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

Transcanal Transpromontorial Approaches to the Internal Auditory Canal: A Systematic Review

OBJECTIVE

Exclusive endoscopic (EETTA) and expanded (ExpTTA) transcanal transpromontorial approaches have shown promising results for treating internal auditory canal (IAC) lesions. We reviewed the literature to answer the question: "Do EETTA and ExpTTA achieve high rates of complete resection and low rates of complications in treating patients with IAC pathologies?"

DATA SOURCES

PubMed, EMBASE, Scopus, Web of Science, and Cochrane were searched.

REVIEW METHODS

Studies reporting EETTA/ExpTTA for IAC pathologies were included. Indications and techniques were discussed and meta-analyzed rates of outcomes and complications were obtained with random-effect model meta-analyses.

RESULTS

We included 16 studies comprising 173 patients, all with non-serviceable hearing. Baseline FN function was mostly House-Brackmann-I (96.5%; 95% CI: 94.9-98.1%). Most lesions were vestibular/cochlear schwannomas (98.3%; 95% CI: 96.7-99.8%) of Koos-I (45.9%; 95% CI: 41.3-50.3%) or II (47.1%; 95% CI: 43-51.1%). EETTA was performed in 101 patients (58.4%; 95% CI: 52.4-64.3%) and ExpTTA in 72 (41.6%; 95% CI: 35.6-47.6%), achieving gross-total resection in all cases. Transient complications occurred in 30 patients (17.3%; 95% CI: 13.9-20.5%), with meta-analyzed rates of 9% (95% CI: 4-15%), comprising FN palsy with spontaneous resolution (10.4%; 95% CI: 7.7-13.1%). Persistent complications occurred in 34 patients (19.6%; 95% CI: 17.1-22.2%), with meta-analyzed rates of 12% (95% CI: 7-19%), comprising persistent FN palsy in 22 patients (12.7%; 95% CI: 10.2-15.2%). Mean follow-up was 16 months (range, 1-69; 95% CI: 14.7-17.4). Post-surgery FN function was stable in 131 patients (75.8%; 95% CI: 72.1-79.5%), worsened in 38 (21.9%; 95% CI: 18.8-25%), and improved in 4 (2.3%; 95% CI: 0.7-3.9%), with meta-analyzed rates of improved/stable response of 84% (95% CI: 76-90%).

CONCLUSION

Transpromontorial approaches offer newer routes for IAC surgery, but their restricted indications and unfavorable FN outcomes currently limit their use. Laryngoscope, 133:2856-2867, 2023.

Full Endoscopic Resection of Intralabyrinthine Schwannomas: A Case Series

Objective: To investigate the technique and efficacy of fully endoscope resection of intralabyrinthine schwannomas (ILS) by transcanal transpromontorial endoscopic approach (TTEA). Study Design: Retrospective case review. Setting: Hospital. Patients: All patients who were affected by ILS, without extension to the internal auditory canal and underwent surgery with TTEA in our hospital in 2020. Intervention(s): Therapeutic. Main Outcome Measure(s): Recovery status, postoperative complications and remaining symptoms after surgery. Results: Three patients were included, all of which underwent gross total resections. The follow-up period was from 10 months to 2 years. No intraoperative and postoperative major complications were observed. There was no facial paralysis or cerebrospinal fluid leakage postoperatively. The hospitalization time of TTEA was 5 days. Three patients' vertigo was relieved after 1 week without receiving vestibular therapy. Only 1 patient complained of transient episodes of vertigo when climbing or holding heavy objects. Conclusions: TTEA has the advantages of clear vision to identify the anatomical structure, enabling complete tumor resection, reduced operation time, and faster postoperative recovery.Level of Evidence: IV.

Understanding the Molecular Mechanism of Vestibular Schwannoma for Hearing Preservation Surgery: Otologists’ Perspective from Bedside to Bench

Vestibular schwannoma is a clinically benign schwannoma that arises from the vestibulocochlear nerve that causes sensorineural hearing loss. This tumor is clinically and oncologically regarded as a benign tumor as it does not metastasize or invade surrounding tissues. Despite being a benign tumor, its management is difficult and controversial due to the potential serious complications, such as irreversible sensorineural hearing loss, of current interventions. Therefore, preventing hearing loss due to the natural course of the disease and complications of surgery is a challenging issue for an otologist. Improvements have been reported recently in the treatment of vestibular schwannomas. These include advances in intraoperative monitoring systems for vestibular schwannoma surgery where the risk of hearing loss as a complication is decreased. Precise genomic analysis of the tumor would be helpful in determining the characteristics of the tumor for each patient, leading to a better hearing prognosis. These procedures are expected to help improve the treatment of vestibular schwannomas. This review summarizes recent advances in vestibular schwannoma management and treatment, especially in hearing preservation. In addition, recent advances in the understanding of the molecular mechanisms underlying vestibular schwannomas and how these advances can be applied in clinical practice are outlined and discussed, respectively. Moreover, the future directions from the bedside to the bench side are presented from the perspective of otologists.

