Intracranial EEG in temporal lobe epilepsy.

Intracranial EEG monitoring before epilepsy surgery, while becoming less commonly performed in patients with unilateral mesial temporal lobe epilepsy, is still widely used when bilateral independent temporal lobe seizures are suspected or when extratemporal foci cannot be ruled out by noninvasive means. Additionally, many epilepsy centers are reporting excellent surgical outcome in patients with neocortical temporal lobe epilepsy, when resections are guided by intracranial EEG studies. This article reviews the indications, technical aspects, risks, and interpretation of intracranial EEG in patients with temporal lobe seizures. It also considers intracranial EEG features predictive of surgical outcome.     

Outcomes of epilepsy surgery in adults and children

Surgery is widely accepted as an effective therapy for selected individuals with medically refractory epilepsy. Numerous studies in the past 20 years have reported seizure freedom for at least 1 year in 53-84% of patients after anteromesial temporal lobe resections for mesial temporal lobe sclerosis, in 66-100% of patients with dual pathology, in 36-76% of patients with localised neocortical epilepsy, and in 43-79% of patients after hemispherectomies. Reported rates for non-resective surgery have been less impressive in terms of seizure freedom; however, the benefit is more apparent when reported in terms of significant seizure reductions. In this Review, we consider the outcomes of surgery in adults and children with epilepsy and review studies of neurological and cognitive sequelae, psychiatric and behavioural outcomes, and overall health-related quality of life.     

How effective is surgery to cure seizures in drug-resistant temporal lobe epilepsy?

It is well recognized that two-thirds of patients with drug-resistant temporal lobe epilepsy will be free of disabling seizures with continued medical treatment after temporal resection. Seizure recurrence has been noted during a five-year follow-up in approximately one-third of these seizure-free patients mostly but not exclusively following planned complete discontinuation of antiepileptic drugs (AEDs). This leaves one-third of patients without disabling seizures and without AEDs several years after surgery. Despite improvements in seizure frequency or severity, seizures persist in another third of patients undergoing surgery. Although cure (five years without any seizures and off AEDs) is the ultimate aim of epilepsy surgery, the percentage of patients cured by surgery cannot be well defined at the moment. We need a long-term randomized controlled trial on AED discontinuation in seizure-free patients followed by long-term open extension to determine if only one in three adult patients with drug-resistant temporal lobe epilepsy is cured by surgical intervention.     

Preference-based quality-of-life measures for neocortical epilepsy surgery

Critical to decision analysis studies are measures of outcome utilities. In epilepsy surgery the benefit versus risk ratio is of particular interest in neocortical resections. Using the standard gamble, we measured preferences of 30 epilepsy patients for 10 outcome states specific to neocortical epilepsy surgery. Although considered preliminary, the findings suggest that the value of being seizure-free may be greater than that of continued disabling seizures, even if some deficits typical of "eloquent" cortex injury are incurred with surgery. Seizure freedom achieved with polytherapy medical management may be less desirable than that achieved with surgery and monotherapy.     

The localizing value of ictal EEG in focal epilepsy.

OBJECTIVE: To investigate the lateralization and localization of ictal EEG in focal epilepsy. METHODS: A total of 486 ictal EEG of 72 patients with focal epilepsy arising from the mesial temporal, neocortical temporal, mesial frontal, dorsolateral frontal, parietal, and occipital regions were analyzed. RESULTS: Surface ictal EEG was adequately localized in 72% of cases, more often in temporal than extratemporal epilepsy. Localized ictal onsets were seen in 57% of seizures and were most common in mesial temporal lobe epilepsy (MTLE), lateral frontal lobe epilepsy (LFLE), and parietal lobe epilepsy, whereas lateralized onsets predominated in neocortical temporal lobe epilepsy and generalized onsets in mesial frontal lobe epilepsy (MFLE) and occipital lobe epilepsy. Approximately two-thirds of seizures were localized, 22% generalized, 4% lateralized, and 6% mislocalized/lateralized. False localization/lateralization occurred in 28% of occipital and 16% of parietal seizures. Rhythmic temporal theta at ictal onset was seen exclusively in temporal lobe seizures, whereas localized repetitive epileptiform activity was highly predictive of LFLE. Seizures arising from the lateral convexity and mesial regions were differentiated by a high incidence of repetitive epileptiform activity at ictal onset in the former and rhythmic theta activity in the latter. CONCLUSIONS: With the exception of mesial frontal lobe epilepsy, ictal recordings are very useful in the localization/lateralization of focal seizures. Some patterns are highly accurate in localizing the epileptogenic lobe. One limitation of ictal EEG is the potential for false localization/lateralization in occipital and parietal lobe epilepsies.     

