and endoscopic transorbital approaches (ETOAs) to the SOR.

METHODS

These approaches were performed in 5 specimens: EEA, ETOAs (superior eyelid and inferolateral), anterolateral MTAs (supraorbital, minipterional, pterional, pterional-transzygomatic, and frontotemporal-orbitozygomatic), and lateral MTAs (subtemporal and subtemporal transzygomatic). All specimens underwent high-resolution computed tomography; an optic neuronavigation system with dedicated software was used to quantify working volume and exposed area for each approach. Mixed linear models with random intercepts were used for statistical analyses.

RESULTS

Anterolateral MTAs offer a direct route to the greater wings (GWs) and lesser wings (LWs); only they guarantee exposure of the anterior clinoid. Lateral MTAs provide access to a large area corresponding to the GW, up to the superior orbital fissure (SOF) anteriorly and the foramen rotundum medially. ETOAs also access the GW, close to the lateral portion of SOF, but with a different angle of view as compared to lateral MTAs. Access to deep and medial structures, such as the lamina papyracea and the medial SOF, is offered only by EEA, which exposes the LW and GW only to a limited extent.

CONCLUSION

This is the first study that offers a quantitative comparison of the most used approaches to SOR. A detailed knowledge of their advantages and limitations is paramount to choose the ideal one, or their combination, in the clinical setting.

Endoscopic Subtemporal Epidural Key-Hole Approach: Quantitative Anatomic Analysis of Three Surgical Corridors

BACKGROUND

The endoscope-assisted subtemporal key-hole epidural approach (ESKEA) has been recently described. The aim of this study was to measure working volumes and exposure of key areas of the middle cranial fossa provided by this approach.

METHODS

Four fresh frozen cadaver heads were dissected to analyze 3 modular corridors (1A, 1B, and 2) harvested through ESKEA. A step-by-step dissection was performed, and key anatomic landmarks were recorded. A GTxEyesII-ApproachViewer was used to quantify the working volume and exposure of 4 different regions (sphenoorbital, parasellar, superior petrous apex, and squamopetrous). For each corridor, 3 incremental degrees of temporal dural retraction (5, 10, and 15 mm) were tested.

RESULTS

The working volume of all corridors progressively increased with degree of retraction: Corridors 1A, 1B, and 2 showed a gain in working volume of 21%, 27%, and 19% from 5 mm to 10 mm retraction, respectively, and a gain of 40%, 45%, and 44% from 5 mm to 15 mm retraction, respectively. The sphenoorbital area was exposed (27%-45%) through corridor 1A, and exposure significantly increased with the degree of retraction. Corridor 1B provided optimal exposure of parasellar areas (86%-100%) and superior petrous apex (70%-87%) regardless of the degree of retraction. The squamopetrous area was satisfactorily addressed through corridor 2 (88%) only with the highest degree of retraction.

CONCLUSIONS

ESKEA can be conceived as a modular approach: the 3 surgical corridors have specific working volumes, which are clearly influenced by the degree of temporal lobe retraction, and provide exposure of different middle cranial fossa areas.

Advances in anatomical visualization on the head and neck through robotic surgery: A Brazilian perspective

Trans Oral Robotic Surgery (TORS) is an emerging technique that provides several benefits over existing treatment regimens for head and neck cancer, including smaller incisions, less bleeding, shorter term inpatient hospitalization, and reduced intensive care unit (ICU) length of stay. TORS allows a high resolution, magnified, three-dimensional wide view of the surgical field through an endoscope, avoiding large external cervical incisions and split-lip mandibulotomy, usually required in cancer surgeries of the oropharynx. The anatomy of the Oropharynx viewed from the perspective of the robotic surgeon is different from the anatomy taught in medical schools and residence/fellowship programs, which is more directly related to emergency procedures, open field surgery, and imaging exams. Developing an understanding of the anatomic relationships and landmarks from the "inside out" perspective is critical for any surgeon willing to perform surgical procedures through a transoral robotic approach. Here we address the major anatomic landmarks and structures in head and neck robotic surgeries and advantages and disadvantages of this approach. We emphasize the importance of imaging for successful outcomes, pointing out important anatomic landmarks considered as blind spots for surgeons in clinical and endoscopic evaluations. We also describe the Brazilian current scenario and future perspectives of Robotic Surgery in terms of training and access to this technique, including institutions that currently offer this service in the different regions of Brazil.

