Surgical Experience in 54 Midline Anterior Cranial Base Meningiomas

Abstract

Introduction: Meningiomas comprise approximately 15 to 20% of all intracranial tumors and skull base meningiomas account for 25 to 30% of all meningiomas. Over the past two decades, skull base surgery has significantly improved. However, their rate of recurrence is disproportionally high at 40 to 50%. The purpose of the study was to examine a subgroup of skull base meningiomas, the midline anterior cranial base meningiomas that were treated in our institution to see if they behave differently and if total and complete resection is possible. Methods: A retrospective review of surgically resected anterior cranial base meningiomas were reviewed from January 1997 to December 2005. Sphenocavernous, orbital roof, and sphenoid wing meningiomas with anterior fossa extension and optic nerve sheath lesions were excluded. Patient demographics, clinical signs and symptoms, tumor size and location, surgical approaches, and outcome were gathered. Results: From the 148 skull base meningiomas, 54 (35 males/19 females) were midline anterior cranial base meningiomas. The mean age was 55 (range 35–75 y). The tumor locations were categorized as olfactory groove (30 patients), planum sphenoidale (9 patients), tuberculum sellae (10 patients) and clinoidal (5 patients). Clinical findings included headaches (45 patients), visual problems (24 patients), anosmia (13 patients), frontal lobe syndrome (12 patients), and seizures (4 patients). Surgical approaches included pterional (17 patients), pterional-orbitozygomatic (7 patients), Dolenc's approach (5 patients), bifrontal-orbitotomy (23 patients), and extended trans-sphenoidal (2 patients). Gross total resection as defined as Simpson Grade I or II was obtained in 50 patients and subtotal resection as defined as Simpson Grade III, IV, or V in 4 patients. In 20 consecutive patients with preoperative visual defects, 15 patients had improved vision, 4 patients' vision remained unchanged, and 2 patients' vision worsened. There was no death noted; however, there were complications immediately and at the 1-year assessment. Six patients had recurrence of which 4 had gamma-knife radiosurgery and 2 were reoperated. Conclusion: Although the emphasis on modern skull base surgery has been to preserve neural function, tumor control through total resection can be achieved in midline anterior cranial base meningiomas. Likewise, vision can be substantially improved. To improve outcome, early detection of tuberculum sellae and clinoidal meningiomas is important because tumor size matters.