Lateral Skull Base Procedures Research Articles

Initial Experience With Robotic-Assisted Otologic and Lateral Skull Base Surgery.

Robotic-assisted surgery has gained popularity for otolaryngology procedures. It provides high-definition images and surgical precision to perform diverse procedures. It is an alternative to the operating microscope, endoscope, or exoscope when reaching hidden anatomical structures in the ear. In this proof-of-concept study, we aim to demonstrate the possibility of using a robotic-assisted device to perform ear surgery in conjunction with the microscope or the endoscope. In total, there were 9 ear and lateral skull base procedures performed with the use of robotic-assisted surgery. All surgeons underwent surveys to assess the performance and workload of the device compared to the microscope or endoscope. There were no postoperative complications. Robotic-assisted surgery was optimal for providing high image quality, ergonomics, and maintaining surgical performance. The size of the device and mental demand were higher compared to the microscope or endoscope. Robotic-assisted surgery can be an adjuvant to perform otologic and neurotologic surgery.

A first exploration of the economic consequences of an autonomous surgical robot for lateral skull base surgery: an early health technology assessment.

Lateral skull base procedures, such as translabyrinthine approach (TLA), are challenging. An autonomous surgical robot might be a solution to these challenges. Our aim is to explore in an early phase the economic consequences of an autonomous surgical robot compared with conventional TLA. An early decision analytic model was constructed in order to perform a step-wise threshold analyses and a sensitivity analysis to analyze the impact of the several factors on the incremental costs. Using surgical robot results in incremental costs - EUR 5,562 per procedure - compared to conventional TLA. These costs are most reduced by higher number of procedures, followed by lower price of the robot, saved operation time, and reduced risk of complication, respectively. The incremental costs of using an autonomous surgical robot can be decreased by choosing applications with a high turnover rate, a long operation time, and a high complication rate.

Systematic Review of Otologic and Neurotologic Surgery Using the 3-dimensional Exoscope.

The 3D exoscope is an emerging technology that has been met with success in neurosurgery and is now increasingly used in otologic and neurotologic surgery. There is currently no consensus on its safety, efficiency, and utility, compared to the traditional microscope for these procedures. This systematic review aims to evaluate the use of the 3-dimensional (3D) exoscope for otologic and neurotologic surgery. MEDLINE/PubMed, Web of Science, Scopus, and EMBASE. A systematic search of the databases was conducted for otologic and neurotologic surgery using the 3D exoscope. English language papers with no limit on the date of publication were considered. Inclusion criteria: full articles studying otologic or neurotologic/skull base surgery using exoscopes. Exclusion criteria: non-otologic surgery and non-neurotologic/skull base surgery, exclusive use of the traditional microscope, editorials, video reports, and letters. Two authors independently reviewed papers for inclusion; discrepancies were settled by consensus. Extracted variables included: number of patients, types of surgical procedures, operative and postoperative complications, setup and operative time, and visualization and ergonomic rating. Six articles containing 128 surgical cases (103 exoscopic and 25 microscopic) were analyzed. Of the exoscopic cases, 21% were surgeries for chronic ear disease, 5% were cochlear implants, and 74% were lateral skull base procedures encompassing a wide variety of approaches. Based on preliminary studies, the exoscope appears to be comparable in safety, visualization, and efficiency compared to the operating microscope, with the potential for increased comfort and ease of use.

