Non-auditory presentations of cerebellopontine angle lesions

Most patients with cerebellopontine angle (CPA) neoplasms present with asymmetric hearing loss and/or tinnitus. For this reason it is well accepted that patients with these symptoms deserve a detailed neurotologic evaluation. Non-auditory presentations of CPA neoplasms, on the other hand, are frequently handled in a more complacent manner which may delay diagnosis and, therefore, result in increased morbidity. Six patients seen in the last 18 months serve to exemplify this point, as all 6 presented with non-auditory symptoms of CPA lesions and, in all cases, the diagnosis was delayed for at least 6 months. Any cranial neuropathy, unless otherwise explained, should suggest the presence of an intracranial or skull base lesion. The practicing physician must learn to give these non-auditory symptoms respect equal to that of asymmetric hearing loss and tinnitus and, therefore, equal evaluation.     

Retrolabyrinthine transtentorial approach to lesions of the anterior cerebellopontine angle.

Various surgical approaches to the cerebellopontine angle have been used for removal of acoustic neuromas. A retrolabyrinthine transtentorial approach has been developed that allows (1) access to the anterior cerebellopontine angle and all portions of the basilar artery, (2) extra dural retraction of the lateral sinus and cerebellum while avoiding the vein of Labbé, and (3) preservation of hearing. This approach allows good exposure of tumor and accurate visualization of cranial nerves. To avoid complications, control of spinal fluid is mandatory and great care must be taken to avoid injury of the cranial nerves. The retrolabyrinthine or translabyrinthine transtentorial approach enables skilled neurosurgeons and neurotologists to gain access to lesions that are located in areas difficult to approach.     

Magnetic resonance imaging of temporal bone and cerebellopontine angle lesions

Lesions of the temporal bone and cerebellopontine angle present a diagnostic challenge because of the complex anatomy, multiplicity of lesions, and difficulty in imaging the dense bone of this area. Magnetic resonance imaging, a new, nonionizing imaging modality, dependent on monitoring a radiofrequency signal emitted by excited nuclei in an external magnetic field, has shown promise in imaging of the temporal bone and posterior fossa.     

Diagnosis of cerebellopontine angle tumors.

Between 1980 and 1990, 9,176 patients suffering from otoneurological disorders were investigated in our clinic. Sixty-six (0.72%) internal auditory canal or other cerebellopontine angle tumors (CPAT) were diagnosed. Brainstem auditory evoked potentials (BAEP), interaural time discrimination, and magnetic resonance imaging (MRI) revealed to be the most sensitive and efficient tests for the detection of CPAT. However, the investigation of otoneurological symptoms cannot be limited to BAEP and MRI on the a priori of a hypothetical CPAT. Electrophysiologic tests such as impedancemetry, and electronystagmographic testing are also needed to elucidate the many causes of otoneurological symptoms.     

Computerized axial tomography with air contrast of the cerebellopontine angle and internal auditory canal.

The introduction of computerized axial tomography (C.T.) in 1973 completely changed the diagnostic evaluation of acoustic neuromas. Seventy to eighty percent of all acoustic neuromas can be diagnosed with intravenous enhanced C.T. scan. Acoustic tumors with a diameter of less than 1.5 cm., however, are not consistently seen on C.T. scan. Twenty-six consecutive patients were evaluated by C.T. scan with air contrast posterior fossa myelography (C.T. air cisternography). Nineteen studies were normal, with complete air filling of the internal auditory canal. Surgically verified acoustic neuromas were demonstrated in four patients. Two studies were inconclusive and there was one false positive. Other than headaches, there is no morbidity associated with this technique. C.T. air cisternography should be considered as the definitive study for evaluating patients for acoustic neuromas who have normal intravenous contrast enhanced C.T. scans. This study reports the first intracanalicular tumor diagnosed with this technique.     

