The newly diagnosed vestibular schwannoma: radiosurgery, resection, or observation?

Abstract

<jats:sec> <jats:title>Object</jats:title> <jats:p>Management recommendations for patients with smaller-volume or newly diagnosed vestibular schwannomas (&lt; 4 cm<jats:sup>3</jats:sup>) need to be based on an understanding of the anticipated natural history of the tumor and the side effects it produces. The natural history can then be compared with the risks and benefits of therapeutic intervention using a minimally invasive strategy such as stereotactic radiosurgery (SRS).</jats:p></jats:sec> <jats:sec> <jats:title>Methods</jats:title> <jats:p>The authors reviewed the emerging literature stemming from recent recommendations to “wait and scan” (observation) and compared this strategy with published outcomes after early intervention using SRS or results from matched cohort studies of resection and SRS.</jats:p></jats:sec> <jats:sec> <jats:title>Results</jats:title> <jats:p>Various retrospective studies indicate that vestibular schwannomas grow at a rate of 0–3.9 mm per year and double in volume between 1.65 and 4.4 years. Stereotactic radiosurgery arrests growth in up to 98% of patients when studied at intervals of 10–15 years. Most patients who select “wait and scan” note gradually decreasing hearing function leading to the loss of useful hearing by 5 years. In contrast, current studies indicate that 3–5 years after Gamma Knife surgery, 61%–80% of patients maintain useful hearing (speech discrimination score &gt; 50%, pure tone average &lt; 50).</jats:p></jats:sec> <jats:sec> <jats:title>Conclusions</jats:title> <jats:p>Based on published data on both volume and hearing preservation for both strategies, the authors devised a management recommendation for patients with small vestibular schwannomas. When resection is not chosen by the patient, the authors believe that early SRS intervention, in contrast to observation, results in long-term tumor control and improved rates of hearing preservation.</jats:p></jats:sec>

Stereotactic radiosurgery for recurrent vestibular schwannoma after previous resection

“…The incidence of VS is estimated to be 1 per 100,000 individuals per year, and it accounts for approximately 8% of all intracranial tumors in adults. 3,14 These tumors are typically slow growing (0-3.9 mm per year), but without management, most VS tumors will grow within 3 years. 4,6,14,15,18,20 For many years, microsurgical resection remained the most commonly recommended treatment for patients with newly diagnosed unilateral VS. 3,20 Although surgical outcomes have improved over the last 30 years, resection of VS was frequently associated with impaired facial nerve function and loss of hearing.…”

“…3,14 These tumors are typically slow growing (0-3.9 mm per year), but without management, most VS tumors will grow within 3 years. 4,6,14,15,18,20 For many years, microsurgical resection remained the most commonly recommended treatment for patients with newly diagnosed unilateral VS. 3,20 Although surgical outcomes have improved over the last 30 years, resection of VS was frequently associated with impaired facial nerve function and loss of hearing. 7,13,20,22 The recurrence rate of VS has been shown to be 2.6%-11.0% after gross-total resection, and 20%-50% of VS tumors progress after subtotal resection.…”

Multisession stereotactic radiosurgery for large vestibular schwannomas

“…4,21,35,36 SRS is generally used to treat small-to medium-sized VSs but has also demonstrated satisfactory results with larger lesions as well. 20,30,31,[39][40][41]45 Nevertheless, the latter represent a challenge for both surgeons and radiosurgeons, because a direct correlation between tumor size and facial nerve damage does exist in the postoperative period. Furthermore, the current standard therapeutic dose (12-13 Gy) may be too high and not well tolerated by healthy surrounding nervous structures, with potential adverse radiation effects, without effecting rapid volume reduction.…”

Hearing subclassification may predict long-term auditory outcomes after radiosurgery for vestibular schwannoma patients with good hearing

“…Previous studies demonstrated that despite variations in methods and technologies, sustained tumor growth control was obtained in 90%-98% of patients. 11,13,22 Complications previously noted with microsurgical management have been virtually eliminated. 10 Despite the high tumor control rates, long-term serviceable hearing preservation rates vary from 60% to 90%, depending on the classification system used and the proportion of patients with normal pre-SRS hearing.…”