Volume assessment of intracranial large meningiomas and considerations about their microsurgical and clinical management.

Objective: To assess the volume of large intracranial meningiomas and analyse their different microsurgical and clinical managements.

Method: The volume of 45 large meningiomas treated in our department during the last 9.5 years was retrospectively assessed using recorded neuronavigation data. The seven most employed microsurgical strategies and five important factors influencing the patient's outcome (tumor location, grade of peritumoral brain swelling, grade of brain atrophy, entrapment of neurovascular structures and the management of the vascular infused fluid volume) were individually analysed. The follow-up ranged from 14 to 84 months.

Results: The assessed volumes exceed 100 cm(3) in 38 supratentorial and 45 cm(3) in seven infratentorial tumors. The highest averaged volume in this series was assessed by tuberculum sellae and olfactory meningiomas (174 cc). A complete resection was achieved in 39 patients and was not influenced by the tumor volume. However, an averaged volume difference of 60 cc was observed between anterior skull base tumors in which their averaged greatest diameter variation was only 1.5 cm. Twelve of 24 patients with deep located tumors and entrapped neurovascular structures presented accentuated brain swelling. A new permanent post-operative neurological deficit was observed only in two patients. In the other patients, cranial nerve deficits, pre-operative hemiparesis and superior cerebral functions improved to varying degrees. Four cases with subtotal resection showed stable residual volumes after 4.5 year follow-up. Three cases underwent additional radiosurgery.

Conclusion: Tumor volume assessment allows an improved meningioma size differentiation. Despite the large volume of the tumors in this series, satisfactory resection was still possible using single-stage procedures. Individual microsurgical strategies and fluids management contributed to reducing patient's morbi-mortality.