Surgical management of pediatric tumor-associated epilepsy

Second-look surgery in postoperative pediatric low-grade glioma

OBJECTIVE

To review the literature on second-look surgery in pediatric low-grade gliomas (LGG) with a view to presenting both sides of the picture of re-exploration.

METHODS

Collection of material from recent literature on pediatric LGG. This was a retrospective review of these publications.

RESULTS

There are a number of publications recommending second-look surgery in selected cases, provided morbidity of the second surgery is minimum, and indeed some in which there is improvement in the neurodeficit after the second resection.

CONCLUSION

There seems a fair balance of articles recommending and dissuading the practice of second-look surgery, but in our limited experience we have found it useful in selected patients.

Seizure outcomes after resection of primary brain tumors in pediatric patients: a systematic review and meta-analysis

PURPOSE

Primary brain neoplasms are the most common solid tumors in pediatric patients and seizures are a common presenting symptom. Surgical intervention improves oncologic outcomes and seizure burden. A better understanding of factors that influence seizure outcomes in the surgical management of primary brain tumors of childhood can guide treatment approach thereby improving patient quality of life.

METHODS

We performed a systematic analysis using articles queried from PubMed, EMBASE, and Cochrane published from January 1990 to August 2022 to determine predictors of seizure outcomes in pediatric patients undergoing resection of primary brain tumors.

RESULTS

We identified 24 retrospective cohort studies, one prospective cohort study, and one mixed retrospective and prospective study for the systematic analysis. A total of 831 pediatric patients were available for analysis. 668 (80.4%) patients achieved seizure freedom after surgery. Complete tumor resection increased the likelihood of a seizure-free (Engel I) outcome compared to subtotal resection (OR 7.1, 95% CI 2.3-21.9). Rates of Engel I seizure outcomes did not significantly differ based on factors such as age at seizure onset, duration of epilepsy, gender, tumor laterality, or age at surgery, but trended towards significance for improved outcomes in temporal lobe tumors.

CONCLUSION

Primary brain tumors in the pediatric population are commonly associated with seizures. Resection of these lesions reduces seizure burden and is associated with high rates of seizure freedom. Complete resection, compared to subtotal resection, significantly increases the likelihood of seizure-free outcomes.

The differential role of magnetic resonance imaging in predicting surgical outcomes between children versus adults with temporal lobe epilepsy

OBJECTIVE

This study aims to investigate the clinical discrepancies and the different predictors of anterior temporal lobectomy (ATL) in children (<18 years at surgery) and adults (>18 years at surgery) with temporal lobe epilepsy (TLE).

MATERIALS AND METHODS

A total of 262 patients (56 children and 206 adults) with TLE who underwent ATL were included in this study. The clinical variables, including patients' characteristics, preoperative evaluations, pathology, surgical prognosis, and surgical predictors were assessed the discrepancies between TLE children versus adults using univariate and multivariate analyses. Kaplan-Meier survival analysis was used to calculate the probability of seizure freedom and AEDs withdrawal after ATL, and the difference between TLE children and adults was analyzed using the Log-Rank test.

RESULTS

There were significant differences including semiology, magnetic resonance imaging (MRI) examinations, numbers of preoperative AEDs, and pathologies between TLE children and adults (P < 0.05, Q < 0.05). The MRI-detected epileptic focus was the only independent predictor of seizure freedom (P = 0.002, Q = 0.036) in TLE children, and the concordance of MRI-detected focus with video-electroencephalography (video-EEG)-detected epileptic zone was the only variable associated with seizure freedom in TLE adults (OR = 2.686, 95% CI = 1.014-7.115, P = 0.047). The TLE children experienced a higher probability of AEDs withdrawal than adults after surgery (P = 0.005).

SIGNIFICANCE

There were remarkable differences in clinical manifestations, MRI examinations, number of preoperative AEDs, and pathologies between TLE children versus adults. TLE children had a higher possibility of AEDs withdrawal than adults after surgery. The favorable seizure outcome of ATL depended on the early complete resection of MRI-detected epileptogenic focus in TLE children, while the concordance of MRI-detected focus with EEG-detected epileptogenic zone was the only predictor of favorable seizure outcomes in TLE adults.

Pre-surgical evaluation challenges and long-term outcome in children operated on for Low Grade Epilepsy Associated brain Tumors

OBJETIVE

Analyze pre-surgical evaluation modalities, surgical failures, long-term results of surgery and neurocognitive outcome in children with Low-grade Epilepsy Associated brain Tumors (LEAT).

METHODS

Retrospective observational study of 37 children who underwent epilepsy surgery, with a minimum follow-up of 12 months. At time of surgery, pharmaco-sensitivity (Group 1; n = 8) and drug-resistance (Group 2; n = 29), were considered.

RESULTS

Age range of seizure onset was 5 months-14 years (mean 5.73years) and age at surgery was 2.2-18.7years (mean 10.7years). Gangliogliomas (35.1%) or DNTs (29.7%), combined or not to a focal cortical dysplasia (FCD), were the most frequent. Extended lesionectomy 16 children (43.2%) were the most frequently used surgical approach in both groups. At one year of follow-up, 36 children (97.2%) were classified as Engel I. Within the age-range studied, duration of epilepsy and time to surgery appeared to have no impact on clinical and neurocognitive outcome in both groups. It is noteworthy, however, that antiseizure medications (ASMs) were withdrawn in 100% of the pharmacosensitive group vs 34.5% of the drug-resistant group (p = 0.002). In children with a pharmaco-sensitive epilepsy, neurocognitive evaluation showed significant improvement in the verbal comprehension index (p = 0.029).

CONCLUSIONS

Epilepsy-surgery is a safe therapeutic option for LEATs including for children with seizures controlled by ASMs. Presence of associated lesions is not rare. Comprehensive pre-surgical evaluation increases the chances for control of the seizures, the early discontinuation of medications and favours neurocognitive development.

Factors associated with seizure and cognitive outcomes after epilepsy surgery for low-grade epilepsy-associated neuroepithelial tumors in children

Low-grade epilepsy-associated neuroepithelial tumors (LEATs) are responsible for drug-resistant chronic focal epilepsy, and are the second-most common reason for epilepsy surgery in children. LEATs are extremely responsive to surgical treatment, and therefore epilepsy surgery should be considered as a treatment option for LEATs. However, the optimal time for surgery remains controversial, and surgeries are often delayed. In this review, we reviewed published article on the factors associated with seizure and cognitive outcomes after epilepsy surgery for LEATs in children to help clinicians in their decision whether to pursue epilepsy surgery for LEATs. The achievement of gross total resection may be the most important prognostic factor for seizure freedom. A shorter duration of epilepsy, a younger age at surgery, and extended resection of temporal lobe tumors have also been suggested as favorable prognostic factors in terms of seizure control. Poor cognitive function in children with LEATs is associated with a longer duration of epilepsy and a younger age at seizure onset.

