Bilateral acoustic neuromas

This article reviews 12 patients with bilateral acoustic neuromas. The sex incidence was equal and the mean age at diagnosis was 26.2 years. The family history was positive in nine of the patients. Five patients have had incomplete surgical removal of acoustic neuromas on both sides. Two of them are completely deaf and the other three have severe sensorineural hearing loss in one ear and no hearing in the other ear. In five patients the tumour on one side has been operated on and the other side is being observed with at least short-term preservation of good hearing. The remaining two patients died of intra-cranial complications, one of them post-operatively. Four patients developed facial palsy immediately following surgery and one developed facial weakness 6 months after surgery. Guidelines are discussed for the care of these patients including the timing of surgery and alternative treatment options (observation, radio-surgery adn chemotherapy). This is essentially a group of young individuals who have had multiple operations for bilateral acoustic tumours and associated manifestations and for whom the disease and the sequelae of treatment can be tragic.     

Non-surgical management of acoustic neuromas.

Watchful waiting is one of the options available in the management of acoustic neuromas and this article deals with 13 patients who were so managed. Non-operative management was advised because of age, poor general health, small size of tumour, only hearing ear, or in patients unwilling to undergo surgery for various reasons. This group was followed up at 6-12-monthly intervals and the follow-up period ranged from 1 to 18 years (mean 5.3 years). Ten patients had small tumours and only in 2 of these was increase in tumour size demonstrated on follow-up CT scan. In one this increase was later followed by regression. Two patients required partial removal of tumour because of increasing symptoms after 3 and 7 years of follow-up; one of them died on the twelfth post-operative day. There appears to be a small group of patients for whom delay is worth while rather than to subject all patients with acoustic neuroma to surgery from which full recovery cannot be guaranteed.     

Evaluating the role of magnetic resonance imaging scans in the surgical management of acoustic neuromas

OBJECTIVE: To assess the reliability of magnetic resonance imaging (MRI) in predicting the size and position of an acoustic neuroma, with particular reference to the intracanalicular portion. STUDY DESIGN: Prospective study comparing the position of the tumor in the internal auditory canal on fast spin-echo MRI with the actual position measured intraoperatively. METHODS: The study was performed in a tertiary referral neurotology center, encompassing both the public and private health care systems. Fifteen consecutive patients admitted for acoustic neuroma removal via the translabyrinthine approach were studied. The main outcome measure was tumor position in the internal auditory canal expressed in millimeters, accurate to the nearest 0.5 mm. RESULTS: The fast spin-echo MRI was accurate within an error of 1 mm in predicting the lateral extent of the tumor in the internal auditory canal. CONCLUSION: Fast spin-echo MRI can accurately predict the lateral extent of an acoustic neuroma and allow accurate planning of the surgical approach.     

Long-term hearing results in gamma knife radiosurgery for acoustic neuromas

Objectives: There are many studies that have examined functional outcomes following Gamma Knife treatment; however, few have reported long‐term audiometric data. This study analyzed the long‐term hearing results of Gamma Knife radiosurgery in the treatment of acoustic neuromas. Study Design: Retrospective cohort study. Methods: Seventeen patients were selected from our acoustic neuroma Gamma Knife registry of 113 patients treated from 1991 to 2005. Pretreatment audiograms were analyzed for pure‐tone average and word recognition scores and assigned a Gardner‐Robertson classification score (GRC). Either a current audiogram was obtained or the most recent audiogram (if the patient was lost to follow‐up) was reviewed from clinic charts and these were compared with the preoperative results. Audiometric data of the pre‐ and posttreatment normal ear were obtained and used as the patient's own control. Results: The tumor size ranged from 0.5 to 2.8 cm (mean, 1.33 cm) and patients received a range of 12.5–16 Gy (mean, 13.82 Gy) to 50% isodose line. Patient follow‐up ranged from 3 to 82 months with a mean of 33.6 months. Pretreatment pure‐tone average for the involved side group was 30.6 dB HL with a word recognition score of 74%. Pretreatment mean GRC was 1.76. posttreatment pure‐tone average for the group was 59.7 dB HL with a word recognition score of 37%. posttreatment mean GRC was 3.29. Comparing pre‐ versus post‐Gamma Knife radiosurgery results on the treatment ear, means were statistically significantly different for both pure‐tone average and word recognition scores, based on a paired‐samples t test (P < .001 for both). The group “normal” ear pure‐tone average was 14 dB HL and 17.75 dB HL pre‐ and posttreat‐ment, respectively. Normal ear pre‐ and posttreatment word recognition score and GRC were 93% and 98%, and 1.13 and 1.31, respectively. Conclusion: Gamma Knife radiosurgery remains a noninvasive treatment option for patients with acoustic neuromas; however, they may experience a delayed hearing loss. Of those patients with useful audition pretreatment, 42% maintained useful hearing posttreatment.     

