Skull base meningiomas: neurological outcome after microsurgical resection

Microsurgical resection is the primary treatment of skull base meningiomas. Maximal resection provides the best tumor control rates but can be associated with high surgical morbidity. To understand the relation between extent of resection (EOR) and functional outcome we have analyzed the neurological improvement and recurrence rate in a large consecutive series of skull base meningioma patients. In addition, we defined anatomical and biological factors predictive for recurrence and overall outcome. We investigated 226 skull base meningioma patients receiving tumor resection in our institution. The most frequent location was the medial sphenoid ridge (29.6 %). EOR was rated according to the Simpson scale. Overall performance was measured by the Karnofsky performance score (KPS); neurological deficits were quantified using the Medical Research Council Neurological Severity Score (MRC-NPS). Complete resection was achieved in 62.8 % and the EOR was significantly correlated to tumor location. The morbidity and mortality rate was 32.1 and 2.7 % respectively, new permanent neurological deficits occurred in 3.5 % of all patients. From all patients with focal neurological deficits, 60.1 % experienced significant improvement. Both the MRC-NPS and the KPS significantly improved from the preoperative status to discharge, however the improvement rate was dependent on the tumor location. Recurrence rate was 15.5 %; tumor size, bone- and venous sinus infiltration, WHO grade, poor EOR but not MIB-1 labeling index were independent factors predictive for recurrence. Microsurgical resection of skull base meningiomas improves neurological impairment in the majority of patients. Specific risk factors for recurrence require consideration for postoperative management.