Seizures following surgery for supratentorial extratemporal low-grade tumors in children: a multicenter retrospective study

OBJECTIVE

Resection of brain tumors may lead to new-onset seizures but may also reduce seizure rates in patients presenting with seizures. Seizures are seen at presentation in about 24% of patients with brain tumors. For lesional epilepsy in general, early resection is associated with improved seizure control. However, the literature is limited regarding the occurrence of new-onset postoperative seizures, or rates of seizure control in those presenting with seizures, following resections of extratemporal low-grade gliomas (LGGs) in children.

METHODS

Data were collected retrospectively from 4 large tertiary centers for children (< 18 years of age) who underwent resection of a supratentorial extratemporal (STET) LGG. The patients were divided into 4 groups based on preoperative seizure history: no seizures, up to 2 seizures, more than 2 seizures, and uncontrolled or refractory epilepsy. The authors analyzed the postoperative occurrence of seizures and the need for antiepileptic drugs (AEDs) over time for the various subgroups.

RESULTS

The study included 98 children. Thirty patients had no preoperative seizures, 18 had up to 2, 16 had more than 2, and 34 had refractory or uncontrolled epilepsy. The risk for future seizures was higher if the patient had seizures within 1 month of surgery. The risk for new-onset seizures among patients with no seizures prior to surgery was low. The rate of seizures decreased over time for children with uncontrolled or refractory seizures. The need for AEDs was higher in the more active preoperative seizure groups; however, it decreased with time.

CONCLUSIONS

The resection of STET LGGs in children is associated with a low rate of postoperative new-onset epilepsy. For children with preoperative seizures, even with uncontrolled epilepsy, most have a significant improvement in the seizure activity, and many may be weaned off their AEDs.

Neurosurgical approaches to pediatric epilepsy: Indications, techniques, and outcomes of common surgical procedures

Epilepsy is a common pediatric neurological condition, and approximately one-third of children with epilepsy are refractory to medical management. For these children neurosurgery may be indicated, but operative success is dependent on complete delineation of the epileptogenic zone. In this review, surgical techniques for pediatric epilepsy are considered. First, potentially-curative operations are discussed and broadly divided into resections and disconnections. Then, two palliative approaches to seizure control are reviewed. Finally, future neurosurgical approaches to epilepsy are considered.

Long-term recurrence of dysembryoplastic neuroepithelial tumor: Clinical case report

BACKGROUND

Dysembryoplastic neuroepithelial tumors (DNETs) are rare, benign brain neoplasms that typically arise in children and adolescents and classically present with intractable, partial complex seizures. DNETs are classically associated with a favorable prognosis after complete surgical resection.

CASE DESCRIPTION

We describe a case of long-term recurrence of a DNET, which initially resected and diagnosed as an oligodendroglioma prior to the recognition of DNETs. This patient was seizure-free for 12 years and had no signs of radiologic progression until 24 years after initial resection. On repeat surgical resection, 31 years after the initial surgery, histopathologic evaluation identified the characteristic features of DNET in both specimens.

CONCLUSIONS

This patient's 24-year disease-free interval prior to radiologic recurrence demonstrates the longest interval to relapse in the literature for a DNET. This case illustrates the possibility of late recurrence of DNETs decades after radiographical complete resection to emphasize the necessity of thoughtful clinical judgment in adult survivors of low grade pediatric neoplasms who present with seizures after a prolonged seizure-free interval.

Seizures caused by brain tumors in children

PURPOSE

To review the epidemiology, clinical features, and treatment of seizures secondary to pediatric brain tumors.

METHOD

Literature review.

RESULTS

Pediatric brain tumors are the most common solid pediatric tumor and the most common cause of death in pediatric cancer. Seizures are one of the most common symptoms of pediatric brain tumors. Factors associated with increased risk of seizures include supratentorial location, gray matter involvement, low-grade, and certain histological features-especially dysembryoplastic neuroepithelial tumor, ganglioglioma, and oligodendroglioma. Leukemic infiltration of the brain, brain metastases of solid tumors, and brain injury secondary to chemotherapy or radiotherapy can also cause seizures. Mechanisms by which brain tumors cause seizures include metabolic, and neurotransmitter changes in peritumoral brain, morphologic changes - including malformation of cortical development - in peritumoral brain, and presence of peritumoral blood products, gliosis, and necrosis. As there is a high degree of uncertainty on how effective different antiepileptic drugs are for seizures caused by brain tumors, choices are often driven by the interaction and side effect profile. Classic antiepileptic drugs - phenobarbital, phenytoin, or carbamazepine - should be avoided as they may alter the metabolism of chemotherapeutic agents. Newer drugs - valproate, lamotrigine, topiramate, zonisamide, and levetiracetam - may be the preferred option in patients with tumors because of their very limited interaction with chemotherapy.

CONCLUSION

Seizures are a common presentation of pediatric brain tumors, especially in supratentorial tumors with gray matter involvement. Antiepileptic drug therapy is usually driven by the interaction and side effect profile and newer drugs with few interactions are generally preferred.

Epilepsy surgery for pediatric low-grade gliomas of the cerebral hemispheres: neurosurgical considerations and outcomes

INTRODUCTION

Pediatric low-grade tumors are found in roughly 1-3 % of patients with childhood epilepsy; seizures associated with these tumors are often medically refractory and often present a significant morbidity, greater than the presence of the tumor itself.

DISCUSSION

The unique morbidity of the seizures often requires an epilepsy surgical approach over a standard oncologic resection to achieve a reduction in morbidity for the child. Multiple quality-of-life studies have shown that unless a patient is seizure-free, they remain disabled throughout their life; the best way to achieve this in our patient population is with a multidisciplinary team approach with treatment goals focusing primarily on the epilepsy.

CONCLUSION

In those patients treated with gross total resection, roughly 80 % will have an Engel class I outcome and 90 % will achieve some reduction in seizure frequency with a significant improvement in quality of life.

