The Far Lateral Approach for Foramen Magnum Meningiomas

• Main Authors: Flores, Bruno C., Boudreaux, Benjamin P., Klinger, Daniel R., Raisanen, Jack M., Lewis, Jeremy J., Mickey, Bruce E., Barnett, Samuel L.
• Format: Conference Proceeding
• Language: English
• ISSN: 2193-6331; 2193-634X
• DOI: 10.1055/s-0034-1370496

Background : Foramen Magnum (FM) meningiomas pose significant challenges to the treating neurosurgeon. The insidious onset of symptoms often contributes to a delayed diagnosis and a relatively large size at the time of presentation. Symptoms are often produced by compression of surrounding structures within a critically confined space. Posterior and posterolateral FM meningiomas can be safely resected via standard midline suboccipital approach. Controversy still exits regarding the optimal management of anterior or anterolateral lesions. Objective : describe a single institution experience with the surgical management of FM meningiomas, with emphasis on the far lateral approach and its variations. Clinical presentation, imaging findings, pathologic features, recurrence rates and functional outcome are discussed. Methods : retrospective review of prospectively collected data was performed. All patients with ventral or ventrolateral FM meningiomas, presenting to UT Southwestern Medical Center between 2000 and 2011, were identified. Preoperative clinical signs/symptoms, duration of symptoms, neurological exam and radiographic findings on MRI were analyzed. Intraoperative technical nuances and surgical variations were individually identified. Functional outcome was assessed at the time of hospital discharge and of last ambulatory visit. Results : 30 patients with FM meningiomas treated surgically were identified. Mean age at time of surgery was 55.6 + 12.2 years. Majority of patients were female (71.4%). Headaches (42.6%) and hemibody sensory deficits (39.3%) were the most common presenting symptoms, followed by hemiparesis (28.6%), neck pain (21.4%) and gait disturbances (21.4%). The incidence of symptomatic cranial nerve deficits preoperatively was low (14.3%). The elapsed time between onset of symptoms and initial diagnosis was 10.3 months. The transcondylar variant was utilized in 89.3% of the cases. Transposition of the VA was done in 10 patients. Gross total resection was achieved in 85.7% of the patients. One patient underwent adjuvant Cyber Knife radiosurgery to a small residual tumor adherent to the VA. There were no recurrences and none of the four patients with subtotal resection have demonstrated tumor growth on serial imaging follow-up. Histologically, 90% of the FM meningiomas were WHO Grade I, with meningothelial the most common subtype. One patient had persistent low postoperative KPS and was dependent for ADLs. Twenty two patients had complete