Long-Term Hearing Outcomes From Gamma Knife Treatment for Vestibulocochlear Nerve Schwannomas in a Large, Tertiary Care, Academic Hospital

Abstract

Objective: Describe long-term hearing outcomes with audiologic data with modern stereotactic radiosurgery techniques for vestibular schwannoma tumors. Background: Since the mid-20th century, stereotactic radiosurgery has been an option for central nervous system tumors. Due to the non-invasive manner of treatment, this was extended to treatment for benign vestibular schwannomas without intracranial surgery. Modern advances have localized radiation and reduced dosage, but data are still lacking in the long-term hearing outcomes of this method of treatment. As one of the national leaders in this procedure, we present our full database of these outcomes over the full time period of our institutions utility of this modality. Methods: A retrospective review was performed of all patients undergoing stereotactic radiotherapy for vestibular schwannomas within the study period of 1998 to 2019 and their audiograms analyzed along with patient data. Laterality Gardner-Robertson hearing score changes were the primary outcome analyzed for each patient; and controls were placed to accommodate for patient demographic data. Results: Long-term, multi-year audiometric evaluation showed statistically significant loss of serviceable hearing and reduction in hearing ability with the use of stereotactic radiosurgery for treatment of vestibular schwannomas. Conclusions: Little long-term data exists on the audiometric outcomes related to stereotactic radiosurgery treatment for vestibular schwannomas. Our institution has performed more than 300 stereotactic radiosurgery treatments showing a continued reduction over time in serviceable hearing. Practitioners should advise patients undergoing treatment for vestibular schwannomas with this treatment of long-term results.

Hearing Outcomes from Gamma Knife Treatment for Intracanalicular Vestibular Schwannomas with Good Initial Hearing

“…After a median follow-up of 5 years, almost 35% remained in class A, and 56.1% kept serviceable hearing. Hearing deterioration has been reported to accelerate between years 5 and 10 [ 8 ]. Some teams argue to manage these tumors conservatively since hearing outcome is better with the “wait and scan” strategy [ 1 ] but others argue that the hearing continues to deteriorate regardless of tumor growth [ 3 ].…”

“…Reporting hearing preservation only focusing on PTA may not be representative of the patient’s ability to understand speech [ 20 ]. Other teams with lots of experience in GKS have not emphasized the importance of these technical GKS parameters [ 5 , 7 , 8 , 21 ].…”

“…The durability of hearing preservation should be reported as well because continued reduction over time in serviceable hearing after GKS is often reported [ 1 , 4 , 27 ], with an acceleration of the decrease between years 5 and 10 [ 8 ], whereas hearing preservation after microsurgery is thought to be more durable [ 5 ]. Moving from class A to class B is still beneficial for the patients because the patients with post-GKS serviceable hearing may benefit from a unilateral hearing aid on the tumor side, whereas CROS or BICROS are more indicated for patients with post-GKS classes C and D.…”

“…Hearing outcomes have been reported as more durable after surgery than after GKS [ 4 , 5 ] with variable hearing preservation rates. Some authors have reported good outcomes with speech discrimination over 50% [ 6 , 7 ]; others have observed poor long-term results with speech discrimination at 10 years under 3% [ 8 ]. In a recent systematic meta-analysis, hearing preservation was observed in 57% to 59% of the patients after follow-up at 47 months [ 9 ] and at least 5 years [ 2 ].…”

Hearing Preservation After Intervention in Vestibular Schwannoma

“…However, with serial observation and radiation, there is uncertainty in the duration of maintaining serviceable hearing. Long-term data are slowly accumulating regarding hearing outcomes with each management approach (6–10), but outcomes beyond 5 (11–18) and 10 (18,19) years remain limited. As VS diagnoses are made at earlier time points in the tumors' natural history, long-term HP data will aid in counseling patients presenting with serviceable hearing.…”