The Role of Endoscopy in the Resection of Sporadic Vestibular Schwannomas: A Systematic Review of Surgical Outcomes

BACKGROUND

Vestibular schwannomas (VS) are benign intracranial tumors originating from the vestibular division of the eighth cranial nerve. Treatment options include microsurgery, radiotherapy, and surveillance. Endoscopy is becoming more widely used as an adjunct in skull base surgery and may influence outcomes in surgically managed VS.

METHODS

A systematic review was conducted according to Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Studies involving endoscope-assisted and fully endoscopic procedures for sporadic VS resection were identified. Facial nerve function, hearing preservation, extent of resection, and complications were analyzed.

RESULTS

Thirty-one studies were included (27 endoscope-assisted, four fully endoscopic). Subgroup analyses were performed to assess outcomes according to tumor size and surgical approach. Overall, endoscopic facial nerve preservation rates were comparable to microsurgical treatment. A subgroup analysis suggested that functional facial nerve preservation rates may be higher when endoscopic assistance is used for smaller (Koos I-II) tumors using the retrosigmoid or translabyrinthine approach. The gross total resection rate for small tumors was higher in retrosigmoid ES-assisted microsurgery (96.2%) compared to rates in the literature for the standard, open retrosigmoid approach. Hearing outcomes were more variable and were under-reported.

CONCLUSIONS

Current data suggest that ES-assisted resection of sporadic VS is not inferior to microsurgical resection with respect to facial nerve outcomes and extent of resection. However, some ES series report poor hearing outcomes, which are under-reported in the literature. Further prospective studies are required to ascertain if endoscopic assistance can improve outcomes for VS resection, particularly for smaller (Koos I-II) tumors.

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.

Simultaneous Nonmastoidectomy Infrapromontorial Tumor Removal and Cochlear Implantation in Vestibular Schwannoma Patient

INTRODUCTION

Restoration of hearing in patients with vestibular schwannoma (VS) and poor hearing poses a great challenge. Simultaneous cochlear implantation during surgery for VS removal offers favorable hearing outcome if the cochlear nerve remains intact. Recent refinement of surgical techniques using the endoscope has made it possible to simultaneously restore the hearing and remove the tumor.

CASE DESCRIPTION

A 62-year-old male had left severe sensorineural hearing loss and a 4 mm intracanalicular VS. We performed simultaneous nonmastoidectomy infrapromontorial VS removal and cochlear implantation in this patient to achieve minimal invasiveness and to provide maximal hearing restoration. The tumor was removed via this corridor while maintaining the integrity of cochlear as well as facial nerves with full insertion of a medium length cochlear implant electrode. After surgery, the patient showed good hearing rehabilitation.

CONCLUSION

Simultaneous infrapromontorial VS removal and nonmastoidectomy cochlear implantation serves as an option for hearing restoration with minimal invasiveness in small VS removal.

Endoscopic Decompression of the Labyrinthine Segment of the Facial Nerve

OBJECTIVE

To describe the outcome and feasibility of an exclusive endoscopic transcanal transpromontorial approach (ETTA) for decompression of the labyrinthine segment of the facial nerve (LSFN).

PATIENT

A 60-year-old man with a left-sided transverse fracture of temporal bone involving the LSFN, resulting in a grade VI House-Brackmann (HB) facial palsy, associated with ipsilateral total sensorineural hearing loss.

INTERVENTION

Surgical decompression of the LSFN by ETTA.

MAIN OUTCOME MEASURE

The patient underwent ETTA which allowed complete exposure and decompression of the LSFN.

RESULTS

One year postoperatively, the patient had recovered with House-Brackmann grade II facial function.

CONCLUSION

ETTA can be considered a valuable and appropriate technique for posttraumatic decompression of LSFN, associated with unilateral total sensorineural hearing loss. The procedure resulted in significant facial nerve function improvement. ETTA should be considered both a scarless, mastoid conserving and less invasive surgical technique for posttraumatic LSFN decompression associated with pre-existing cochlear impairment.

Intracanalicular Vestibular Schwannoma: A Systematic Review and Meta-analysis of Therapeutics Outcomes

OBJECTIVE

To perform a systematic review and meta-analysis summarizing the current evidence on the management of intracanalicular vestibular schwannoma.