Surgical strategies for pediatric epilepsy

Pediatric epilepsy is a debilitating condition that impacts millions of patients throughout the world. Approximately 20-30% of children with recurrent seizures have drug-resistant epilepsy (DRE). For these patients, surgery offers the possibility of not just seizure freedom but significantly improved neurocognitive and behavioral outcomes. The spectrum of surgical options is vast, ranging from outpatient procedures such as vagus nerve stimulation to radical interventions including hemispherectomy. The thread connecting all of these interventions is a common goal-seizure freedom, an outcome that can be achieved safely and durably in a large proportion of patients. In this review, we discuss many of the most commonly performed surgical interventions and describe the indications, complications, and outcomes specific to each.

Review of seizure outcomes after surgical resection of dysembryoplastic neuroepithelial tumors

Dysembryoplastic neuroepithelial tumors (DNETs) are rare tumors that present with seizures in the majority of cases. We report the results of a review of seizure freedom rates following resection of these benign lesions. We searched the English literature using PubMed for articles presenting seizure freedom rates for DNETs as a unique entity. Patient demographics, tumor characteristics, and operative variables were assessed across selected studies. Twenty-nine articles were included in the analysis. The mean age at surgery across studies was a median of 18 years (interquartile range 11-25 years). The mean duration of epilepsy pre-operatively was a median 7 years (interquartile range 3-11 years). Median reported gross-total resection rate across studies was 79% (interquartile range 62-92%). Authors variously chose lesionectomy or extended lesionectomy operations within and across studies. The median seizure freedom rate was 86% (interquartile range 77-93%) with only one study reporting fewer than 60% of patients seizure free. Seizure outcomes were either reported at 1 year of follow-up or at last follow-up, which occurred at a median of 4 years (interquartile range 3-7 years). The number of seizure-free patients who discontinued anti-epileptic drugs varied widely from zero to all patients. Greater extent of resection was associated with seizure freedom in four studies.

Gross-total resection of temporal low grade gliomas is a critically important factor in achieving seizure-freedom

OBJECTIVE

To present a surgical series of patients with low grade temporal gliomas causing intractable epilepsy, focusing on long-term seizure outcome.

METHOD

A retrospective study was conducted with patients with temporal low-grade gliomas (LGG).

RESULTS

Sixty five patients with were operated in our institution. Males were more affected than females and the mean age at surgery was 32.3 ± 8.4 (9-68 years). The mean age at seizure onset was 25.7 ± 9.2 (11-66 years). Seizure outcome was classified according with Engel classification. After one year of follow up, forty two patients (64.6%) were Engel I; seventeen (26.2%) Engel II; four (6.2%) Engel III and two (3.1%) Engel IV. Statistically significant difference in seizure outcome was obtained when comparing the extension of resection. Engel I was observed in 39 patients (69.6%) with total resection and in only 3 (33.3%) patients with partial resection.

CONCLUSION

Gross-total resection of temporal LGGs is a critically important factor in achieving seizure-freedom.

Seizure outcomes in children with epilepsy after resective brain surgery

PURPOSE

To assess the role of resective brain surgery in childhood epilepsy.

METHODOLOGY

We retrospectively analysed the seizure outcomes in 55 children with epilepsy who had resective brain surgery between 1997 and 2012, at our centre. The children were 1.5-18 years at the time of surgery; their seizure onset was between 0.2 andto 15 years of age. 48 had refractory epilepsy. One child died of tumour progression. Follow-up duration in the survivors ranged from 2 to -16 years (mean: 9).Presurgical evaluation included clinical profiles, non-invasive V-EEG monitoring, neuroimaging with MRIs in all; SPECT and PET in selected patients. 54 had intraoperative ECoG.

RESULTS

An Engel Class 1 outcome was seen in 78% of the cohort, with 67% being off all AEDs at the most recent follow-up. Children with tumours constituted the majority (56%), with 87% of this group showing a Class 1 outcome and 84% being off AEDs. Children with cortical dysplasia had a Class 1 outcome in 56%.

CONCLUSION

Resective brain surgery is an efficacious option in some children with epilepsy. We found ECoG useful to tailor the cortical resection and in our opinion ECoG contributed to the good seizure outcomes.

Seizures in children with dysembryoplastic neuroepithelial tumors of the brain--A review of surgical outcomes across several studies

PURPOSE

In children and adolescents, dysembryoplastic neuroepithelial tumors (DNETs) of the brain present with seizures almost 100% of the time, potentially creating significant long-term morbidity and disability despite the generally indolent course of the lesion. These tumors also tend to be quite resistant to anti-epileptic drugs which, themselves, can be associated with long-term side effects and resultant disability. Many clinicians advocate early surgical resection of these lesions, but how effective this approach is, and how aggressive tumor removal should be, continues to be debated.

METHODS

We performed a systematic review of the relevant literature to identify all reports of DNET resections in pediatric patients published over the past 20 years. In all, over 3000 MEDLINE abstracts were reviewed, ultimately resulting in 13 studies with 185 pediatric DNET patients to review.

RESULTS

Surgical resection of the lesion was effective at improving seizures in over 98% of patients and at achieving long-term seizure freedom in 86%. Surgical resection of DNETs also appeared to be quite safe, with no reported perioperative deaths and an overall rate of postoperative complications of 12%; the vast majority of these complications were transient.

CONCLUSIONS

Total gross resection of the lesion was the only factor statistically correlated with long-term seizure freedom (r = 0.63, p = 0.03). However, data remain lacking regarding whether this translates into more extensive procedures-like brain mapping and partial lobectomies-being any more effective than simple lesionectomies alone. Further research is clearly needed to address this and other crucial questions.

Recurrence after gross-total resection of low-grade pediatric brain tumors: the frequency and timing of postoperative imaging

OBJECT

Low-grade glial and glioneuronal brain tumors are frequently encountered in the pediatric population and can be effectively treated by resection. The authors aimed to use imaging to evaluate how often tumors recurred and to determine if recurrences were associated with any clinical symptoms, along with the financial costs of imaging, in patients with radiographically proven gross-total resection (GTR) at Boston Children's Hospital. These data were assessed to propose guidelines regarding postoperative surveillance.

METHODS

The authors performed a retrospective cohort analysis of the Pediatric Brain Tumor Program database from 1993 to 2003 to identify patients with glial or glioneuronal tumors initially evaluated at Boston Children's Hospital. Among the 888 patients evaluated for any type of brain tumor during this period, 67 patients had WHO Grade I glial or glioneuronal lesions with radiographically proven GTR and available follow-up data. The frequency and timing of postoperative imaging was compared with the institutional protocol. Recurrence-free survival was calculated using the Kaplan-Meier method. Financial costs of imaging were available from 2001 to 2009 and were averaged to extrapolate the postoperative surveillance costs.

