Increased preservation of functional hearing after gamma knife surgery for vestibular schwannoma

Abstract

Reducing the maximum dose to 20 Gy seems to be an effective treatment, which probably increases preservation of functional hearing without sacrificing the high tumor control rates achieved in radiosurgery. Postradiosurgery tumor swelling occurred in 25% of the cases and was not correlated with hearing deterioration.

Tumor-Volume Changes after Radiosurgery for Vestibular Schwannoma: Implications for Follow-Up MR Imaging Protocol

“…25 In more recent series, an incidence of 25%-62% has been reported, but the definition of transient swelling was not always clearly stated. 17,18,26,27 In our current series, we defined "transient swelling" as a tumor-volume decrease to a volume smaller than that in pretreatment, preceded by a tumor-volume increase. It was found in 11 (24.4%) patients.…”

Efficacy of Corticosteroids in Hearing Preservation after Radiosurgery for Vestibular Schwannoma: A Prospective Study

“…Although an association between transient volume expansion and cranial nerve (5th or 7th) dysfunction was reported in several studies, the correlation between transient volume expansion and hearing deterioration remains controversial [9,11,21] . Nagano et al [21] and van Eck and Horstmann [6] reported that transient volume expansion was observed in more than half of their patients within 1 year; however, this did not correlate significantly with hearing deterioration. In contrast, Wowra et al [9] reported that risk of hearing loss was significantly correlated with transient tumor swelling.…”

“…and seventh cranial nerve dysfunction, after radiosurgery for VS has been reported as being less than 5%, the hearing preservation rate is not satisfactory in most reports, ranging from 40 to 78% [1,[5][6][7] . Previously, we reported that the 5-year serviceable hearing preservation rate in VS patients with serviceable hearing was 46% [8] .…”

“…25% was considered stable. Because transient volume expansion has a tendency to develop within 1 year after radiosurgery and to decrease gradually over the period of 1 year without any additional treatments [6,9] , we analyzed tumor volume changes at 6 and 12 months, and compared the average volume change between these times with the initial tumor volume. Transient volume expansion was defined as an increase in tumor volume during the follow-up period of 1 25% of the initial tumor volume within 1 year after radiosurgery, and it gradually decreased during follow-up MRI scans.…”

Increasing dose gradient and uniformity in small fields using modulation: Theory and prototypes for cone-based stereotactic radiosurgery

“…This plan quality metric has been correlated to toxicities, for example, in radiosurgery for meningioma. 7 Additionally, the homogeneity of the dose distribution inside the target, as measured by the maximal point dose, 8 or as an integrated dose to a clinically relevant subvolume of the target, 9 has been correlated to toxicities after treatment for benign diseases such as vestibular schwanoma and meningioma with stereotactic radiosurgery. Given these two examples of clinical correlates to plan quality metrics, any technological development that allows either an increase in dose gradient, or an increase in dose homogeneity, may have a potential role in improving patient care in stereotactic radiosurgery.…”