Retrolabyrinthine Meatotomy as Part of Retrosigmoid Approach to Expose the Whole Internal Auditory Canal: Rationale, Technique, and Outcome in Hearing Preservation Surgery for Vestibular Schwannoma

Abstract BACKGROUND Vestibular schwannoma extending to the fundus of the internal auditory canal is currently considered an unfavorable condition for hearing preservation surgery via a retrosigmoid approach because the lateral end of the canal is hard to view directly during microsurgery. OBJECTIVE To present an improved retrolabyrinthine meatotomy (RLM) technique that enables the full length of the cochlear and facial nerves to be inspected up to their orifices on the fundus. Long-term results are briefly reported. METHODS A consecutive series of 100 cases with various degrees of fundus involvement underwent surgery via a retrosigmoid approach and RLM. The follow-up ranged from 4 to 14 yr. Outcomes on hearing and facial nerve function were recorded, and preoperative MRI findings of the tumor on the fundus were correlated with the surgical findings and the long-term radicality of the tumor resection. RESULTS Residual tumor on the fundus was identified in 3 cases, all belonging to the group with tumors adhering to the fundus. The functional results were in line with the best reported outcomes of this surgery. CONCLUSION RLM via a retrosigmoid approach seemed adequate for the purposes of hearing preservation surgery and enabled the full course of the facial and cochlear nerves through the internal auditory canal to be exposed to direct view. Tumors adhering to the vestibular quadrant of the fundus were more difficult to remove, and there were a few cases of local residual tumor.

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Hearing Preservation Surgery via Retrosigmoid Approach with Retrolabyrinthine Meatotomy in Small Vestibular Schwannoma

Journal of Neurological Surgery Part B Skull Base ◽

10.1055/s-0039-1677847 ◽

2019 ◽

Vol 80 (S 03) ◽

pp. S281-S283 ◽

Cited By ~ 1

Author(s):

Diego Cazzador ◽

Daniele Borsetto ◽

Enrico Alexandre ◽

Chiara Pavone ◽

Domenico d'Avella ◽

...

Keyword(s):

Care Center ◽

Tertiary Care ◽

Internal Auditory Canal ◽

Hearing Preservation ◽

Anatomical Landmarks ◽

Main Function ◽

Hearing Function ◽

Brainstem Response ◽

Unfavorable Condition ◽

Hearing Preservation Surgery

Objectives Vestibular schwannomas (VS) extending into the internal auditory canal (IAC) are currently considered as an unfavorable condition for hearing preservation surgery (HPS) via retrosigmoid (RS) approach due to the poor direct visualization of the facial and cochlear nerves course through the IAC and the fundus during microsurgery. Design The operative steps are described in a surgical instructional video. Setting The surgery took place at a tertiary-care center. Participants Patient is a 45-year-old man who was incidentally diagnosed with an extrameatal VS extending for 9 mm into the left cerebellopontine angle (CPA). Hearing function at diagnoses was excellent, with pure tone average (PTA) = 15 dB and speech discrimination score (SDS) = 100% (class A according to the Tokyo classification) and minimal impairments on auditory brainstem response (ABR). Given these preoperative features in small VS, hearing was the main function to look into in the treatment planning. Initial observation or HPS were proposed. Results The patient underwent surgical excision for HPS via RS approach combined with retrolabyrinthine meatotomy (RLM). RLM enables the complete exposure of the IAC to the fundus, after drilling the bony surface of the posterior IAC wall, under guidance of the anatomical landmarks, namely, the endolymphatic duct, the blue lines of the posterior, and superior semicircular canals, and common crus. Nor intra-, neither postoperative complications occurred. Histologic examination confirmed the diagnosis of VS. A 3-month short-term follow-up revealed a class B hearing function with PTA = 30 dB, SDS = 100%, and normal facial nerve status. Conclusions RLM via RS approach proved to be effective for HPS, enabling the full course of the facial and cochlear nerves through the IAC to be directly exposed.The link to the video can be found at: https://youtu.be/KC1S4pxpLCk.

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Microsurgical and Endoscope Assisted Resection of a Right Intracanalicular Vestibular Schwannoma Two-Dimensional Operative Video

Journal of Neurological Surgery Part B Skull Base ◽

10.1055/s-0038-1676840 ◽

2019 ◽

Vol 80 (S 03) ◽

pp. S288-S289

Author(s):

Chun-Yu Cheng ◽

Zeeshan Qazi ◽

Laligam N. Sekhar

Keyword(s):