内窥镜下桥小脑角手术

目的 探讨内窥镜在桥小脑角手术中的适应症、技术方法。方法 气管插管全身麻醉,通过录像监视器观察,内窥镜经乙状窦后进路进入桥小脑角,首先看到面、听神经和内听道,内窥镜向上可看到三叉神经、外展神经、岩静脉,向下可看到颈静脉孔和舌咽、迷走神经、然后根据下同的手术要求进行神经根减压、梳理及选择性切断术。结果 面神经根梳理术3例;三叉神经根减压术1例;感觉根选择性切断术9例;前庭神经切断术3例。结论 内窥镜扩大了桥小脑角区的手术视野,可以观察到手术显微镜下不易观察到的部位,减少了手术创伤,增加了手术的安全性。     

内耳道及桥小脑角非听神经瘤病变的临床分析

目的　探讨内耳道及桥小脑角非听神经瘤病变的诊断以及影像学检查在鉴别诊断中的作用。方法　回顾分析上海交通大学医学院耳科学研究所2001年1月～2016年12月185例内耳道及桥小脑角非听神经瘤的病例资料,其中后组颅神经鞘瘤65例,面神经瘤55例,脑膜瘤25例,胆脂瘤9例,恶性肿瘤9例,三叉神经鞘瘤8例,海绵状血管瘤6例,蛛网膜囊肿5例,脂肪瘤3例。所有病例均接受手术治疗,术前诊断和手术入路根据术前临床表现、颞骨高分辨率CT和MRI检查结果确定,术后均病理确诊。结果　185例患者中男96例,女89例,年龄11～77岁,平均（46.4±25.6）岁,术后平均随访（5.1±3.2）年,病变均全切除,术后并发症脑脊液漏4例（2.2%）,术后随访过程中死亡4例（均为桥 小脑角恶性肿瘤）,1例胆脂瘤复发。各类内耳道及桥小脑角非听神经瘤病变有特征性影像学表现,根据术前临床表现、颞骨高分辨率CT和MRI检查结果诊断准确率为93.5% （173/185）。结论　准确的术前诊断对制定内耳道及桥小脑角病变的治疗策略具有重要意义;术前结合临床表现、颞骨高分辨率CT和MRI检查结果可明显提高诊断准确率。     

Bilateral cerebellopontine angle lipomas

Cerebellopontine angle (CPA) lipomas are extremely rare lesions and usually unilateral. We describe a case of a 36-year-old man with bilateral aural fullness that was discovered to have bilateral CPA lipomas associated with an abnormal hindbrain segmentation appearance. The patient was evaluated with 3.0T magnetic resonance imaging (MRI) system. MRI demonstrated the presence of bilateral CPA masses partially extending into the internal auditory canals. These lesions were hyperintense on both T1- and T2 weighted images. Facial and vestibulo-cochlear nerves together with tortuous vascular structures and fibro-connective septa were identified on T2-weighted 3D Fast Imaging Employing Steady-state Acquisition (FIESTA) sequences as areas of lower intensity coursing through the masses. Gadolinium administration yielded no enhancement. Conservative management was adopted.     

Transotic approach to the cerebellopontine angle.

The transotic approach to the cerebellopontine angle for resection of tumors invading the internal auditory canal provides superior illumination and exposure for optimal preservation of facial nerve function. Separation of facial nerve from tumor is enhanced with an anterior exposure that allows visualization of the intracranial segment of the nerve before tumor removal without significantly increasing total operative time. Facial nerve grafting or hypoglossal-facial anastomosis may be incorporated into the procedure at the time of tumor resection using the transotic approach. When combined with a musculofascial patch secured to the dural defect, the initial subtotal petrosectomy with eustachian tube and middle ear cleft obliteration generally avoids the complication of an immediate or delayed postoperative cerebrospinal fluid leak. The transotic approach is indicated for tumors up to 2.5 cm in size that are not adherent to the brain stem.     

