title: Management of anterolateral foramen magnum meningiomas: surgical vs conservative decision making.
abstract: BACKGROUND
  Anterolateral meningiomas of the foramen magnum (FMMs) represent a neurosurgical challenge because they grow in close contact with osteoarticular, nervous, and vascular structures that cannot be sacrificed or retracted.
  
  
  OBJECTIVE
  To evaluate our strategy and results in 26 patients with FMMs and analyze factors affecting the decision-making process, resection, and outcome.
  
  
  METHODS
  Among 26 consecutive symptomatic FMM (10 anterior, 16 lateral) patients (16 women, 10 men, ages 28-82 years), 4 older than 70 years of age were untreated. Twenty-two were operated on using a posterolateral approach, with the vertebral artery transposed in 19 and the occipital condyle drilled in 10. We analyzed the characteristics and outcome of untreated cases, the utility of THE occipital condyle drilled, the difficulties of microdissection, morbidity and total removal rates, the outcome of tumor residues, and the literature on radiosurgery.
  
  
  RESULTS
  Three of 4 untreated patients remained clinically stable at 2 to 5 years. After systematic vertebral artery medial transposition and occipital condyle drilled in 6 cases, our technique evolved with experience in the next 16 (vertebral artery transposed in 13 of 16; occipital condyle drilled in 4 of 13) for dissecting anteriorly beyond midline (anterior FMMs). Retrocondylar access was sufficient for lateral FMMs. Tumors were totally removed in 16 of 22 (73%). One patient died, and 4 had permanent deficits. Follow-up of more than 5 years in 12 patients showed no C0-1 instability, and slight increase of tumor residue size 7 years after surgery. In the literature, 15 FMMs treated with radiosurgery are reported, 13 at diagnosis and 2 at recurrence, with short-term clinical and radiological safety and efficacy.
  
  
  CONCLUSIONS
  We currently recommend (1) aiming for subtotal removal in difficult cases, (2) remaining conservative in asymptomatic or elderly patients with mild symptoms, and (3) considering radiosurgery at diagnosis for small (<30 mm) symptomatic FMMs or as an adjunct for evolving residues/recurrences in poor candidates for resection.
authors.affiliation: Department of Neurosurgery, Erasme Hospital, University of Brussels, Brussels, Belgium. bpirotte@ulb.ac.be
authors.forename: Benoit J M
authors.initials: BJ
authors.lastname: Pirotte
authors.forename: Jacques
authors.initials: J
authors.lastname: Brotchi
authors.forename: Olivier
authors.initials: O
authors.lastname: DeWitte
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003657:Decision Making; D005260:Female; D005500:Follow-Up Studies; D005539:Foramen Magnum / Q000000981:diagnostic imaging / Q000601:surgery*; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008577:Meningeal Neoplasms / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008579:Meningioma / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008866:Microsurgery / Q000379:methods; D008875:Middle Aged; D019635:Neurosurgical Procedures / Q000379:methods*; D009777:Occipital Bone / Q000601:surgery; D011859:Radiography; D012189:Retrospective Studies; D012720:Severity of Illness Index; D016896:Treatment Outcome; D055815:Young Adult