Efficacy and outcomes of facial nerve–sparing treatment approach to cerebellopontine angle meningiomas

Abstract

ABBREVIATIONS CN = cranial nerve; CPA = cerebellopontine angle; EMG = electromyography; EOR = extent of resection; GKRS = Gamma Knife radiosurgery; GTR = gross-total resection; IAC = internal auditory canal; STR = subtotal resection; TTP = time to progression. SUBMITTED August 3, 2016 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 ef...

Clinical Studies and Pre-clinical Animal Models on Facial Nerve Preservation, Reconstruction, and Regeneration Following Cerebellopontine Angle Tumor Surgery–A Systematic Review and Future Perspectives

“…The most commonly reported pathology by far was VS, diagnosed in 17,946 (93.9%) individuals, followed by CPA-meningioma in 513 (2.6%) individuals and rare pathologies in 677 (3.5%) individuals, being consistent with previous reports (Grey et al, 1996a;D'Amico et al, 2017). Understanding the different growth patterns and their anatomical relationship to the FN is essential when surgical management is necessary (Sampath et al, 1997(Sampath et al, , 1998Prasad et al, 2016;D'Amico et al, 2017). The current review revealed severe FN palsy in 7 to 15 % after vestibular schwannoma surgery, and 6% following the resection of CPA-meningioma (Tables 1-6).…”

“…In tumors that extend anterior and inferior to the FN, the tumor parts between the FN and the lower cranial nerves are carefully debulked up to a rest of tumor anterior to the FN. Finally, the tumor attached to the deep aspects of the FN is dissected off the surface (Table 5; Sekhar and Jannetta, 1984;Schaller et al, 1995;Thomas and King, 1996;Mallucci et al, 1999;Voss et al, 2000;Roberti et al, 2001;Batra et al, 2002;Bassiouni et al, 2004;Roser et al, 2005;Jiang et al, 2006;Baroncini et al, 2011;Nowak et al, 2013;D'Amico et al, 2017). Eight of the included studies (Fichten et al, 2006;Bakar, 2008;Sharma et al, 2008;Cho et al, 2009;Gunther et al, 2010;Mowry et al, 2012;Llorente et al, 2014;Ramos et al, 2015) report on FN outcomes after resection of non-vestibular nerve schwannomas in n = 364 individuals.…”

Petrous Face Meningiomas: Classification, Clinical Syndromes, and Surgical Outcomes

“…This is particularly challenging when removing adherent tumors that have compressed the brainstem and nerves for years. These findings highlights the utility of neuromonitoring in guiding the surgeon and protecting the sensitive cranial nerves 13,15,25 . It is also notable that only patients with posterior petrous face tumors had post-operative hydrocephalus.…”

Small Cerebellopontine Angle Meningioma—Surgical Experience of 162 Patients and Literature Review

“…The nutrient vessels around the facial and auditory nerves should be preserved as much as possible. Although the facial and auditory nerves are anatomically preserved after surgery, the loss of nerve function still exists in many patients, which may be result from the invasive growth of tumors, intraoperative traction, and heat conduction injury caused by electrocoagulation ( 10 ). Effective intraoperative neuroelectrophysiological monitoring can lessen the neuron injury by enabling the timely location of the facial and auditory nerves, thus increasing the rate of nerve function preservation.…”