Conservative management of unilateral acoustic neuromas

OBJECTIVE: The aim of this study was to analyze the natural course of unilateral acoustic neuromas and to evaluate the advantages and disadvantages of an initial conservative approach. METHODS: Between 1989 and 1994, 74 consecutive patients with the diagnosis of unilateral acoustic neuroma were evaluated at the Department of Otorhinolaryngology, University of Zurich. Their charts and magnetic resonance imaging scans were retrospectively analyzed regarding duration and type of symptoms, initial tumor size, tumor growth pattern, and audiometric data. RESULTS: Of the 74 tumors, 68.9% (51/74) did not grow during a mean follow-up of 35 months. Eight (16%) of these tumors had radiologically documented tumor regression. Twenty-three tumors did grow, 16 of them (70%) with a growth rate of <2 mm/year. There was a statistically significant correlation between the first-year and the total growth rate, indicating that the tumor's behavior in the first year is highly predictive of its subsequent growth pattern. Patients with progressive hearing loss as a first symptom had a significantly lower tumor growth than those presenting with tinnitus, sudden hearing loss, or dizziness. Patients with tumor growth showed a greater tendency for hearing loss, although this trend was significant only for isolated frequencies. In 12% of the cases (9/74), the initial conservative approach had to be abandoned in favor of surgery. CONCLUSION: Watchful expectation can be regarded as a safe approach for selected cases of acoustic neuromas. Surgery or irradiation is indicated in patients with proven growth of their tumors.     

Conservative management of acoustic neuromas.

The results of this study and others document the biologic behavior of acoustic neuromas. In view of the evidence presented, which describes both variable rates of individual tumor growth and spontaneous regression in size, it would seem prudent that before selecting a nonsurgical treatment modality, the growth rate for the particular tumor in question should be established. To date, none of the literature that addresses the use of focused irradiation has attempted to do so. Our study as well as those of others suggests that the growth rate of acoustic neuromas becomes predictable over time. Based on this observation, a conservative (nontumor excision) management strategy is proposed for selected individuals. Patients to whom this management philosophy has been recommended or who themselves have chosen this option are seen twice yearly. Each visit consists of a thorough neurotologic examination as well as high-definition CT or MRI. Careful comparison of the clinical course as well as calculation of the tumor size is carried out in each instance. If the clinical course and rate of tumor growth remain unchanged over a 3-year follow-up, annual assessments are recommended. In the event of tumor enlargement, surgery may or may not be recommended, depending on the rate of growth and the age of the patient. Our experience suggests that a rate of growth equal to or exceeding 0.2 cm per year constitutes an indication for tumor removal.     

Conservative management of sporadic unilateral acoustic neuromas

Our objective was to review retrospectively patients with a unilateral acoustic neuroma managed by observation. One hundred patients with tumours (<24 mm) were followed a median 25.5 months. Thirty-six acoustic neuromas grew with four growth patterns. No factors were associated with growth. Eighty percent of growing tumours grew in the first year. Eleven patients proceeded to surgery. Twenty-two patients were eligible for hearing preservation surgery; five of the 15 available for analysis subsequently lost eligibility. In conclusion, selected patients can be safely observed with serial imaging and follow up. Size increase in the first year may predict future growth. Delaying surgery until required by symptoms or tumour growth does not result in more morbidity for the patient. Some may lose the opportunity for hearing preservation surgery but operating on all would result in more sustaining a loss of hearing in the first few years after diagnosis.     

Conservative management of acoustic neuroma in the elderly patient

A subtotal resection through the translabyrinthine approach should be used in the treatment of large symptomatic acoustic neuromas in patients over the age of 65. This approach will consistently relieve the patient's symptoms of brain stem compression, reduce postoperative morbidity and complications, and preserve facial nerve function. In the elderly, after subtotal resection, the remaining tumor in 80% of cases appears to remain dormant during the average six year follow-up (1-16 year range). Eighty percent of acoustic neuromas not operated upon, appear to grow at a slow rate (0.2 cm/yr) while 20% grow at a fast rate (1 cm/yr). Patients over the age of 65 with small acoustic neuromas do not need surgical intervention. Yearly CT scanning is recommended to determine the growth rate of the acoustic neuroma. A conservative approach should be used in the treatment of all acoustic neuromas in the elderly.     

