Transcanal Transpromontorial Approach Research Articles

Transcanal transpromontorial approach for vestibular schwannoma: experience of a single center.

The expanded transpromontorial transcanal approach (ExpTTA) represents a recent addition to the surgical approaches available for the treatment of vestibular schwannoma. An initial purely endoscopic version has been complemented by the use of the microscope and it is now one of the possible surgical options for small to medium-sized vestibular schwannomas with a predominantly intracanalar development. This is a series of 54 patients who underwent microsurgical resection of sporadic, unilateral vestibular schwannoma, mainly Koos I-II with non-serviceable hearing, between January 2016 and January 2023 using the expanded transcanal transpromontorial approach. We describe the surgical technique, focusing on anatomical landmarks, and analyzing its advantages and shortcomings. Retrospective analysis of clinical outcomes is presented, including early and late complications. The mean follow-up was 46.7months. We achieved gross total resection of the lesion in all cases, confirmed on the first follow-up MRI at least 6months after each procedure. We did not record any intraoperative complication nor disease recurrence. We recorded two postoperative severe facial nerve palsies, one of which was permanent. No cases of disabling vertigo or imbalance were reported, and all patients reported full recovery of autonomy in daily activities. Three cases of otoliquorrhea were managed conservatively successfully. The transcanal transpromontorial approach combines the advantages of endoscopy with the possibilities provided by microsurgery. Our experience confirms its safety in terms of surgical complications and facial nerve outcome. This approach is amongst the treatment options for small-medium schwannomas in patients with impaired hearing, especially in young patients, ensuring radical resection, disease control, and minimal morbidity.

Vestibular schwannoma removal through expanded transcanal transpromontorial approach: a multicentric experience.

Expanded Transcanal Transpromontorial Approach (ExpTTA) is an endomicroscopic technique that allow surgical excision of small and symptomatic neuromas limited to the internal auditory canal (IAC) or minimally invasive the cerebellopontine angle (CPA). ExpTTA is a safer alternative to the exclusive endoscopic technique as it allows a wider surgical field and better management of the auditory porus and CPA. We report a retrospective case series of 34 patients who underwent ExpTTA between 2017 and 2022 at the ENT Departments of the University Hospital of Modena, Bologna and Verona. Tumor size was defined according to the Koos staging and hearing function was classified according to the AAOHNS. A clinical evaluation of facial nerve (FN) function was performed using the House and Brackman scale (HBs). Our cohort consists of 34 patients. At time of surgery all patients had a normal preoperative facial function. Gross total resection was achieved in all patients, without intraoperative complications, and FN continuity was preserved in all cases. No major complications were observed. Regarding post-operative FN function, at hospital discharge ten patients had impairment equal or greater than IV grade according to H&Bs. At 6months after surgery only two patients presented with moderate/severe facial paralysis (grade IV H&Bs) and finally at 12-month follow-up all patients had a satisfactory recovery of nervous function (grade < III H&Bs). ExpTTA is a safe and effectively technique for treatment of small VS (Koos I, II and selected cases of Koos III) with low postoperative morbidity.

Radiological evaluation of temporal bone surgical landmarks for a transcanal transpromontorial approach to the internal auditory canal using three-dimensional computed tomography.

This study aimed to analyse a three-dimensional transcanal transpromontorial approach to the internal auditory canal using three-dimensional computed tomography. This study was a retrospective investigation of 48 ears of 24 patients using three-dimensional reconstruction data from normal temporal bone computed tomography. The inner structures of the temporal bone were three-dimensionally reconstructed. Eight points were marked in the three-dimensional object with reference to the axial, coronal and sagittal plane images of the computed tomography scans. Distances and angles to each point were measured from the oval and round windows. The point of the facial nerve from the internal auditory canal to the labyrinthine segment could be traced between the cochlear apex and the geniculate ganglion based on the oval window. This technique helps with identifying the locations of important surgical landmarks using three-dimensional reconstructions of pre-operative computed tomography scans and to identify the facial nerve from the internal auditory canal during surgery.

Topographic Anatomy of the Medial Labyrinthine Wall: Implications for the Transcanal Endoscopic Approach to the Internal Auditory Canal.

