Costs and effects of microsurgery versus radiosurgery in treating acoustic neuroma

Summary This study analyses costs and effects of treating acoustic neuroma patients by using microsurgery compared to radiosurgery. Radiosurgery is the stereotactic application of radiotherapy and an innovative medical technology. Cost and effect estimates of conventional treatment were based on a retrospective study in the Netherlands. Similar data for a comparable group of patients in Sweden were collected for radiosurgery, as this treatment option is currently not available in the Netherlands.Fifty-three acoustic neuroma patients who had been operated on the University Hospital Rotterdam between November 1990 and February 1995 were included. This group was compared with 92 acoustic neuroma patients treated with radiosurgery (Gamma Knife. Stockholm, Sweden) in the same period. Data on health care use were collected from patient files. To obtain data on production losses and quality of life, a questionnaire was sent by mail in February 1995. This booklet consisted of the Health and Labour-questionnaire (HLQ), the Short Form-36 (SF36) and the EuroQol. The response rate was 92%.Direct costs for microsurgery amounted to Dfl. 20.072,- and for radiosurgery to Dfl. 14. 272,-. Indirect costs were respectively Dfl. 16.400,- and Dfl. 1.020,-. General health rating was better for radiosurgery than for microsurgery. On the whole, differences in clinical outcomes between the two patient groups were small. Assuming a reasonable occupancy rate of the expensive radiosurgery equipment, we demonstrated that for the short term treating patients with acoustic neuroma with an extra-meatal tumour diameter of less than 3 centimeters, radiosurgery is more cost-effective than microsurgery.     

Immediate neurological deterioration after gamma knife radiosurgery for acoustic neuroma. Case report

The authors describe acute deterioration in facial and acoustic neuropathies following radiosurgery for acoustic neuromas. In May 1995, a 26-year-old man, who had no evidence of neurofibromatosis Type 2, was treated with gamma knife radiosurgery (GKS; maximum dose 20 Gy and margin dose 14 Gy) for a right-sided intracanalicular acoustic tumor. Two days after the treatment, he developed headache, vomiting, right-sided facial weakness, tinnitus, and right hearing loss. There was a deterioration of facial nerve function and hearing function from pretreatment values. The facial function worsened from House-Brackmann Grade 1 to 3. Hearing deteriorated from Grade 1 to 5. Magnetic resonance (MR) images, obtained at the same time revealed an obvious decrease in contrast enhancement of the tumor without any change in tumor size or peritumoral edema. Facial nerve function improved gradually and increased to House-Brackmann Grade 2 by 8 months post-GKS. The tumor has been unchanged in size for 5 years, and facial nerve function has also been maintained at Grade 2 with unchanged deafness. This is the first detailed report of immediate facial neuropathy after GKS for acoustic neuroma and MR imaging revealing early possibly toxic changes. Potential explanations for this phenomenon are presented.     

Optimal dose of stereotactic radiosurgery for acoustic neuromas: A systematic review

Radiosurgery is increasingly employed in the treatment of acoustic neuroma, but the optimal dose in terms of long-term tumour control and minimal adverse effects has not been established. We performed a systematic review of the published literature of radiosurgery of acoustic neuroma to assess whether the use of low dose radiosurgery is as effective as high dose treatment. Reports of radiosurgery for acoustic neuroma were identified through a Medline search. Studies with at least 15 patients and a median follow-up longer than 12 months were included. The relationship between actuarial 5-year progression-free survival (PFS), and tumour and treatment parameters was examined. Forty-two studies were included. Tumour control following lower radiosurgery doses was similar to that reported following high doses. Only 12 studies reported actuarial outcomes at 5 years. There was no relationship between PFS at 5 years and dose to the tumour margin. Radiosurgery of larger tumours was associated with lower 5 year PFS (p < 0.05). Although on initial inspection radiosurgery of acoustic neuroma with doses of 12 - 13 Gy seems to be as effective as higher dose treatment, the available reports are subject to a number of confounding factors, are not sufficiently statistically powered and there is only limited long-term actuarial outcome data. Currently, available studies do not provide sufficient confidence to support the claim that low dose radiosurgery is equally effective as higher doses in the long-term control of acoustic neuroma.     

听神经瘤显微手术治疗和面听神经功能保护的探讨

目的探讨听神经瘤显做于术治疗和面听神经功能保护的疗效。方法分析1999年10月至2002年10月收治经枕下乙状窦后内听道入路手术切除30例听神经瘤的资料，全部病例采用保留面听神经功能的显做外科技术。结果听神经瘤手术全切除29例（96．7％），次全切除1例；面神经解剖保留25例（83．3％），手术后12周面神经功能保留21例（70％）；耳蜗神经解剖保留25例83．3％），手术后2周有效听力保留2例（占术前存在有效听力患者的28．6％），有效听力丧失但可测听力保留15例。结论枕下乙状窦后经内听道入路的听神经显微手术，能够取得较好的肿瘤全切除率和面听神经功能保留率.     