Early detection of small bilateral acoustic tumors

Bilateral acoustic tumors are one of the most difficult problems in acoustic tumor surgery. Total tumor removal with preservation of hearing has seldom been achieved in the past. Recently, hearing has been successfully preserved if the tumors are small when removed. We present the case of a child with a family history of von Recklinghausen's disease associated with bilateral acoustic tumors. A high index of suspicion of bilateral tumors and a thorough work-up resulted in the early diagnosis of small tumors. The tumors were removed with preservation of normal hearing.     

Conservative management versus surgery for small vestibular schwannomas

Conclusion

A high rate of deterioration in hearing function and the loss of patient compliance during conservative management should be taken into account when considering hearing preservation strategies for patients with vestibular schwannoma (VS).

Objective

To compare conservative management with surgery for solitary small VS.

Material and methods

Among 693 patients followed up for VS between 1991 and 2002, 114 (16%) intracanalicular VSs (stage 1) and 302 (44%) VSs measuring <15 mm in the cerebellopontine angle (stage 2) were included in this study. Initially, surgery was performed in 305 (73%) cases (50 stage 1, 255 stage 2) and 111 (27%) were managed conservatively (64 stage 1, 54 stage 2) by means of annual MRI scans and audiometry. Conservative management was chosen in patients aged >60 years and in those who refused surgery. In this subgroup, the mean follow-up period was 33 months (range 6–111 months).

Results

In the conservative management group, 47% of VSs showed significant growth, 47% were stable and 6% showed regression. Seventeen patients (15%) were operated on secondarily for tumour growth and 1 (1%) was irradiated for tumour growth and because surgery was contraindicated. Deterioration of hearing function by ≥1 class was observed in 56% of cases, 34% of patients were initially in hearing class D and only 10% showed stable hearing function. Of the conservative management group, 17% were lost during follow-up. After surgery, grade 1 or 2 facial function was obtained in 86% of cases. Following hearing preservation attempts (n=137), 54% of patients were in hearing classes A–C.     

Conservative management versus surgery for small vestibular schwannomas

A high rate of deterioration in hearing function and the loss of patient compliance during conservative management should be taken into account when considering hearing preservation strategies for patients with vestibular schwannoma (VS).To compare conservative management with surgery for solitary small VS.Among 693 patients followed up for VS between 1991 and 2002, 114 (16%) intracanalicular VSs (stage 1) and 302 (44%) VSs measuring <15 mm in the cerebellopontine angle (stage 2) were included in this study. Initially, surgery was performed in 305 (73%) cases (50 stage 1, 255 stage 2) and 111 (27%) were managed conservatively (64 stage 1, 54 stage 2) by means of annual MRI scans and audiometry. Conservative management was chosen in patients aged >60 years and in those who refused surgery. In this subgroup, the mean follow-up period was 33 months (range 6-111 months).In the conservative management group, 47% of VSs showed significant growth, 47% were stable and 6% showed regression. Seventeen patients (15%) were operated on secondarily for tumour growth and 1 (1%) was irradiated for tumour growth and because surgery was contraindicated. Deterioration of hearing function by > or =1 class was observed in 56% of cases, 34% of patients were initially in hearing class D and only 10% showed stable hearing function. Of the conservative management group, 17% were lost during follow-up. After surgery, grade 1 or 2 facial function was obtained in 86% of cases. Following hearing preservation attempts (n=137), 54% of patients were in hearing classes A-C.     