RESULTS

Among the 67 patients with GTR, 13 recurrences were detected radiographically with a mean time to recurrence of 32.4 months (range 2.9-128.5 months). The mean duration of follow-up after surgery was 6.6 years. The recurrence-free survival at 2 and 5 years after GTR for all low-grade glial and glioneuronal tumors was 0.90 (95% CI 0.82-0.97) and 0.82 (95% CI 0.73-0.92), respectively. No clinical symptoms were associated with any of the recurrences, and no deaths occurred. Under the institutional protocol of surveillance imaging, the estimated cost per recurrence at 5 years was $104,094 per patient. The proposed protocol would reduce the number of MR scans in the first 5 years from 10 to 5, providing a potential cost savings of $52,047 per recurrence.

CONCLUSIONS

Given the slow-growing, clinically asymptomatic nature of low-grade glial and glioneuronal tumors coupled with the financial and psychological costs of repeated imaging, the authors propose a postoperative surveillance MRI schedule that is less intensive than current institutional practice.

Low-grade temporal gliomas: surgical strategy and long-term seizure outcome

Low-grade gliomas (LGGs) are generally located in temporal lobe and cause medically-intractable seizure so that surgical treatment becomes inevitable. This study includes a retrospective analysis of our patients with temporal LGGs retrieved from our epilepsy surgery data base and tries to present appropriate surgical approach and long-term seizure and anti-epileptic drug (AED) outcomes. Fifty-three patients including children and adults underwent surgery on temporal lobe LGGs and 35 patients were reached to report seizure and AED outcomes. On the non-dominant temporal lobe, anterior temporal resection with hippocampectomy whether mesial structure are involved or not is the appropriate approach. On the dominant temporal lobe mesial structures should be respected. However, total resection of the tumor should be the goal of surgery. Mean follow-up period was 8.3 years and favorable seizure outcome was found to be 91.4%. Surgery decreased AED usage and mean number of AED significantly decreased. Children also benefited from surgery as adults. Surgical treatment of tumor-related epilepsy from temporal lobe controls seizures, and total removal should be the main goal of surgery as neuropsychological testing permit.

Seizure control after subtotal lesional resection

Reports on seizure outcomes following surgery for lesional epilepsy consistently cite extent of resection as a significant predictor of outcome. Unfortunately, gross-total resection is not technically feasible in all cases of medically refractory tumor-associated epilepsy. Here, the authors present the case of a 4-year-old girl whose epilepsy was medically controlled after 1-stage electrocorticography-guided subtotal resection (STR) of a large diffuse protoplasmic astrocytoma. They also review the modern literature on epilepsy associated with brain tumors. Outcomes are compared with those following surgical treatment of focal cortical dysplasia and vascular lesions. Gross-total lesional resection shows significant superiority across pathologies and anatomical regions. Despite a considerable number of STRs yielding seizure freedom, other favorable treatment factors have not been defined. Although gross-total lesional resection, if possible, is clearly superior, tailored surgery may still offer patients a significant opportunity for a good outcome. Treatment factors yielding successful seizure control following STR remain to be fully elucidated.

Seizure outcomes of lesionectomy in pediatric lesional epilepsy with brain tumor -- single institute experience

PURPOSE

To determine the clinical characteristics, surgical strategy, and outcome in pediatric lesional epilepsy patients younger than 5years of age undergoing surgery in a single institute.

METHOD

Retrospective data were collected and analyzed on patients younger than 5years of age who underwent lesionectomy for lesional epilepsy at single institute from January 2001 to August 2010. Fourteen pediatric lesional epilepsy patients were enrolled in this study. Engel classification was used to classify seizure outcome.

RESULTS

Median preoperative seizure period was 1month (range, 1-21). Median post-operative follow up period was 35months (range 13-84). Ten patients who underwent gross total resection of tumor showed Engel class Ia seizure outcome without any antiepileptic drug (AED). Subtotal resection was performed in four patients to avoid eloquent area injury. Two of these four patients with subtotal removal became seizure-free (Engel class Ia) without AED, while two were in Engel class Ib with AED medication. There was no significant surgical morbidity or mortality.

CONCLUSION

Lesionectomy in children younger than 5years of age is relatively safe and effective in controlling seizures. Short preoperative seizure periods and total removal of tumor might be associated with good outcome. Therefore, early and complete lesionectomy alone may help allow for seizure freedom and optimal brain development in pediatric patients.

Chronic epilepsy due to low grade temporal lobe tumors and due to hippocampal sclerosis: do they differ in post-surgical outcome?

Chronic seizures as a presenting feature of low grade temporal lobe gliomas and hippocampal sclerosis (HS) are reported to have similar outcomes although the prognostic indicators may not be the same. This study seeks to identify the variables that are associated with poor surgical outcome in both conditions. A retrospective analysis from our epilepsy data base was performed. All low-grade temporal lobe gliomas were selected and relevant variables were compared to the same variables in HS patients. There were 34 tumors (out of 233 cases of chronic temporal lobe epilepsy = 14.6 %) with a mean age of onset of 19 years, and the preoperative duration was 12.3 years. When compared to 120 HS patients both of these factors were significantly different (p < 0.001). Age at the time of surgery for tumors was 31.08 (p = 0.5). Tumors were left sided in 20 patients. In tumor cases amygdala resection was complete in 75 %, for hippocampus 24 % were complete and 39 % partial. Astrocytoma, ganglioglioma and oligodendroglioma constituted 80 % of tumor cases. Good outcome (Engel's Class I) was achieved in 88.2 % of tumor cases and 71 % of HS cases while poor outcome (Class III + IV) was seen in 5.9 and 16.7 % respectively. The follow up period for the two groups was not significantly different. In multivariate logistic regression analysis, the groups differed significantly in preoperative delay (between diagnosis and surgery) and in epilepsy outcome. Chronic temporal lobe epilepsy due to low-grade tumors had significantly better surgical outcome with considerably less preoperative delay. The age of onset of seizures was younger in HS patients but a delay in surgical treatment was significantly longer. Given that the diagnosis of treatment-resistant TLE secondary to HS can be established after two failed AED trials at optimal doses, shortening the interval between diagnosis and surgery may improve epilepsy outcome.