Vestibular Schwannoma ◽

Coming Out ◽

Internal Auditory Canal ◽

Brain Magnetic Resonance Imaging ◽

Hearing Preservation ◽

Retrosigmoid Approach ◽

Two Dimensional ◽

Speech Discrimination ◽

Far Lateral Approach ◽

Hearing Test

A 36-year-old lady presented with tinnitus and hearing loss for 1 year which was progressively worsening. A hearing test revealed pure tone average (PTA) between 48 to 65 dB and speech discrimination of 56% at 95 dB. Brain magnetic resonance imaging (MRI) showed a right vestibular schwannoma 5 × 8 mm (Fig. 1) which extended far laterally to the fundus of internal auditory canal (IAC). A translabyrinthine approach was suggested by another neurosurgeon/neurotologist team, but the patient decided to undergo operation by retrosigmoid approach with attempted hearing preservation.She underwent a right retrosigmoid craniotomy, craniectomy, and mastoidectomy with far lateral approach. We performed petrous transcanalicular microsurgical approach with the assistance of neuroendoscope. Intraoperatively, the internal auditory artery was looping into the IAC between cranial nerves VII and VIII, and coming out inferiorly. The IAC was opened by the diamond drill, ultrasonic bone curette, and fine rongeurs. The tumor was grayish in color with filling the lateral aspect of the IAC. After circumferential dissection of the tumor capsule, the tumor was removed completely. It was arising from the inferior vestibular nerve which was stretched. The patient had vertigo and nausea postoperatively but it is steadily improving. Her hearing test has improved to a PTA of 22 dB and speech discrimination of 100% at 70 dB at 6 weeks. The postoperative MRI showed total resection.This two-dimensional video shows the technical nuances of microsurgical retrosigmoid approach and endoscopic assisted resection of an intracanalicular vestibular schwannoma and the value of attempting hearing preservation in all vestibular schwannomas (Fig. 2).The link to the video can be found at: https://youtu.be/KHrO_iDI2tw.

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Can You Hear Me Now? Long-Term Hearing Preservation in Intracanalicular Vestibular Schwannoma

Skull Base ◽

10.1055/s-2006-958300 ◽

2007 ◽

Vol 16 (S 1) ◽

Author(s):

Stephen Haines ◽

Samuel Levine ◽

Scott Turner

Keyword(s):

Vestibular Schwannoma ◽

Hearing Preservation

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Spreading of the vestibular schwannoma into porus acusticus internus. Endoscopic removal possibilities

OTORHINOLARYNGOLOGY 2-3(2) 2019 - OTORHINOLARYNGOLOGY ◽

10.37219/2528-8253-2018-1-40 ◽

2018 ◽

pp. 40-44

Author(s):

Orest Palamar ◽

Andriy Huk ◽

Dmytro Okonskyi ◽

Ruslan Aksyonov ◽

Dmytro Teslenko

Keyword(s):

Vestibular Schwannoma ◽

Internal Auditory Canal ◽

Residual Tumor ◽

Endoscopic Technique ◽

Vestibular Schwannomas ◽

Endoscopic Removal ◽

Tumor Removal ◽

Tumor Spread ◽

Microsurgical Technique ◽

Tumor Visualization

Aim: To investigate the features of the vestibular schwannoma spread into the internal auditory canal and the possibilities of endoscopic removal. Objectives: To improve tumor visualization in the internal auditory canal; to create a sufficient view angle for tumor removal during endoscopic opening of the internal auditory canal. Materials and methods: The results of surgical treatment of 20 patients with vestibular schwannomas in which the tumor spread to the internal auditory canal were analyzed. Microsurgical tumor removal was performed in 14 cases; Fully endoscopic removal of vestibular schwannomas was performed in 6 cases. The internal auditory canal opening was performed in 14 cases using microsurgical technique and in 6 cases with fully the endoscopic technique. Results: Gross total removal was achieved in 18 cases, subtotal removal in 2 cases. The tumor spread into the internal auditory canal was removed in all cases (100%). Opening the internal auditory canal using the endoscopic technique allows to increase the view angle (up to 20%) and to visualize along the axis of canal. Conclusions: 1) Endoscopic assistance technique allows to improve residual tumor visualization much more better then microsurgical technique; 2) Internal auditory canal opening using endoscopic technique is much more effective than the microsurgical technique (trepanning depth is larger); 3) Endoscopic methods for the internal auditory canal opening allows to increase canal angle view up to 20% (comparing to the microsurgical view).