Parenchymal lesions in pharmacoresistant temporal lobe epilepsy: dual and multiple pathology

OBJECTIVES: Dual pathology is reported in 5-30% of temporal lobe resections performed in pharmacoresistant epilepsy. Dual pathology may be of importance for surgical planning and also for the understanding of the pathogenesis of epilepsy. We describe the frequency of dual or multiple pathology, i.e. more than one histopathological diagnosis, in adults with temporal lobe resections. MATERIAL AND METHODS: Surgical specimens from 33 consecutive patients with resections including mesial as well as neocortical temporal structures were reviewed. All histopathological findings were recorded. Post-mortem specimens from 11 control subjects were also reviewed. RESULTS: Dual or multiple pathology was found in almost half of the epilepsy patients (48%). Hippocampal sclerosis was found in 25 patients (76%), malformations of cortical development in 15 (46%), of which 12 (36%) were microdysgenesis, and low-grade tumours in seven (21%). Apart from mild gliosis, there were no histopathological changes in the control specimens. CONCLUSION: Dual or multiple pathology was a common finding in this group of adults with temporal lobe resections. In order to increase our understanding of how aetiological factors may combine in the development of seizures, we consider it relevant and important to report all histopathological findings in epilepsy surgery series.     

Epilepsy surgery outcomes in temporal lobe epilepsy with a normal MRI

Purpose:   To determine the long-term efficacy of anterior temporal lobectomy for medically refractory temporal lobe epilepsy in patients with nonlesional magnetic resonance imaging (MRI).
Methods:   We identified a retrospective cohort of 44 patients with a nonlesional modern "seizure protocol" MRI who underwent anterior temporal lobectomy for treatment of medically refractory partial epilepsy. Postoperative seizure freedom was determined by Kaplan-Meyer survival analysis. Noninvasive preoperative diagnostic factors potentially associated with excellent surgical outcome were examined by univariate analysis in the 40 patients with follow-up of >1 year.
Results:   Engel class I outcomes (free of disabling seizures) were observed in 60% (24 of 40) patients. Preoperative factors associated with Engel class I outcome were: (1) absence of contralateral or extratemporal interictal epileptiform discharges, (2) subtraction ictal single photon emission computed tomography (SPECT) Coregistered to MRI (SISCOM) abnormality localized to the resection site, and (3) subtle nonspecific MRI findings in the mesial temporal lobe concordant to the resection.
Discussion:   In carefully selected patients with temporal lobe epilepsy and a nonlesional MRI, anterior temporal lobectomy can often render patients free of disabling seizures. This favorable rate of surgical success is likely due to the detection of concordant abnormalities that indicate unilateral temporal lobe epilepsy in patients with nonlesional MRI.     

Outcome and life prospects after surgical management of medically intractable epilepsy in patients under 18 years of age

A retrospective analysis of seizure outcome and quality of life assessment was done in 64 patients under 18 years of age with medically refractory epilepsy who underwent 64 primary and 16 repeat operative procedures in an attempt to control their epilepsy. At least 2 years' follow-up data were available for each patient. Operative procedures were 44 temporal lobe resections; 16 extratemporal resections; and 4 hemispherectomies. Effective control of previously intractable seizures was obtained in most patients: 55%, 11%, and 17% achieved Engel class I, II, and III status, respectively. Successful seizure control was thus obtained in 83%, while 17% (Engel class IV) failed to improve significantly after operation. Quality-of-life measures parallelled the improvements in seizures control, being highest in Engel I, outcome group and lowest in Engel IV outcome group. In appropriately selected pediatric and adolescent patients with medical refractory epilepsy, surgical management can offer a safe and effective adjunct to medication. Received: 25 March 1997     