Seizure outcomes after temporal lobectomy in pediatric patients

Temporal lobe epilepsy (TLE) is the most common form of epilepsy in adults and is responsible for 15%-20% of epilepsy cases in children. Class I evidence strongly supports the use of temporal lobectomy for intractable TLE in adults, but fewer studies have examined seizure outcomes and predictors of seizure freedom after temporal lobectomy in pediatric patients. The authors performed a systematic review and meta-analysis of studies including 10 or more pediatric patients (age ≤ 19 years) published over the last 20 years examining seizure outcomes after temporal lobectomy for TLE. Thirty-six studies met their inclusion criteria. These 36 studies included 1318 pediatric patients with a mean age (± SEM) of 10.7 ± 0.3 years. Overall, seizure freedom (Engel Class I outcome) was achieved in 1002 cases (76%); 316 patients (24%) continued to have seizures (Engel Class II-IV outcome). All patients had at least 1 year of follow-up. Statistically significant predictors of seizure freedom after surgery included lesional epilepsy etiology (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.02-1.15), abnormal findings on preoperative MRI (OR 1.27, 95% CI 1.16-1.40), and lack of generalized seizures (OR 1.36, 95% CI 1.20-1.56). Among lesional epilepsy cases, there was a trend toward better outcome with gross-total lesionectomy than with subtotal resection. Approximately three-fourths of pediatric patients with TLE attain seizure freedom after temporal lobectomy. Favorable outcomes may be predicted by lesional epilepsy etiology, abnormal MRI, and lack of generalized seizures. Pediatric patients with medically refractory TLE should be referred to a comprehensive pediatric epilepsy center for surgical evaluation.

Seizure outcomes after resective surgery for extra-temporal lobe epilepsy in pediatric patients

While temporal lobe epilepsy (TLE) is the most common epilepsy syndrome in adults, seizures in children are more often extratemporal in origin. Extra-temporal lobe epilepsy (ETLE) in pediatric patients is often medically refractory, leading to significantly diminished quality of life. Seizure outcomes after resective surgery for pediatric ETLE vary tremendously in the literature, given diverse patient and epilepsy characteristics and small sample sizes. The authors performed a systematic review and meta-analysis of studies including 10 or more pediatric patients (age ≤ 19 years) published over the last 20 years examining seizure outcomes after resective surgery for ETLE, excluding hemispherectomy. Thirty-six studies were examined. These 36 studies included 1259 pediatric patients who underwent resective surgery for ETLE. Seizure freedom (Engel Class I outcome) was achieved in 704 (56%) of these 1259 patients postoperatively, and 555 patients (44%) continued to have seizures (Engel Class II-IV outcome). Shorter epilepsy duration (≤ 7 years, the median value in this study) was more predictive of seizure freedom than longer (> 7 years) seizure history (odds ratio [OR] 1.52, 95% confidence interval [CI] 1.07-2.14), suggesting that earlier intervention may be beneficial. Also, lesional epilepsy was associated with better seizure outcomes than nonlesional epilepsy (OR 1.34, 95% CI 1.19-1.49). Other predictors of seizure freedom included an absence of generalized seizures (OR 1.61, 95% CI 1.18-2.35) and localizing ictal electroencephalographic findings (OR 1.55, 95% CI 1.24-1.93). In conclusion, seizure outcomes after resective surgery for pediatric ETLE are less favorable than those associated with temporal lobectomy, but seizure freedom may be more common with earlier intervention and lesional epilepsy etiology. Children with continued debilitating seizures despite failure of multiple medication trials should be referred to a comprehensive pediatric epilepsy center for further medical and surgical evaluation.

Seizures as the clinical presenting symptom in children with brain tumors

This study summarizes our clinical and surgical experience with pediatric brain tumors that were initially presented with seizures. The records of 367 consecutive children, treated for brain tumors between the years 1996 and 2007, were retrospectively analyzed, focusing on the clinical manifestations, diagnostic gap, and postoperative seizure follow-up that lasted at least 2 years. Seizures, mainly focal, were the clinical manifestation of brain tumor in 57 of 367 children. Normal neurologic examination and electroencephalography (EEG) were in 77.8% and 37.5%, respectively. Diagnostic gap correlated with low-grade and temporal lobe tumors. Postoperative follow-up revealed freedom of seizure in 77.6%. Favorable seizure outcome correlated with low preoperative seizures frequency, preoperative response to antiepileptic drugs, and hemispheric tumor location. We conclude that response to antiepileptic drugs, generalized seizures, normal EEG, and normal neurologic examination should not exclude tumor etiology. Moreover, broader indications for imaging should be employed while evaluating a child with a seizure.

Extent of Surgical Resection Predicts Seizure Freedom in Low-Grade Temporal Lobe Brain Tumors

BACKGROUND:

Achieving seizure control in patients with low-grade temporal lobe gliomas or glioneuronal tumors remains highly underappreciated, because seizures are the most frequent presenting symptom and significantly impact patient quality-of-life.

OBJECTIVE:

To assess how the extent of temporal lobe resection influences seizure outcome.

METHODS:

We performed a quantitative, comprehensive systematic literature review of seizure control outcomes in 1181 patients with epilepsy across 41 studies after surgical resection of low-grade temporal lobe gliomas and glioneuronal tumors. We measured seizure-freedom rates after subtotal resection vs gross-total lesionectomy alone vs tailored resection, including gross-total lesionectomy with hippocampectomy and/or anterior temporal lobe corticectomy.

RESULTS:

Included studies were observational case series, and no randomized, controlled trials were identified. Although only 43% of patients were seizure-free after subtotal tumor resection, 79% of individuals were seizure-free after gross-total lesionectomy (OR = 5.00, 95% confidence interval [CI]: 3.33-7.14). Furthermore, tailored resection with hippocampectomy plus corticectomy conferred additional benefit over gross-total lesionectomy alone, with 87% of patients achieving seizure freedom (OR = 1.82, 95% CI: 1.23-2.70). Overall, extended resection with hippocampectomy and/or corticectomy over gross-total lesionectomy alone significantly predicted seizure freedom (OR = 1.18, 95% CI: 1.11-1.26). Age &lt;18 years and mesial temporal location also prognosticated favorable seizure outcome.

CONCLUSION:

Gross-total lesionectomy of low-grade temporal lobe tumors results in significantly improved seizure control over subtotal resection. Additional tailored resection including the hippocampus and/or adjacent cortex may further improve seizure control, suggesting dual pathology may sometimes allow continued seizures after lesional excision.