To characterize transcanal endoscopic landmarks of the medial labyrinthine wall and correlate these with anatomical features of the fundus of the internal auditory canal (IAC). The transcanal transpromontorial approach (TTA) enables minimally invasive access to the IAC. The establishment of a landmark-based dissection technique for the approach is crucial to avoid injury to the facial nerve. Twenty temporal bones were dissected endoscopically through the TTA. Furthermore, high-resolution computed tomography (CT) scans from ten adult normal temporal bones were analyzed and three-dimensionally reconstructed. A stepwise dissection technique for the TTA was demonstrated depending on a newly described landmark used in the identification of the facial nerve. The proposed landmark, which was named the intervestibulocochlear crest (IVCC), is an integrated part of the otic capsule. It can be differentiated after the excision of the lateral labyrinthine wall as a laterally based bony pyramid between the cochlea and the vestibule. Its medially directed apex blends with the central part of the falcifrom crest and points to the distal part of the meatal facial nerve. The IVCC is best detected on axial CT images at the level of the tympanic facial nerve. The union between the IVCC and the falciform crest appears radiologically as a short stem or mini-martini glass. The proposed IVCC is a novel landmark with a consistent relationship to the IAC fundus and the facial nerve. It may be utilized in conjunction with the falciform crest to identify the facial nerve during minimally invasive transcanal surgeries.

An Endoscopic Transcanal Transpromontorial Approach for Vestibular Schwannomas using a Computer-Based Three-Dimensional Imaging System.

A 2D monocular endoscope has been used in transcanal transpromontory vestibular schwannoma surgery instead of craniotomy. However, the absence of depth perception is the limitation of this approach. With the loss of depth perception, the surgeon will be not able to perform delicate and particularly complicated surgery. A binocular endoscope has been developed to provide stereoscopic vision with better depth perception for complicated anatomic structures and has been applied in some endoscopic surgeries. However, the diameter of the endoscope is a limitation in the performance of transcanal otologic surgeries. A small diameter endoscope facilitates easier surgery in a restricted space. A computer-based 3D imaging system can obtain 3D images in real-time using a small monocular endoscope. In this study, to evaluate the feasibility of a computer-based 3D imaging system for endoscopic lateral skull base surgery, we applied this 3D imaging system in a transcanal transpromontorial approach in two patients with vestibular schwannomas. The surgical procedure was completed without complication in these two cases. There was no mortality, perioperative complications, nor notable postoperative complications. Using this computer-based 3D imaging system, a better depth perception and stereoscopic vision was observed compared to a conventional 2D endoscope. The improvement in depth perception offers superior management of the complicated surgical anatomy.

Endoscopic intracanalicular vestibular schwannoma excision via middle ear corridors a surgical options

Background With more intracanalicular vestibular schwannoma (ICVS) diagnosed, treatment options are limited either to wait-and-see or surgery. The transpromontorial and infrapromontorial approaches allow direct route to the fundus of internal auditory canal with certain advantages in preserving facial nerve and even cochlear nerve. Objectives To describe the middle ear corridor approach for ICVS excision. Methodology All transpromontorial and infrapromontorial approaches for ICVS excision were recruited. The surgeries were performed at an otologic center by a single experienced otologist. Results Three cases of ICVS Koos Type I were included in this review. Two cases were operated with exclusive endoscopic transcanal transpromontorial approach excision of tumor. One case underwent concurrent transcanal excision of ICVS through infrapromontorial approach with cochlear implantation. Two of them developed facial nerve paresis. The last patient recovered fully with viable cochlear nerve enabling hearing restoration with cochlear implant. Conclusion The potential of surgery in ICVS via middle ear approach is a safe and direct route with promising outcome. This approach offers removal of the ICVS without interrupting facial and cochlear nerves. Hence, the preservation of facial function and hearing are possible.

A microscope-assisted endoscopic transcanal transpromontorial approach for vestibular schwannoma resection: a preliminary report.