小听神经瘤的手术治疗策略

目的　总结小听神经瘤的手术治疗效果,探讨小听神经瘤手术治疗策略。方法　回顾分析在我科手术治疗的26例小听神经瘤患者临床资料。1例术前听力分级为B者,行颅中窝入路;其余25例术前听力分级均为C与D者,行迷路入路听神经瘤切除术。回顾分析术前术后的面肌力弱、平衡障碍、耳鸣等情况,分析术中蜗神经的解剖完整性保存、肿瘤控制及复发情况、并发症发生率,以及患者获益情况。结果　25例（96.2%）达到肿瘤全切除,1例因与面神经粘连过于紧密,做近全切除。术后随访时间6个月～7年,随访19例,7例失访。无死亡、颅内感染病例。术后脑脊液耳漏1例,二次手术进行咽鼓管封堵,脑脊液耳漏消失。面神经解剖保存率100%,蜗神经解剖保存率88%。19例随访者中术后17例（89.5%）具有良好面神经功能,HB I与II级;另2例面瘫,HB III级。经颅中窝入路患者,术后听力C级。19例随访者中术前眩晕6例,术后5例（83.3%）眩晕消失,1例与术前相同。另13例术前无眩晕者,术后12例仍无眩晕与平衡障碍,1例出现体位改变时头晕或者快走时走路不稳。术前耳鸣15例,术后5例（33.3%）耳鸣消失或减轻,8例（53.3%）耳鸣程度与术前相同,2例耳鸣加重。术前4例无耳鸣,术后仍没有耳鸣。结论　小听神经瘤是否手术需要考虑患者年龄,合并全身疾病、症状的严重程度,肿瘤生长速度,采取个性化治疗策略。对于没有实用听力者,推荐经迷路入路切除肿瘤,术中尽量保存蜗神经完整性,为人工耳蜗植入重建听力创造条件。     

Neuro-otological findings in patients with small acoustic neuromas

Summary The method of choice for the diagnosis of even the smallest acoustic neuromas is CT gas cisternography. Lumbar puncture and gas insufflation, however, is an intervention demanding strict indication. Neuro-otological examinations should lead to this indication. The aim of this paper is to demonstrate neuro-otological findings on 19 patients presenting small acoustic neuromas. These neuro-otological findings are not necessarily comparable to earlier reports in the literature dealing with mainly larger tumours at a time when early diagnosis was not so advanced.     

Conservative management of acoustic neuroma: a meta-analysis and proposed treatment algorithm

OBJECTIVES/HYPOTHESES: Conservative management is a viable treatment alternative for acoustic neuroma. Using previous studies to provide evidence-based support, we have attempted to more clearly define the role of conservative management. STUDY DESIGN: Retrospective review of literature and patient charts. METHODS: Published studies on conservative management of acoustic neuroma were found using a key word search through PubMed in addition to the bibliographies of these selected studies. A spreadsheet was made to tabulate the selection criteria for conservative management, duration and frequency of follow-up, patient demographics, initial tumor size and rate of growth, change in hearing status, and the need for definitive treatment. RESULTS: A total of 21 studies comprising 1,345 patients were included in our meta-analysis. The average length of follow-up these studies was 3.2 years. The average initial tumor size was 11.8 mm (n = 900); 43% of 1,244 acoustic neuromas showed growth, whereas 57% showed either no growth or tumor regression. The average growth rate was 1.9 mm/year in 793 individuals. Hearing loss occurred in 51% of 347 individuals. In 15 studies, 20.0% of 1,001 individuals eventually failed conservative management. CONCLUSIONS: Our meta-analysis supports the role of conservative management of acoustic neuromas in properly selected patients on the basis of a slow overall rate of growth and a substantial incidence of no growth. However, the lack of predictive factors, the relatively short duration of follow-up, and the variability of inclusion criteria underscore the need for continued collection of long-term data. An algorithm for acoustic neuroma management is proposed based on initial tumor size, patient age, and hearing status.     

Stereotactic radiosurgery in the treatment of patients with acoustic tumors.

