BACKGROUND: Vestibular schwannomas (VSs) are rare, benign intracranial tumours that have prompted clinical practice guideline (CPG) creation given their complex management. Our aim was to utilize the Appraisal of Guidelines for Research and Evaluation (AGREE II) instrument to assess if such CPGs on the management of VSs with radiosurgery and radiotherapy are of acceptable quality.
METHODS: Relevant CPGs were identified following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocols. Experienced reviewers then extracted general CPG properties and rated their quality via the AGREE II instrument. Intraclass correlation coefficients (ICCs) were quantified to assess interrater reliability.
RESULTS: Nine CPGs on the management of VSs with radiosurgery and radiotherapy were identified. All CPGs were created in the past six years and developed recommendations based on literature review and expert consensus. One guideline was deemed as high quality with seven others being moderate and one being low in quality. The clarity of the presentation domain had the highest mean scaled domain score of 96.0%. The domains of stakeholder involvement and applicability had the lowest means of 49.2% and 47.2%, respectively. ICCs were either good or excellent across all domains.
CONCLUSIONS: Current CPGs on the management of VSs with radiosurgery and radiotherapy are of acceptable quality but would greatly benefit from improvements in applicability, stakeholder involvement, editorial independence and rigour of development. We recommend CPG authors reference the European Association of Neuro-Oncology (EANO) guideline as a developmental framework with the Congress of Neurological Surgeons/American Association of Neurological Surgeons (CNS/AANS) CPG being a valid alternative.

BACKGROUND: Vestibular schwannoma (VS) is the most common tumour of the cerebellopontine angle. The greater accessibility to radiological tests has increased its diagnosis. Taking into account the characteristics of the tumour, the symptoms and the age of the patient, three therapeutic strategies have been proposed: observation, surgery or radiotherapy. Choosing the most appropriate for each patient is a frequent source of controversy.
METHODS: This paper includes an exhaustive literature review of issues related to VS that can serve as a clinical guide in the management of patients with these lesions. The presentation has been oriented in the form of questions that the clinician usually asks himself and the answers have been written and/or reviewed by a panel of national and international experts consulted by the Otology Commission of the SEORL-CCC.
RESULTS: A list has been compiled containing the 13 most controversial thematic blocks on the management of VS in the form of 50 questions, and answers to all of them have been sought through a systematic literature review (articles published on PubMed and Cochrane Library between 1992 and 2023 related to each thematic area). Thirty-three experts, led by the Otology Committee of SEORL-CCC, have analyzed and discussed all the answers. In Annex 1, 14 additional questions divided into 4 thematic areas can be found.
CONCLUSIONS: This clinical practice guideline on the management of VS offers agreed answers to the most common questions that are asked about this tumour. The absence of sufficient prospective studies means that the levels of evidence on the subject are generally medium or low. This fact increases the interest of this type of clinical practice guidelines prepared by experts.

Accurate Magnetic Resonance Imaging (MRI) simulation is fundamental for high-precision stereotactic radiosurgery and fractionated stereotactic radiotherapy, collectively referred to as stereotactic radiotherapy (SRT), to deliver doses of high biological effectiveness to well-defined cranial targets. Multiple MRI hardware related factors as well as scanner configuration and sequence protocol parameters can affect the imaging accuracy and need to be optimized for the special purpose of radiotherapy treatment planning. MRI simulation for SRT is possible for different organizational environments including patient referral for imaging as well as dedicated MRI simulation in the radiotherapy department but require radiotherapy-optimized MRI protocols and defined quality standards to ensure geometrically accurate images that form an impeccable foundation for treatment planning. For this guideline, an interdisciplinary panel including experts from the working group for radiosurgery and stereotactic radiotherapy of the German Society for Radiation Oncology (DEGRO), the working group for physics and technology in stereotactic radiotherapy of the German Society for Medical Physics (DGMP), the German Society of Neurosurgery (DGNC), the German Society of Neuroradiology (DGNR) and the German Chapter of the International Society for Magnetic Resonance in Medicine (DS-ISMRM) have defined minimum MRI quality requirements as well as advanced MRI simulation options for cranial SRT.