Otology/Neurotology

Session Description: The COVID-19/SARS-CoV2 pandemic has highlighted concerns regarding disease transmission to both surgeons and assisting staff during procedures that generate droplets and aerosols. Aerosol and droplet formation is known to occur during otologic and lateral skull base surgery, particularly when powered instrumentation is used. This expert panel will review both the basic science and clinical studies regarding risk identification. Recommendations regarding minimization of these risks will be thoroughly discussed in both scientific and practical terms that can be utilized by practicing otolaryngologists in real-life scenarios. In addition, the panel will address controversies regarding these risks and mitigation schemes and address real-life situations using case-based examples relevant to both the general otolaryngologist and neurotologic specialist. The discussion will focus not only on mitigation of spread of SARS-CoV2 virus but also on other currently identified pathogens of the middle ear and mastoid and future threats. This panel will address emerging pathogens that have not yet become threats in the United States and Western Europe but have affected otolaryngologists in other areas of the world. It will also provide guidance for hypothetical novel future threats that have not yet presented in clinical practice. This presentation is highly relevant to practicing otolaryngologists, including general otolaryngologists, pediatric otolaryngologists, and neurotologists and will provide the attendee with a thorough update clinical practice patterns, potential spread of contagion, and strategies of spread mitigation. Outcome Objectives: (1) Examine the basic and clinical science of pathogens of the middle ear, mastoid, and cerebrospinal fluid and the patterns of spread of these pathogens during otologic and lateral skull base procedures. (2) Understand and implement strategies to mitigate spread of currently known pathogens in otologic and lateral skull base procedures, including limitation of the spread of SARS/CoV2. (3) Understand a framework of strategies and best practices for mitigation of spread of emerging pathogens and future pathogens.

Hearing and balance complaints as presenting symptoms of petrous bone malignancies

Objective: Hearing loss and imbalance are specific symptoms of inner ear disease which could hide severe condition, such as endolymphatic sac tumour (ELST) or squamous cell carcinoma (SCC). The audiologist or the otologist, starting from not specific audiologic and vestibular symptoms can be faced by malignant tumours with severe prognosis, where early diagnosis can make the difference in outcome of treatment.Methods: We assessed the presenting symptoms, the audiological pattern, therapy and outcomes in 17 cases of ear malignancies (seven patients affected by ELST and ten by SCC).Results: All of ELST cases reported hearing loss as presenting symptom. Dizziness and imbalance were present in most cases. The mean diagnostic delay from the clinical onset was 26 months. Most patients were treated with extensive lateral skull base procedures. The recurrence rate and disease free-survival were 20% and 80%, respectively. In SCC patients, ear pain was the most frequent symptom, followed by dizziness and fullness. In all cases, treatment involved surgery with large extensive procedures. The recurrence and disease free-survival were 50% and 50%, respectively.Conclusion: Ear malignancies are difficult to detect, a specific audiological and vestibular symptoms should not be underestimated, early diagnosis and therapy influence the unfavourable outcome.

Quantitative Analysis of Surgical Freedom and Area of Exposure in Minimal-Invasive Transcanal Approaches to the Lateral Skull Base.

We aim to provide objective data regarding the area of exposure (AOE) and the surgical freedom (SF) offered by the transcanal approaches to the lateral skull base. Minimal-invasive transcanal lateral skull base procedures have been recently developed and their clinical feasibility demonstrated. The reduced access size requires careful analysis and selection of suitable cases, qualifying for a minimal-invasive approach. We performed the mentioned approaches in standardized dissection using human whole heads. Surgical freedom is defined as the degree of movement liberty of the surgical instrument at predefined landmarks. We assessed SF at anatomical landmarks throughout the lateral skull base. Moreover, we measured the AOE, defined as the surface on the lateral skull base reached by every approach. We performed a total of 48 dissections under stereotactic image guidance in a total of 12 sides. The mean SF was assessed for the inferior petrous apex 602 mm, for the geniculate ganglion 1,916 mm, and for the fundus of internal auditory canal 1,337 mm. The AOE was measured for the infracochlear approach 55 mm, suprageniculate approach 67 mm, transpromontorial approach 11 mm, and for the expanded transpromontorial approach 93 mm at the fundus and 108 mm at the porus of the internal auditory canal. This study provides a quantitative description of minimal-invasive transcanal approaches to the lateral skull base. The AOE offered by the expanded transcanal transpromontorial approach is inferior but comparable to the reported AOE of transmastoidal approaches. The reported objective measurements may provide important information for future preoperative planning and patient counseling.

