The Barrow Neurological Institute Experience with Stereotactic Radiosurgery for Vestibular Schwannomas: Single vs. Multiple Fraction and Hearing Outcomes

Randall W. Porter, MD1, Mark Syms, MD1, Peter Weisskopf, MD1

1Phoenix, AZ United States

Keywords: vestibular schwannoma, hearing function, radiosurgery, outcome, fractionated stereotactic radiotherapy

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     The treatment of vestibular schwannomas (VS) has evolved with stereotactic radiosurgery (SRS) playing an increasing role.
     Fractionated radiosurgery has been suggested as a treatment strategy to preserve hearing in patients with VS.
     We treated 386 patients with VS either single fraction or multiple fraction radiosurgery.
     VS were treated with SRS using Gamma Knife or CyberKnife, from 1997 through 2011. Gamma Knife patients were treated with single fraction radiosurgery (SFRS), most Cyberknife patients were treated with hypo-fractionated radiosurgery (HFRS).
     We excluded patients with less than six months of follow-up, those with NF2 and those without both pre- and post-treatment audiograms. The study sample consisted of 210 patients: 94 HFRS and 116 SFRS. Mean age was 55 years for HFRS and 62 years for SFRS (p =0.001). Mean tumor volume (cc) in HFRS was 2.78 , SFRS of 2.28 (p=0.222). At last follow-up, hearing was preserved in 38% of SFRS and 61% HFRS (p=0 .019). Hearing preservation rate was higher in those with AAO grade A prior to SRS; 52% of SFRS, 74% of HFRS subjects (p=0.161). Tumor volume had no impact on hearing preservation (p= 0.154). Resection-free tumor control was found in 97.7% of HFRS subjects and 98.4% of SFRS subjects. Cochlear dose did not appear to impact hearing outcomes in the hypo-fractionated group. Regression analysis found HFSR statistically significant in hearing preservation (p= 0.004, OR 4.426, 95% CI, 1.587-12.347).
     This is a retrospective study.
     HFRS appears to have superior outcomes compared with SFRS with respect to hearing outcomes when VS are treated with stereotactic radiosurgery.


Project Roles:

R. Porter (), M. Syms (), P. Weisskopf ()