To the Editor:
Breivik et al1 make a well-documented and coherent case for Gamma Knife radiosurgery rather than conservative management in the treatment of extracanalicular vestibular schwannomas (VSs). According to their protocol, VSs <20 mm underwent conservative management, VSs >25 mm underwent microsurgery, and intermediate/smaller but growing lesions were treated either with Gamma Knife radiosurgery or microsurgery. Follow-up magnetic resonance imaging scans and clinical examinations were scheduled at 6 months and 1, 2, and 5 years.
The question arises: What was the protocol for conservatively managed patients with VSs <20 mm with stable magnetic resonance imaging volumes on serial imaging but decreased hearing?
An unaddressed issue with the “wait and scan” protocol has unintended professional and medicolegal consequences. It is entirely possible that a VS <20 mm in diameter in a neurologically unchanged patient undergoing conservative management may have a stable magnetic resonance imaging appearance at 6 months, 1 year, and 2 years but may grow to >25 mm in the 3 years until the 5-year scan. At that point, Gamma Knife radiosurgery may no longer be an option. This may adversely affect patients who clearly want to avoid microsurgery (n = 26 in this series) for, perhaps, quality-of-life reasons or because of medical comorbidities and advancing age.2 The reason is that the growth rate of VSs is erratic, may occur in the presence of unchanged hearing, and is therefore difficult to predict.3 It is prudent to inform patients of such a possibility, and not just that of progressive hearing loss, while discussing their treatment options.4-6
The author has no personal financial or institutional interest in any of the drugs, materials, or devices described in this article.
1. Breivik CN, Nilsen RM, Myrseth E, et al.. Conservative management or gamma knife radiosurgery for vestibular schwannoma: tumor growth, symptoms, and quality of life. Neurosurgery. 2013;73(1):48–56.
2. Pollock BE, Driscoll CL, Foote RL, et al.. Patient outcomes after vestibular schwannoma management: a prospective comparison of microsurgical resection and stereotactic radiosurgery. Neurosurgery. 2006;59(1):77–85.
3. Bakkouri WE, Kania RE, Guichard JP, Lot G, Herman P, Huy PT. Conservative management of 386 cases of unilateral vestibular schwannoma: tumor growth and consequences for treatment. J Neurosurg. 2009;110(4):662–669.
4. Wackym PA. Stereotactic radiosurgery, microsurgery, and expectant management of acoustic neuroma: basis for informed consent. Otolaryngol Clin North Am. 2005;38(4):653–670.
5. Sharma MS, Singh R, Kale SS, Agrawal D, Sharma BS, Mahapatra AK. Tumor control and hearing preservation after gamma knife radiosurgery for vestibular schwannomas in neurofibromatosis type 2. J Neurooncol. 2010;98(2):265–270.
6. Flickinger JC. Observation versus early stereotactic radiotherapy of acoustic neuroma: what are you waiting for? Int J Radiat Oncol Biol Phys. 1999;44(3):481–482.