The choice of an appropriate strategy for intracanalicular vestibular schwannoma (ICVS) is still debated. We conducted a systematic review and meta-analysis with the aim to compare treatment outcomes amongst management strategies (conservative surveillance (CS), microsurgical resection (MR), or stereotactic radiosurgery (SRS)) aiming to inform guideline recommendations on behalf of the International Stereotactic Radiosurgery Society (ISRS).
Using PRISMA guidelines, we reviewed manuscripts published between January 1990 and October 2021 referenced in PubMed or Embase. Inclusion criteria were peer-reviewed clinical studies or case series reporting a cohort of ICVS managed with CS, MR, or SRS. Primary outcome measures included tumor control, the need for additional treatment, hearing outcomes, and posttreatment neurological deficits. These were pooled using meta-analytical techniques and compared using meta-regression with random effect.
Forty studies were included (2371 patients). The weighted pooled estimates for tumor control were 96% and 65% in SRS and CS series, respectively (P < .001). Need for further treatment was reported in 1%, 2%, and 25% for SRS, MR, and CS, respectively (P = .001). Hearing preservation was reported in 67%, 68%, and 55% for SRS, MR, and CS, respectively (P = .21). Persistent facial nerve deficit was reported in 0.1% and 10% for SRS and MR series, respectively (P = .01).
SRS is a noninvasive treatment with at least equivalent rates of tumor control and hearing preservation as compared to MR, with the caveat of better facial nerve preservation. As compared to CS, upfront SRS is an effective treatment in achieving tumor control with similar rates of hearing preservation.

OBJECTIVE: To perform a systematic review of literature specific to single-fraction stereotactic radiosurgery (SRS) for large vestibular schwannomas (VS), maximum diameter ≥ 2.5 cm and/or classified as Koos Grade IV, and to present consensus recommendations on behalf of the International Stereotactic Radiosurgery Society (ISRS).
METHODS: The Medline and Embase databases were used to apply the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) approach. We considered eligible prospective and retrospective studies, written in the English language, reporting treatment outcomes for large VS; SRS for large post-operative tumors were analyzed in aggregate and separately.
RESULTS: 19 of the 229 studies initially identified met the final inclusion criteria. Overall crude rate of tumor control was 89% (93.7% with no prior surgery vs 87.7% with prior surgery). Rates of salvage microsurgical resection, need for shunt, and additional SRS in all series versus those with no prior surgery were 9.6% vs 3.3%, 4.7% vs 6.4% and 1% vs 0.9%, respectively. Rates of facial palsy and hearing preservation in all series versus those with no prior surgery were 1.3% vs 3.4% and 34.2% vs 40.4%, respectively.
CONCLUSIONS: Upfront SRS resulted in high rates of tumor control with acceptable rates of facial palsy and hearing preservation as compared to the results in those series including patients with prior surgery (level C evidence). Therefore, although large VS are considered classic indication for microsurgical resection, upfront SRS can be considered in selected patients and we recommend a prescribed marginal dose from 11 to 13 Gy (level C evidence).

Objective  An operative workflow systematically compartmentalizes operations into hierarchal components of phases, steps, instrument, technique errors, and event errors. Operative workflow provides a foundation for education, training, and understanding of surgical variation. In this Part 1, we present a codified operative workflow for the retrosigmoid approach to vestibular schwannoma resection. Methods  A mixed-method consensus process of literature review, small-group Delphi\'s consensus, followed by a national Delphi\'s consensus, was performed in collaboration with British Skull Base Society (BSBS). Each Delphi\'s round was repeated until data saturation and over 90% consensus was reached. Results  Eighteen consultant skull base surgeons (10 neurosurgeons and 8 ENT [ear, nose, and throat]) with median 17.9 years of experience (interquartile range: 17.5 years) of independent practice participated. There was a 100% response rate across both Delphi\'s rounds. The operative workflow for the retrosigmoid approach contained three phases and 40 unique steps as follows: phase 1, approach and exposure; phase 2, tumor debulking and excision; phase 3, closure. For the retrosigmoid approach, technique, and event error for each operative step was also described. Conclusion  We present Part 1 of a national, multicenter, consensus-derived, codified operative workflow for the retrosigmoid approach to vestibular schwannomas that encompasses phases, steps, instruments, technique errors, and event errors. The codified retrosigmoid approach presented in this manuscript can serve as foundational research for future work, such as operative workflow analysis or neurosurgical simulation and education.