MRI in the detection of acoustic neuromas — a suggested protocol for screening

Magnetic resonance imaging (MRI) is the definitive investigation in the detection of an acoustic neuroma and its use is becoming increasingly widespread for this purpose. In the Oxford region, this facility has been available for 3 years, resulting in the scanning of the internal auditory meati and cerebellopontine angeles of 892 patients and the detection of 38 acoustic neuromas. Based on our use of this investigation over this time period, we have attempted to rationalize our entry protocol for screening by limiting the availability of the test to those patients up to 70 years of age presenting with unilateral audiovestibular symptoms in the absence of significant neurological symptoms or signs, with an average difference in hearing threshold of 15 dB between normal and symptomatic ears or unilateral tinnitus with normal hearing. By following these entry criteria, we would hope to maximize the available resources.     

MRI在听神经瘤检查中的作用探讨

目的 :探讨MRI在听神经瘤检查中的作用。方法 :2 0例听神经瘤均行MRI检查 ,取矢状位作定位像 ,行横断T1 WI、T2 WI扫描及矢状和冠状T1 WI/T2 WI扫描。均用造影剂Gd DTPA。结果 :肿瘤位于左侧 4例 ,右侧 1 6例。肿瘤直径 <2cm 4例 ,2 4cm 1 4例 ,>4cm 2例。T1 加权像呈等信号或低信号 ,T2 加权像呈高信号 ,出血或坏死可呈低高信号混杂。结论 :MRI是听神经瘤检查的首选方法 ,并在肿瘤的囊变、出血、周围情况了解上具有一定优越性 ,从而指导手术治疗     

The conservative management of acoustic neuroma: a review of forty‐four patients with magnetic resonance imaging

The management of acoustic neuromas is directed towards early diagnosis and surgical removal. The routine use of magnetic resonance imaging (MRI) has permitted the diagnosis of very small acoustic neuromas. However, it is becoming evident that not all acoustic neuromas will grow if left alone. In our series we followed 44 patients with acoustic neuromas for an average of 30.5 months and assessed their growth by serial MRI scanning. We followed 20 intracanalicular and 24 cerebello‐pontine angle lesions. In both groups the phenomenon of arrested growth was demonstrated in the majority. When growth did occur, it did so at a variable rate, but was always evident within the first year. We recommend an initial observation period of 1 year in all small neuromas. If growth occurs at this stage removal is indicated. When growth does not occur serial MRI review at increasing intervals indicated.     

双侧听神经瘤

目的探讨双侧听神经瘤的临床表现、生长特性及治疗。方法回顾性分析１９８７年６月～１９９７年５月间收治５例双侧听神经瘤的临床资料。结果本病约占全部听神经瘤患者的５％（５／９２）。５例的首发症状均为耳鸣伴听力减退。来诊时除位听神经症状外,有多个颅神经和脑干受累的临床表现。２例有孤立的浅褐色皮肤色素斑,５例有数量不等、分布不一的其它神经纤维瘤。５例中４例行一侧听神经瘤切除术,其中１例术后因脑水肿、高颅压、脑疝死亡。对１例术前、术后颅脑冠状位和轴位ＭＲＩ检查表明,其肿瘤平均每年朝上下、左右方向各生长１．１ｃｍ和０．７ｃｍ。结论双侧听神经瘤的治疗与单侧听神经瘤有不同。     