DATA SOURCES

Embase (1947-), Medline (1946-), Cochrane library (1947-), Scopus (2010-), and CINAHL (1961-) were searched from 1969 to October 5, 2019 (50 years).

STUDY SELECTION

A search strategy was performed to identify patients with vestibular schwannoma confined to the internal auditory canal without extension to the cerebellopontine angle. Studies with patients aged less than 18, Neurofibromatosis type 2, revision cases, and non-English language were excluded.

DATA EXTRACTION

A standardized collection sheet was used for the extracted data and a quality assessment was performed using the Newcastle-Ottawa Scale with the comparability criterion omitted.

DATA SYNTHESIS

Seventy-one studies were included with 24 on observation, 14 on radiotherapy, and 34 on surgery. The primary outcome was serviceable hearing preservation. Secondary outcomes were preservation of facial nerve function, growth, involution, and dizziness. Sub-analysis on the type of surgery and type of radiotherapy were performed. Excel 2016 with MIX 2.0 Pro add-on package was used to analyze the data and create forest plots. Data were presented in proportion with a 95% confidence interval.

CONCLUSIONS

Serviceable hearing was observed in 31% of patients after observation, 56% after radiotherapy, and 51% after surgical treatment with mean follow-up time of 4.04 years, 4.92 years, and 2.23 years, respectively. Facial nerve function was found to be best preserved in both observation and radiotherapy groups. Vestibular schwannoma growth occurred in 33% of patients under observation. Involution occurred in 2% of patients under observation and in 38% after radiotherapy.

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

OBJECTIVE

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.

METHODS

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.

RESULTS

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 5 days. The average operation time was 161.41 ± 18.42 min. All patients presented normal facial nerve function 1 month after surgery.

CONCLUSION

The METTA was effective in the removal of intrameatal VS. It can be an alternative surgical option for intrameatal VS with no serviceable hearing.

Machine learning approach for prediction of hearing preservation in vestibular schwannoma surgery

In vestibular schwannoma patients with functional hearing status, surgical resection while preserving the hearing is feasible. Hearing levels, tumor size, and location of the tumor have been known to be candidates of predictors. We used a machine learning approach to predict hearing outcomes in vestibular schwannoma patients who underwent hearing preservation surgery: middle cranial fossa, or retrosigmoid approach. After reviewing the medical records of 52 patients with a pathologically confirmed vestibular schwannoma, we included 50 patient’s records in the study. Hearing preservation was regarded as positive if the postoperative hearing was within serviceable hearing (50/50 rule). The categorical variable included the surgical approach, and the continuous variable covered audiometric and vestibular function tests, and the largest diameter of the tumor. Four different algorithms were lined up for comparison of accuracy: support vector machine(SVM), gradient boosting machine(GBM), deep neural network(DNN), and diffuse random forest(DRF). The average accuracy of predicting hearing preservation ranged from 62% (SVM) to 90% (DNN). The current study is the first to incorporate machine learning methodology into a prediction of successful hearing preservation surgery. Although a larger population may be needed for better generalization, this study could aid the surgeon’s decision to perform a hearing preservation approach for vestibular schwannoma surgery.

The first Malaysian experience on totally endoscopic ear surgery

Introduction:

Totally endoscopic ear surgery (TEES) is defined as exclusive application of endoscope transcanally in otologic surgery. This study is aimed to highlight indications and ear pathologies for TEES. In addition, intraoperative, early postoperative and delayed postoperative complications of TEES will be also described in this study.

Methodology:

This is a retrospective study of TEES performed by a single experienced and trained otologist in endoscopic ear surgery in a single institution between 1 July 2014 and 31 June 2018. A total of 43 patients were recruited in this study. Sociodemographic information, indications for TEES, ear pathologies, type of surgery performed and complications of TEES were analyzed.

Results:

The indications for TEES comprised middle ear lesion (65.1%), followed by second look surgery (14.0%), external auditory canal lesion (11.6%) and internal acoustic meatus lesion and surgery for conductive hearing loss which were 4.7%. Various external auditory canal pathologies encountered for TEES were ear canal osteoma (4.7%), acquired ear canal stenosis (2.3%) and tumor (4.7%). Regarding middle ear pathologies, limited atticoantral cholesteatoma accounted for most of the cases, 46.5%. Other middle ear lesions included adhesive otitis media (14.0%), recurrent cholesteatoma (14.0%), tumor (4.7%), otosclerosis (2.3%) and ossicular discontinuity (2.3%). Internal acoustic meatus lesion constituted 4.7% of cases. Some 4.7% of cases developed intraoperative complications, while early and delayed complications were 7.0%.

Conclusion:

TEES is a feasible surgical technique for diverse ear pathologies in the otologic specialty. It is also proven to be safe with good surgical outcomes.