Abstract
Foramen magnum meningiomas (FMMs) are a major surgical challenge, due to relevant surgical morbidity and mortality. The paper aims to review the clinical (symptomatic improvement, complication rate, length of hospital stay) and radiological outcome (completeness of resection) of microsurgical resection of FMMs, and to identify predictors of complications. A multi-institutional retrospective review of prospectively maintained database of FMMs included 51 patients (74.5% females) with a median tumor volume of 8.18cm3 (range, 1.77-57.9cm3) and median follow-up of 36months (range, 0.30-180.0months). Tumors were resected though suboccipital approach (58.8%) or posterior-lateral approaches (39.3%), including far-lateral, extreme lateral and transcondylar approaches. Gross-total resection (GTR) was achieved in 80.4% and 98% of cases did not present tumor regrowth or recurrence. Clinical symptoms improved in 34 patients (66.7%) and worsened in 5 (9.8%). The median length of hospital stay was 5days. Mortality was null. Postoperative complications developed in 15 patients (29.4%), with cerebrospinal fluid leak (7.8%) and lower cranial nerves deficits (7.8%) as the most frequent. Craniospinal location (p = 0.03), location anterior to the dentate ligament (DL) (p = 0.02), involvement of vertebral artery (VA) (p = 0.03) were significantly associated with complication rate. These three elements allow calculating the Foramen Magnum Meningioma Risk Score (FRMMRS), to estimate the risk of post-operative complications. Microsurgical resection allows for high GTR rate and low rate of tumor regrowth or recurrence, despite complications in one third of the patients. The FMMRS allows classifying FMMs and estimating the risk of post-operative complications.
Highlights
Foramen Magnum Meningiomas (FMMs) are benign slow-growing tumors located at the craniocervical junction
The aim of the present study is to review the clinical and radiological outcome of FMMs treated surgically as well as to explore the prognostic value of pre- and peri-operative variables on the clinical and radiological outcome, including patient and tumor characteristics, and surgical approaches
All the lateral extensions of the suboccipital approach (SOA), such as farlateral approach [9, 10],[16] and extreme-lateral approach,[11] requiring some degree of condylar drilling can be classified as transcondylar approach (TCA). [15, 19] This approach is ideal for tumors located anteriorly to the dentate ligament (DL), in anterior or anterolateral position with respect to the medulla
Summary
Foramen Magnum Meningiomas (FMMs) are benign slow-growing tumors located at the craniocervical junction. [1] These lesions represent 0.3 to 3.2% of all meningiomas, 4.2 to 20% of all posterior fossa meningiomas, and 60 to 77% of all benign extramedullary tumors at the craniocervical junction.[2, 3] The optimal management of FMMs is still controversial due to the significant risk for surgical morbidity and mortality related to the presence of several critical neurovascular structures in a narrow space.[4,5,6] Several surgical approaches have been adopted for effective and safe resection of FMMs including, but not limited to: anterior transoral approach,[5] endoscopic endonasal approach,[6] lateral transcervical approach,[7] suboccipital craniotomy,[8] far-lateral approach,[11,12,13] and extreme lateral approach.[11]. Foramen Magnum Meningiomas (FMMs) are benign slow-growing tumors located at the craniocervical junction. The aim of the present study is to review the clinical and radiological outcome of FMMs treated surgically as well as to explore the prognostic value of pre- and peri-operative variables on the clinical and radiological outcome, including patient and tumor characteristics, and surgical approaches. Understanding these factors is of paramount importance in choosing the best course of treatment for these patients and for estimating the surgical risk
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