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Endoscopic-assisted microsurgical resection of giant vestibular schwannoma in semi-sitting position

Neurosurgical Focus: Video ◽

10.3171/2021.7.focvid2176 ◽

2021 ◽

Vol 5 (2) ◽

pp. V3

Author(s):

Gang Song ◽

Liyong Sun ◽

Yuhai Bao ◽

Jiantao Liang

Keyword(s):

Vestibular Schwannoma ◽

Internal Auditory Canal ◽

Residual Tumor ◽

Nerve Function ◽

Tumor Removal ◽

Function Preservation ◽

Microsurgical Resection ◽

Dissection Technique ◽

Total Tumor Removal ◽

Facial Function

The main objectives of microsurgery for vestibular schwannoma are total tumor removal and preservation of facial and cochlear nerve function. For giant tumors, total tumor removal and facial nerve function preservation are challenging. The semisitting position has some advantages. In this video the authors show the removal of a giant vestibular schwannoma with the patient in a semisitting position. They demonstrate the advantages of the semisitting technique, such as the two-handed microsurgical dissection technique and a clear operative field. Finally, a small residual tumor in the internal auditory canal was removed by endoscopy. The patient’s facial function was House-Brackmann grade I at discharge. The video can be found here: https://stream.cadmore.media/r10.3171/2021.7.FOCVID2176

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Hearing Preservation After Translabyrinthine Vestibular Schwannoma Excision: Audiometry and Electrocochleography Results

Annals of Otology Rhinology & Laryngology ◽

10.1177/0003489418783788 ◽

2018 ◽

Vol 127 (8) ◽

pp. 563-567 ◽

Cited By ~ 4

Author(s):

Kenneth Akakpo ◽

William J. Riggs ◽

Michael S. Harris ◽

Edward E Dodson

Keyword(s):

Hair Cell ◽

Vestibular Schwannoma ◽

Cranial Nerve ◽

Cell Activity ◽

Internal Auditory Canal ◽

Hearing Preservation ◽

Healthy Patient ◽

Cochlear Hair Cell ◽

Translabyrinthine Approach ◽

Cranial Nerve Viii

Objectives: To describe a case of inadvertent hearing preservation following a classical translabyrinthine resection of a vestibular schwannoma of the internal auditory canal in an otherwise healthy patient. Methods: Herein, we describe the case of an otherwise healthy patient who underwent resection of an intracanalicular vestibular schwannoma via a translabyrinthine approach. Furthermore, as part of an ongoing study aimed at characterizing hearing changes due to intraoperative events, cochlear hair cell and nerve activity were monitored using electrocochleography throughout surgery. Unexpectedly, the patient maintained serviceable hearing following surgery. As a result, we are able to provide electrophysiologic evidence of cochlear hair cell activity at various stages of this surgery. Results: Hair cell responses across tested frequencies were detectable prior to and following completion of the translabyrinthine procedure. Neural integrity of the auditory division of cranial nerve VIII was maintained throughout. Lastly, postoperative audiometric testing supported the patient’s subjective assertion of serviceable hearing in the surgical ear. Conclusion: Our results suggest that some degree of hair cell and neural integrity can be maintained throughout the course of the translabyrinthine approach, and if preservation of the auditory division of cranial nerve VIII is feasible, a functional amount of hearing preservation is attainable.

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32 Long Term Results of 120 Cases of Vestibular Schwannoma Treated with Cyberknifetm Robotic Stereotactic Radiosurgery at the Ottawa Hospital Cancer Centre

Radiotherapy and Oncology ◽

10.1016/s0167-8140(19)33318-3 ◽

2019 ◽

Vol 139 ◽

pp. S16-S17

Author(s):

Eduardo Gaviolli ◽

Jack Zheng ◽

John Sinclair ◽

Janos Szanto ◽

Fahad Alkherayf ◽

...

Keyword(s):

Stereotactic Radiosurgery ◽

Vestibular Schwannoma ◽

Long Term Results ◽

Cancer Centre ◽

Ottawa Hospital

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Stereotactic radiosurgery for vestibular schwannomas: average 10-year follow-up results focusing on long-term hearing preservation

Journal of Neurosurgery ◽

10.3171/2016.7.gks161494 ◽

2016 ◽

Vol 125 (Supplement_1) ◽

pp. 64-72 ◽

Cited By ~ 34

Author(s):

Shinya Watanabe ◽

Masaaki Yamamoto ◽

Takuya Kawabe ◽

Takao Koiso ◽

Tetsuya Yamamoto ◽

...

Keyword(s):

