Cerebellopontine angle surgery. Part 1: General remarks

OBJECTIVES: Cerebellopontine angle tumors, although uniform in location, are diverse with regard to the site of tumor origin and displacement of the neurovascular structures. With the increasing use of magnetic resonance imaging in the diagnosis of brain lesions, the treatment of tumors of the cerebellopontine angle has changed extraordinarily. An appreciation of the vascular and cranial nerve microanatomy and the intimate relationship between neurovascular structures and the tumor is essential for achieving optimal surgical results METHODS: A review was made of the current literature. RESULTS AND CONCLUSIONS: The different treatment options are compared with microsurgical tumor resection with respect to neurological outcome and long-term follow-up. As microsurgical removal is still the treatment of choice for such tumors, the indication for surgical treatment is analyzed and the different surgical approaches to the cerebellopontine angle are described in terms of their frequency of involvement in the surrounding neural and vascular structures with varying tumor size. The etiology of facial and cochlear nerve injury, as well as complications involving other cranial nerves, are discussed with emphasis on pathophysiological and anatomical considerations. In conclusion, the great variation in the anatomical location and the involvement of neurovascular structures in the cerebellopontine angle is demonstrated.     

Cerebellopontine angle tumors

Acoustic neuromas account for approximately 80 to 90 per cent of cerebellopontine angle tumors. Useful imaging studies include (1) high-resolution CT of the internal auditory canals using extended scale and "bone algorithm" techniques, (2) infusion study of the cerebellopontine cisterns, (3) gaseous or opaque CT cisternography, and (4) MRI.     

Cerebellopontine angle lipomas

Lipomas of the intracranial vault are uncommon lesions. Rarely, lipomas of the cerebellopontine angle have been identified. The two cases of cerebellopontine angle lipomas reported herein brings the number of recorded cases to 13.     

Cerebellopontine angle lipomatous hamartoma of nerve: case report.

Cerebellopontine angle lipoma has been previously described in 21 patients and is frequently unresectable. An intracanalicular lipomatous hamartoma in a 60-year-old male is presented. MRI enabled a correct preoperative diagnosis to be made. Complete surgical excision, without major neurologic deficit was achieved. A review of the literature reveals that the tumor is frequently infiltrative, especially when vascular elements are prominent. The histologic characteristics and the hamartomatous nature of the lesion are discussed.     

Cerebellopontine angle lesions: an audiological test protocol

Audiological test protocols were devised for use in patients suspected of having a cerebellopontine angle tumor. Data supporting the logic for inclusion of each test are presented. Protocol design was based on test results obtained in 45 tumor and 554 non-tumor patients. In summary, we found: 1) speech-in-noise results were of some value in those patients with normal hearing and of no value in those patients with hearing loss, 2) the acoustic reflex test gave misleading information in 25% of patients, and 3) the ABR test proved to be the most effective test in separating tumor and non-tumor patients. All individuals having cerebellopontine angle tumors and 11% of those without such lesions had abnormal ABR results in this series.     

Cerebellopontine angle involvement by nasopharyngeal carcinoma

OBJECTIVE: This article describes a series of patients with nasopharyngeal carcinoma involvement of the cerebellopontine angle and discusses the clinical significance of this entity. SETTING: Tertiary referral center. STUDY DESIGN: Retrospective case study. PATIENTS: Patients who were diagnosed with nasopharyngeal carcinoma with clinical features of cerebellopontine involvement by tumor. INTERVENTIONS: Cerebellopontine involvement by tumor confirmed by computed tomography, magnetic resonance imaging, or both. RESULTS: Patients with this entity either had advanced disease or had been treated previously for advanced nasopharyngeal carcinoma. They had varied clinical features attributable to cerebellopontine involvement, such as sensorineural deafness, dizziness, facial palsy, and facial numbness. CONCLUSIONS: Cerebellopontine angle involvement by nasopharyngeal carcinoma is a difficult entity, both from the diagnostic and therapeutic points of view. In high-risk patients, particularly in patients who were previously treated for advanced nasopharyngeal carcinoma, a high index of suspicion for nasopharyngeal carcinoma involvement of the cerebellopontine angle is warranted when they experience unexplained neurootologic symptoms such as sensorineural hearing loss, dizziness and facial palsy.     