Utilization of multichannel magnetoencephalography in the guidance of ablative seizure surgery

Magnetoencephalography (MEG) was used to evaluate 50 seizure surgery candidates. Interictal spikes were recorded in 42 cases. Of 20 cases with other data suggesting a convexity (lateral neocortical) focus, MEG spikes were recorded from 19. In 17, MEG and electrographic data were localized to the same region. Invasive studies were or could have been avoided in 11 cases based on MEG and other noninvasive data. MEG spike data were present in 14 of 18 cases with anteromesial temporal foci, being localized to the same lobe as electrographic data in 11. MEG was not of value in surgical planning of cases with orbitofrontal foci, or depth nonlocalized seizures. Twenty-seven patients with MEG epileptiform data have had postoperative follow-up. Fourteen of 19 with electrographic and MEG data localized to the same region are seizure-free. Four of eight with spatial discordance of MEG and electrographic data are seizure-free. Preliminary conclusions are as follows: When MEG and electrographic data are localized to the same region, seizure-free surgical outcome is more likely. In convexity cases with MEG and noninvasive electrographic data localized to the same region, preoperative invasive studies may be unnecessary.     

Neuronal Disconnection for the Surgical Treatment of Pediatric Epilepsy

Summary: The surgical methods and results of disconnective surgery for pediatric epilepsy were retrospectively analyzed. The techniques of neuronal disconnection included multiple subpial resection (MST), corpus callosotomy, and functional hemisphercctomy by disconnection. Of 158 total pediatric operations, disconnective techniques were employed in more than 60% of the cases. MST was applied when the epileptic focus was located in unresectable cortices such as speech or motor areas. MST was also instrumental when the epileptogenic zone was extensive and was widely disseminated, as is often observed in cases of neocortical epilepsy. Of 25 patients who underwent MST, surgical outcomes after > 1 year follow-up showed Engel Class I or II in 10 cases, Class III in 12, and Class IV in 3. No mortality or morbidity was encountered during surgery or postoperatively. Corpus callosotomy was applied to cases of disabling generalized seizures and showed a marked effect in alleviating potentially injurious drop attacks. Of 34 patients with drop attacks, 29 became free from this type of seizure, 4 had infrequent attacks, and only 1 showed no beneficial effect. Postoperative improvement of cognition and speech was recognized in 77% of the cases. We developed a new method of functional hemispherectomy by fiber disconnection and applied this less invasive technique to 23 cases of hemispheric lesions. Of the 17 cases with > 1 year follow-up, 13 were in Class I or II, and 3 in Class III, and 2 in Class IV. Development partially normalized in infants with good seizure outcomes.     

Musicogenic seizures can arise from multiple temporal lobe foci: intracranial EEG analyses of three patients

PURPOSE: To determine the ictal-onset zone of musicogenic seizures by using intracranial EEG monitoring. METHODS: Musicogenic seizures in three patients with medically intractable musicogenic epilepsy were first localized by using noninvasive methods including, in one patient, ictal magnetoencephalography (MEG) and magnetic resonance spectroscopy (MRS). The ictal-onset zones in these patients were then further localized using by intracranial EEG monitoring, and the outcomes of the two patients who underwent epilepsy surgery were determined. RESULTS: Patient 1's musicogenic seizures localized to the right lateral temporal lobe, patient 2's originated in the right mesial temporal lobe, and patient 3's arose independently from both mesial temporal lobes. Patients 1 and 2 underwent resective epilepsy surgery and are seizure free (Engel class I). CONCLUSIONS: Musicogenic epilepsy is a heterogeneous syndrome with seizures that can arise from multiple temporal lobe foci. Patients with medically intractable musicogenic epilepsy and with unilateral ictal onset zones may be considered candidates for resective epilepsy surgery.     

The chance of cure following surgery for drug-resistant temporal lobe epilepsy. What do we know and do we need to revise our expectations?