The intraoral growth patterns of parapharyngeal tumors: A proposed classification system

OBJECTIVE

Nearly half of parapharyngeal space (PPS) tumors present as an intraoral mass, which is diagnostically challenging. In this study, we studied whether preoperative growth patterns were associated with histopathological diagnosis for planning surgery.

METHODS

We performed a cross-sectional study in patients with PPS tumors. A simplified classification scheme based on intraoral tumor growth patterns (patterns 1 and 2) was then proposed. In pattern 1, tumors bulge submucosally to the oropharynx from the soft palate, with the center convexity above the uvula. In pattern 2, tumors bulge submucosally to the oropharynx from the lateral oropharynx wall, with the center convexity below the uvula. The association of this classification with postoperative histopathological diagnosis and surgical-related events was studied.

RESULTS

Twenty-two patients were enrolled in this study (12 with pattern 1, 10 with pattern 2). Of these, 91.7% (11/12) of pattern 1 tumors were salivary gland tumors (P < .001), and 90% (9/10) of pattern 2 tumors were neurogenic (P < .001). Pattern 2 tumors had fewer bleeding complications or needed external approaches when a transoral approach was chosen.

CONCLUSIONS

This new classification of PPS tumors facilitates the prediction of salivary gland and neurogenic tumors and can improve the accuracy of preoperative radiologic diagnosis. This system will be helpful for planning surgical interventions, such as implementing transoral approaches.

Adenoid cystic carcinoma of the parotid metastasising to the dura fifteen years post primary resection: A case report

Adenoid cystic carcinoma (ACC), regardless of the primary site, is typically characterized by a long clinical course associated with a high rate of distant metastases. Intracranial metastasis of ACC is a very rare entity with only few reported cases in the literature. In this study, we report an unusual case of extra-axial intracranial metastasis of ACC in the dura. The primary parotid gland tumour was resected 15 y back. No recurrence had been detected before the occurrence of extra-axial metastasis. After surgical decompression, palliative radiotherapy was administered. To our knowledge, this is the longest interval for the development of metastases following excision of a parotid adenoid cystic carcinoma. This case can raise awareness across specialties that patients with adenoid cystic carcinoma are still at risk of developing metastases even following specialist discharge.

Quantitative anatomical comparison of transnasal and transcranial approaches to the clivus

BACKGROUND AND OBJECTIVE

The clivus was defined as "no man's land" in the early 1990s, but since then, multiple approaches have been described to access it. This study is aimed at quantitatively comparing endoscopic transnasal and microsurgical transcranial approaches to the clivus in a preclinical setting, using a recently developed research method.

METHODS

Multiple approaches were performed in 5 head and neck specimens that underwent high-resolution computed tomography (CT): endoscopic transnasal (transclival, with hypophysiopexy and with far-medial extension), microsurgical anterolateral (supraorbital, mini-pterional, pterional, pterional transzygomatic, fronto-temporal-orbito-zygomatic), lateral (subtemporal and subtemporal transzygomatic), and posterolateral (retrosigmoid, far-lateral, retrolabyrinthine, translabyrinthine, and transcochlear). An optic neuronavigation system and dedicated software were used to quantify the working volume of each approach and calculate the exposure of different clival regions. Mixed linear models with random intersections were used for statistical analyses.

RESULTS

Endoscopic transnasal approaches showed higher working volume and larger exposure compared with microsurgical transcranial approaches. Increased exposure of the upper clivus was achieved by the transnasal endoscopic transclival approach with intradural hypophysiopexy. Anterolateral microsurgical transcranial approaches provided a direct route to the anterior surface of the posterior clinoid process. The transnasal endoscopic approach with far-medial extension ensured a statistically larger exposure of jugular tubercles as compared with other approaches. Presigmoid approaches provided a relatively limited exposure of the ipsilateral clivus, which increased in proportion to their invasiveness.

CONCLUSIONS

This is the first anatomical study that quantitatively compares in a holistic way exposure and working volumes offered by the most used modern approaches to the clivus.

Preauricular retromandibular trans tympanic plate and styloid process keyhole approach to parapharyngeal lesions: a laboratory study

BACKGROUND

The surgical removal of the infratemporal parapharyngeal lesions (IPL) is challenging due to its anatomical complexity. Previous surgical approaches have often been too invasive and necessitated sacrifice of normal function and anatomical structures, particularly in the retromandibular nerve region. Therefore, we sought to identify an approach corridor to this area that requires less sacrifice and report an innovative approach through a retromandibular fossa route to the IPL.