Cerebellopontine angle lymphoma presenting as chronic mastoiditis

Middle-ear tumours are not uncommonly mistaken for mastoiditis on presentation. We report a case of cerebellopontine angle non-Hodgkin's B-cell lymphoma originally presenting as a middle-ear inflammatory process. In mastoiditis not resolving with conventional treatment it is important to look for an underlying cause.     

Cerebellopontine angle tumor composed of Schwann and meningeal proliferations.

Tumors found in the cerebellopontine angle are predominantly vestibular schwannomas. Mixed tumors found within the cerebellopontine angle are thought to be exceedingly rare and exclusively associated with neurofibromatosis 2. We report a case of a mixed tumor composed of Schwann and meningeal cell proliferations in a patient who was not diagnosed as having neurofibromatosis 2. Mixed tumors composed of neoplastic Schwann and meningeal cells have rarely been reported. However, new evidence indicates that these mixed tumors may be more common than was previously thought and may have an interrelated mechanism of pathogenesis. Although the case we describe does not fulfill the current diagnostic criteria for neurofibromatosis 2, a presumptive diagnosis was given, suggesting that the current diagnostic criteria for neurofibromatosis 2 may be too narrow.     

Cerebellopontine angle epidermoid in a noise-exposed patient

A cerebellopontine angle epidermoid was identified in a noise-exposed patient as part of an occupational hearing conservation program. The patient is a 24-year-old employee of a major national newspaper who, because of workplace noise levels, was required to be part of a hearing conservation program. A shift in thresholds in 1 year was identified by the audiologic reviewer and referral for audiologic and otologic services was recommended and carried out. The steps leading from the initial air-conduction, pure-tone audiogram to final neurosurgical removal of the epidermoid CPA lesion was described. Such referral is essential if potentially health and life threatening conditions are to be identified and managed, although the primary objectives of the hearing conservation program remains the prevention of sensorineural hearing loss from workplace noise exposure.     

Cerebellopontine angle meningioma resulting in middle-ear polyp

Extracranial spread of meningiomas to involve the middle ear is very rare. We present the case of a 43-year-old woman with a known cerebellopontine angle meningioma who subsequently presented with left-sided otalgia and a middle-ear mass extruding through the tympanic membrane due to local invasion of the meningioma. The tumour was excised surgically. A discussion of the relevant literature is also presented.     

部分迷路切除行小脑桥脑角区手术的临床解剖学测量

目的　为临床上保留半规管功能和听力处理小脑桥脑角区病变提供解剖学资料。方法　在 2 0例40侧国人成人尸头上模拟单纯后半规管切除及后、上半规管切除处理小脑桥脑角区病变 ,对暴露的范围进行解剖测量 ,比较相关数据。结果　岩上窦下缘至颈静脉球顶的垂直线距离为 (15.0 2± 3 .69)mm (7.80～ 2 1.3 0 ) ,乙状窦内侧至内淋巴管起始处的水平距离为 (10 .62± 2 .0 9)mm (6.2 0～ 16.80 ) ,颞骨岩部后硬脑膜至外半规管后壶腹后缘的水平距离为 (6.2 1± 1.78)mm (3 .80～ 10 .10 ) ,至后半规管中点后缘水平距离为 (4.0 7± 1.2 6)mm (2 .10～6.60 )。乙状窦内侧至内听道口后缘中点水平距离为 (19.89± 3 .10 )mm (14 .70～ 2 4.60 ) ,岩骨后硬脑膜至上半规管前壶腹后缘间水平距离为 (12 .60± 2 .73 )mm (8.2 0～ 19.10 )。结论　颞骨径路处理小脑桥脑角区病变同时保留听力和平衡功能是可能的 ,相对而言 ,后上半规管切除比单纯后半规管切除所得的术野大 ,暴露好且操作相对简单 ,不易发生并发症     