耳内镜辅助下桥小脑角手术

目的探索耳内镜在桥小脑角(CPA)手术中的应用.方法自2002年11月以来采用耳内镜结合显微镜开展CPA微创手术12例,手术均采用全麻下乙状窦后入路,并行面神经肌电位和听性脑干诱发电位术中监测.听神经瘤7例,桥小脑角面神经肿瘤2例,三叉神经鞘瘤1例,对肿瘤病例内镜主要用于检查内耳道底部有否残留病灶,探查面神经位置和走行,分离残留瘤体.舌咽神经痛1例,内镜下显露CPA和内听道口,显露后组颅神经,并确认舌咽神经,将其游离,用微型剪将之切断.半面痉挛1例,用30°内镜观察内听道口的解剖和后组颅神经的位置,在不牵拉小脑的情况下寻找对面神经形成压迫的责任血管.面神经功能按House-Brackmann分级标准评价.结果所有病例均顺利完成,无死亡病例,无并发后组颅神经损伤.听神经瘤7例,6例全切,1例绝大部分切除,残留脑干表面和内听道内的少许囊壁;均保留面神经解剖结构完整,术后一周面神经功能Ⅰ级2例,Ⅱ级3例(术后3个月Ⅰ级),Ⅲ级2例(术后3个月分别为Ⅰ级和Ⅱ级).面神经鞘瘤2例,肿瘤均全切,1例保留面神经解剖结构完整,术后面神经功能Ⅲ级,术后3个月Ⅱ级,另1例面神经连同肿瘤一起切除,一期面神经-舌下神经吻合,术后1年面神经功能Ⅱ级.三叉神经鞘瘤1例,肿瘤全切,术后一周面神经功能Ⅲ级,术后3个月Ⅱ级.听神经瘤7例术前有残余听力4例,术后有1例保存术前听力;面神经肿瘤2例,术后保存残余听力1例;其余肿瘤病例术后均未保存听力.舌咽神经切断术后症状完全消失,随诊6个月未复发.面神经微血减管压并梳理术后症状明显好转,间断轻度抽搐,面神经功能Ⅱ级,随访1年仍只为轻度抽搐.结论耳内镜与手术显微镜有机结合,达到桥小脑角手术微创的目的,既可清除病变,又能最大限度地保存功能.但耳内镜目前还只是一种辅助的手段,仍有一定局限性,需进一步完善.     

Lipoma of the cerebellopontine angle

Lipomas of the cerebellopontine angle (CPA) are unusual tumors that typically present with hearing loss, tinnitus, dizziness, and occasionally facial neuropathies. We describe the case of a healthy 42-year-old woman who presented with left-sided hearing loss and facial synkinesis. T1-weighted magnetic resonance imaging revealed an enhancing lesion of the left CPA with no signal on fat suppression sequences. Despite conservative therapy, the patient developed progressive hemifacial spasm, and a suboccipital craniotomy approach was used to debulk the tumor, which encased cranial nerves V, VII, VIII, IX, X, and XI. Surgical histopathology demonstrated mature adipocytes, consistent with lipoma. Two years after surgery, the patient remains free of facial nerve symptoms. Cerebellopontine angle lipomas are rare lesions of the skull base and are reliably diagnosed with T1-weighted and fat suppression magnetic resonance sequences, which we recommend in the routine radiologic workup of CPA tumors. Accurate preoperative diagnosis is crucial because most CPA lipomas should be managed conservatively. Partial surgical resection is indicated only to alleviate intractable cranial neuropathies or relieve brainstem compression.     

The diagnosis and management of cerebellopontine angle tumors.

The diagnosis and surgical management of cerebellopontine angle tumors remains a challenge. Early detection and microsurgical technique have lowered mortality rates and have allowed surgeons to preserve facial nerve function in a high percentage of cases. The purpose of this paper is to report a series of 171 lesions removed through the middle fossa, translabyrinthine, and combined translabyrinthine-suboccipital approaches. Results and complications are covered in detail.     

小脑脑桥角脑膜瘤的显微手术治疗

目的：提高小脑脑桥角（CPA）脑膜瘤的显微手术治疗效果。方法：回顾性分析27例CPA脑膜瘤，根据影像学特征及肿瘤生长方式分为3种类型：Ⅰ型肿瘤基底位于内听道附近者（包括向天幕下生长者）12例；Ⅱ型肿瘤基底在CPA和岩尖向中上斜坡及中颅窝延伸者12例；Ⅲ型肿瘤基底在颈静脉孔附近主要向枕骨大孔延伸者3例。Ⅰ型采用枕下乙状窦后入路；Ⅱ型采用颞枕开颅乙状窦前入路；Ⅲ型采用枕下开颅远外侧入路。结果：按脑膜瘤切除Kabayashi法分级：Ⅰ级4例，Ⅱ级6例，Ⅲ-ⅣA级7例。2例于术后2周内因脑干缺血、水肿或肺部感染死亡。20例随访（平均3.8年），19例恢复良好。2例肿瘤复发，行伽玛刀治疗。结论：Ⅰ型经CPA开颅乙状窦后入路手术切除容易，主要注意保护面神经和听神经；Ⅱ型采用颞枕开颅乙状窦前入路肿瘤全切除可能性大；Ⅲ型采用枕下开颅远外侧入路肿瘤暴露佳，但要注意后组脑神经的保护。     

