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.     

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。     

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.     

Cochlear implantation concurrent with translabyrinthine acoustic neuroma resection

OBJECTIVES/HYPOTHESIS: Cochlear implants provide successful auditory rehabilitation for patients with profound sensorineural hearing loss who do not derive at least marginal benefit from conventional hearing aids. Patients with neurofibromatosis type 2 can present with bilateral profound sensorineural hearing loss caused by bilateral vestibular schwannomas. Auditory rehabilitation in these patients can be challenging. We present the case of one such patient who underwent a concurrent translabyrinthine vestibular schwannoma resection and cochlear implantation in the same ear. STUDY DESIGN: A case report and review of the literature. METHODS: Review the patient's medical record and MEDLINE literature search. RESULTS: The patient presented with a relatively small tumor that was situated in the fundus of the internal auditory canal with intralabyrinthine extension. Postoperative performance with implant stimulation was in the higher range of that for other cochlear implant patients. CONCLUSIONS: To the best of our knowledge, this is the first case reported of simultaneous cochlear implant and translabyrinthine acoustic neuroma resection in the same ear of a patient with neurofibromatosis type 2.     

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.     

Bilateral acoustic neuromas]

OBJECTIVE: To investigate the clinical course, growth character and treatment of bilateral acoustic neuromas (BANs). METHODS: Five cases of BANs were reported. RESULTS: From 1986 to 1996, 92 patients with acoustic tumors were managed. Of them, 5(5%) bilateral acoustic neuromas were observed. All patients were males, the age at the time of testing ranged from 16 to 31 years (mean 23.8 years). In all patients, progressive hearing loss and tinnitus were the most common initial symptoms. In addition, signs of other cranial nerve deficits were detected in all patients. Two cases had cafe au lait spots and all cases had neurofibromas of varying sizes and shapes in subcutaneous tissues. Four had unilateral acoustic tumors operated on, one by the translabyrinthine approach, 3 by the suboccipital approach. One patient died due to encephaledema and hernia of brain after operation. According to the MRI data in one case, the average growth rate of acoustic tumor was 1.1 cm (superior/inferior) and 0.7 cm (medical/lateral) per year. CONCLUSION: The management of BANs patients presents challenging problems different from the unilateral acoustic tumors.     

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     

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.     

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     

Expression of steroid receptors in acoustic neuroma

The expression of steroid receptors has been investigated in an attempt to clarify the role of steroid hormones in the proliferation and progression of acoustic neuromas. Specimens of tumours taken during translabyrinthine surgery were tested for cytosolic (c) and nuclear (n) steroid receptors. Oestrogen and progesterone receptor levels were evaluated by enzymatic immuno-assay, while androgen receptor binding levels were detected by dextran-coated charcoal method in a single-step determination. In some cases, the six point Scatchard analysis of cytosolic and nuclear androgen receptor was also performed. Threshold values were: 3 fmol/mg of proteins for cytosolic steroid receptors and 20 fmol/mg DNA for nuclear steroids, which corresponded to approximate median values of cytosolic and nuclear oestrogen and progesterone, respectively. Oestrogen and progesterone appeared to be localized more frequently in the nuclei rather than in the cytosol (70% oestrogen and progesterone positivity in the nuclei; 30% oestrogen, 40% progesterone positivity in the cytosol), while androgen receptors were preferentially localized in the cytosol (80% positivity in the cytosol; 40% positivity in the nuclei). A negative non-linear correlation between cytosolic oestrogen and cytosolic androgen receptors was found. There was a direct linear correlation between cytosolic oestrogen and nuclear oestrogen levels. A strict correlation between nuclear oestrogen and nuclear progesterone incidence was shown. Preliminary analysis of clinical data and biochemical parameters showed that cytosolic progesterone levels inversely correlated with tumour size.     

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     

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.     

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。     

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。     

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.