Although surgery is often seen as a curative treatment for patients with drug-resistant temporal lobe epilepsy, little information is available how many cases can be considered cured after surgery, i.e. are seizure-free for several years without taking antiepileptic drugs (AEDs). In our review, 13 retrospective and five prospective clinical observations published since 1980 provided data on long-term seizure control off AEDs in a total of 1658 patients. No randomized studies were found. Following temporal lobe surgery, approximately one in four adult patients and approximately one in three children or adolescents can currently shown to be seizure-free for 5 years without AEDs (25%, mean of eight studies in adults, 95% CI: 21–30%, and 31%, mean of three studies in children, 95% CI: 20–41%). The rate of seizure control off AEDs seemed to be stable after 2 years of follow-up. However, as 55% of patients free of disabling seizures preferred not to discontinue their medication completely as late as 5 years after surgery, it is impossible to know if they are cured or not. No features predictive of surgical cure were detected except for better cure outcome in children versus adults with hippocampal sclerosis and in patients with typical versus atypical Ammonshorn's sclerosis or tumor in one small study each. In conclusion, the available evidence on seizure outcome off AEDs after temporal lobe surgery is based on non-randomized studies and, in part, data were collected retrospectively. A randomized controlled trial is needed to determine if, in fact only one in three to four patients with temporal lobe epilepsy undergoing surgery can be considered cured.     

From lateral to mesial: the quest for a surgical cure for temporal lobe epilepsy

PURPOSE: A gap of more than a hundred years occurred between the first accounts of mesial temporal sclerosis and recognition of its role in the pathogenesis of psychomotor seizures. This paper reviews how the understanding and surgical treatment of temporal lobe epilepsy developed, particularly from the work of Penfield, Jasper, and their associates at the Montreal Neurological Institute (MNI). METHODS: Publications on EEG and surgery for temporal lobe seizures from 1935 to 1953 were reviewed and charts of selected patients operated on at the MNI in the same period were examined. Attention was focused on the evolution of surgical techniques for temporal lobe epilepsy. RESULTS: In the late 1930s, some EEG findings suggested deep-lying disturbances originating in the temporal lobe. However, it took another two decades before the correlation of clinical, neurophysiological, and anatomical findings provided evidence for the involvement of the mesial structures in psychomotor or temporal lobe seizures. From 1949 and onward, Penfield and his associates applied this evidence to extend the surgical resections to include the uncus and the hippocampus. CONCLUSION: The collaborative work of a team led by Penfield and Jasper at the MNI helped to define the role of neurophysiological studies in epilepsy surgery. As a result, the importance of removing the mesial structures in order to obtain better seizure control in patients with temporal lobe epilepsy became firmly established.     

Neurophysiologic and neuroradiologic features of intractable epilepsy after traumatic brain injury in adults

BACKGROUND: There is controversy regarding the precise mechanism by which epilepsy results after traumatic brain injury (TBI). Previous reports have suggested that mesial temporal lobe epilepsy may result from TBI only in young children, while neocortical epilepsy arises from TBI in later life. These conclusions were based on surgical series and may be biased because of patient selection. OBJECTIVE: To determine the frequency of mesial temporal lobe as opposed to neocortical epilepsy in patients with intractable epilepsy resulting from TBI after the age of 10 years. PATIENTS AND METHODS: We identified 23 patients with intractable epilepsy who had TBI after the age of 10 years, preceding the onset of epilepsy. Patients were studied by simultaneous videotape and scalp electroencephalographic recording of typical seizures; magnetic resonance imaging; neuropsychologic studies; and, when appropriate, intracarotid amobarbital testing. Two patients underwent anterior temporal lobectomies. RESULTS: Of the 23 patients, 8 (35%) had mesial temporal lobe epilepsy, based on the finding of hippocampal sclerosis on a magnetic resonance imaging scan, consistent interictal and ictal electroencephalographic recordings, evidence of temporal lobe dysfunction on neuropsychologic testing, and characteristic seizure semiology. Two of these patients underwent anterior temporal lobectomies with clinical benefit, and hippocampal sclerosis was confirmed pathologically. In 2 cases, patients were not treated surgically because of bilateral temporal lobe dysfunction noted on intracarotid amobarbital testing. Eleven patients had neocortical epilepsy; 1 had primary generalized epilepsy; and, in 3, the site of seizure onset was not localized. CONCLUSIONS: Mesial temporal lobe epilepsy can result from TBI in adolescents and adults as well as in children, and can often be bilateral and associated with multifocal injury. This information may be useful in developing prophylactic therapy for posttraumatic epilepsy.     

