title: Efficacy and outcomes of facial nerve-sparing treatment approach to cerebellopontine angle meningiomas.
abstract: OBJECTIVE Advanced microsurgical techniques contribute to reduced morbidity and improved surgical management of meningiomas arising within the cerebellopontine angle (CPA). However, the goal of surgery has evolved to preserve the quality of the patient's life, even if it means leaving residual tumor. Concurrently, Gamma Knife radiosurgery (GKRS) has become an acceptable and effective treatment modality for newly diagnosed, recurrent, or progressive meningiomas of the CPA. The authors review their institutional experience with CPA meningiomas treated with GKRS, surgery, or a combination of surgery and GKRS. They specifically focus on rates of facial nerve preservation and characterize specific anatomical features of tumor location with respect to the internal auditory canal (IAC). METHODS Medical records of 76 patients with radiographic evidence or a postoperative diagnosis of CPA meningioma, treated by a single surgeon between 1992 and 2016, were retrospectively reviewed. Patients with CPA meningiomas smaller than 2.5 cm in greatest dimension were treated with GKRS, while patients with tumors 2.5 cm or larger underwent facial nerve-sparing microsurgical resection where appropriate. Various patient, clinical, and tumor data were gathered. Anatomical features of the tumor origin as seen on preoperative imaging confirmed by intraoperative investigation were evaluated for prognostic significance. Facial nerve preservation rates were evaluated. RESULTS According to our treatment paradigm, 51 (67.1%) patients underwent microsurgical resection and 25 (32.9%) patients underwent GKRS. Gross-total resection (GTR) was achieved in 34 (66.7%) patients, and subtotal resection (STR) in 17 (33.3%) patients. Tumors recurred in 12 (23.5%) patients initially treated surgically, requiring additional surgery and/or GKRS. Facial nerve function was unchanged or improved in 68 (89.5%) patients. Worsening facial nerve function occurred in 8 (10.5%) patients, all of whom had undergone microsurgical resection. Upfront treatment with GKRS for CPA meningiomas smaller than 2.5 cm was associated with preservation of facial nerve function in all patients over a median follow-up of 46 months, regardless of IAC invasion and tumor origin. Anatomical origin was associated with extent of resection but did not correlate with postoperative facial nerve function. Tumor size, extent of resection, and the presence of an arachnoid plane separating the tumor and the contents of the IAC were associated with postoperative facial nerve outcomes. CONCLUSIONS CPA meningiomas remain challenging lesions to treat, given their proximity to critical neurovascular structures. GKRS is a safe and effective option for managing CPA meningiomas smaller than 2.5 cm without associated mass effect or acute neurological symptoms. Maximal safe resection with preservation of neurological function can be performed for tumors 2.5 cm or larger without significant risk of facial nerve dysfunction, and, when combined with GKRS for recurrence and/or progression, provides excellent disease control. Anatomical features of the tumor origin offer critical insights for optimizing facial nerve preservation in this cohort.
authors.affiliation: Departments of1Neurological Surgery and.
authors.forename: Randy S
authors.initials: RS
authors.lastname: D'Amico
authors.affiliation: Departments of1Neurological Surgery and.
authors.forename: Matei A
authors.initials: MA
authors.lastname: Banu
authors.affiliation: Departments of1Neurological Surgery and.
authors.forename: Petros
authors.initials: P
authors.lastname: Petridis
authors.affiliation: Departments of1Neurological Surgery and.
authors.forename: Alexandra S
authors.initials: AS
authors.lastname: Bercow
authors.affiliation: Departments of1Neurological Surgery and.
authors.forename: Hani
authors.initials: H
authors.lastname: Malone
authors.affiliation: Departments of1Neurological Surgery and.
authors.forename: Moshe
authors.initials: M
authors.lastname: Praver
authors.affiliation: 2Radiation Oncology, Columbia University Medical Center, New York, New York.
authors.forename: Tony J C
authors.initials: TJC
authors.lastname: Wang
authors.affiliation: Departments of1Neurological Surgery and.|2Radiation Oncology, Columbia University Medical Center, New York, New York.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Isaacson
authors.affiliation: Departments of1Neurological Surgery and.|2Radiation Oncology, Columbia University Medical Center, New York, New York.
authors.forename: Michael B
authors.initials: MB
authors.lastname: Sisti
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005154:Facial Nerve / Q000000981:diagnostic imaging / Q000601:surgery*; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008579:Meningioma / Q000000981:diagnostic imaging / Q000532:radiotherapy / Q000601:surgery*; D008866:Microsurgery / Q000379:methods*; D008875:Middle Aged; D009464:Neuroma, Acoustic / Q000000981:diagnostic imaging / Q000532:radiotherapy / Q000601:surgery*; D019635:Neurosurgical Procedures / Q000379:methods*; D016634:Radiosurgery; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome
keywords: CN = cranial nerve; CPA = cerebellopontine angle; EMG = electromyography; EOR = extent of resection; GKRS = Gamma Knife radiosurgery; GTR = gross-total resection; Gamma Knife; IAC = internal auditory canal; STR = subtotal resection; TTP = time to progression; brain tumor; cerebellopontine angle; intracranial; meningioma; microsurgery; oncology; skull base