Factors associated with seizure freedom in the surgical resection of glioneuronal tumors

PURPOSE

Gangliogliomas (GGs) and dysembryoplastic neuroepithelial tumors (DNETs) are low-grade brain tumors of glioneuronal origin that commonly present with seizures. Achieving seizure control in patients with glioneuronal tumors remains underappreciated, as tumor-related epilepsy significantly affects patients' quality-of-life.

METHODS

We performed a quantitative and comprehensive systematic literature review of seizure outcomes after surgical resection of GGs and DNETs associated with seizures. We evaluated 910 patients from 39 studies, and stratified outcomes according to several potential prognostic variables.

KEY FINDINGS

Overall, 80% of patients were seizure-free after surgery (Engel class I), whereas 20% continued to have seizures (Engel class II-IV). We observed significantly higher rates of seizure-freedom in patients with ≤1 year duration of epilepsy compared to those with >1 year of seizures [odds ratio (OR) 9.48; 95% confidence interval (CI) 2.26-39.66], and with gross-total resection over subtotal lesionectomy (OR 5.34; 95% CI 3.61-7.89). In addition, the presence of secondarily generalized seizures preoperatively predicted a lower rate of seizure-freedom after surgery (OR 0.40; 95% CI 0.24-0.66). Outcomes did not differ significantly between adults and children, patients with temporal lobe versus extratemporal tumors, pathologic diagnosis of GG versus DNET, medically controlled versus refractory seizures, or with the use of electrocorticography (ECoG). Extended resection of temporal lobe tumors, with hippocampectomy and/or corticectomy, conferred additional benefit.

SIGNIFICANCE

These results suggest that early operative intervention and gross-total resection are critically important factors in achieving seizure-freedom, and thus improving quality-of-life, in patients with glioneuronal tumors causing epilepsy.

Pediatric temporal low-grade glial tumors: epilepsy outcome following resection in 48 children

PURPOSE

This paper summarizes our experience with surgical treatment of pediatric low-grade glial temporal lobe tumors focusing on the long-term outcome of seizures and identifying factors associated with seizure control and failure.

METHODS

We reviewed all medical records of pediatric patients that underwent temporal lobe surgery due to seizures at our institution between 1997 and 2009. Only patients with temporal lobe tumors were included in this series. The files were retrospectively reviewed for seizure history. All children had undergone pre- and postoperative evaluation, neurological examination, EEG, and MRI.

RESULTS

The cohort includes 48 children with mean follow-up time of 5.15 years (1-12 years). The mean age at surgery was 8.2 years (1-18.1) and the mean seizure duration until surgery was 2.6 years. All lesions in the cohort were low-grade tumors; pilocytic astrocytoma was the most common (41%). Eighty-three percent of the patients were classified as Engel class I following surgery. There was no correlation between Engel score and the preoperative epilepsy duration, age of seizure onset or type of seizures, and pathology. The surgical complication rate was 4.1% (2/48).

CONCLUSIONS

Surgical treatment for seizure control in children and adolescents with low-grade temporal tumors provides excellent long-term results.

Surgical management of glioneuronal tumors with drug-resistant epilepsy

In this review, we discuss the options for the surgical management of glioneuronal tumors (GNTs) associated with drug-resistant epilepsy, with an emphasis on the surgical issues involved in addressing the epileptogenic nature of these lesions. We briefly summarize the pathological hallmarks of these lesions in order to outline how these tumors contribute to seizure activity. Understanding the pathophysiology of these lesions is important in discussing the advantages and disadvantages of different surgical strategies. There have been a number of studies that have investigated the utility of different surgical approaches in improving seizure outcome, and we highlight some of these studies in order to shed light on surgical issues related to these tumors.

Surgery of children with frontal lobe lesional epilepsy: neuropsychological study

AIM OF THE STUDY

was to provide new data about the evolution of neuropsychological findings in patients with lesional frontal lobe epilepsy (FLE) operated on with lesion excision.

PATIENTS AND METHODS

Twelve patients with lesional FLE underwent full clinical examination including neurological, neuropsychological and developmental assessments, high-resolution magnetic resonance imaging (MRI), ictal and interictal prolonged EEG monitoring and evaluation of seizure semeiology before and after surgery. The mean follow-up duration was 2 years and 10 months (range=14 months-7 years). Another group of lesional temporal lobe epilepsy, matched for the age at surgery and side of surgery, was likewise studied in order to compare neuropsychological patterns and to try to find out specific features in frontal lobe epilepsy evolution.

RESULTS

All patients resulted seizure free at outcome except one belonging to Engel's class II. Before surgery general intelligence was similar in FLE as well as in TLE group. Executive functions and motor coordination were frequently affected in FLE whereas patients with TLE often presented with deficits in naming, visual memory and visuo-spatial attention. After surgery there was a frequent decline of IQ in FLE group together with a slight deterioration, especially of executive functions in some patients. An improvement of behaviour was often observed in both groups.

CONCLUSIONS

As already reported in literature, neuropsychological pre-surgical data confirms the involvement of attention and executive functions in lesional FLE. No significant neuropsychological improvement was produced by surgery that determined in some cases a slight decline of general intelligence and specific frontal abilities. Yet, generally behaviour improved and seizures were controlled.

Electrocorticography and seizure outcomes in children with lesional epilepsy

PURPOSE

The use of electrocorticographically (ECoG)-guided cortical resection in children with lesional epilepsy is controversial. Given the important developmental issues associated with recurrent childhood seizures, sustained seizure control is a key therapeutic goal. We therefore evaluated the effect of the decision to perform lesionectomy or ECoG-guided cortical resection on seizure outcome and surgical morbidity in the pediatric population.

METHODS

We retrospectively analyzed seizure outcomes in 67 patients between the ages of 3 months and 16 years who underwent surgery for lesional epilepsy at British Columbia Children's Hospital. Thirty-four patients underwent ECoG, and 33 patients had lesionectomy without ECoG.

RESULTS

One year post-operatively, 80% of patients who had ECoG-guided cortical resection or lesionectomy were seizure free. However, there was a trend toward improved seizure freedom in patients who had ECoG at most recent follow-up (79% patients with ECoG seizure free, vs. 61% with lesionectomy only; mean follow-up time 5.8 year, P=0.078). There was no increase in neurological morbidity in patients who had ECoG-guided cortical resection, and these patients were less likely to experience repeat epilepsy surgery.

CONCLUSIONS

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.