Objective  An operative workflow systematically compartmentalizes operations into hierarchal components of phases, steps, instrument, technique errors, and event errors. Operative workflow provides a foundation for education, training, and understanding of surgical variation. In this Part 2, we present a codified operative workflow for the translabyrinthine approach to vestibular schwannoma resection. Methods  A mixed-method consensus process of literature review, small-group Delphi\'s consensus, followed by a national Delphi\'s consensus was performed in collaboration with British Skull Base Society (BSBS). Each Delphi\'s round was repeated until data saturation and over 90% consensus was reached. Results  Seventeen consultant skull base surgeons (nine neurosurgeons and eight ENT [ear, nose, and throat]) with median of 13.9 years of experience (interquartile range: 18.1 years) of independent practice participated. There was a 100% response rate across both the Delphi rounds. The translabyrinthine approach had the following five phases and 57 unique steps: Phase 1, approach and exposure; Phase 2, mastoidectomy; Phase 3, internal auditory canal and dural opening; Phase 4, tumor debulking and excision; and Phase 5, closure. Conclusion  We present Part 2 of a national, multicenter, consensus-derived, codified operative workflow for the translabyrinthine approach to vestibular schwannomas. The five phases contain the operative, steps, instruments, technique errors, and event errors. The codified translabyrinthine approach presented in this manuscript can serve as foundational research for future work, such as the application of artificial intelligence to vestibular schwannoma resection and comparative surgical research.

The level of evidence to provide treatment recommendations for vestibular schwannoma is low compared with other intracranial neoplasms. Therefore, the vestibular schwannoma task force of the European Association of Neuro-Oncology assessed the data available in the literature and composed a set of recommendations for health care professionals. The radiological diagnosis of vestibular schwannoma is made by magnetic resonance imaging. Histological verification of the diagnosis is not always required. Current treatment options include observation, surgical resection, fractionated radiotherapy, and radiosurgery. The choice of treatment depends on clinical presentation, tumor size, and expertise of the treating center. In small tumors, observation has to be weighed against radiosurgery, in large tumors surgical decompression is mandatory, potentially followed by fractionated radiotherapy or radiosurgery. Except for bevacizumab in neurofibromatosis type 2, there is no role for pharmacotherapy.

What is the expected diagnostic yield for vestibular schwannomas when using a magnetic resonance imaging (MRI) to evaluate patients with previously published definitions of asymmetric sensorineural hearing loss?
These recommendations apply to adults with an asymmetric sensorineural hearing loss on audiometric testing.
Level 3: On the basis of an audiogram, it is recommended that MRI screening on patients with ≥10 decibels (dB) of interaural difference at 2 or more contiguous frequencies or ≥15 dB at 1 frequency be pursued to minimize the incidence of undiagnosed vestibular schwannomas. However, selectively screening patients with ≥15 dB of interaural difference at 3000 Hz alone may minimize the incidence of MRIs performed that do not diagnose a vestibular schwannoma.
What is the expected diagnostic yield for vestibular schwannomas when using an MRI to evaluate patients with asymmetric tinnitus, as defined as either purely unilateral tinnitus or bilateral tinnitus with subjective asymmetry?
These recommendations apply to adults with subjective complaints of asymmetric tinnitus.
Level 3: It is recommended that MRI be used to evaluate patients with asymmetric tinnitus. However, this practice is low yielding in terms of vestibular schwannoma diagnosis (<1%).
What is the expected diagnostic yield for vestibular schwannomas when using an MRI to evaluate patients with a sudden sensorineural hearing loss?
These recommendations apply to adults with a verified sudden sensorineural hearing loss on an audiogram.
Level 3: It is recommended that MRI be used to evaluate patients with a sudden sensorineural hearing loss. However, this practice is low yielding in terms of vestibular schwannoma diagnosis (<3%).  The full guideline can be found at: https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_2.