Accuracy and feasibility of a dedicated image guidance solution for endoscopic lateral skull base surgery

We aimed to design, build and validate a surgical navigation system which fulfills the accuracy requirements for surgical procedures on the ear and the lateral skull base, and which integrates with the endoscopic workflow and operating room setup. The navigation system consists of portable tablet computer (iPad Pro, Apple Computer, USA) and an optical tracking system (Cambar B1, Axios3D, Germany), both connected via a wireless Bluetooth link and attached directly to the OR table. Active optical tracking references are rigidly fixed to both the patient and surgical tools. Software to support image import, registration and 2D/3D visualization has been developed. Two models were used for targeting accuracy assessment: a technical phantom model and an ex vivo temporal bone model. Additionally, workflow integration and usability of the navigation system during endoscopic lateral skull base procedures was investigated in ex vivo experiments on 12 sides of cadaver head specimens. The accuracy experiments revealed a target registration error in the technical phantom model of 0.20 ± 0.10mm (n = 36) and during the ex vivo assessment of 0.28 ± 0.10mm (n = 21). Navigation was successfully carried out in n = 36 procedures (infracochlear, suprageniculate and transpromontorial approach), with navigated instruments usable without interference with the endoscope. The system aided in the successful and accurate identification of vital anatomical structures. Useful surgical navigation is, to a large extent, a result of sufficiently accurate tracking technology. We have demonstrated sufficient accuracy and a potentially suitable integration for surgical application within endoscopic lateral skull base procedures.

Lateral skull base surgery in a pediatric population: A 25-year experience in a referral skull base center

ObjectiveTo analyze the pathology and surgical outcomes of lateral skull base (LSB) procedures in a pediatric population. Study designRetrospective case review in a referral skull base center. MethodsCharts of pediatric patients who underwent defined LSB procedures from 1983 to 2015 for various pathologies were evaluated at our center. A systematic review of literature was performed and our results were compared with the literature. Results63 patients presented with 65 diseased ears. The mean age was 13 years. 29 (44.6%) presented with hearing loss and 28 (44.4%) and chronic otorrhea. The most common pathology was petrous bone cholesteatoma (27, 42.5%) followed by vestibular schwannoma (10, 15.8%). Subtotal petrosectomy (24, 35.8%) was the most common surgical procedure followed by, transotic (18, 26.8%). The facial nerve function was preserved in 45 (67.1%) and the hearing in 28 (41.7%) cases respectively. No major complications, including mortality was encountered in our series. ConclusionIn rare and extensive pathologies involving the skull base in a pediatric population, the surgeon is posed with the dilemma of trying to achieve facial and hearing preservation while dealing with total tumor clearance. Mastery over LSB procedures can ensure complete disease clearance with optimal functional outcomes. Level of evidence2b.

Use of bone anchoring device in electromagnetic computer-assisted navigation in lateral skull base surgery

Conclusion: The use of the bone anchoring device associated with a fiducial marker, both fixed close to the operating field, improves the reproducibility and effectiveness of the computer-assisted navigation in lateral skull base surgery. Objectives: Computer-assisted navigation in lateral skull base surgery using the electromagnetic system Digipointeur® needs an external fiducial marker (titanium screw) close to the operating field to increase position accuracy (PA) to about 1 mm. Displacement of the emitter placed in the mouth (Buccostat®) induces a drift of the system, leading to at least 20% of unsuccessful procedures. The aim of this study was to evaluate the PA, stability, and reproducibility of computer-assisted navigation in lateral skull base surgery using a bone anchoring device to provide a fixed registration system near the operating field. Methods: Forty patients undergoing a lateral skull base procedure with the Digipointeur® system performed with both the titanium screw and bone anchoring device were included in this prospective study. They were divided in two groups. In the first one (n = 9), the PA was measured before and after screw registration for five intratemporal landmarks, during a translabyrinthine approach. In the second group (n = 31), all lateral skull base procedures were included and the PA was evaluated visually by the surgeon on different landmarks of the approaches as well as the stability of the system. Results: In the first group, the PA was 7.08 ± 0.59 mm and 0.77 ± 0.17 mm (mean ± SEM, p < 0.0001) before and after screw registration, respectively. In the second group, the PA was considered as accurate by the surgeon in all cases and no drift of the system was observed. Computer-assisted surgery was never abandoned due to increased stability of the bone-anchored emitter.