Pediatric epilepsy surgery at the University of Alberta: 1988-2000

Epilepsy surgery is considered a treatment option for patients with intractable seizures. Relatively few studies of efficacy, safety, and long-term outcome are available for the pediatric age group. This study describes a 12-year experience with pediatric epilepsy surgery at the University of Alberta. Records of pediatric epilepsy surgery patients admitted to the Comprehensive Epilepsy Program at the University of Alberta between 1988 and 2000 were reviewed. All patients received preoperative and postoperative clinical evaluation, seizure charts, testing of drug levels, electroencephalogram, computed tomography/magnetic resonance imaging, neuropsychologic testing, and long-term video electroencephalogram monitoring. The patients were reassessed after surgery at 6 weeks, 6 months, and 1 year and then yearly. The duration of follow-up was 1 year to 12 years. Forty-two patients underwent temporal lobectomies; 35, extratemporal resection. The age at surgery ranged from 6 months to 16 years. Thirty-two (76%) of temporal lobe patients became seizure-free (Engel Class I) vs 24 (68%) for the extratemporal group (Engel Class I). One patient (2%) in the temporal group had an Engel Class II outcome and one patient (3%) in the extratemporal group had the same Engel Class II outcome. Three patients (4%) manifested postoperative complications, and there were no deaths. Patients reported improvement in cognitive abilities, behavior, and quality of life after the surgery. Epilepsy surgery in children is effective and safe. Many children are seizure-free after the operation and remain so, although the results of temporal lobectomy are better than for extratemporal resections. There are few complications, and children often have an improved quality of life.     

Perisylvian vulnerability to postencephalitic epilepsy

ObjectivePostencephalitic epilepsy is often resistant to antiseizure medications, leading to evaluation for epilepsy surgery. Characterizing its localization carries implications for optimal surgical approach. We aimed to determine whether a prior history of encephalitis is associated with specific epileptogenic networks among patients with drug resistant epilepsy undergoing stereotactic EEG (SEEG).MethodsWe conducted a retrospective cohort study of drug resistant epilepsy, with and without a prior history of encephalitis. We analyzed SEEG recordings to identify patterns of seizure onset and organization. Seventeen patients with a history of encephalitis (of infectious etiology in two subjects) were identified from a database of patients undergoing SEEG and were compared to seventeen drug-resistant epilepsy controls without a history of encephalitis matched for confounding variables including pre-implantation hypotheses, epilepsy duration, age, and sex.ResultsIndependent bilateral seizures were noted in 65% of the postencephalitic epilepsy cohort. We identified four SEEG-ictal patterns in patients with a prior history of encephalitis: (1) anteromesial temporal onset (24%), (2) anteromesial temporal onset with early spread to the perisylvian region (29%), (3) perisylvian (59%) and (4) synchronized anteromesial temporal and perisylvian (29%) onsets. Patterns 3 and 4, with perisylvian involvement at onset, were unique to the encephalitis group (p = 0.0003 and 0.04 respectively) and exhibited a “patchwork” organization. None of the encephalitis patients vs 5/7 matched controls had Engel I outcome (p = 0.0048).ConclusionsPostencephalitic epilepsies involve anteromesial temporal and perisylvian networks, often in a bilateral independent manner. Unique ictal patterns involving the perisylvian regions was identified in the encephalitis group, but not in the matched control group. Significance: These findings may reflect a selective vulnerability of the perisylvian regions to epilepsy resulting from encephalitis, significantly mitigating the chances of success with SEEG-guided temporal resections.     

