Correspondence
Management of Acoustic Neuroma
N Engl J Med 1999; 340:1119-1121April 8, 1999
- Article
To the Editor:
Kondziolka et al. in their study (Nov. 12 issue)1 and Pitts and Jackler in their accompanying editorial2 miss two important issues concerning radiosurgery for acoustic neuromas. First, since the age of the patient is relevant to the decision about treatment, a more detailed analysis of age is required. We and a number of others recommend observation, not surgery, for patients over the age of 65 years with acoustic neuromas that are not causing distortion of the brain stem. Imaging is repeated as necessary, depending on the size of the tumor, and most of these older patients never require any intervention — either surgery or radiosurgery. In patients over 65 with acoustic neuromas, the issue is not whether radiosurgery is better than conventional surgery but whether any therapy is necessary. Second, the size of the tumor is very important. Kondziolka et al. do not give enough information about tumor size or about how the diameter of a tumor was determined, and no information correlating size and age was provided.
2 ReferencesRobert W. Broad, M.D.
University of Alberta Skull Base Centre, Edmonton, AB T6G 2B7, Canada1
Kondziolka D ,Lunsford LD ,McLaughlin MR ,Flickinger JC . Long-term outcomes after radiosurgery for acoustic neuromas. N Engl J Med 1998;339:1426-1433
Full Text | Web of Science | Medline2
Pitts LH ,Jackler RK . Treatment of acoustic neuromas. N Engl J Med 1998;339:1471-1473
Full Text | Web of Science | Medline
To the Editor:
Although there have been great strides in radiosurgery, Kondziolka et al. did not discuss how single-fraction gamma-knife radiosurgery (radiation delivered in one dose) compares with fractionated treatment. Historically, radiation has been given in divided doses to minimize damage to normal tissue.
Fractionated stereotactic radiosurgery gives excellent results, with the same dose used since the inception of this technique more than five years ago, for acoustic neuromas from 0.1 to 32 ml in volume and up to 5 cm in diameter, including those in patients with type 2 neurofibromatosis.1-3 Despite the presence of large neuromas and type 2 neurofibromatosis, the preservation rate of the facial and trigeminal nerves in 142 patients was 100 percent, and 86 percent of the patients retained hearing. With fractionated radiosurgery, a noninvasive frame for the head obviates the need for skull pins, anesthesia, sedation, and hospitalization.4
In comparison, gamma-knife radiosurgery caused hearing loss in 49 percent of the patients in the study by Kondziolka et al., facial neuropathy in 21 percent, and damage to the trigeminal nerve in 27 percent. Thirty-one percent of previously employed patients who underwent gamma-knife radiosurgery became unemployed after the procedure. Kondziolka et al. report that 18 percent of their patients underwent craniotomy followed by radiosurgery as primary treatment. This two-step strategy is associated with greater morbidity, but it makes subsequent single-fraction radiosurgery appear safer, since the patients will probably have surgically induced neurologic deficits, such as hearing loss and facial neuropathy, before radiosurgery.
4 ReferencesGil Lederman, M.D.
Ehud Arbit, M.D.
Joseph Lowry, M.D.
Staten Island University Hospital, Staten Island, NY 103051
Lederman G ,Lowry J ,Wertheim S , et al. Acoustic neuroma: potential benefits of fractionated stereotactic radiosurgery. Stereotact Funct Neurosurg 1997;69:175-182
CrossRef | Web of Science | Medline2
Lederman G, Wertheim S, Lowry J, et al. Acoustic neuromas treated by fractionated stereotactic radiotherapy. In: Kondziolka D, ed. Radiosurgery. Basel, Switzerland: Karger, 1998:25-30.
3
Rashid H ,Lowry J ,Wertheim S , et al. Improved results for acoustic neuroma treated with fractionated stereotactic radiosurgery. Int J Radiat Oncol Biol Phys 1998;42:Suppl-Suppl4
Gill SS ,Thomas DG ,Warrington AP ,Brada M . Relocatable frame from stereotactic external beam radiotherapy. Int J Radiat Oncol Biol Phys 1991;30:599-603
To the Editor:
The article by Kondziolka et al. does little to define the place radiosurgery may have in the treatment of acoustic neuromas. The authors claim to have evaluated 162 consecutive patients prospectively over an extended period of time while frequently changing the criteria for entry into the study. However, only 38 patients were available for follow-up at seven to eight years. Have the authors forgotten that they reported treating no fewer than 134 patients with acoustic tumors between August 17, 1989, and June 1, 1991?1 Where have all their patients gone? What they report on is not a group of consecutive patients but a highly selected sample from a much larger series.
The outcome measure in the study was a change of ±2 mm in tumor size. The detection of such minute changes would tax the abilities of the most experienced radiologist working under optimal conditions. These tumors were measured by general radiologists at several hospitals with the use of various criteria. It seems highly implausible that these radiologists could measure tumors of irregular size, especially recurrent tumors in surgical defects, with the accuracy the study demanded. The authors failed to validate the interobserver reliability of tumor mensuration so critical to this study. The doses of radiation used throughout the study varied, and in some instances, even the wishes of the patient determined the amount of irradiation offered. Given such variation, the claims made by the authors about the effects of the dose on therapeutic efficacy are not well founded. The authors' description of the multivariate analyses does not include the statistical tests used or even which variables were studied. Unlike the authors of other quality-of-life studies in this area,2 the authors failed to use a validated instrument to determine health status.
