Hearing preservation in patients with unilateral vestibular schwannoma who undergo stereotactic radiosurgery: Reinterpretation of the auditory brainstem response.
ABSTRACT The objective of this study was to identify the prognostic factors for hearing preservation that would allow the more accurate stratification of patients who undergo stereotactic radiosurgery (SRS) for unilateral, sporadic vestibular schwannoma (VS).
In total, 119 patients with VS who had serviceable hearing underwent SRS as primary treatment. The mean (±standard deviation) patient age was 48 ± 11 years, and the mean (±standard deviation) follow-up duration was 55.2 ± 35.7 months. The median marginal radiotherapy dose was 12.0 grays (Gy), and the mean (±standard deviation) tumor volume was 1.95 ± 2.24 cm(3) . The mean (±standard deviation) pure tone average (PTA) score was 26 ± 12 decibels (dB) (range, 4-50 dB), and the mean (±standard deviation) maximum speech discrimination score was 91 ± 12% (range, 52-100%). The mean (±standard deviation) baseline values for the interlatency (IL) of waves I and III (IL I-III) and the IL of waves I through V (IL I-V) on auditory brainstem response were 2.58 ± 0.60 milliseconds (mS) (range, 1.92-4.30 mS) and 4.80 ± 0.61 mS (range, 3.80-6.40 mS), respectively.
In multivariate analysis, the PTA score and IL I-V were significant and independent prognostic factors (hazard ratio, 1.072; 95% confidence interval, 1.046-1.098; P < .001; and hazard ratio, 1.534; 95% confidence interval, 1.008-2.336; P = .046, respectively). By using the PTA score and IL I-V, the patients were classified into 4 groups. The ratios of patients with serviceable hearing after SRS were 89.6%, 64.0%, 25.8%, and 6.7%, respectively, in Groups A through D (P < .001).
The current results indicated that the classification system based on using the PTA score and the IL I-V of the auditory brainstem response may be useful and specific for predicting the rate of hearing preservation in each individual. Cancer 2012. © 2012 American Cancer Society.
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ABSTRACT: The purpose of this study was to analyze tumor control and possible complications of gamma knife radiosurgery (GKRS) in patients with vestibular schwannomas using low marginal doses and conformal multiple shots to fit irregular tumor shapes. The authors evaluated 152 patients with more than 5 years of follow-up. Marginal doses were 9-15 Gy (median 12 Gy), with corresponding treatment volumes ranging from 0.1 to 18.7 cm3 (median 2.0 cm3). The number of isocenters varied from 2 to 24 shots (median 9 shots). The actuarial tumor control rates were 94% at 5 years and 92.4% at 8 years. Larger tumors (p < 0.0001) and those in younger patients (p = 0.018) tended to recur significantly more often. Useful hearing, facial and trigeminal functions were preserved at 71, 100 and 97.4%, respectively. Seventeen percent of all patients developed transient dizziness, with dizziness persisting in 2% of the total. Fifty-six other patients not included in the long-term evaluation consecutively underwent caloric testing and static stabilometry as well as neurological examinations to evaluate vestibular function in detail, both before and after GKRS. The results revealed 90% of the patients to have already developed vestibular dysfunction prior to the treatment despite reported symptoms of dizziness. GKRS did not significantly affect vestibular function. Hydrocephalus was recognized in 5.3% of all patients, and tended to occur in cases with larger tumors (p = 0.0024). GKRS provides a safe and effective therapy for small to medium-sized tumors. However, indications for larger tumors must be carefully considered, as they are more difficult to control and liable to produce ataxia due to transient expansion.Progress in neurological surgery 01/2009; 22:45-62.
- Acta chirurgica Scandinavica 02/1971; 137(8):763-5.
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ABSTRACT: Radiosurgery is a management approach used to treat patients with vestibular schwannomas. The goals are long-term tumour growth control, maintenance of cranial nerve function and prevention of new deficiencies. We sought to determine long-term outcomes measuring the potential benefits against the neurological risks of primary radiosurgery. Gamma Knife radiosurgery was applied as a treatment modality for 289 patients with vestibular schwannomas from April 1992 to April 2002. The long-term results of 100 patients who underwent radiosurgery were evaluated. 60 patients received a primary treatment, 40 other cases presented with previously performed subtotal microsurgical resection or recurrence of disease (12-96 months, median 39). The median treatment volume was 3.4 ccm and the median dose to the tumour margin was 13 Gy. The median patient follow-up time was 76 months (range 60-120 months). Four tumours progressed after primary radiosurgery. Tumour control rate was 96%. Useful hearing (Gardner-Robertson I/II) was preserved in 16 patients (55%). Clinical neurological improvement occurred in 50%. Adverse effects comprised neurological symptoms (incomplete facial palsy) (House-Brackman II/III) in six cases (four recovered completely), mild transient trigeminal neuropathy in five cases, and morphological changes displaying rapid enlargement of preexisting macrocysts in two patients and tumour growth in two other patients. Microsurgical resection was performed in four cases (4%) and two patients underwent a shunting procedure because of hydrocephalus formation (2%). In patients who had undergone previous microsurgery, no new cranial nerve deficit was observed. Radiosurgery is an effective method for growth control of vestibular schwannomas and is associated with both a low mortality rate and a good quality of life. Accordingly, for the preservation of cranial nerve function radiosurgery is a useful method for the management of properly selected patients and is comparable to microsurgery.Acta neurochirurgica. Supplement 02/2002; 84:77-83.