Outcomes and Prognostic Factors in the Treatment of Intracanalicular Vestibular Schwannomas Using Gamma Knife Stereotactic Radiation.

BACKGROUND: No gold standard has been developed for the therapy of intracanalicular vestibular schwannomas (IVS). Options for treatment include a conservative approach, microsurgery, or radiosurgery. Although the efficacy of these treatment has been well-documented, little is known about the determinants of outcome in IVSs following radiosurgery. Therefore, we examined the results in relation to age, gender, tumor volume, distance to fundus, microcyst existence, and radiosensitivity in this group. In addition, we investigated possible predictors of facial nerve function and hearing preservation. METHODS: Ninety-four patients with unilateral IVS were included in the evaluation (52 women and 42 males). The patients were separated into younger and older age groups based on their median age (55 years). The median IVS volume was 138 mm3, microcysts were identified in 16 tumors, and 63 tumors were adjacent to the fundus. The data were analyzed using Statistica software package ver. 13.3. RESULTS: At final follow-up, a statistically significant decrease in tumor volume and no statistically significant decline in hearing were noted, but no differences between age groups were found. The sex had no effect on overall tumor growth control, facial nerve preservation, or hearing preservation. Localization of IVS close to the fundus and the presence of tumor microcysts had no effect on the control of tumor growth, preservation of hearing, and sparing of facial nerve following radiosurgery. Cochlear dose had no influence on hearing preservation. Higher tumor volume was associated with its pseudoprogression during early follow-up and a greater risk of hearing loss. CONCLUSIONS: Age, sex, tumor volume, proximity to the fundus, and the existence of a microcyst were not predictive of radiosensitivity nor preservation of facial nerve function and hearing, based on the findings. There was no effect of cochlear dose on hearing. Initial greater tumor volume was associated with an increased probability of tumor pseudoprogression.

Tumor control and hearing preservation after radiosurgery of intracanalicular vestibular schwannomas - systematic review.

Intracanalicular vestibular schwannomas (IVS) account for 8% of all vestibular schwannomas and their detection is still increasing due to high availability of magnetic resonance (MRI). Radiosurgery is one of several commonly acceptable methods of IVS treatment, but some risk may still exist with that treatment. The aim of this study is to analyze the clinical outcomes in tumor control and hearing preservation after radiosurgery of IVS. The retrospective analysis included 14 scientific papers available in the PubMed database. Assessment of tumor volume was performed based on gadolinium-enhanced T1-weighted scans. Hearing preservation was assessed using the Gardner-Robertson classification (GR class). Statistical analysis was performed using IBM SPSS Statistics 27. It was revealed that tumor growth control in IVS treated with radiosurgery was higher than in the wait-and-see strategy. The hearing preservation was similar in patients after wait and see and the surgical group. Radiosurgery was associated with low risk of facial nerve dysfunction.