Extraventricular subependymal giant cell tumor in a child with tuberous sclerosis complex

Subependymal giant cell tumors (SGCTs) are observed in 5-20% of patients with tuberous sclerosis complex (TSC) but account for approximately 25% of neurological morbidity. The authors report the case of a 7-year-old girl with TSC and multiple cortical tubers who presented with worsening seizures in the context of the rapid growth of a cystic, calcified, extraventricular SGCT in the right frontal lobe, initially thought to represent a cortical tuber. The tumor and surrounding tubers were excised, and clinical seizures resolved. This is the first report of an extraventricular SGCT in a child with TSC outside the neonatal period.

Lesionectomy in the pediatric age

INTRODUCTION

Due to the development of electrophysiological recordings and the advancement in neuroimaging, which has allowed the identification of underlying focal abnormalities, in some patients with partial seizures, the surgical removal of such lesions has gained widespread recognition as a treatment modality for medically intractable epilepsy.

DISCUSSION

In patients having a well-defined lesion, a good correlation between clinical and electrophysiological features, suggesting a zone of seizures onset around (or even in) the lesion, is the best guarantee to achieve good seizure control by "lesionectomy". However, other factors correlate with the seizure outcome.

CONCLUSION

The persistency of seizures was found to be significantly associated with the completeness of the resection of the lesion and the preoperative duration of epilepsy, and, in some cases, the de novo brain damage induced by the surgical procedure itself. However, given the benefits of seizure control on the developing brain and the risk of secondary epileptogenesis, early surgery is recommended in children.

Application of neuronavigator coupled with an operative microscope and electrocorticography in epilepsy surgery

Application of neuronavigator coupled with an operative microscope and electrocorticography (ECoG) is a new trial for epilepsy surgery for achieving better seizure outcome and better efficiency for lesionectomy. We used a neuronavigator coupled with a microscope to delineate the magnetic resonance image-detected lesion for lesionectomy and used ECoG for evaluation of the epileptogenic foci. There were 46 patients with medically intractable partial seizures who underwent craniotomy for epilepsy surgery. Half of the patients had lesions at the temporal lobe and another half at the extratemporal lobe. Sixty-one percent of the patients were seizure-free (grade I) and 22% were nearly seizure-free (grade II). Overall, 83% of the patients had satisfactory seizure control. Complete lesion removal was successful in 37 patients (80%). For lesions with requiring complete removal, neuronavigator coupled with a microscope was 95% effective for lesionectomy. Class A of postresection ECoG had a higher rate of seizure-free outcome (92%) (P < .05). On the other hand, 93% of patients (26/28) with seizure-free outcome (grade I) needed complete lesion resection (P < .05). Lesions at the extratemporal lobe yielded a higher rate of seizure-free outcome (78.2%, 18/23) (P < .05). Application of neuronavigator and ECoG (additional cortical resection) is usually necessary for temporal lobe lesions. All patients with cavernous hemangioma were seizure-free. The complication rate in our study was 8.7%. Neuronavigator coupled with a microscope provides efficacy and safety to complete lesionectomy, which is a key point of seizure outcome. Intraoperative ECoG is valuable for evaluating the epileptogenic foci for epilepsy surgery especially for lesions at the temporal lobe.

Pediatric epilepsy surgery: lessons and challenges

Pediatric epilepsy surgery has come of age, from being considered as a last resort in medically refractory focal epilepsy, after failure of numerous antiepileptic drug trials spanning many years, to a preferred treatment option in carefully selected candidates. There have been certain key developments that have catalyzed this change. First, we are able to predict medical intractability earlier during the course of epilepsy. Second, improved understanding of how the maturing brain recovers from neurologic insults has led to earlier consideration of surgical intervention during a window of developmental plasticity. Finally, improved diagnostic and surgical capabilities now enable us to identify more candidates suitable for surgery. At the same time, as the surgical frontier has been rapidly pushed to new horizons, we have also unearthed new challenges. In this review, several pediatric epilepsy syndromes are discussed to highlight these important developments.

The spectrum of long-term epilepsy-associated tumors: long-term seizure and tumor outcome and neurosurgical aspects

PURPOSE

To describe the histologic spectrum and clinical characteristics of patients with neuroepithelial tumors and drug-resistant epilepsy and to analyze clinical data and treatment related to seizure outcome and survival.

METHODS

Data were analyzed from 207 consecutive patients with intractable epilepsy (aged 2-54 years), who between 1988 and 1999 had >or=50% resection of supratentorial, neuroepithelial tumors. Extent of resection was assessed on postoperative magnetic resonance imaging (MRI); seizure outcome was classified according to Engel's outcome scale; and follow-up data were prospectively updated.

RESULTS

Median follow-up was eight years (range, 2-14 years). Histologic examination revealed 154 classic epilepsy-associated tumors (ganglioglioma, dysembryoplastic neuroepithelial tumor, pleomorphic xanthoastrocytoma, and pilocytic astrocytomas) and 53 others (astrocytomas and oligodendrogliomas). Four World Health Organization (WHO) grade III tumors were found (astrocytoma, n = 3; ganglioglioma, n = 1). After surgery, 82% of the patients were seizure free (class I). The following factors were associated with improved seizure outcome: Short duration of epilepsy before surgery, single EEG focus, absence of additional hippocampal sclerosis or cortical dysplasia, transsylvian approach, other than astrocytomas, and complete tumor resection. After 5 years, only nine (4%) patients had tumor recurrence, four (2%) with malignant transformation and death. None of the four patients with anaplastic tumors died. Even patients with astrocytomas of WHO grade II or III showed 10-year recurrence of only 25% and 10-year survival of 90%.

CONCLUSIONS

Tumors associated with long-term epilepsy should be removed early for two different reasons: high rate of seizure freedom and rare but potential risk of malignant tumor progression. The unexpected long survival of these astrocytomas should be investigated by using immunohistochemistry and molecular biology.

Long-term neurological outcome of childhood brain tumors treated by surgery only

PURPOSE

To evaluate the pattern of neurological late effects in patients who have received surgery only for a brain tumor in childhood and to identify possible risk factors for neurological sequelae.

PATIENTS AND METHODS

The medical, histologic, and operative records were reviewed for 65 consecutive patients operated for a benign brain tumor from 1970 to 1997, and all patients were re-examined after a median length of follow-up of 10.7 years. Thirty-four patients had posterior fossa tumors, 22 patients had cerebral hemisphere tumors, and nine patients had midline tumors.