To evaluate the feasibility of a microscope-assisted endoscopic transcanal transpromontorial approach (METTA) for the removal of small vestibular schwannomas (VS) limited to the internal auditory canal (IAC), and introduce a modification without external auditory canal (EAC) closure. Between August 2018 and February 2019, seven patients with intrameatal VS underwent surgery in our center, endoscopic transcanal transpromontorial approach was applied in the first 2 patients and the rest 5 patients were operated via METTA. Treatment outcomes including efficacy of tumor resection, facial nerve outcome, operation time and post-operative course were recorded and analyzed. All seven patients were pathologically confirmed to have intrameatal VS. Total tumor removal was achieved in all cases. Two patients experienced cerebrospinal fluid leakage which resolved spontaneously within 5days. The average operation time was 161.41 ± 18.42min. All patients presented normal facial nerve function 1month after surgery. The METTA was effective in the removal of intrameatal VS. It can be an alternative surgical option for intrameatal VS with no serviceable hearing.

Relationship Between the Cochlear Aqueduct and Internal Auditory Canal: Surgical Implications for Transcanal Transpromontorial Approaches to the Lateral Skull Base.

The cochlear aqueduct (CA) is subject to considerable anatomical variability. We hypothesize a topographical relationship between the CA and the internal auditory canal (IAC). The CA represents the lower limit of dissection during transcanal transpromontorial approaches to the lateral skull base due to its close relationship to the lower cranial nerves and jugular vein. Three-dimensional models from high-resolution computed tomography scans of normal human temporal bones were created using threshold-based segmentation. The CA was classified into four categories. Five points were determined on the three-dimensional models to measure the surgically relevant relationships. Segmentation was performed on 26 high-resolution computed tomography scans. The average length of the virtual and visual part of the CA was 6.6 mm (SD ±1.7 mm) and 5.5 mm (SD ±1.3 mm) respectively. The mean distance between the IAC and the medial end of the visual part of the CA was 3.8 mm (±0.7 mm), while the average distance between the IAC and the lateral end was 1.4 mm (±0.6 mm). The distance between the visual part of the CA and the IAC increased by 0.25 mm per from the fundus of the IAC. A close relationship between the CA and the IAC could be established, despite the anatomical variability of the CA. The distance between CA and IAC increases by 0.25 per mm from the fundus to the porus of the IAC. These findings quantify the inferior limit of dissection of the transcanal transpromontorial approach to the lateral skull base.

Facial Nerve Neurophysiologic Assessment in Vestibular Schwannoma Removal with Transcanal Approach: A Pilot Clinical Study

The transcanal transpromontorial approach has been introduced to remove vestibular schwannomas. As with other techniques, preservation of the facial nerve (FN) is challenging. This pilot study described FN outcomes of patients preoperatively and postoperatively assessed with electromyography (EMG) and blink reflex (BR). Between September 2017 and December 2018, 10 patients (5 men; 5 women; mean age, 59.8 years; age range, 25-77 years) underwent removal of vestibular schwannoma via the transcanal transpromontorial approach. FN assessment using EMG/BR and clinical evaluation with the House-Brackmann (HB) grading scale was performed preoperatively and 2 months postoperatively. If facial impairment was present postoperatively, further analysis was performed 6 months after surgery. All 10 patients had normal FN function on preoperative EMG/BR. After 2 months, 4 patients had normal FN function on EMG/BR, 4 patients showed a slight delay of FN responses, 1 patient had moderate dysfunction, and 1 patient had consistent damage. After 6 months, among the 6 patients with a pathologic neurophysiologic study, consistent EMG/BR improvement was shown, with complete recovery in 3 cases. At the last follow-up, 8 patients had HB grade I, 1 patient had HB grade II, and 1 patient had HB grade III in 1, showing progression toward healing in 9 of 10 cases. The transcanal transpromontorial approach is an effective procedure for vestibular schwannoma removal. EMG/BR represents an objective evaluation method to verify FN recovery after surgery and confirms the low impact of this surgical procedure on the FN.

