21.1IntroductionMeningiomas are the second most common tumors of the cerebellopontine angle (CPA) after vestibular schwanno-mas, comprising 6–15% of cases [3, 19, 34]. They share a common location, the area of the CPA, but their site of dural origin and their relationship to surrounding neu-rovascular structures of the CPA are variable. Therefore, the clinical presentation and outcome after surgery may be different.Rokitansky in 1856 [23] was the first to report a tumor, which is classified as a CPA meningioma, and Virchow later described a psamomma originating from the poste-rior lip of the meatus acusticus [36]. In 1928, Cushing and Eisenhardt reported a series of seven patients with me-ningiomas “simulating acoustic neuromas,” emphasizing the high surgical risk in dealing with these tumors [5].Posterior fossa meningiomas involving the CPA have been recognized as a particular entity since then [8, 13, 15, 22, 24, 31]. With the advent of microsurgical tech-niques, Yasargil et al. [38], Sekhar and Janetta [32], Oje-mann [21], Al-Mefty et al. [1, 11, 12], and Samii et al. [17, 25, 26, 28] reported results after resection of these tumors. The term CPA meningioma has been used to include meningiomas, which share a common location, that is, occupancy of the CPA. Despite this common loca-tion, these tumors may have diverse origins with regard to the site of dural attachment, which can be outside the CPA. Accordingly, the relationship of the tumor to the surrounding neurovascular structures, especially the fa-cial and cochlear nerve, can be quite variable [17, 25, 28, 30, 37].Previous reports have indicated that the clinical pre-sentation and outcome differs between CPA meningio-mas lying anterior or posterior to the IAC [25, 30]. The surgical series of CPA meningiomas at the Nordstadt Hospital, Hannover, Germany, allowed further detailed investigation of the tumor location related to the inner auditory canal (IAC), with special consideration of the pre- and postoperative facial and cochlear nerve func-tion. A subclassificaiton of CPA meningiomas into five groups was enabled based on the large number of patients treated at our institution.21.2Patients and MethodsBetween 1978 and 2002, a total of 1800 cases of menin-giomas were operated at the Nordstadt Hospital. Among them, there were 421 CPA meningiomas. Evaluation of pre- and postoperative clinical data, with special empha-sis on audiologic and facial nerve findings, and neurora-diological imaging studies was based on 347 patients with complete data material.Our clinical data analysis included 270 females (77.8%) and 77 males (22.2%). The mean age of the patients was 53.4 years (range 17.6–84 years). The pre- and postop-Contents21.1 Introduction (221)21.2 Patients and Methods (221)21.3 Results (222)21.3.1 Tumor Location (222)21.3.2 Nerve–Tumor Relationship (222)21.3.3 Tumor Resection (224)21.3.4 Complications . . . . . . . . . . . . . . . . . . . . . . . . . 225 21.3.5 Facial Nerve Function (225)21.3.6 Auditory Function (226)21.3.7 Long-term Follow Up (226)21.4 Discussion (227)21.5 Conclusion (229)References (229)
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