Radiosurgery Induced Ototoxicity in Patients Treated for a Vestibular Schwannoma

The investigators aim to study the impact of stereotactic radiosurgery, for the treatment of vestibular Schwannoma, on the cochlear, vestibular, gustatory, and facial nerve functions and compare it with a conservatively treated group. The predictive value of radiological tumor characteristics on hearing preservation and vestibular function will be also evaluated.

Additionally, the investigators will invite patients with vestibular Schwannoma to fill out questionnaires to assess their quality of life.

The study will have a retrospective part and a prospective part. The retrospective study will be based on a series of consecutive patients with vestibular Schwannoma (VS) treated either with stereotactic radiosurgery (SRS) or followed up radiologically between 2014 and 2021 in our institution. The following data will be retrieved from the hospital archiving system and will be subsequently analyzed: demographics, patient characteristics, details regarding SRS planning, clinical baseline and follow-up data, hearing, vestibular and taste function assessment initially and during follow-up, presence of additional symptoms (tinnitus, hemifacial spasm, trigeminal neuralgia), radiosurgery parameters and MRI characteristics of tumors. The following parameters will be retrospectively measured on MRI images by an experienced radiologist in each VS: tumor volume, ratio of brain stem compression, tumor shape and distance to the fundus of the internal auditory canal, length of the tumor in the internal auditory canal, and signal intensity in the cochlea and vestibule. The MRI textural features extracted from whole tumor segmentation of VSs will be calculated and analyzed with MatLab®. They include shape features, first order and second order textural features.

The prospective study part aims to obtain more precise and predefined follow-up data from patients treated either with SRS or followed up conservatively from now on. Our institution's multidisciplinary skull base tumor board will be responsible for treatment decisions independently of the study. It will be a single-center observational cohort study investigating the respective impact of tumor morphology and SRS on the inner ear, the facial nerve function, and the quality of life of these patients. As data collection will be done prospectively, MRI acquisition parameters will be standardized, as well as quantification of hearing, vestibular, facial nerve function, and quality of life. Additionally, the investigators will analyze the characteristics of the tumors and several parameters of the irradiation protocol to develop predictive models for ototoxicity.

Eligibility Criteria:
Inclusion Criteria:

* Aged 18 years or above
* Patients with unilateral VS treated either with SRS or MRI-based observation strategy, as proposed by the institution's skull base tumor board independently of the study
* Patients willing to take part in the study and give their informed consent

Exclusion Criteria:

* Previous surgical or radiation therapy for VS (including SRS)
* Patients diagnosed with neurofibromatosis type II
* Preexisting profound hearing loss, with a pure tone average (PTA) \>90 and word recognition score (WRS) \<10%, upon initial assessment
* Previous middle ear surgery of the affected ear
* Concurrent treatment with other experimental drugs