24-hour rhythmicity of seizures in refractory focal epilepsy

The occurrence of seizures in specific types of epilepsies can follow a 24-hour nonuniform or nonrandom pattern. We described the 24-hour pattern of clinical seizures in patients with focal refractory epilepsy who underwent video-electroencephalography monitoring. Only patients who were candidates for epilepsy surgery with an unequivocal seizure focus were included in the study. A total of 544 seizures from 123 consecutive patients were analyzed. Specific time of seizures were distributed along 3- or 4-hour time blocks or bins throughout the 24-hour period. The mean age of the subjects was 37.7 years, with standard deviation of 11.5 years, median of 37. The majority were females (70/56%). The majority of patients had a seizure focus located in the mesial temporal lobe (102/83%) and in the neocortical temporal lobe (13/11%). The remaining patients had a seizure focus located in the extratemporal lobe (8/6%). The most common etiology was mesial temporal sclerosis (86/69.9%). Nonuniform seizure distribution was observed in seizures arising from the temporal lobe (mesial temporal lobe and neocortical temporal lobe), with two peaks found in both 3- and 4-hour bins: 10:00–13:00/16:00–19:00 and 08:00–12:00/16:00–20:00 respectively (p = 0.004). No specific 24-hour pattern was identified in seizures from extratemporal location. The 24-hour rhythmicity of seizure distribution is recognized in certain types of epilepsy, but studies on the topic are scarce. Their replication and validation is therefore needed. Our study confirms the bimodal pattern of temporal lobe epilepsy independently of the nature of the lesion. However, peak times differ between different studies, suggesting that the ambient, rhythmic exogenous factors or environmental/social zeitgebers, may modulate the 24-hour rhythmicity of seizures. Characterization of these 24-hour patterns of seizure occurrence can influence diagnosis and treatment in selected types of epilepsy, such as the case of temporal lobe epilepsy, the most common drug-resistant epilepsy.     

Beyond Pharmacotherapy: Surgical Management

Summary:  Purpose: To review the recent advances in the field of temporal lobe epilepsy (TLE) surgery.
Results: TLE surgery has recently demonstrated a highly significant superiority over optimal medical therapy in a randomized trial. Accordingly, a median rate of 70% of class I outcome (patients free of disabling seizures postoperatively) has emerged from the pooling of all data published since the early 1990s. In addition, successful TLE surgery appears likely to reduce the risk of seizure-related death. However, it remains largely underused and overly delayed, partly because of the legitimate fears of possible surgical complications, such as verbal memory deficits or failure to control seizures. Reasons for surgical failures are not completely understood, and include bitemporal, pseudotemporal, and temporal-plus epilepsies, as well as insufficient resection of the mesial temporal structures. Developing techniques such as intraoperative MRI, gamma-knife radiosurgery, and various types of cranial nerves or intracerebral chronic stimulation have the potential to alleviate part of the limitations of TLE surgery.
Conclusions: The overall benefit of surgical treatment in patients with drug-resistant TLE should encourage a more frequent and earlier referral of such patients to epilepsy surgery centers. Important progress toward higher rates of seizure-free outcome and lower morbidity remains to be made and may be obtained by taking advantage of the new available technologies.     

The impact of temporal lobe surgery on cure and mortality of drug-resistant epilepsy: summary of a workshop

The Third International Spring Epilepsy Research Conference took place in Georgetown, Cayman Islands from April 26 to May 3, 2003. One workshop discussed the impact of epilepsy surgery on seizure outcome and mortality of antiepileptic drug (AED)-resistant temporal lobe epilepsy. This article summarizes the information presented at this workshop. Although two-thirds of adult patients undergoing epilepsy surgery become seizure-free with continued AED treatment, current clinical experience shows that seizure recurrence occurs in one-third of patients when AEDs are withdrawn under medical supervision. Additional seizure recurrence occurring after AED taper, poor drug compliance and even while patients continue on AEDs after surgery leave only approximately one-third of patients cured after temporal lobe resection. Mostly because so many patients prefer to stay on AEDs although they are free of disabling seizures after surgery, a randomised controlled trial of AED discontinuation is needed to determine if in fact only one-third of patients are cured after surgery. Based on the functional anatomy of temporal lobe surgery two hypotheses are presented why only a minority of patients are cured after surgery. The type and the prognostic significance of seizures after surgery is discussed. Recent studies have suggested that successful temporal lobe surgery may be able to normalize the increased standard mortality ratio (SMR) of drug-resistant temporal lobe epilepsy. However, pre-existing differences in SMR between those cured and those not cured by temporal lobe surgery and other unresolved methodological issues make it difficult at present to fully evaluate the impact of surgery on mortality. Future studies are thus warranted to specifically address the impact of temporal lobe surgery on cure and mortality.     

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.