Results of acoustic neuroma radiosurgery: an analysis of 5 years' experience using current methods

OBJECT: The goal of this study was to define tumor control and complications of radiosurgery encountered using current treatment methods for the initial management of patients with unilateral acoustic neuroma. METHODS: One hundred ninety patients with previously untreated unilateral acoustic neuromas (vestibular schwannomas) underwent gamma knife radiosurgery between 1992 and 1997. The median follow-up period in these patients was 30 months (maximum 85 months). The marginal radiation doses were 11 to 18 Gy (median 13 Gy), the maximum doses were 22 to 36 Gy (median 26 Gy), and the treatment volumes were 0.1 to 33 cm3 (median 2.7 cm3). The actuarial 5-year clinical tumor-control rate (no requirement for surgical intervention) for the entire series was 97.1+/-1.9%. Five-year actuarial rates for any new facial weakness, facial numbness, hearing-level preservation, and preservation of testable speech discrimination were 1.1+/-0.8%, 2.6+/-1.2%, 71+/-4.7%, and 91+/-2.6%, respectively. Facial weakness did not develop in any patient who received a marginal dose of less than 15 Gy (163 patients). Hearing levels improved in 10 (7%) of 141 patients who exhibited decreased hearing (Gardner-Robertson Classes II-V) before undergoing radiosurgery. According to multivariate analysis, increasing marginal dose correlated with increased development of facial weakness (p = 0.0342) and decreased preservation of testable speech discrimination (p = 0.0122). CONCLUSIONS: Radiosurgery for acoustic neuroma performed using current procedures is associated with a continued high rate of tumor control and lower rates of posttreatment morbidity than those published in earlier reports.     

Stereotactic radiosurgery and radiotherapy for acoustic neuromas

Neuromas are benign intracranial tumors with indolent natural history. Surgery is the mainstay of treatment and only after the introduction of single-fraction stereotactic radiosurgery (SRS), radiotherapy emerged as an alternative viable option. In this review, we focused on SRS or conventionally fractionated stereotactic radiotherapeutic (FSRT) approaches. We described the results of different doses used for SRS and FSRT, the current status, and a comparison between the two radiotherapy approaches. Stereotactic radiotherapy techniques aim to control tumor growth with minimal toxicity. SRS using either a cobalt unit or a linear accelerator has given high rates of tumor control and of cranial nerve function preservation with marginal doses range of 12–14 Gy. Fractionated stereotactic radiotherapy (FSRT) is optimal for tumors larger than 3 cm. Doses as low as 50.4 Gy provide excellent control rates and low morbidity. Overall, both SRS and FSRT are equally effective and safe options for neuroma patients who do not need immediate surgical decompression.     

Comparison of different wound closure techniques in translabyrinthine acoustic neuroma surgery

In a series of 277 patients with translabyrinthine acoustic neuroma, three techniques of wound closure were used to prevent cerebrospinal fluid (CSF) leakage. In the first group, we used a piece of fascia to cover the dural defect and then placed several pieces of fat on the fascia. The incidence of CSF leak was 28.2%; 7.7% required reoperation. In the second group, in addition to the fasia-fat complex, we made a large musculoperiosteal flap to compress the fat. The incidence of CSF leak and revision were not reduced, however. In recent cases, we placed several pieces of fat directly into the operative cavity without fascia graft; then it was covered with a musculoperiosteal flap. With this technique, CSF leak was significantly reduced to 7.4%, and reoperation was rare (3.7%). The direct application of fat into the translabyrinthine operation cavity appears to be effective to prevent CSF leaks.     

显微手术辅以内镜切除大型听神经瘤

目的 探讨神经内镜辅助的显微神经外科手术治疗大型听神经瘤的临床意义和手术方法。方法 16例大型听神经瘤，均施行患侧枕下乙状窦后入路显微手术切除，同时辅以神经内镜配合。结果 肿瘤全切除13例，次全切除者3例。面神经保留14例，短期并发症4例。所有患者神经功能均有不同程度的恢复。结论 神经内镜辅助显微手术切除大型听神经瘤，具有微创及提高肿瘤全切除率等优点。     

囊性听神经瘤的诊断与治疗

目的 总结囊性听神经瘤的临床特点及治疗效果。方法 22例患者术前均应用CT和MRI进行诊断,应用乙状窦后入路手术切除肿瘤。术中证实,术后病理确诊囊性听神经瘤。结果 22例肿瘤全切除18例,术后面神经功能分级：Ⅱ级4例、Ⅲ级7例、Ⅳ级3例、Ⅴ级2例、Ⅵ级2例;次全切除4例,面神经功能Ⅱ级。结论 由于囊性听神经瘤的临床特点及疗效差,应把它作为一种特殊亚型来处理。     

Selection of surgical approach to acoustic neuroma. 1992

A variety of surgical approaches are available in the management of acoustic neuroma. Each procedure has certain advantages and disadvantages in terms of surgical exposure, the capability of preserving cranial nerve function, and postoperative morbidity. This article advocates tailoring the operative approach to each acoustic neuroma according to its size, location, and clinical manifestations.     