Transcanal Transpromontorial Approach to Lateral Skull Base: Maximal Area of Exposure and Surgical Extensions

To determine the possible surgical extensions and maximal area of exposure (AOE) achievable through the transcanal transpromontorial approach (TTA) to the internal auditory canal (IAC) and cerebellopontine angle. We hypothesize a possible extension of indication for this minimally invasive approach to the lateral skull base. In this experimental anatomic study, the expanded TTA was first carried out in 4 temporal bones to define the anatomic boundaries of the maximal exposure, from 2 perspectives, the middle ear and the porus of the IAC. Consecutively, these identified boundaries were translated on segmented 3-dimensional (3D) surface models of 32 temporal bone high-resolution computed tomography scans. The dissections performed were the basis followed during the determination of the AOE on the 3D surface models. The measurements revealed that the AOE at the middle ear was 152.9 ± 33.6 mm2, whereas it was 151.9 ± 24.8 mm2 at the porus of the IAC. The mean superoinferior and anteroposterior extensions at the middle ear were 14.7 ± 2.5 mm and 16.9 ± 2.5 mm, respectively. On the other hand, the mean superoinferior and anteroposterior extensions at the IAC porus were 10.3 ±1.3 mm and 18.5 ± 1.9 mm, respectively. Consistent with the minimally invasive approaches, the AOE is limited; however, if compared with traditional approaches, it appears of considerable size. Our results may assist the surgeon in the selection process of the appropriate candidates for the TTA and to tailor the approach to the disease.

Is endoscopic inspection necessary to detect residual disease in acoustic neuroma surgery?

To analyze how and when the endoscope is used in vestibular schwannoma surgery and identify the benefits of using endoscopy in this type of surgery. It is currently unclear if there is any benefit from using an endoscope in vestibular schwannoma surgery so this retrospective analysis set out to study this. All the patients who underwent vestibular schwannoma surgery at our clinic were included for all the vestibular schwannoma approaches taken. We studied when endoscopy was used during surgery and the goal of using endoscopy. Several pre- and postoperative factors were assessed such as complications, facial function, and hearing function in the case of techniques that allow hearing preservation. From January 2015 to September 2018, 280 patients underwent lateral skull base surgery. Of these, 112 were included in this study. The endoscope was used in all 112 patients, and in eight cases it was possible to identify residual disease using the endoscope to check the surgical field, and then to remove the disease under endoscopic view. Moreover, in two other cases, the endoscope was used to resolve a vasculoneural conflict between the anterior inferior cerebellar artery (AICA) loop and facial nerve in one case, and for deafferentation of the superior and inferior vestibular nerves in the second case. No major intraoperative complications occurred in our series. There was no statistically significant difference in postoperative facial nerve function between patients in whom the endoscope was used as a diagnostic tool and patients in whom it was used as an operative tool (p = 0.3152). The endoscope may be useful, especially in surgical techniques where there is poor control of the internal auditory canal (IAC). An endoscopic support technique is strongly recommended to avoid residual disease, particularly in retrosigmoid and retrolabyrinthine approaches. Moreover, the recent introduction of the transcanal transpromontorial approach allows the endoscope to be used during all the procedures in patients affected by a vestibular schwannoma limited to the IAC or to support surgical procedures during an enlarged microscopic approach.

Transcanal Microscopic Transpromontorial Approach for Vestibular Schwannoma.

Objectives  This video demonstrates the transcanal transpromontorial approach for resection of vestibular schwannoma. Design/Setting/Participants  Present study is based on a video of a single patient undergoing the above approach at a tertiary care skull base surgery program. Results  This video demonstrates a transcanal microscopic transpromontorial approach for resection of an enlarging intracanalicular vestibular schwannoma in a young patient with nonserviceable hearing. The video highlights the pertinent surgical anatomy and outlines, in a step-by-step fashion, the approach to the internal auditory canal via this minimally invasive approach. The surgical indications and reconstructive techniques are also discussed ( Fig. 1 ). Conclusions  A transcanal microscopic transpromontorial approach for vestibular schwannoma is feasible and offers a minimally invasive option for patients electing for microsurgical resection. The link to the video can be found at: https://youtu.be/-oKkRooytws .

The Feasibility of a Modified Exclusive Endoscopic Transcanal Transpromontorial Approach for Vestibular Schwannomas.