Unusual presentations of acoustic tumours

A series of 238 consecutive patients with acoustic neuromas, operated on in Paris has been studied to identify unusual presentations and varied symptomatology. The most common history was that of a progressive unilateral hearing loss (in 68.1%), with tinnitus (in 49.1%) or disequilibrium (in 49.1%) or both. Sudden hearing loss (in 14.7%) or fluctuating hearing loss (in 6.3%), and a single or repeated episodes of acute vertigo (in 8.8%) were seen less commonly. Headaches occurred as an associated symptom in 10.5%, tinnitus was the sole symptom in 2.8% and other uncommon symptoms included otalgia, facial nerve palsy, facial or ocular pain, altered sensation in the face or eye, or tingling of the tongue. Some 11.3% of patients presented with normal pure tone auditory thresholds and a 100% speech discrimination score and of these patients acoustic reflex thresholds were normal in 53% and brainstem auditory evoked responses were suggestive of the retro-cochlear abnormality in only 76.2%. Amongst the less common presentations, the initial symptoms mimicked such diagnoses as Meniére's disease, benign positional vertigo, vertebro-basilar migraine, vertebro-basilar insufficiency, Bell's palsy and Trigeminal neuralgia. Overall, 20.6% of patients had unusual initial presenting symptoms, 36.5% of the symptoms were unusual and these were found in isolation in 11.8% of patients. An awareness of the spectrum of more subtle symptoms of acoustic tumours may lead to the correct diagnosis at     

The translabyrinthine approach for the removal of large acoustic neuromas

Summary The results and the sequelae are reported from a series of consecutive 400 translabyrinthine removals of acoustic neuromas comprising almost all such tumors in Denmark during a 12-year period from 1976 to 1988. There were two intrameatal, 137 mediansized, 112 large and 149 advanced tumors, the latter having a diameter exceeding 40 mm. The mortality rate in the overall series was 2%. The incidence of cerebrospinal fluid leak occurred in 11%, and persisted for more than 2 weeks in 4%. Facial nerve function was completely normal in 67% of the patients, while only 5% required a nerve anastomosis.Presented at the First European Congress of Oto-Rhino-Laryngology and Cervico-Facial Surgery, Paris, 26–29 September 1988     

扩大迷路进路切除大听神经瘤18例报告

目的：探讨通过扩大的迷路进路切除大听神经瘤的方法和效果。方法：充分暴露乙状窦及其后方硬脑膜、岩上窦、颅中窝硬脑膜,暴露并下压颈静脉球,内听道周转骨质２７０℃以上切除。肿瘤切除从前下极处开始,以早期暴露脑干及脑干表面面神经,随后即从内侧向外侧解剖面神经。结果：１８例直径在３ｃｍ以上的听神经瘤（平均直径４．２ｃｍ）,均手术全切,脑组织无明显损伤。２例术后一过性脑脊液漏自愈,无颅内感染。面神经解剖及功能     

并发慢性中耳乳突炎的大听神经瘤经扩大迷路进路二期手术切除

目的：探讨经扩大迷路进路摘除伴发慢性中耳乳突炎的大听神经瘤的手术方法。方法：先一期手术彻底清除鼓室乳突病灶，术毕封闭中耳乳突腔；2周后行二期手术，经一期径路进行听神经瘤切除术。结果：2例并发慢性中耳炎的大听神经瘤均得到全切，术后面神经功能正常，切口一期愈合。随访半年以上无感染发生。结论：并发慢性中耳乳突炎的大听神经瘤同样可经扩大迷路进路进行手术切除。     

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.     