Impact of a self-developed planning and self-constructed navigation system on skull base surgery: 10 years experience

Conclusion. Our self-developed planning and navigation system has proven its capacity for accurate surgery on the anterior and lateral skull base. With the incorporation of augmented reality, image-guided surgery will evolve into 'information-guided surgery’. Objective. Microscopic or endoscopic skull base surgery is technically demanding and its outcome has a great impact on a patient's quality of life. The goal of the project was aimed at developing and evaluating enabling navigation surgery tools for simulation, planning, training, education, and performance. This clinically applied technological research was complemented by a series of patients (n=406) who were treated by anterior and lateral skull base procedures between 1997 and 2006. Materials and methods. Optical tracking technology was used for positional sensing of instruments. A newly designed dynamic reference base with specific registration techniques using fine needle pointer or ultrasound enables the surgeon to work with a target error of < 1 mm. An automatic registration assessment method, which provides the user with a color-coded fused representation of CT and MR images, indicates to the surgeon the location and extent of registration (in)accuracy. Integration of a small tracker camera mounted directly on the microscope permits an advantageous ergonomic way of working in the operating room. Additionally, guidance information (augmented reality) from multimodal datasets (CT, MRI, angiography) can be overlaid directly onto the surgical microscope view. The virtual simulator as a training tool in endonasal and otological skull base surgery provides an understanding of the anatomy as well as preoperative practice using real patient data. Results. Using our navigation system, no major complications occurred in spite of the fact that the series included difficult skull base procedures. An improved quality in the surgical outcome was identified compared with our control group without navigation and compared with the literature. The surgical time consumption was reduced and more minimally invasive approaches were possible. According to the participants’ questionnaires, the educational effect of the virtual simulator in our residency program received a high ranking.

P.215 Resection of a tumour of the parapharyngeal space with double mandibulotomy and coronoidectomy

Neoplasms affecting the anterolateral and lateral skull base have different sites of origin and histology, and its resection is technically difficult. The purpose of this study was to describe the surgical outcome and overall and disease-free survival of patients who had anterolateral and lateral skull base procedures for treatment of neoplasms with and without adjuvant therapy.A retrospective study was performed on 26 patients who underwent anterolateral or lateral skull-base procedures through subcranial approaches such as maxillectomy with ethmoidectomy, osteoplastic maxillotomy, transmandibular, infratemporal, and transtemporal/infratemporal techniques for treatment of neoplastic diseases. Twenty-one cases were malignancies, with no evidence of metastasis. These approaches were combined frequently with a transbasal, pterional, subtemporal, or temporo-occipital craniotomy. Survival and disease-free intervals were evaluated with the Kaplan-Meier product limit method.Nine cases were maxillary antrum malignancies with extension to the middle fossa and/or infratemporal fossa, 7 with nasopharyngeal neoplasms, 3 malignant lesions in the infratemporal fossa, and 3 with auditory canal carcinomas. The rest had miscellaneous diagnosis. Major morbidity occurred in 15% of cases. Perioperative mortality was 0. From 21 cases with malignancies, 4 had recurrences and the overall survival was 78% at 36 months of follow-up.Anterolateral and lateral skull-base surgery is done with low morbidity and no operative mortality. The oncologic results are better than those reported in the literature probably because of a stringent selection of cases, although a longer follow-up period is required.

Application of Bone-Anchored Referencing with an Electromagnetic Navigation System to the Lateral Skull Base?

Introduction: Currently, electromagnetic navigation systems are mainly used in the procedures of the frontal skull base. Within the scope of a cadaver ex vivo study, we used the navigation system InstaTrak 3500 of the GE Medical® Company to evaluate the possibility of using electromagnetic navigation systems in lateral skull base procedures.