Cerebellopontine angle and internal auditory canal metastasis from ductal carcinoma of the breast

This is the first formal case report of internal auditory canal and cerebellopontine angle metastasis from infiltrative ductal carcinoma of the breast. Only three previous cases have been reported of isolated metastasis in the cerebellopontine angle and internal auditory canal from breast cancer. Currently, no therapeutic guidelines for isolated metastasis from breast cancer in this location exist. We report a case and review the current literature in order to help characterize the clinicopathologic features and management. A 72-year-old female with a 5-year history of left infiltrative ductal carcinoma of the breast reported progressive left-sided facial palsy and ipsilateral hearing loss accompanied by the development of tinnitus and unsteadiness during the previous 3 months. MRI identified a lesion in the cerebellopontine angle and internal auditory canal. The lesion was completely excised via a retrosigmoidal approach and adjuvant radiotherapy was used subsequently. The patient remains well 18 months after treatment, with no evidence of recurrence on repeat MRI. The rapid evolution of symptoms involving the Vth, VIIth or VIIIth cranial nerve, or multiple cranial nerves, is suggestive of a malignant lesion of the cerebellopontine angle and/or internal auditory canal. A previous history of neoplasm is important due to the possibility of a metastasis. Cerebellopontine angle metastasis can be found many years after the initial diagnosis of breast neoplasm. Surgery and adjuvant radiotherapy seems to be a good choice for the treatment of patients with this specific type of metastasis.     

Cerebellopontine angle and internal auditory canal metastasis from ductal carcinoma of the breast

This is the first formal case report of internal auditory canal and cerebellopontine angle metastasis from infiltrative ductal carcinoma of the breast. Only three previous cases have been reported of isolated metastasis in the cerebellopontine angle and internal auditory canal from breast cancer. Currently, no therapeutic guidelines for isolated metastasis from breast cancer in this location exist. We report a case and review the current literature in order to help characterize the clinicopathologic features and management. A 72-year-old female with a 5-year history of left infiltrative ductal carcinoma of the breast reported progressive left-sided facial palsy and ipsilateral hearing loss accompanied by the development of tinnitus and unsteadiness during the previous 3?months. MRI identified a lesion in the cerebellopontine angle and internal auditory canal. The lesion was completely excised via a retrosigmoidal approach and adjuvant radiotherapy was used subsequently. The patient remains well 18?months after treatment, with no evidence of recurrence on repeat MRI. The rapid evolution of symptoms involving the Vth, VIIth or VIIIth cranial nerve, or multiple cranial nerves, is suggestive of a malignant lesion of the cerebellopontine angle and/or internal auditory canal. A previous history of neoplasm is important due to the possibility of a metastasis. Cerebellopontine angle metastasis can be found many years after the initial diagnosis of breast neoplasm. Surgery and adjuvant radiotherapy seems to be a good choice for the treatment of patients with this specific type of metastasis.     

Cerebellopontine pantopaque cisternography and tomography of the internal acoustic meatus in the diagnosis of angle tumors.

The results of 106 consecutive Pantopaque cisternographies performed at the neuro-radiological department, Rigshospitalet, are presented. 41 positive and 65 negative examinations were found. Good accordance between radiological tumor size estimation and size of actual, surgically verified tumor was noted. A comparison between tomography of the internal auditory canal and pantopaque cisternography of the posterior fossa has been made, and we found 6 cases with normal tomography and positive cisternography. Furthermore 17 cases (26%) with pathological tomographic examination of internal auditory canal as well as a negative finding at Pantopaque cisternography, were encountered. Therefore we conclude that asymmetry of the radiological appearance of the internal auditory canal at tomography is not of decisive importance in the indication for cisternography, but the examination should be included in the test battery in search for cerebellopontine angle pathology. We agree with other authors that Pantopaque cisternography is without any doubt the final and most conclusive examination available for the diagnosis of cerebellopontine angle tumors. A system of grading the different objective findings giving indication for Pantopaque cisternography has been made.     

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。