METHODS

Five cadaveric specimens were dissected bilaterally with a trans-tympanic plate and styloid process approach. These specimens were investigated microanatomically and morphometrically to examine the extent of the approach in the parapharyngeal space. The clinical application of this approach was compared to previous approaches to the IPL used in our clinical series of 20 cases.

RESULTS

Using this novel approach, the inferior alveolar nerve was identified in all specimens, while the chorda tympani and lingual nerve were identified in 6 (60%) and 4 (40%) dissections, respectively. In all specimens, the petrous portion of the internal carotid artery and the exit of the lower cranial nerve were identified. The average length of the exposed lower cranial nerves was 16.6 ± 3.8 mm (range: 11-25 mm).

CONCLUSIONS

The described approach is feasible for accessing the IPL at the retromandibular nerve and is less invasive than conventionally used approaches.

Quantitative Anatomical Comparison of Anterior, Anterolateral and Lateral, Microsurgical and Endoscopic Approaches to the Middle Cranial Fossa

OBJECTIVE

To quantitatively compare different microsurgical and endoscopic approaches to the middle cranial fossa in a preclinical setting with a novel, computer-based research method.

METHODS

Different approaches were performed bilaterally in 5 head and neck specimens that underwent high-resolution computed tomography scans: 5 transcranial anterolateral (supraorbital, mini-pterional, pterional, pterional-transzygomatic, fronto-temporal-orbito-zygomatic) without and with anterior clinoidectomy; 2 transcranial lateral (subtemporal and subtemporal-transzygomatic); 2 endoscopic transnasal (transpterygoid, transpterygoid to infratemporal fossa); 2 endoscopic transorbital (superior eyelid and inferolateral), and endoscopic transmaxillary. A dedicated navigation system was used to quantify surgical working volumes and exposure of different areas of the middle cranial fossa (ApproachViewer, part of GTx-Eyes II, University Health Network, Toronto, Canada). Statistical analysis was performed using a mixed linear model with bootstrap resampling.

RESULTS

Endoscopic transnasal and fronto-temporal-orbito-zygomatic approaches with anterior clinoidectomy showed the largest surgical volumes. Endoscopic approaches allowed a wider exposure of medial anatomical surfaces (e.g., the petrous apex) compared with transcranial ones. Transcranial approaches with larger craniotomies allowed the widest exposure of superomedial anatomical structures (e.g., roof of cavernous sinus). The resection of the zygomatic arch allowed exposure of more medial surfaces with an inferior to superior trajectory.

CONCLUSIONS

This study implemented a novel neuronavigation-based research method to quantitatively compare different approaches to the middle cranial fossa; its results might guide, after consideration of clinical implications, the choice of the neurosurgical approach to different areas of this complex skull base region.

A minimally invasive endoscopic transnasal retropterygoid approach to the upper parapharyngeal space: anatomic studies and surgical implications

BACKGROUND

Surgery remains the mainstay of treatment for lesions in the parapharyngeal space. However, gaining access to the parapharyngeal space is often challenging. In this study we aim to describe a minimally invasive technique of approaching the upper parapharyngeal space through an endoscopic transnasal retropterygoid approach, based on anatomic studies and surgeries.

METHODS

Six fresh human cadaver heads were prepared for anatomic study at the Surgical Neuroanatomy Laboratory of the Center for Cranial Base Surgery within the Department of Neurological Surgery at the University of Pittsburgh School of Medicine. Three clinical cases seen in the Department of Otolaryngology, Eye, Ear, Nose, and Throat Hospital, Shanghai Medical College of Fudan University, were used to illustrate the technique and feasibility of this approach and to assess its indications, advantages, and drawbacks.

RESULTS

The medial pterygoid plate is the primary landmark of the endoscopic transnasal retropterygoid approach to the upper parapharyngeal space. Access to the upper parapharyngeal space could be obtained by removing the mucosa on the medial pterygoid plate and the mucosa below the pharyngeal orifice of the Eustachian tube. The 3 patients in our study tolerated the procedure well and had no serious complications after surgery.

CONCLUSION

The anatomic data and clinical cases in this study confirm that an endoscopic transnasal retropterygoid approach is a feasible and effective surgical treatment for selected tumors in the upper parapharyngeal space.