Neurotologic Skull Base Surgery in Pediatric Patients

Innovations in diagnosis, surgical techniques, and perioperative care have dramatically improved outcomes in lateral skull base procedures in recent years. There is a belief, however, that children with skull base tumors have yet to benefit from these technological and procedural advances. The purpose of this study is to provide a clinical review of neurotologic skull base surgery in the pediatric population. Retrospective case review. Private practice tertiary referral center. Eighty-nine pediatric patients undergoing 115 neurotologic procedures for lateral skull base tumors from July 1992 to September 2003. Initial clinical presentation, tumor type, pre- and postoperative hearing and facial nerve status, treatment course, complications, and functional outcomes. The majority of tumors in this series were vestibular schwannomas, and 65 patients were diagnosed with neurofibromatosis Type 2. Surgical approaches included 70 middle fossa, 40 translabyrinthine, 2 transcochlear, 2 infratemporal fossa, and 1 retrosigmoid craniotomy. Complete tumor removal was accomplished in the majority of cases (97%), with good preservation of facial nerve function (House-Brackmann Grade I or II) in 80% of patients. In patients undergoing middle fossa surgery for hearing preservation, measurable hearing was preserved in 61.4% of cases. The incidence of complications was low. With advances in diagnostic procedures and use of current neurotologic techniques, pediatric patients may undergo successful treatment of lateral skull base tumors, with good functional outcomes and minimal morbidity.

Anterolateral and lateral skull-base approaches for treatment of neoplastic diseases

Purpose Neoplasms affecting the anterolateral and lateral skull base have different sites of origin and histology, and its resection is technically difficult. The purpose of this study was to describe the surgical outcome and overall and disease-free survival of patients who had anterolateral and lateral skull base procedures for treatment of neoplasms with and without adjuvant therapy. Materials and methods A retrospective study was performed on 26 patients who underwent anterolateral or lateral skull-base procedures through subcranial approaches such as maxillectomy with ethmoidectomy, osteoplastic maxillotomy, transmandibular, infratemporal, and transtemporal/infratemporal techniques for treatment of neoplastic diseases. Twenty-one cases were malignancies, with no evidence of metastasis. These approaches were combined frequently with a transbasal, pterional, subtemporal, or temporo-occipital craniotomy. Survival and disease-free intervals were evaluated with the Kaplan-Meier product limit method. Results Nine cases were maxillary antrum malignancies with extension to the middle fossa and/or infratemporal fossa, 7 with nasopharyngeal neoplasms, 3 malignant lesions in the infratemporal fossa, and 3 with auditory canal carcinomas. The rest had miscellaneous diagnosis. Major morbidity occurred in 15% of cases. Perioperative mortality was 0. From 21 cases with malignancies, 4 had recurrences and the overall survival was 78% at 36 months of follow-up. Conclusion Anterolateral and lateral skull-base surgery is done with low morbidity and no operative mortality. The oncologic results are better than those reported in the literature probably because of a stringent selection of cases, although a longer follow-up period is required.

Comparison of Different Computer-Aided Surgery Systems in Skull Base Surgery

Computer-aided surgery (CAS) based on high-resolution imaging techniques represents an important adjunct to precise intraoperative orientation when anatomical landmarks are distorted or missing. Several commercial systems, mostly based on optical or electromagnetic navigation principles, are on the market. This study investigated the application of EasyGuide;rM, VectorVision;rM, and InstaTrak;rM CAS systems in ENT surgery under practical and laboratory conditions. System accuracy, time required, handling, individual features, and practicality were examined in 155 patients who underwent endonasal sinus surgery and in 23 patients who underwent anterior or lateral skull base procedures. The VectorVision;rM and InstaTrak;rM CAS systems proved to be suitable for routine application in surgery involving the paranasal sinuses and various regions of the anterior skull base by helping to avoid critical structures and to determine minimally invasive approaches.

Use of the LandmarX™ Surgical Navigation System in Lateral Skull Base and Temporal Bone Surgery

Despite the widespread availability of surgical navigation devices, their use in lateral skull base and temporal bone surgery has been limited. Problems with current systems include difficulty of use and inadequate accuracy. We present a series of cases using the LandmarXtrade mark surgical navigation system as an adjunct for lateral skull base and temporal bone procedures. This infrared emitting diodes (IRED)-driven system has a post that carries the IREDs and bypasses the need to place the patient in a Mayfield head holder. This configuration allows greater mobility of the surgical field. Registration of the patient can include a combination of fiducial and anatomic landmarks that significantly increase accuracy compared to fiducial calibration alone. We introduced the use of the lateral process of the malleus as a landmark, thereby increasing accuracy within the temporal bone to a range of 0.9 to 1.5 mm. We used the system on encephaloceles, glomus tumors, meningiomas, and schwannomas, and revision surgery for chronic otitis media. It decreased operating time, allowed more effective use of "keyhole" approaches, and increased safety. As the availability and flexibility of these systems increase, their use should become the standard of care in revision temporal bone and lateral skull base procedures.