Physiological identification of the auditory nerve during surgery for acoustic neuroma

We report the design and clinical use of an electrode which can locate the acoustic nerve fibres in the normal eighth nerve and also in eighth nerves deformed by acoustic neuromas. The improvement in facial nerve preservation during acoustic neuroma surgery is partly due to the use of a facial nerve stimulator to anatomically locate the fibres. Our new acoustic nerve detector has the capability of anatomical location of cochlear fibres which may help to improve hearing preservation in selected cases of acoustic neuroma. The device functions by detecting the compound action potential evoked by no frequency auditory simulation at 500 Hz. The 500 Hz compound action potential is detected with a bipolar probe and then amplified and filtered. This results in a 500 Hz tone when the probe contacts the auditory nerve. Detection is virtually instantaneous. The acoustic nerve detector (AND) is demonstrated in a normal eighth nerve complex and its use is then described in the total removal of an acoustic neuroma with a 1 cm extracanalicular extension in which useful hearing was saved post-operatively. The present prototype may not be sensitive enough to detect the very low signals that may result when cochlear fibres are widely distorted around a large tumour or in cases where slight contusion of the nerve occurs during dissection. In all other cases the real time anatomical information is extremely helpful in guiding acoustic nerve dissection and also in monitoring the effects of petrous bone drilling.     

髓鞘结构在听神经瘤组织中的检测

目的:探讨来源于施万细胞的人类听神经细胞瘤组织中是否存在髓鞘结构及其细胞学特点。方法:应用免疫荧光标记、Western blotting及电镜等方法检测听神经瘤组织中的髓鞘结构及重要髓鞘蛋白。结果:电镜结果发现:听神经瘤组织中虽然缺失成熟的轴索结构但可以检测到早期的髓鞘样结构。免疫荧光研究和Western blotting研究结果显示:听神经瘤组织中检测不到轴索的标志性抗体——神经丝200的表达。并且启动髓鞘化的前哨信号及髓鞘致密化的重要组成蛋白——髓鞘碱性蛋白在听神经瘤组织中也无法检测到。而一种非成熟施万细胞的标志抗体——神经生长因子受体p75,在听神经瘤组织中可以检测到其表达。结论:在听神经瘤组织中的施万细胞失去了完成髓鞘化进程和重新形成致密的髓鞘并包绕轴索的能力,处于前髓鞘化施万细胞阶段。     

Effectiveness of conservative management of acoustic neuromas

OBJECTIVE: The goal of this study was to assess the effectiveness of the conservative management in patients with acoustic neuroma (vestibular schwannoma). STUDY DESIGN: This retrospective study was performed in a university hospital. PATIENTS: Patients were selected for this wait-and-see policy on the basis of age, general condition, audiometric results, tumor size, and patient preference. The study group included 97 patients, 87 of whom had at least two neuroradiologic examinations. The mean age of this population was 63 years (29 to 89 years). The mean length of follow-up of this population was 31 months. Eighty-seven of these patients had at least two radiologic examinations (magnetic resonance imaging or computed tomography). The mean interval between the initial and follow-up radiologic examinations was 15 months. MAIN OUTCOME MEASURES: Tumor size was measured by use of two-dimensional data in all patients. The mean tumor size was 12 mm. The growth rate of the tumor was estimated by comparison of the results of the measurements from the initial and follow-up neuroradiologic examinations. RESULTS: Of the 97 patients studied, 6 patients required surgery and 6 required radiotherapy. Sixty patients (62%) were still being treated conservatively at the end of the study period. Three patients of 28 who were classified as candidates for hearing preservation surgery lost their candidacy during the observation period. The mean annual tumor growth rate was 1.52 mm/year. The tumor was stable in size in 36% of patients, regressed in 11% of patients, or grew in 53% of patients. The growth patterns of the acoustic neuroma fell into five categories: continuous growth in 15% of patients, negative growth in 5%, growth followed by negative growth in 40%, negative growth followed by growth in 20%, and no variation of tumor size in 20%. CONCLUSION: Conservative management of acoustic neuromas carries difficulties: long-term follow-up of the patients and unpredictability of the tumor growth pattern. A reliable and reproducible radiologic method for evaluating tumor size is of great importance.