Stereotactic Radiosurgery ◽

Tumor Volume ◽

Hearing Preservation ◽

Interquartile Range ◽

Vestibular Schwannomas ◽

Long Term Results ◽

Tumor Control ◽

Univariable Analysis

OBJECTIVEThe aim of this study was to reappraise long-term treatment outcomes of stereotactic radiosurgery (SRS) for vestibular schwannomas (VSs). The authors used a database that included patients who underwent SRS with a unique dose-planning technique, i.e., partial tumor coverage designed to avoid excess irradiation of the facial and cochlear nerves, focusing on tumor control and hearing preservation. Clinical factors associated with post-SRS tumor control and long-term hearing preservation were also analyzed.METHODSThis institutional review board–approved, retrospective cohort study used the authors' prospectively accumulated database. Among 207 patients who underwent Gamma Knife SRS for VSs between 1990 and 2005, 183 (who were followed up for at least 36 post-SRS months) were studied. The median tumor volume was 2.0 cm3 (range 0.05–26.2 cm3). The median prescribed dose at the tumor periphery was 12.0 Gy (range 8.8–15.0 Gy; 12.0 Gy was used in 171 patients [93%]), whereas tumor portions facing the facial and cochlear nerves were irradiated with 10.0 Gy. As a result, 72%–99% of each tumor was irradiated with the prescribed dose. The mean cochlear doses ranged from 2.3 to 5.7 Gy (median 4.1 Gy).RESULTSThe median durations of imaging and audiometric follow-up were 114 months (interquartile range 73–144 months) and 59 months (interquartile range 33–109 months), respectively. Tumor shrinkage was documented in 110 (61%), no change in 48 (27%), and enlargement in the other 22 (12%) patients. A further procedure (FP) was required in 15 (8%) patients. Thus, the tumor growth control rate was 88% and the clinical control rate (i.e., no need for an FP) was 92%. The cumulative FP-free rates were 96%, 93%, and 87% at the 60th, 120th, and 180th post-SRS month, respectively. Six (3%) patients experienced facial pain, and 2 developed transient facial palsy. Serviceable hearing was defined as a pure tone audiogram result better than 50 dB. Among the 66 patients with serviceable hearing before SRS who were followed up, hearing acuity was preserved in 23 (35%). Actuarial serviceable hearing preservation rates were 49%, 24%, and 12% at the 60th, 120th, and 180th post-SRS month, respectively. On univariable analysis, only cystic-type tumor (HR 3.36, 95% CI 1.18–9.36; p = 0.02) was shown to have a significantly unfavorable association with FP. Multivariable analysis followed by univariable analysis revealed that higher age (≥ 65 years: HR 2.66, 95% CI 1.16–5.92; p = 0.02), larger tumor volume (≥ 8 cm3: HR 5.36, 95% CI 1.20–17.4; p = 0.03), and higher cochlear dose (mean cochlear dose > 4.2 Gy: HR 2.22, 95% CI 1.07–4.77; p = 0.03) were unfavorable factors for hearing preservation.CONCLUSIONSStereotactic radiosurgery achieved good long-term results in this series. Tumor control was acceptable, and there were few serious complications in patients with small- to medium-sized VSs. Unfortunately, hearing preservation was not satisfactory. However, the longer the observation period, the more important it becomes to compare post-SRS hearing decreases with the natural decline in untreated cases.

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Preservation of hearing in patients undergoing excision of acoustic neuromas and other cerebellopontine angle tumors

Journal of Neurosurgery ◽

10.3171/jns.1985.63.2.0168 ◽

1985 ◽

Vol 63 (2) ◽

pp. 168-174 ◽

Cited By ~ 47

Author(s):

Charles H. Tator ◽

Julian M. Nedzelski

Keyword(s):

Tumor Size ◽

Cerebellopontine Angle ◽

Internal Auditory Canal ◽

Hearing Preservation ◽

Cochlear Nerve ◽

Consecutive Series ◽

Speech Discrimination ◽

Content Type ◽

Acoustic Neuromas ◽

Fine Print

✓ Microsurgical techniques have made it possible to identify and preserve the cochlear nerve from its origin at the brain stem and along its course through the internal auditory canal in patients undergoing removal of small or medium-sized acoustic neuromas or other cerebellopontine angle (CPA) tumors. In a consecutive series of 100 patients with such tumors operated on between 1975 and 1981, an attempt was made to preserve the cochlear nerve in 23. The decision to attempt to preserve hearing was based on tumor size and the degree of associated hearing loss. In cases of unilateral acoustic neuroma, the criteria for attempted preservation of hearing were tumor size (2.5 cm or less), speech reception threshold (50 dB or less), and speech discrimination score (60% or greater). In patients with bilateral acoustic neuromas or tumors of other types, the size and hearing criteria were significantly broadened. All patients were operated on through a suboccipital approach. Hearing was preserved postoperatively in six (31.6%) of the 19 patients with unilateral acoustic neuromas, although the cochlear nerve was preserved in 16. Of the six patients with postoperative hearing, three retained excellent hearing, and the other three had only sound awareness and poor discrimination. Hearing was preserved in three cases with other CPA tumors, including an epidermoid cyst and small petrous meningiomas in the internal auditory canal. Of the two cases with bilateral tumors, hearing was preserved in one. Of the 23 patients in whom hearing preservation was attempted, nine (39.1%) had some postoperative hearing, which in six was equal to or better than the preoperative level. Thus, it is worthwhile to attempt hearing preservation in selected patients with CPA tumors.

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