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BackgroundThe management of solely intracanalicular acoustic neurinoma (iAN) includes observation, microsurgical resection and radiation therapy. Treatment goals are long-term tumor control, hearing preservation and concurrently low side-effects. Stereotactic radiosurgery (SRS) has evolved as an alternative first-line treatment for small AN. Here we report about the long-term follow-up of a unique cohort of patients with iAN after LINAC or Cyberknife® based SRS.MethodsIn this single center retrospective analysis, we included all patients with iAN who underwent single session LINAC or Cyberknife® based SRS between 1993 and 2015, and who had a minimum follow-up period of six weeks. Patient data were analyzed in terms of radiological and clinical tumor control (no further treatment necessary), subjective preservation of serviceable hearing, objective change in pure tone averages (PTA), and adverse events rated by the Common Terminology Criteria for Adverse Events (CTCAE; v4.03).ResultsForty-nine patients (f/m = 21/28, median age 54 ± 12, range 20–77 years) were identified. Mean tumor volumes were 0.24 ± 0.12 cm3 (range, 0.1–0.68 cm3), the mean marginal dose was 12.6 ± 0.6 Gy (range, 11.0–14.0 Gy) and the prescription isodose was 75 ± 7.4% (range, 47–86%). Mean follow-up time was 65 months (range, 4–239 months).Radiological tumor control was 100% during further follow-up. 17 (35%) out of 49 patients had lost serviceable hearing prior to SRS. Those with preserved serviceable hearing remained stable in 78% (n = 25/32) at the last follow-up (LFU). The median PTA (n = 16) increased from 25.6 dB prior to SRS to 43.8 dB at LFU.Mild adverse events were observed temporarily in two patients (4%): one with CTCAE grade 1 facial nerve disorder after 3 months, resolving three months later, and one with CTCAE grade 2 facial muscle weakness resolving after 12 months. Three patients described permanent mild symptoms CTCAE grade 1 without limiting daily life (facial weakness n = 1, vertigo n = 2).ConclusionSRS for iAN shows long-term reliable tumor control with a high rate of hearing preservation without considerable permanent side effects, and can be proposed as a safe and effective treatment alternative to microsurgical resection.

Stereotactic radiosurgery (SRS) has evolved as widely accepted treatment option for small-sized (Koos i up to ii) vestibular schwannoma (VS). for larger tumors (prevalent Koos Vi), microsurgery or combined treatment strategies are mostly recommended. However, in patients not suited for microsurgery, SRS might also be an alternative to balance tumor control, hearing preservation and adverse effects. The purpose of this analysis was to evaluate the efficacy and toxicity of SRS for VS with regard to different Koos grades. All patients with untreated VS who received SRS at our center were included. outcome analysis included tumor control, preservation of serviceable hearing based on median pure tone averages (ptA), and procedure-related adverse events rated by the common terminology criteria for Adverse Events (CTCAE; v4.03) classification. In total, 258 patients (median age 58 years, range 21-84) were identified with a mean follow-up of 52 months (range 3-228 months). Mean tumor volume was 1.8 ml (range 0.1-18.5). The mean marginal dose was 12.3 Gy ± 0.6 (range 11-13.5). The cohort was divided into two groups: A (Koos grades i and ii, n = 186) and B (Koos grades III and IV, n = 72). The actuarial tumor control rate was 98% after 2 years and 90% after 5 and 10 years. Koos grading did not show a significant impact on tumor control (p = 0.632) or hearing preservation (p = 0.231). After SRS, 18 patients (7%) had new transient or permanent symptoms classified by the CTCAE. The actuarial rate of ctcAe-free survival was not related to Koos grading (p = 0.093). Based on this selected population of Koos grade iii and iV VS without or with only mild symptoms from brainstem compression, SRS can be recommended as the primary therapy with the advantage of low morbidity and satisfactory tumor control. The overall hearing preservation rate and toxicity of SRS was influenced by age and cannot be predicted by tumor volume or Koos grading alone.

Background New-onset vestibular disorders (VD), such as dizziness and imbalance, are common side effects after stereotactic radiosurgery (SRS) for vestibular schwannomas (VS). Although these symptoms can severely affect the daily life of VS patients, there are limited data available providing prognostic information on the risk of developing VD after SRS. Material and Methods We included patients who received Cyberknife® SRS for newly diagnosed unilateral VS between 2012 and 2015. The incidence of vestibular disorders before and after treatment was recorded and correlated with tumor, patient, and treatment characteristics. Results We identified 71 patients with a median age of 58 years (range: 21-82) and a median follow-up of 66 months (range: 3-105). Tumor volume before treatment was 1.5 cm3 ± 1.4 (range: 0.1-8.6). A mean marginal dose of 12.9 Gy ± 0.3 (range: 12-14) was administered, and all studied patients remained free of tumor recurrence. Forty-one (58%) of the patients had VD prior to SRS. Of the remaining 30 patients who did not have VD before treatment, 16 (53%) developed new VD (vertigo, n=4; balance disorders, n=8; mixture of VD, n=4). The median time to onset of symptoms was 6 months (range: 2-36). In most patients (n=11, 69%), the new symptoms completely resolved within a median time of 21 months (range: 1-63). In multivariate analysis, neither tumor volume (p=0.7), age (p=0.06), nor radiation dose (p=0.16) were significantly associated with the occurrence of VD. Conclusion In this cohort, about half of the patients develop new onset of transient VD after SRS. The incidence of VD after SRS was found to be independent from usual tumor-, patient- and treatment-related factors. Therefore, a detailed analysis of the dose exposure to the structures of the vestibular apparatus is recommended.