Surgical Management of Pediatric Tumor-Associated Epilepsy

Abstract

Brain tumors are a common cause of seizures in children. Early surgical treatment can improve seizure outcome, but controversy exists regarding the most appropriate type of surgical intervention. Some studies suggest tumor resection alone is sufficient, while others recommend mapping and resection of the surrounding epileptogenic foci to optimize seizure outcome. To address this issue, we reviewed the charts of 34 pediatric patients aged 18 months to 20 years with medically intractable epilepsy and primary brain tumors. The average age at operation was 12.6 years, and patients had seizures for an average of 6.4 years. The majority of tumors were located in the temporal lobe. Seventeen patients, because of tumor location near an eloquent area, underwent extraoperative mapping using subdural electrode grids prior to definitive tumor resection. Fourteen of these patients had a gross total tumor resection, yet only two had a distinct zone of ictal onset identified and resected. The remaining 17 patients had tumors either in the nondominant hemisphere or far removed from speech-sensitive areas, and therefore did not undergo extraoperative subdural electroencephalograph mapping. Fourteen of these patients also had a gross total tumor resection, while none had intraoperative electrocorticography to guide the resection of additional nontumoral tissue. Overall, of the 28 patients treated with a gross total tumor resection, 24 (86%) are seizure free, while the other four are significantly improved. Of the six patients who had a subtotal tumor removal, five have persistent seizures. The mean follow-up was 3.6 years. We conclude that in children and adolescents, completeness of tumor resection is the most important factor in determining seizure outcome. The routine mapping and resection of epileptogenic foci might not be necessary in the majority of patients. As a corollary, the use of subdural electrode grids in pediatric patients with tumor-associated epilepsy should be limited to cases requiring extraoperative cortical stimulation for localization of nearby eloquent cortex.

Seizure control after subtotal lesional resection

“…7 This includes case series in which ECoG was used to localize interictal spikes intraoperatively and ictal onset extraoperatively. 8,20,23,28 Although GTR is not always technically achievable, this limitation does not necessarily leave patients in these cases with ongoing uncontrolled epilepsy. However, the treatment factors that could predispose toward a good outcome in the context of STR have not been well established.…”

Surgical strategies for pediatric epilepsy

“…Defining the epileptogenic zone including a structural lesion frequently requires advanced imaging and invasive monitoring techniques. Resection of extra-lesional cortex based on these techniques has been shown in some series to improve rates of seizure freedom (61,62).…”

“…Rates of seizure freedom after resection of neoplasms have, overall, been excellent, ranging from 72% to 92% in selected series (45,63,64). The most robust predictor of complete seizure freedom across available studies has been the extent of tumor resection (61,64 (65,66). The high rate of seizure freedom after surgery in patients with neoplasm-related epilepsy is especially meaningful given the long expected survival in children harboring low-grade brain tumors (67).…”

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

“…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).…”

“…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.…”