RESULTS

At the time of follow-up, 20 patients (31%) had no neurological deficits, 22 patients (34%) had minor deficits that did not interfere with their daily life activities, and 23 patients (35%) had moderate or severe deficits such as severe ataxia, spastic paresis, seriously reduced vision, or epilepsy with more than two seizures per year. Fourteen of the 31 patients (45%) registered with ataxia preoperatively had recovered fully. Six of seven patients had persistence of a pre- or postoperatively developed hemiparesis. Thirteen of 23 patients had persistence of cranial nerve deficits that developed second to surgery. Fifty-five percent of the 18 patients with seizures at diagnosis were seizure-free at follow-up. At follow-up both ataxia and hemiparesis were significantly more frequent among females (P =.02 and P =.03, respectively).

CONCLUSION

In patients who received operation as the only treatment for their brain tumor, there was a good chance of total or partial recovery of preoperative and postoperative neurological deficits, although only one third of the patients will have no long-term neurological deficits.

Frontal lobe tumoral epilepsy: clinical, neurophysiologic features and predictors of surgical outcome

PURPOSE

To review the clinical, neurophysiologic features and surgical outcomes in patients with frontal lobe tumors and chronic intractable seizures.

METHODS

Medical records of patients with intractable epilepsy who underwent resection or stereotactic biopsy of frontal lobe tumor (confirmed by surgical pathology) seen between 1985 and 1999 at Yale University School of Medicine Epilepsy Center were reviewed for age at diagnosis, age at onset of seizures, delay between seizure onset and tumor diagnosis, types and frequencies of seizures, EEG results, use of anticonvulsants, extent of surgery, pathological diagnosis, and tumor recurrence.

RESULTS

Thirty-seven patients were included. Mean age at seizure onset was 31.6 years, and at tumor diagnosis was 36.2 years. Mean duration between onset of seizures and tumor diagnosis was 6.1 years. Seventeen patients had auras. Seizure frequency averaged 7.6 seizures per week, with 58% of patients having more than one seizure type. All patients used anticonvulsants, with 90% eventually using polytherapy. All patients eventually underwent at least one surgical procedure. Only 13 (35.1%) patients were class I. Twelve (32.4%) patients were class II, seven (18.9%) class III, and five (13.5%) class IV. No statistically significant differences were seen between good and poor long-term seizure outcome in relation to specific tumor pathology, seizure types, or type of resection.

CONCLUSIONS

Long-term surgical outcomes in tumoral frontal lobe epilepsy are more favorable than those in nontumoral intractable frontal lobe epilepsy (65% class I or II) and less favorable than those in other tumoral epilepsy (overall, 70% class I). Frontal location of intracranial neoplasm may predict a less favorable long-term epilepsy prognosis than tumoral epilepsy in general, an observation for which several explanations are proposed.

MEG predicts epileptic zone in lesional extrahippocampal epilepsy: 12 pediatric surgery cases

PURPOSE

To discover whether the spatial distribution of spike sources determined by magnetoencephalography (MEG) provides reliable information for planning surgery and predicting outcomes in pediatric patients with lesional extrahippocampal epilepsy.

METHODS

We retrospectively studied 12 children with extrahippocampal epilepsy secondary to cortical dysplasia (CD), tumor, or porencephalic cyst. We compared interictal MEG spike source locations and somatosensory evoked fields derived from equivalent-current dipole modeling with intraoperative or extraoperative electrocorticography (ECoG).

RESULTS

MEG spike sources were found in proximity to the lesion in all patients and extended from lesions in five patients with CD. Marginal spike sources were noted in three patients with tumors, one patient with a cyst, and one with CD, and extramarginal sources in three patients with tumors. Three patients with tumors underwent lesionectomy only; two had further cortical excisions. One patient with CD underwent lesionectomy only, three had lesionectomy and cortical excisions, and two had lesionectomy and multiple subpial transection. Asymmetric MEG spike sources correlated with ECoG findings in all patients. Residual epileptiform discharges on postexcisional ECoG corresponded to spike sources in three patients with tumors and one patient with a cyst. Eleven patients have been seizure free for 1-6 years (mean, 4 years). One patient had residual seizures after incomplete excision of right temporal CD.

CONCLUSIONS

MEG delineated asymmetric epileptogenicity surrounding lesions and the eloquent cortex. Complete tumor resection produced favorable outcomes despite residual postexcisional ECoG spikes and extramarginal MEG spike sources. CD characterized by clusters of MEG spike sources within and extending from lesions seen on magnetic resonance imaging (MRI) should be removed to prevent seizures.

[Functional neurosurgery for epilepsy]

Introduced at the end of the last century, epilepsy surgery is indicated in patients with intractable partial seizures and based on the resection of the epileptogenic cerebral tissue from which ictal discharges originate. Palliative procedures include seizure spread pathways interruption (callosotomy, multiple subpial transections) and chronic stimulation of the vagus nerve. Complete preoperative investigations including seizure observation, clinical tests, video-EEG, MRI and functional MRI, and PET-scan are performed in order to identify the epileptogenic zone. In difficult cases, invasive seizure monitoring through depth electrode implantation (SEEG) is performed. Resections for temporal lobe seizures are associated with favorable outcome: 60 to 90% of patients will be seizure-free after surgery. A less favorable outcome is observed after extra-temporal resections: 40 to 60% seizure-free patients. A better outcome is observed after surgery for epilepsy associated with an image-defined lesion, most often a tumor, rather than for cryptogenic epilepsy. Tumors associated with chronic partial epilepsy are indolent, most of them are dysembryoplastic neuroepithelial tumors (DNET). Outcome after palliative procedures are more variable, depending on the etiology of epilepsy.

Complications and results of subdural grid electrode implantation in epilepsy surgery

BACKGROUND

We assessed the risk of delayed subdural hematoma and other complications associated with subdural grid implantation.

METHODS

Forty-nine patients underwent subdural grid implantation with/without subdural strips or depth electrodes from January 1994 to August 1998. To identify the risk associated with subdural grid implantation, a retrospective review of all patients' medical records and radiological studies was performed.

RESULTS

The major complications of 50 subdural grid electrode implantations were as follows: four cases (7.8%) of delayed subdural hematoma at the site of the subdural grid, requiring emergency operation; two cases (3.9%) of infection; one case (2.0%) of epidural hematoma; and one case (2.0%) of brain swelling. After subdural hematoma removal, the electrodes were left in place. CCTV monitoring and cortical stimulation studies were continued thereafter. No delayed subdural hematoma has occurred since routine placement of subdural drains was begun.

CONCLUSIONS

In our experience the worst complication of subdural grid implantation has been delayed subdural hematoma. Placement of subdural drains and close observation may be helpful to prevent this serious complication.