Objective  We evaluated the feasibility of an exclusive endoscopic transcanal transpromontorial approach (EETTA) for the treatment of small vestibular schwannomas (VSs) limited to the internal auditory canal (IAC), and introduced a modification without external auditory canal closure. Methods  Between June 2016 and June 2017, seven patients with VS underwent surgery using a modified EETTA. Treatment outcomes, including efficacy of tumor resection, preservation of function, operation time, and quality of life (QOL), were evaluated. Results  The patients preoperatively exhibited Koos Grade I/II tumors and severe-to-profound hearing loss. Gross total resection was accomplished in all cases. There were no major complications, and all patients exhibited normal facial nerve function immediately after surgery. The mean follow-up period was 12.9 months. The operation time (average 196.3 ± 64.9 minutes) and hospitalization period (average 7.4 ± 1.0 days) were favorable. Short Form-36 scores for QOL showed unremarkable results compared with previous reports. Conclusions  The modified EETTA was effective in the removal of VSs in the IAC. It can be an alternative surgical option for small VSs.

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.

Intralabyrinthine schwannomas: a new surgical treatment.

To define a new surgical option, with lower morbidity, for the treatment of intralabyrinthine schwannomas. Retrospective case review. Tertiary referral centers. Eight patients affected by an intralabyrinthine schwannoma, with or without extension to the internal auditory canal, that underwent surgery with a transcanal transpromontorial approach, were included in the study. The average age at presentation was 47years. Patients' characteristics, symptoms, tumor features, and surgical results were analyzed. All patients were diagnosed and evaluated pre-operatively with high-resolution, gadolinium-enhanced MRI and CT scan of the temporal bone, and underwent surgery via either transcanal transpromontorial endoscopic approach (TTEA) or enlarged transcanal transpromontorial endoscopic approach (ETTA). Hearing function was evaluated with the Hearing Classification System according to the Committee on Hearing and Equilibrium Guidelines. Facial nerve function was evaluated using the House-Brackmann grading system (HB). In six patients out of eight, a TTEA was performed, whereas, due to the extension of the pathology to the cerebellopontine angle, two patients underwent an ETTA. The mean follow-up period was 15.5months (range 1-69). No intra-operative and post-operative major complications were observed. Post-operative facial nerve function was normal in seven out of eight patients (grade I HB). One patient presented a grade II HB. The endoscopic approach to cochlear schwannoma represents a good treatment option for patients and should be preferred to other more invasive surgical techniques when indicated, to reduce complications, hospitalization, and offer to patients the chance to eradicate the disease, thus avoiding the stress of a long-life radiological follow-up. 4.

Expanded Transcanal Transpromontorial Approach: A Novel Surgical Technique for Cerebellopontine Angle Vestibular Schwannoma Removal.

Objective Vestibular schwannoma (VS) is a benign tumor of the lateral skull base. Different microscopic surgical techniques are described in literature: the retrosigmoid and translabyrinthine approaches are used to treat big tumors located in the cerebellopontine angle, and the middle cranial fossa approach is utilized for small tumors with good hearing preservation. The expanded transcanal transpromontorial (ExpTT) approach is a combined microscopic-endoscopic technique previously indicated for Koos stage I and II VS and now proposed for larger VS, up to 3 cm in diameter, with linear progression into the cerebellopontine angle and touching the brainstem. Study Design The study was a retrospective case series of patients who underwent ExpTT surgery for VS in our ear, nose, and throat department. Setting We reviewed the surgical videos and electrophysiologic data recorded during the surgical operations. Subjects and Methods From January 2015 to January 2017, 20 patients affected by Koos stage II and III VS underwent surgery in our department with the ExpTT approach. This novel technique is described step by step, with a focus on the surgical procedure and anatomic landmarks; outcomes are detailed in terms of early and late complications. The mean follow-up was 15 months. Results The ExpTT approach permitted, in all patients, gross total resection of the tumor without any complication and with preservation of facial nerve function. All patients had a good postoperative recovery. Conclusion The ExpTT technique is a new approach that combines the advantages of a microscopic technique with the ones offered by the endoscope in removal of VS.

Transcanal Transpromontorial Acoustic Neuroma Surgery: Results and Facial Nerve Outcomes.

