CyberKnife Radiosurgery for Vestibular Schwannoma

Abstract

Objective: The CyberKnife is newly developed equipment for radiosurgery and fractionated radiosurgery. The authors report on their experience using the CyberKnife in 38 patients with vestibular schwannoma who were treated between 1998 to 2002.

Methods: During this period, 38 patients with vestibular schwannoma were treated using CyberKnife fractionated radiosurgery. Before undergoing fractionated radiosurgery, 14 patients had Gardner Robertson classes I or II hearing (the serviceable hearing group), and 24 patients had classes III to V hearing (the non-serviceable hearing group). The treatment volumes of these two groups were 0.5 to 24.0 cm³ (mean 4.7 cm³), and 0.5 to 41.6 cm³ (mean 8.2 cm³). Target irradiation was administered in 1 - 3 fractions (mean 2.5 fractions). The total marginal radiation doses were 15.0 to 20.5 Gy (mean 17.0 Gy), and 11.9 to 20.1 Gy (mean 16.9 Gy), respectively.

Results: After a mean follow-up period of 31.9 months (range 12 to 59 months, median 27 months), 94 % of the tumors were controlled. Only one patient in the group with non-serviceable hearing underwent additional surgical resection for a presumed increase in tumor size. The hearing preservation rate was 93 %. Facial weakness did not develop in any of the patients in the serviceable hearing group. New trigeminal symptoms did not develop in any patients in either group.

Conclusion: Although a longer and more extensive follow-up is needed, CyberKnife fractionated radiosurgery is considered to be safe and effective, even in patients with large tumors.

Key words

Acoustic neuroma - CyberKnife - fractionated radiotherapy - vestibular schwannoma

References

• 1 Flickinger J C, Kondziolka D, Niranjan A, Lunsford L D. Results of acoustic neuroma radiosurgery: an analysis of 5 year's experience using current methods.  J Neurosurg. 2001;  94 1-6
• 2 Kondziolka D, Lunsford L D, McLaughlin M R, Flickinger J C. Long-term outcomes after radiosurgery for acoustic neuromas.  N Engl J Med. 1998;  339 1426-1433
• 3 Petit J H, Hudes R S, Chen T T, Eisenberg H M, Simard J M, Chin L S. Reduced-dose radiosurgery for vestibular schwannomas.  Neurosurgery. 2001;  49 1299-1306
• 4 Adler Jr J R, Chang S O, Murphy M J, Doty J, Geis P, Hancock S L. The Cyberknife: a frameless robotic system for radiosurgery.  Stereotact Funct Neurosurg. 1997;  69 124-128
• 5 Chang S O, Murphy M, Geis P, Martin D P, Hancock S L, Doty J R, Adler Jr J R. Clinical experience with image-guided robotic radiosurgery (the Cyberknife) in the treatment of brain and spinal cord tumors.  Neurol Med Chir (Tokyo). 1998;  38 780-783
• 6 Yu C, Jozsef G, Apuzzo M L, Petrovich Z. Dosimetric comparison of CyberKnife with other radiosurgical modalities for an ellipsoidal target.  Neurosurgery. 2003;  53 1155-1162
• 7 Yu C, Jozsef G, Apuzzo M L, Petrovich Z. Measurements of the relative output factors for CyberKnife collimators.  Neurosurgery. 2004/2003;  54/53 157-161/1155 - 1162
• 8 Fowler J F. The linear-quadratic formula and progress in fractionated radiotherapy.  Br J Radiol. 1989;  62 679-694
• 9 Gardner G, Robertson J H. Hearing preservation in unilateral acoustic neuroma surgery.  Ann Otol Rhinol Laryngol. 1988;  97 55-66
• 10 House J W, Brackmann D E. Facial nerve grading system.  Otolaryngol Head Neck Surg. 1985;  93 146-147
• 11 Flickinger J C, Kondziolka D, Lunsford L D. Dose and diameter relationships for facial, trigeminal, and acoustic neuropathies following acoustic neuroma radiosurgery.  Radiother Oncol. 1996;  41 215-219
• 12 Foote R L, Coffey R J, Swanson J W, Harner S G, Beatty C W, Kline R W, Stevens L N, Hu T C. Stereotactic radiosurgery using the gamma knife for acoustic neuromas.  Int J Radiat Oncol Biol Phys. 1995;  32 1153-1160
• 13 Mendenhall W M, Friedman W A, Bova F J. Linear accelerator-based stereotactic radiosurgery for acoustic schwannomas.  Int J Radiat Oncol Biol Phys. 1994;  28 803-810
• 14 Flickinger J C, Lunsford L D, Coffey R J, Linskey M E, Bissonette D J, Maitz A H, Kondziolka D. Radiosurgery of acoustic neurinomas.  Cancer. 1991;  67 345-353
• 15 Ito K, Shin M, Matsuzaki M, Sugasawa K, Sasaki T. Risk factors for neurological complications after acoustic neurinoma radiosurgery: refinement from further experiences.  Int J Radiat Oncol Biol Phys. 2000;  48 75-80
• 16 Miller R C, Foote R L, Coffey R J, Sargent O J, Gorman D A, Schomberg P J, Kline R W. Decrease in cranial nerve complications after radiosurgery for acoustic neuromas: a prospective study of dose and volume.  Int J Radiat Oncol Biol Phys. 1999;  43 305-311
• 17 Foote K D, Friedman W A, Buatti J M, Meeks S L, Bova F J, Kubilis P S. Analysis of risk factors associated with radiosurgery for vestibular schwannoma.  J Neurosurg. 2001;  95 440-449
• 18 Fuss M, Debus J, Lohr F, Huber P, Rhein B, Engenhart-Cabillic R, Wannenmacher M. Conventionally fractionated stereotactic radiotherapy (FSRT) for acoustic neuromas.  Int J Radiat Oncol Biol Phys. 2000;  48 1381-1387
• 19 Sawamura Y, Shirato H, Sakamoto T, Aoyama H, Suzuki K, Onimaru R, Isu T, Fukuda S, Miyasaka K. Management of vestibular schwannoma by fractionated stereotactic radiotherapy and associated cerebrospinal fluid malabsorption.  J Neurosurg. 200;  99 85-692
• 20 Pendl G, Ganz J C, Kitz K, Eustacchio S. Acoustic neurinomas with macrocysts treated with Gamma knife radiosurgery.  Stereotact Funct Neurosurg. 1996;  66 (Suppl 1) 103-111
• 21 Unger F, Walch C, Haselsberger K, Papaefthymiou G, Trummer M, Eustacchio S, Pendl G. Radiosurgery of vestibular schwannomas: a minimally invasive alternative to microsurgery.  Acta Neurochir (Wien). 1999;  141 1281-1286