Fractionated and Single-Fraction Radiosurgery among Vestibular Schwannoma Patients with Serviceable Hearing: Comparison of Treatment and Hearing Outcomes

Introduction: Vestibular schwannoma (VS), a benign tumor of cranial nerve VIII, is the most common cerebellopontine angle tumor. Along with the hearing loss patients present with balance difficulty, tinnitus, and facial nerve dysfunction. Multiple treatment options are available including microsurgical resection, stereotactic radiosurgery (SRS), and observation. SRS is considered as the hearing preserving option and preferred for the patients presenting with sizeable lesions and serviceable hearing. SRS can be given in single-fraction or multiple-doses (fractionated).

Objectives: To compare the tumor control, treatment outcomes, and hearing outcomes among vestibular schwannoma (VS) patients undergoing single-fraction SRS (single-SRS) or fractionated SRS (FSRS) who presented with serviceable hearing.

Methods: Adult patients who underwent SRS at our institute and had serviceable hearing were enrolled. A serviceable hearing was defined as the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) class A and B. Patients with Neurofibromatosis type 2 and less than 2-year of follow-up were excluded. Data for the demographic details, clinical presentation, treatment details, and post-treatment follow-up were collected retrospectively. Mean (standard deviation) was used for continuous variables and proportions were used for categorical variables. t-test and chi-square were used for the analysis of continuous and categorical variables, respectively.

Results: In total, 84 patients were enrolled. 42 patients underwent single-SRS and 42 had FSRS. All but one did not have any prior SRS. Patients who underwent single-SRS were older (p = 0.005). In the FSRS group, 32 (76.2%) patients had pretreatment AAO-HNS class A, whereas in the single-SRS group 23 (54.76%) had class A (p = 0.1). Pretreatment pure tone average (PTA) was higher in the single-SRS group, p = 0.02. In both groups, House-Brackmann grade I was the most common. KOOS grade distribution was similar between the two groups (p > 0.05). The mean target volume in FSRS and single SRS were 1.94 cc (2.07) and 1.77 cc (2.51), respectively, p = 0.73. The mean treatment dose was higher in the FSRS group 18.52 Gy (1.42) as compared with single SRS 12.58 Gy (0.77); p < 0.01. The mean cochlear dose was found to be similar in FSRS (7.18 Gy) and single SRS (6.24 Gy), p = 0.2. Tumor control was better in single SRS (97.5%) when compared with FSRS (83.33%), p = 0.03. The radiology follow-up was greater for the single SRS group, p = 0.003. However, a higher proportion of patients were able to preserve hearing in the fractionated group (66.67%) as compared with the single-fraction group (40.48%), p = 0.018. The hearing follow-up was similar between the two groups, p = 0.79. The mean duration of clinical follow-up was 68.26 (38.61) months for FSRS and 89 (58.52) months for single SRS, p = 0.06.

Conclusion: We report better hearing preservation with FSRS as compared with single SRS. Our data indicate that even the treatment dose was higher in the fractionated group; the mean cochlear dose was similar in both groups. However, we found better tumor control with the single-fraction SRS as compared with fractionated SRS. It is important to compare the outcomes of both types of radiosurgery for vestibular schwannoma patients presenting with serviceable hearing.

Publication History

Article published online:
12 February 2021