Recently, the transcanal approach for the removal of acoustic neuromas has been introduced. Facial nerve (FN) preservation is one of the main challenges of this kind of surgery. To describe our experience in the surgical treatment of acoustic neuromas, focusing on the functional results of FN preservation after a transcanal approach. A retrospective chart review was carried out on clinical data and videos from operations on 49 patients who underwent surgery with a totally transcanal exclusive endoscopic approach for Koos stage I-II lesions, or an enlarged transcanal transpromontorial approach for Koos stage II-III tumors, between March 2012 and February 2017. Patients and tumor characteristics, clinical manifestations, radiologic features, audiological results, FN outcomes (according to the House-Brackmann [HB] grading system) and complications were evaluated. Tumors were classified according to the Koos grading system. The age of the patients (34 females and 15 males) ranged from 27 to 77 years (mean age: 54.9 yr). Preoperative diagnosis was "vestibular schwannoma" in all patients. At the last follow-up (range 1-60 mo, mean 13.9 mo), 42 of 49 showed grade I HB FN function, 5 of 49 grade II HB, and 2 of 49 grade III HB. Overall, in 95.9%, FN function was preserved (grade I-II HB) with stable results at follow-up; in 4.1% of cases, FN function was reduced, but not worse than grade III. The transcanal approach represents a feasible, minimally invasive, and conservative technique for the management of acoustic neuromas of the internal auditory canal.

Expanded transcanal transpromontorial approach to the internal auditory canal: Pilot clinical experience.

The aim of this study was to describe and evaluate the feasibility of an expanded transcanal transpromontorial approach, developed from the exclusive endoscopic transcanal transpromontorial approach. Retrospective case series. Retrospective chart review of 10 patients operated by an expanded transcanal transpromontorial approach in two tertiary referral centers (University Hospital of Modena, Italy and University Hospital of Verona, Italy). Data from charts and video documentation were collected and analyzed. Between April 2015 and January 2016, 10 patients underwent an expanded transcanal transpromontorial approach for vestibular schwannoma Koos stage I or II and were enrolled in the study. The size of the tumors ranged from 7 to 19 mm in maximum diameter. A gross total resection was achieved in all cases. One subject experienced postoperative cerebrospinal fluid otorhinorrhea and three subjects experienced temporary postoperative facial weakness, all of which completely resolved. The mean follow-up was 5 months. The expanded transcanal transpromontorial approach allowed bimanual dissection using a microscopic technique for the treatment of pathologies of the internal auditory canal and cerebellopontine angle. This novel approach resulted in minimal morbidity and comparable facial nerve preservation rates to the traditional approaches to the internal auditory canal. The expanded transpromontorial approach to the internal auditory canal holds promise for addressing pathology in this region of the temporal bone from the external auditory canal. 4. Laryngoscope, 127:2608-2614, 2017.

Exclusive endoscopic transcanal transpromontorial approach: a new perspective for internal auditory canal vestibular schwannoma treatment.

OBJECTIVE The aim of this study was to describe the first case series in which an exclusive endoscopic transcanal transpromontorial approach (EETTA) was used to treat small vestibular schwannomas (VSs) and meningiomas of the internal auditory canal (IAC). METHODS The authors performed a retrospective review of patients who had undergone surgery using an EETTA to the IAC at 2 university tertiary care referral centers during the period from November 2011 to January 2015. RESULTS Ten patients underwent surgery via an EETTA for the treatment of VS in the IAC at the University Hospital of Modena or the University Hospital of Verona. The patients had Koos Grade I or II tumors and American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) Class D hearing status preoperatively. Gross-total resection was achieved in all patients. No major complications such as cerebrospinal fluid leakage or hemorrhage were reported. In 7 of 10 (70%) patients, facial nerve function was normal immediately after surgery (Rough Grading System [RGS] Grade I). Two patients presented with a transitory facial palsy immediately after surgery (RGS Grade II-III) but experienced complete recovery during the follow-up period. The mean follow-up was 10 months. CONCLUSIONS The EETTA proved to be successful for the removal of VS or meningioma involving the cochlea, fundus, and IAC, with possible lower complication rates and less invasive procedures than those for traditional microscopic approaches. The potential for the extensive and routine use of this approach in lateral and posterior skull base surgery will depend on the development of technology and surgical refinements and on the diffusion of skull base endoscopic skills among the otolaryngological and neurosurgical communities.