What sequences should be obtained on magnetic resonance imaging (MRI) to evaluate vestibular schwannomas before and after surgery?
Adults with vestibular schwannomas.
Initial Preoperative Evaluation Level 3: Imaging used to detect vestibular schwannomas should use high-resolution T2-weighted and contrast-enhanced T1-weighted MRI. Level 3: Standard T1, T2, fluid attenuated inversion recovery, and diffusion weighted imaging MR sequences obtained in axial, coronal, and sagittal plane may be used for detection of vestibular schwannomas. Preoperative Surveillance Level 3: Preoperative surveillance for growth of a vestibular schwannoma should be followed with either contrast-enhanced 3-dimensional (3-D) T1 magnetization prepared rapid acquisition gradient echo (MPRAGE) or high-resolution T2 (including constructive interference in steady state [CISS] or fast imaging employing steady-state acquisition [FIESTA] sequences) MRI. Postoperative Evaluation Level 2: Postoperative evaluation should be performed with postcontrast 3-D T1 MPRAGE, with nodular enhancement considered suspicious for recurrence.
Is there a role for advanced imaging for facial nerve detection preoperatively (eg, CISS/FIESTA or diffusion tensor imaging)?
Adults with proven or suspected vestibular schwannomas by imaging.
Level 3: T2-weighted MRI may be used to augment visualization of the facial nerve course as part of preoperative evaluation.
What is the expected growth rate of vestibular schwannomas on MRI, and how often should they be imaged if a \"watch and wait\" philosophy is pursued?
Adults with suspected vestibular schwannomas by imaging.
Level 3: MRIs should be obtained annually for 5 yr, with interval lengthening thereafter with tumor stability.
Do cystic vestibular schwannomas behave differently than their solid counterparts?
Adults with vestibular schwannomas with cystic components.
Level 3: Adults with cystic vestibular schwannomas should be counseled that their tumors may more often be associated with rapid growth, lower rates of complete resection, and facial nerve outcomes that may be inferior in the immediate postoperative period but similar to noncystic schwannomas over time.
Should the extent of lateral internal auditory canal involvement be considered by treating physicians?
Adult patients with vestibular schwannomas.
Level 3: The degree of lateral internal auditory canal involvement by tumor adversely affects facial nerve and hearing outcomes and should be emphasized when interpreting imaging for preoperative planning.
How should patients with neurofibromatosis type 2 (NF2) and vestibular schwannoma be imaged and over what follow-up period?
Adult patients with NF2 and vestibular schwannomas.
Level 3: In general, vestibular schwannomas associated with NF2 should be imaged (similar to sporadic schwannomas) with the following caveats: 1. More frequent imaging may be adopted in NF2 patients because of a more variable growth rate for vestibular schwannomas, and annual imaging may ensue once the growth rate is established. 2. In NF2 patients with bilateral vestibular schwannomas, growth rate of a vestibular schwannoma may increase after resection of the contralateral tumor, and therefore, more frequent imaging may be indicated, based on the nonoperated tumor\'s historical rate of growth. 3. Careful consideration should be given to whether contrast is necessary in follow-up studies or if high-resolution T2 (including CISS or FIESTA-type sequences) MRI may adequately characterize changes in lesion size instead.
How long should vestibular schwannomas be imaged after surgery, including after gross-total, near-total, and subtotal resection?
Adult patients with vestibular schwannomas followed after surgery.
Level 3: For patients receiving gross total resection, a postoperative MRI may be considered to document the surgical impression and may occur as late as 1 yr after surgery. For patients not receiving gross total resection, more frequent surveillance scans are suggested; annual MRI scans may be reasonable for 5 yr. Imaging follow-up should be adjusted accordingly for continued surveillance if any change in nodular enhancement is demonstrated.  The full guideline can be found at https://www.cns.org/guidelines/guidelines-management-patients-vestibular-schwannoma/chapter_5.