Cholesterol granuloma of the cerebellopontine angle

Two unusual cases of cholesterol granuloma of the temporal bone manifested as cerebellopontine angle tumors. To our knowledge, cerebellopontine angle extension of this lesion has not previously been reported. Obstruction of ventilation and drainage of any air complex in the temporal bone may produce cholesterol granuloma. Asymptomatic involvement of the mastoid air cell system is common in chronic otitis media. Surgical management of cholesterol granuloma with cerebellopontine angle extension is recommended. Total excision of the lesion is preferred; marsupialization into the mastoid air cell system is an alternative if excision would produce a major neurologic deficit.     

Congenital cholesteatomas of the cerebellopontine angle

Thirty cases of congenital cholesteatomas of the cerebellopontine angle (CPA) treated over a period of 20 years are reviewed with regard to their clinical features, the pathophysiology of their symptoms, and their management. The predominant symptoms were related to cranial nerves VII and VIII and headaches. Signs and symptoms were divided into those caused by local involvement of the cholesteatoma, increased intracranial pressure, or both. Diagnostic procedures from invasive procedures such as ventriculography to more sophisticated noninvasive procedures including computed tomography and magnetic resonance imaging are discussed. The surgical management of 27 congenital cholesteatomas was accomplished via a posterior cranial fossa approach. Total excision of the cholesteatoma was the aim but was carried out in only five (18%) patients because of concern regarding the preservation of nearby neurovascular structures. Partial excision was possible in 22 (82%) patients. To minimize re-formation, the residual cholesteatoma was carefully cauterized with the aid of the operating microscope and bipolar diathermy without damaging surrounding neurovascular structures. Follow-up has ranged from 2 to 15 years, with four (13%) cases of re-formation.     

Audiologic presentation of cerebellopontine angle cholesteatoma

OBJECTIVE: The aim of this study was to examine the audiologic presentation of patients with cerebellopontine angle (CPA) cholesteatoma. DESIGN: Retrospective case review. SETTING: Neuro-otologic tertiary referral centre. METHODS: The study population consisted of 11 patients with CPA cholesteatomas. The patients underwent a standard audiologic investigation in the preoperative setting, which consisted of pure-tone audiometry, speech audiometry, and auditory brainstem response (ABR). MAIN OUTCOME MEASURES: The audiologic parameters that were analyzed were the pure-tone threshold, pure-tone average (PTA), and speech discrimination scores (SDSs). The morphology and latency of the ABR were evaluated. In addition, the clinical and radiologic presentations of the lesions were reviewed. RESULTS: The mean PTA in the diseased ear was 22.6 dB HL (SD 18.2), whereas in the contralateral ear, it was 19.1 dB HL (SD 19.6). In 4 patients, the hearing loss was asymmetric, with the diseased ear being the worse ear. The mean SDS was 82.28% in the affected ear and 95.28% in the contralateral ear. ABR was abnormal in 9 of 10 cases (90%), with only the affected ear being abnormal in 4 cases. In the other 5 cases, the ABR was bilaterally abnormal. CONCLUSIONS: CPA cholesteatomas are very slow-growing lesions that involve the eighth cranial nerve. The paucity and insidious onset of symptoms mean that the diagnosis is often late, permitting the lesions to reach impressive dimensions at the time of diagnosis. Although magnetic resonance imaging represents the gold standard in the diagnosis of these lesions, ABR proved to be of value in the assessment of the auditory pathway, especially in those patients referred with a vague symptomatology and with normal hearing.     

Mixed glioma of the cerebellopontine angle

A rare case of mixed ependymoma and astrocytoma of the cerebellopontine angle is reported. Its clinical presentation, characteristics on evaluation, and prognosis are compared with those of the acoustic neuroma and glioma. The central form of von Recklinghausen's disease and familial multiple lipomatosis as it applies to the patient is also discussed.