Background: The resection of convexity meningiomas should harbour a low rate of morbidity. Functional preservation should be the main goal of surgery and have higher priority over radicality. Involvement of the primary motor cortex (PMC) increases surgical risk. The goal of this study was to evaluate the effect of cortical mapping on surgical morbidity after rolandic area meningioma treatment.
Methods: From January 2005 to March 2011, 42 patients were operated on for rolandic meningioma involving or compressing the PMC. The cohort consisted of 25 (59.5%) convexity, 10 (23.8%) parasagittal and 7 (16.7%) falcine meningiomas. Four patients were treated for recurrent disease and 25 (59.5%). Intraoperative cortical mapping was used to identify location of PMC. The threshold stimulation current was set at every site of cortical monopolar anodal stimulation around the tumour and at the tumour-cortex junction repeatedly during the meningioma dissection.
Results: Radical resection (Simpson 1 and 2) was achieved in 30 patients (71.4%) and partial resection (Simpson 4) in 12 (28.6%). New permanent deficit occurred in three patients (7.1%). All patients had moderate preoperative deficit (muscle strength ≤ 3). WHO-I was in 28 cases (66.7%), WHO-II in 14 cases (33.3%). Average follow-up was 33.2 months. Five patients (11.9%) suffered from recurrence after an average of 23.8 months.
Conclusions: Rolandic area meningiomas should be classified as a higher risk group. Intraoperative cortical mapping is in our experience useful in a situation when the cleavage plane at the PMC is lost. In such a scenario, resection outside the PMC is radical and only at the PMC is a thin remnant left without cortical damage, which helps to be safer with a better long-term prognosis.