A WHO Grade II glioma (diffuse low-grade glioma [LGG]) is a continuously growing lesion that migrates along white matter pathways and that will inescapably evolve toward a higher grade of malignancy. 39This tumor is usually revealed by inaugural seizures in young adults with no or only mild neurological deficits. 11Despite the lack of prospective randomized trials, a large amount of data reported in the modern literature strongly supports the impact of early and maximal resection on the natural history of the disease, by delaying malignant transformation and thus by significantly increasing survival. 1,15,20,21,30,46,49 Recently the French Glioma Network published the largest surgical series of LGG ever reported, in which multivariate analysis was used to show that extent abbreviatioNs AED = antiepileptic drug; EOR = extent of resection; ILGG = incidental low-grade glioma; KPS = Karnofsky Performance Scale. submitted June 22, 2014. accepted September 10, 2014. iNclude wheN citiNg Published online February 27, 2015; DOI: 10.3171/2014.9.JNS141396. disclosure The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.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 occurrence 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) ...

Although a large amount of data supports early surgical resection for symptomatic diffuse low-grade glioma, the therapeutic strategy is still a matter of debate regarding incidentally discovered diffuse low-grade glioma. Indeed, early and "preventive" surgery has recently been proposed in asymptomatic patients with silent diffuse low-grade glioma with better outcomes. The present review discusses the importance of an early diagnosis and of a preventive surgical treatment to improve the outcomes of incidental diffuse low-grade glioma and suggests the possible relevance of a tailored screening policy.