Is there a risk of seizures in preventive awake surgery for incidental diffuse low-grade gliomas?

OBJECT Although a large amount of data supports resection for symptomatic diffuse low-grade glioma (LGG), the therapeutic strategy regarding incidental LGG (ILGG) is still a matter of debate. Indeed, early preventive surgery has recently been proposed in asymptomatic patients with LGG, after showing that the extent of resection was larger than in symptomatic patients with LGG. However, the quality of life should be preserved by avoiding both neurological deficit and epilepsy. The aim of this study was to determine the risk of seizures related to such a prophylactic surgical treatment in ILGG. METHODS The authors report a prospective series of 21 patients with ILGG who underwent awake surgery with a minimum follow-up of 20 months following resection. Data regarding clinicoradiological features, surgical procedures, and outcomes were collected and analyzed. In particular, the eventual ocourrence and type of seizures in the intra- and postoperative periods were studied, as follows: early (< 3 months) and long-term (until last follow-up) periods. RESULTS There were no intraoperative seizures in this series. During the early postoperative period, the authors observed only a single episode of partial seizures in a patient with no antiepileptic drug (AED) prophylaxis-all other patients were given antiepileptic treatment following resection. The AEDs were discontinued in all cases, with a mean delay of 8 months after surgery (range 3-24 months). No patient had permanent neurological deficits. All 21 patients returned to an active familial, social, and professional life (working full time in all cases). Total or even supratotal resection (the latter meaning that a margin around the tumor visible on FLAIR-weighted MRI was removed) was achieved in 14 cases (67%). In 7 patients (33%) subtotal resection was performed, with a mean residual tumor volume of 1.5 ml (range 1-7 ml). No oncological treatment was administered in the postsurgical period. The mean follow-up after surgery was 49 months (range 20-181 months). Only 2 patients had seizures during the long-term follow-up. Indeed, due to tumor progression after incomplete resection, seizures occurred in 2 cases, 39 and 78 months postsurgery, leading to administration of AEDs and adjuvant treatment. So far, all patients are still alive and enjoy a normal life. CONCLUSIONS The risk of inducing seizures is very low in ILGG, and it does not represent an argument against early surgery. These data strongly support the proposal of a screening policy for LGG that will evolve toward a preventive treatment in a more systematic manner.