The article is less than forthcoming in addressing the hazards of stereotactic radiosurgery for acoustic tumors. In particular, the authors do not acknowledge the risk of cancer known to follow stereotactic radiosurgery. Of the five patients in the Copenhagen series, cancer developed in one after radiosurgery.3 Finally, the authors would do well to remember that acoustic tumors may remain quiescent for years and that the rates of “control” attributed to radiosurgery may be no more than what would have happened had no treatment been given.
3 ReferencesGerard M. O'Donoghue, M.D.
Thomas Nikolopoulos, M.D., Ph.D.
University Hospital, Nottingham NG7 2UH, United KingdomJens Thomsen, M.D., Ph.D.
Gentofte University Hospital, DK-2900 Copenhagen, Denmark1
Lunsford LD, Linskey ME, Flickinger JC. Stereotactic radiosurgery for acoustic nerve sheath tumors. In: Tos M, Thomsen J, eds. Acoustic neuroma. Amsterdam: Kugler, 1992:279-87.
2
Nikolopoulos TP ,Johnson I ,O'Donoghue GM . Quality of life after acoustic neuroma surgery. Laryngoscope 1998;108:1382-1385
CrossRef | Web of Science | Medline3
Thomsen J, Tos M, Borgensen SE, Charabi B. Radiosurgery — a referring surgeon's experience. Presented at the European Skull Base Congress, London, 1997. abstract.
Author/Editor Response
The authors reply:
To the Editor: Dr. Broad notes the importance of the age of the patient in selecting a management strategy. As stated in our article, acoustic tumors in elderly patients are first managed conservatively with an evaluation of the volume of the tumor by serial imaging studies. Radiosurgery is recommended only when clinical progression or tumor growth has been documented.
The factor of tumor size is also important. As we stated, tumor size was determined by five separate measurements performed with the caliper technique, a method we have described previously.1 Dr. O'Donoghue and colleagues also missed this statement in our paper. We do not know why they believe that “tumors were measured by general radiologists at several hospitals with the use of various criteria,” since this was not stated in our article. All images were reviewed by our group with the use of the five separate measurements with calipers. O'Donoghue et al. also criticize our failure to use a “validated instrument to determine health status.” Although we did not use their instrument, we chose to develop and use one that included neurologic function and potential complications specific to radiosurgery.
We agree with O'Donoghue et al. that some acoustic tumors can remain quiescent for years, although data on the natural history of acoustic neuroma indicate an average growth rate of 2 mm per year.2 In our experience, more than 80 percent of acoustic neuromas followed with serial images show objective, measurable growth within five years. However, whether the effect of radiosurgery may be no different from that of no treatment is an argument that ended years ago.
We also clearly stated that this study was of a series of consecutive, unselected patients that included every patient whose acoustic neuroma was managed with radiosurgery at the University of Pittsburgh from August 1987 (when we began) through July 1992. This series allowed the maximal follow-up of all patients.
Finally, the purpose of our report was to define long-term outcomes after radiosurgery, not after fractionated-radiation therapy. Lederman et al. believe that fractionated-radiation therapy may offer better tumor control or neurologic outcomes than gamma-knife radiosurgery. However, they provide no peer-reviewed comparative data.
The goal of the management of acoustic tumors, whether with observation, microsurgical resection, stereotactic radiosurgery, or some other emerging method, is to maintain lifelong function. Our systematic evaluation of an unselected, consecutive series of patients who underwent radiosurgery during our first 5 to 10 years of using this technique substantiates the value of stereotactic radiosurgery. Anecdotes and small series of patients aside, we await any comprehensive, long-term evaluation of other treatment strategies.
2 ReferencesDouglas Kondziolka, M.D.
L. Dade Lunsford, M.D.
John C. Flickinger, M.D.
University of Pittsburgh, Pittsburgh, PA 15213-25821
Linskey ME ,Lunsford LD ,Flickinger JC . Neuroimaging of acoustic nerve sheath tumors after stereotaxic radiosurgery. AJNR Am J Neuroradiol 1991;12:1165-1175
Web of Science | Medline2
Bederson JB ,von Ammon K ,Wichmann WW ,Yasargil MG . Conservative treatment of patients with acoustic tumors. Neurosurgery 1991;28:646-651
CrossRef | Web of Science | Medline
- Citing Articles (3)
Citing Articles
1
Christine Kopp, Claudius Fauser, Axel Müller, Sabrina T. Astner, Vesna Jacob, Christianto Lumenta, Bernhard Meyer, Jörg-Christian Tonn, Michael Molls, Anca-Ligia Grosu. (2011) Stereotactic Fractionated Radiotherapy and LINAC Radiosurgery in the Treatment of Vestibular Schwannoma—Report About Both Stereotactic Methods From a Single Institution. International Journal of Radiation Oncology*Biology*Physics 80:5, 1485-1491
CrossRef2
Yutaka Sawamura, Hiroki Shirato, Touru Sakamoto, Hidefumi Aoyama, Keishiro Suzuki, Rikiya Onimaru, Toyohiko Isu, Satoshi Fukuda, Kazuo Miyasaka. (2003) Management of vestibular schwannoma by fractionated stereotactic radiotherapy and associated cerebrospinal fluid malabsorption. Journal of Neurosurgery 99:4, 685-692
CrossRef3
N. Bateman, T. P. Nikolopoulos, K. Robinson, G. M. O'Donoghue. (2000) Impairments, disabilities, and handicaps after acoustic neuroma surgery. Clinical Otolaryngology 25:1, 62-65
CrossRef