Surgery combined with radiosurgery of large acoustic neuromas

The treatment of acoustic neuromas has been improved by advancements in microsurgical techniques and in radiosurgery. To further elucidate the degree of clinical improvement, we evaluated the treatment results of a combination of surgery and radiosurgery for large acoustic neuromas. METHODS: From January 1994 through December 2000, we treated 14 patients with large acoustic neuromas using a combination of surgery and radiosurgery. Of these, 8 were male and 6 were female patients, with an average age of 47 years (range, 18-64). The average maximum diameter of the tumor was 42 mm (range, 30-58 mm). All patients underwent operations using the retrosigmoid approach, and one patient was retreated using the transpetrosal transtentorial approach. The tumors were removed subtotally in thirteen patients and partially in one who had a very large hypervascular acoustic neuroma. There were no mortality and no surgical complications, such as hemorrhage or CSF leakage. Postoperative facial palsy was avoided in 10 patients (71%). Radiosurgery was performed 1 to 6 months (mean, 2.9 months) after surgery. At the time of radiosurgery, the treatment size (mean diameter) became 19.2 mm (range, 9.8-36.1 mm). The average tumor marginal dose was 12.1Gy (range, from 10-14 Gy). The mean follow-up period was 32 months after radiosurgery. RESULTS: The tumor size decreased in 6 patients, unchanged in 5 patients, and increased in 3 patients. Only 1 patient (7%) with extra large tumor needed surgical resection 1 year after radiosurgery. Excellent facial nerve function (House & Brackmann Grade I or II) was preserved in 12 patients (85.7%) in the final follow-up. CONCLUSIONS: In the case of large acoustic neuromas, subtotal removal and subsequent radiosurgery is one option for maintaining cranial nerve function and long-term tumor growth control.     

Fractionated stereotactic radiosurgery for treatment of acoustic neuromas

BACKGROUND: Microsurgery and single-fraction radiosurgery for acoustic neuromas are associated with high rates of control, but can result in facial palsy and trigeminal neuropathy. To reduce the morbidity of treatment for acoustic neuromas while maintaining efficacy, we explored fractionated stereotactic radiosurgery (FSR). METHODS: We reviewed data for 31 acoustic neuromas in 30 patients treated with 25 Gy (linear accelerator) given in 5 consecutive daily fractions. The minimum follow-up was 6 months (6-44 months). The mean tumor volume was 1.1 cm(3) (0.1-8.74 cm(3)). RESULTS: All tumors remain controlled (9 smaller, 22 unchanged). No patient has experienced post-radiosurgery facial motor dysfunction. Two patients developed new trigeminal neuropathy; 2 patients with preexisting trigeminal nerve symptoms had improvement after FSR. Balance improved in 3 patients, was unchanged in 20 and worsened in 7 patients. Of the 12 patients with useful hearing (PTA < or = 50 dB) prior to treatment, 9 patients retained useful hearing following FSR. Subjectively, of 25 patients with any hearing prior to treatment, 2 had improvement, 10 remained unchanged and 13 had worsening. CONCLUSIONS: Short course FSR for acoustic neuromas results in acceptable toxicity and may provide high control of tumors. Longer follow-up is needed to assess outcomes.     

Iatrogenic impairment of hearing during surgery for acoustic neuroma

Isolated or combined labyrinthine, neural, and vascular damage account for failure to preserve hearing during removal of acoustic neuromas. However, the specific mechanisms of auditory impairment remain unclear unless surgical maneuvers can be related to peri- and postoperative hearing on the basis of intraoperative monitoring of auditory function.Among the different auditory monitoring techniques, recording of cochlear nerve action potentials (CNAPs) from the intracranial portion of the nerve has proven particularly useful for identifying the mechanisms of iatrogenic auditory injury.The present investigation analyzes intra- and postoperative auditory impairment in relation to surgical steps in a group of 38 subjects with acoustic neuroma (size ranging from 5 to 24 mm) undergoing removal via a retrosigmoid approach.Coagulation close to the cochlear nerve, drilling of the internal auditory canal, and removal of the intrameatal portion of the acoustic neuroma have prove to be the most critical surgical steps in hearing preservation.Changes were correlated with intra- and extrameatal tumor size, the relationship between the internal auditory canal and vestibule, and internal auditory canal enlargement, anatomic involvement of the cochlear nerve, preoperative auditory level, and ABR and ENG test findings.Changes in CNAP morphology and latency are detailed, and mechanisms of injury are analyzed and discussed as a function of these variables.