Stereotactic radiosurgery is performed under local anesthesia, and most patients can be discharged from the hospital within 24 hours of treatment. All patients in our series returned to their preoperative level of employment or function within 5 to 7 days of treatment, and this functional level was maintained over the period of follow-up. "Tumor control" was achieved in 96% of patients during an average follow-up of 1.7 years. Tumor shrinkage occurred in 45% of patients who had at least 1.5 years of follow-up. Useful hearing preservation rates were 50% at 6 months and 30% 1 year after treatment. New delayed facial or trigeminal neuropathy occurred in 34% and 32% of patients, respectively, with a median onset of 5 to 6 months after treatment. The vast majority of cranial neuropathies were partial at onset and tended to improve over time. Other complications included tumor growth (4%), communicating hydrocephalus (4%), and transient adjacent brain parenchymal changes best seen on T2-weighted MRI (9%). Stereotactic radiosurgery is an important alternative treatment for carefully selected patients with acoustic tumors. Indications for treatment include sufficient medical problems to pose excessive surgical risk, advanced age, the presence of bilateral acoustic tumors or contralateral deafness, recurrent tumor despite surgical resection, or refusal to undergo microsurgery. Radiosurgery is contraindicated in patients with symptomatic brain stem or cerebellar compression from a large acoustic tumor. Previous posterior fossa radiotherapy is a relative contraindication that must be considered on a patient to patient basis. Stereotactic radiosurgery should be viewed as an additional weapon in our arsenal for combating acoustic tumors rather than feared as a potential replacement for surgical excision. The strategic role of stereotactic radiosurgery in the overall treatment of patients with acoustic tumors will continue to be refined as longer-term, carefully assessed results become available.     

Asymmetric optokinetic afterresponse in patients with small acoustic neurinomas.

Directional asymmetry of primary and secondary optokinetic afternystagmus (OKAN I and OKAN II, respectively) was studied in 20 patients with small acoustic neurinomas (< or = 20 mm), and results were compared to those for 24 normal controls. The optokinetic afterresponse was induced by 60 s of horizontal whole-field optokinetic stimulation in both directions. Among patients, the optokinetic afterresponse was asymmetric, OKAN I and OKAN II beating toward the lesioned ear being significantly weaker than the OKAN I and OKAN II beating toward the healthy ear. Hence, in these patients with gradual deterioration of vestibular function, the vestibular side-difference was reflected both in OKAN I and OKAN II. Although asymmetry in OKAN I was frequently observed among controls, it was significantly more pronounced among the patients. Moreover, patients could be distinguished by the occurrence of OKAN II, as it did not occur at all among controls exposed to the same stimulation.     

The treatment of small acoustic tumors: Now or later?

Prior to the advent of microneurosurgery, the operative mortality for acoustic tumor removal was high and management often consisted of observation until sufficient symptoms warranted removal. The treatment of these tumors has evolved, and recent introduction of gadolinium-enhanced magnetic resonance imaging (MRI) allows the diagnosis of very small intracanalicular acoustic tumors before hearing has been significantly affected. For such tumors, some surgeons advocate the premicrosurgical philosophy of observation rather than removal. Our results of small acoustic tumor removal with attempt at hearing preservation were reviewed. From 1961 to June 1989, 39 acoustic tumors 0.5 cm or less were removed by the middle fossa approach. Measurable hearing was preserved in 67%, and facial function 1 year postoperatively was normal or nearly normal in 97%. There was no other permanent operative morbidity. Given our results, early surgical removal of small acoustic tumors is advocated.     

An immunohistochemical study of the endolymphatic sac in patients with acoustic tumors

Intraosseous endolymphatic sacs obtained from patients with acoustic neuromas who had undergone total labyrinthectomy during tumor removal were examined for the presence of T helper/inducer and T suppressor/cytotoxic lymphocytes, B lymphocytes, plasma cells, and macrophages. Immunoperoxidase staining of cryostat sections revealed the presence of T helper/inducer lymphocytes, T suppressor/cytotoxic lymphocytes, and macrophages. The number of B lymphocytes and plasma cells was much smaller than the number of T lymphocytes. The number of T suppressor/cytotoxic lymphocytes was higher than the number of T helper/inducer lymphocytes. This study supports the notion of local immune responsiveness in the human inner ear. This is the first immunohistochemical study to analyze lymphocyte subpopulations; specifically, to provide insight into T-cell function in the endolymphatic sac.