Facial nerve outcome in lateral skull base surgery for benign lesions.

To statistically identify factors most important in affecting CN7 outcome in lateral skull base surgery for benign lesions. A retrospective review of 217 nonmalignancy lateral skull base procedures from 1970 to 1995 at the Otology Group in Nashville. Charts were reviewed for epidemiology, histopathology, staging, type of CN7 mobilization (none, short, long, severance with reanastomosis, and resection), preoperative and postoperative CN7 function, surgery performed, and survival. Average House-Brackman (HB) scores for mobilizations were as follows: short, 1.65: long, 2.74: and grafting, 4.33. Factors found to affect outcome in a statistically significant fashion were preoperative HB score, staging, type of CN7 manipulation, and surgical approach. Meningiomas were found to have a worse outcome than glomus tumors. Complete resection of tumors should be performed with minimal manipulation of the facial nerve based on regional anatomy and tumor anatomy.

P-3-359 - The microsurgical anatomy of the transoral and transmaxillary approaches

Neoplasms affecting the anterolateral and lateral skull base have different sites of origin and histology, and its resection is technically difficult. The purpose of this study was to describe the surgical outcome and overall and disease-free survival of patients who had anterolateral and lateral skull base procedures for treatment of neoplasms with and without adjuvant therapy.A retrospective study was performed on 26 patients who underwent anterolateral or lateral skull-base procedures through subcranial approaches such as maxillectomy with ethmoidectomy, osteoplastic maxillotomy, transmandibular, infratemporal, and transtemporal/infratemporal techniques for treatment of neoplastic diseases. Twenty-one cases were malignancies, with no evidence of metastasis. These approaches were combined frequently with a transbasal, pterional, subtemporal, or temporo-occipital craniotomy. Survival and disease-free intervals were evaluated with the Kaplan-Meier product limit method.Nine cases were maxillary antrum malignancies with extension to the middle fossa and/or infratemporal fossa, 7 with nasopharyngeal neoplasms, 3 malignant lesions in the infratemporal fossa, and 3 with auditory canal carcinomas. The rest had miscellaneous diagnosis. Major morbidity occurred in 15% of cases. Perioperative mortality was 0. From 21 cases with malignancies, 4 had recurrences and the overall survival was 78% at 36 months of follow-up.Anterolateral and lateral skull-base surgery is done with low morbidity and no operative mortality. The oncologic results are better than those reported in the literature probably because of a stringent selection of cases, although a longer follow-up period is required.

Management of petrous bone fractures in children: Analysis of 127 cases : Glarner H.; Meuli M.; Hof E.; Gallati V.; Nadal D.; Fisch U.; Stauffer U.G.J. Trauma (Che) (1994) 36/2 (198–201)

To analyze the pathology and surgical outcomes of lateral skull base (LSB) procedures in a pediatric population.Retrospective case review in a referral skull base center.Charts of pediatric patients who underwent defined LSB procedures from 1983 to 2015 for various pathologies were evaluated at our center. A systematic review of literature was performed and our results were compared with the literature.63 patients presented with 65 diseased ears. The mean age was 13 years. 29 (44.6%) presented with hearing loss and 28 (44.4%) and chronic otorrhea. The most common pathology was petrous bone cholesteatoma (27, 42.5%) followed by vestibular schwannoma (10, 15.8%). Subtotal petrosectomy (24, 35.8%) was the most common surgical procedure followed by, transotic (18, 26.8%). The facial nerve function was preserved in 45 (67.1%) and the hearing in 28 (41.7%) cases respectively. No major complications, including mortality was encountered in our series.In rare and extensive pathologies involving the skull base in a pediatric population, the surgeon is posed with the dilemma of trying to achieve facial and hearing preservation while dealing with total tumor clearance. Mastery over LSB procedures can ensure complete disease clearance with optimal functional outcomes.2b.