Electrocorticography and seizure outcomes in children with lesional epilepsy

Abstract

Overall, using ECoG to guide additional cortical resection may lead to more robust seizure freedom in children with lesional epilepsy without increasing their risk of surgical morbidity.

Seizures in Children with Brain Tumours — Epidemiology, Significance, Management, and Outcomes

“…However, at a mean followup of 5.8 years, there was a trend towards improved seizure freedom in patients in the ECoG group, with 79% versus 61% patients still seizure free (p=0.08). The investigators also noted no increase in neurological morbidity among patients who had undergone the more extensive ECoG-guided cortical resection, and that these patients were less likely to require repeat epilepsy surgery [214]. Why this has implications post-operatively relates to the potential need for re-operation, as discussed in the next section.…”

“…But how successful is tumour resection in terms of controlling or eliminating seizures? [214][215][216][217][218][219][220][221][222][223] published over the past two decades in which seizure outcomes in children and adolescents undergoing surgery to remove epileptogenic brain neoplasms were examined. Across these 26 studies are 741 patients, ranging in age from one month to 21 years of age, with a mean age of 9.1 years and a mean duration of post-operative follow-up of more than four years (overall mean=52 months, with individual study means ranging from 12 to 148 months).…”

“…Though one study [86] included six paediatric patients with high-grade gliomas (either GBM or grade III astrocytoma), and another indicated 11 patients with either grade III or grade IV lesions [35], almost all of the remaining 724 patients had low-grade (grade I or II) lesions, including various low-grade gliomas and glioneuronal tumours, and less typically epileptogenic tumours like craniopharyngiomas and a dysplastic cyst. Spanning these studies, surgical approaches clearly differed, with some surgeons either largely or exclusively performing lesionectomies alone, others performing further procedures like partial lobectomies [86,148] and amygdylohypocampectomies [182], and still others using various intra-operative mapping technologies like electrocortography (ECoG) [63,132,184,214] to identify and ultimately resect extra-tumoral epileptogenic tissue. However, the ubiquitous goal was total tumour resection, whenever possible, an objective that was achieved in roughly two-thirds of cases.…”

“…The major concern with the latter two scenarios is that tumour resection either was incomplete, or that extra-tumoral epileptogenic tissue was not removed. Over the years, attempts have been made to optimize the resection of epileptogenic lesions by both better delineating their margins and identifying extra-tumoral epileptogenic tissue, using intra-operative tools like electrocorticography (ECoG) to identify potential seizure-inducing tissue irregularities like cortical dysplasia [63,77,93,132,1 [6] 3 , 184,214,216,240,241]. This has led to debate regarding the relative benefits and safety of performing epilepsy surgery rather than just lesionectomies in patients with tumour-triggered seizures [242]; though, in fact, many surgeons have been utilizing additional surgical steps like lobectomies, amygdylohypocampectomies and, in extreme cases, hemispherectomies for decades [63,86,94,117,132,148,149,168,182,185,214,217,218,222,227,243].…”

“…To date, almost no direct empirical comparisons have been undertaken. In perhaps the most methodologically sound study, Gelinas et al retrospectively compared 34 patients who underwent ECoG-aided epilepsy surgery and 33 patients who had undergone simple lesionectomies without ECoG, all between the ages of 3 months and 16 years, in Vancouver, Canada [214]. One year post-operatively, the two treatment arms were virtually identical, with roughly 80% of patients in each group seizure free.…”